Amanda Knox: post mortem

post by gwern · 2011-10-20T16:10:07.553Z · LW · GW · Legacy · 484 comments

Contents

  2 Probabilities
    Outliers
None
484 comments

Continuing my interest in tracking real-world predictions, I notice that the recent acquittal of Knox & Sollecito offers an interesting opportunity - specifically, many LessWrongers gave probabilities for guilt back in 2009 in komponisto’s 2 articles:

Both were interesting exercises, and it’s time to do a followup. Specifically, there are at least 3 new pieces of evidence to consider:

  1. the failure of any damning or especially relevant evidence to surface in the ~2 years since (see also: the hope function)
  2. the independent experts’ report on the DNA evidence
  3. the freeing of Knox & Sollecito, and continued imprisonment of Rudy Guede (with reduced sentence)

Point 2 particularly struck me (the press attributes much of the acquittal to the expert report, an acquittal I had not expected to succeed), but other people may find the other 2 points or unmentioned news more weighty.

2 Probabilities

I was curious how the consensus has changed, and so, in some spare time, I summoned all the Conscientiousness I could and compiled the following list of 54 entries based on those 2 articles’ comments (sometimes inferring specific probabilities and possibly missing probabilities given in hidden subthreads), where people listed probabilities for Knox’s guilt, Sollecito’s guilt, and Guede’s guilt:

Knox Sollecito Guede LWer
.20 .20 .70 badger
.05 .10 .90 mattnewport
.20 .25 .90 AngryParsley
.05 .05 .95 tut
.05 .05 .95 bentarm
.85 .60 .20 bgrah449
.01 .01 .99 kodos96
.01 .01 .99 Daniel_Burfoot
.40 .40 .90 nerzhin
.45 .45 .60 Matt_Simpson
.33 .33 .90 Cyan
.50 .50 .95 jimmy
.05 .05 .99 Psychohistorian
.40 .40 .90 Threads
.50 .50 .80 Morendil
.15 Eliezer_Yudkowsky
.20 .35 .98 LauraABJ
.10 .10 .90 curious
.20 .20 .96 jpet
.06 .06 .70 saliency
.80 .60 .95 Mario
.20 .20 .95 Yvain
.70 Shalmanese
.05 .05 .95 gelisam
.05 .05 .90 Mononofu
.90 .90 .90 lordweiner27 (changed mind)
.50 .50 .99 GreenRoot
.99 .99 .99 dilaudid
.13 .15 .97 Jack
.05 .05 .90 wedrifid
.01 .01 .90 Nanani
.35 .35 .95 imaxwell
.01 .01 .99 jenmarie
.25 .25 .75 Jawaka
.41 .38 .99 magfrump
.40 .20 .60 gwern
.08 .10 .95 loqi
.25 .25 .50 JamesAndrix
.90 .85 .99 Unknowns
.35 .35 .90 Sebastian_Hagen
.90 .90 .99 brazil84
.30 .30 .40 ChrisHibbert
.02 .02 .98 wnoise
.50 .40 .90 John_Maxwell_IV
.10 .10 k3nt
.01 .01 .99 Sinai
.00 .00 1.0 KayPea
.00 .00 .60 MerleRideout
.15 .10 .80 TheRev
.01 .01 .99 komponisto
.30 pete22
.01 SforSingularity
.00 .00 .90 AnnaGilmour
.05 .05 .95 Seth_Goldin
.60 .60 .95 bigjeff5

It’s interesting how many people assign a high-probability to Knox being guilty; I had remembered LW as being a hive of Amanda fans, but either I’m succumbing to hindsight bias or people updated significantly after those articles. (For example, Eliezer says .15 is too high, but doesn’t seem otherwise especially convinced; and later one reads in Methods of Rationality that "[Hagrid] is the most blatantly innocent bystander to be convicted by the magical British legal system since Grindelwald's Confunding of Neville Chamberlain was pinned on Amanda Knox.")

EDIT: Jack graphed the probability against karma:

2.1 Outliers

If we look just at >41% (chosen to keep contacts manageable), we find 12 entries out of 54:

Knox Sollecito Guede LWer
.45 .45 .60 Matt_Simpson
.50 .40 .90 John_Maxwell_IV
.50 .50 .80 Morendil
.50 .50 .95 jimmy
.50 .50 .99 GreenRoot
.60 .60 .95 bigjeff5
.70 Shalmanese
.80 .60 .95 Mario
.85 .60 .20 bgrah449
.90 .85 .99 Unknowns
.90 .90 .90 lordweiner27
.90 .90 .99 brazil84
.99 .99 .99 dilaudid

I have messaged each of them, asking them to comment here, describing if and how they have since updated, and any other thoughts they might have. (I have also messaged the first 12 commenters or so, chronologically, with <41% confidence in Knox’s guilt, with the same message.) The commenters:

AngryParsley / Cyan / Daniel_Burfoot / Eliezer_Yudkowsky / GreenRoot / John_Maxwell_IV / LauraABJ / Mario / Matt_Simpson / Morendil / Psychohistorian / Shalmanese / Threads / Unknowns / badger / bentarm / bgrah449 / bigjeff5 / brazil84 / dilaudid / jimmy / kodos96 / lordweiner27 / mattnewport / nerzhin / tut

I look forward to seeing their retrospectives, or indeed, anyone's retrospectives on the matter.

Allknowing and most merciful Bayes;
We have erred, and strayed from thy ways like biased sheep.
We have followed too much the devices and desires of our own hearts.
We have offended against thy axiomatic laws.
We have left undone those updates which we ought to have done;
And we have done those updates which we ought not to have done;
And there is no calibration in us.
But thou, O Bayes, have mercy upon us, miserable wannabes.
Spare thou them, O Bayes, who confess their faults.

484 comments

Comments sorted by top scores.

comment by bentarm · 2011-10-21T11:24:16.592Z · LW(p) · GW(p)

Over the summer, Eliezer suggested (approximately, I am repeating this from memory) the following method for making an important decision:

  1. write down a list of all of the relevant facts on either side of the argument.
  2. assign numerical weights to each of the facts, according to how much they point you in one direction or another.
  3. burn the piece of paper on which you wrote down the facts, and go with your gut.

This was essentially the method I used in coming to my (probably slightly low) estimate of the probability that Knox and Sollecito were innocent. It just felt like they were innocent, and I saw essentially no reason to suspect they were guilty. I will note that the 'pro-guilt' site that komponisto linked to was just horribly devoid of anything that I might consider evidence (if anything, that site did more to convince me of Knox's innocence than the pro-innocence site), and I did spend probably about 10 minute trying to find some evidence that they had missed, but completely failed.

On a different not, as I said at the time, 0.95 and 0.05 were just proxies for "pretty damn sure" and "pretty damned unlikely" - I have very little idea what 5% probability feels like, and I'm sure that if arbitrary scientific convention had settled on some different number for significance, I'd have picked that one instead. I have made some progress since a year ago on calibrating my estimates of small probabilities, but I absolutely do not think that I would be wrong approximately 1 time in 20 when making predictions to which I assign a probability of 0.95.

Replies from: Eliezer_Yudkowsky, lessdazed, wedrifid
comment by Eliezer Yudkowsky (Eliezer_Yudkowsky) · 2011-10-21T15:35:05.813Z · LW(p) · GW(p)

This is a better summary of what I said than what I actually said, so I hereby declare your distorted version to be my true teaching.

comment by lessdazed · 2011-10-21T17:39:53.633Z · LW(p) · GW(p)

I have very little idea what 5% probability feels like

???

1d20!!!

Replies from: FiftyTwo
comment by FiftyTwo · 2011-10-24T22:13:21.050Z · LW(p) · GW(p)

I don't have an intuitive feeling for d20s, but it occurs to me that a useful resource might be a list of day to day events of certain probabilities so we can calibrate our intuitions to them.

Googling hasn't found me anything useful, could anyone give an example of an normal event that has a 5% chance of occuring?

Replies from: saturn, JoshuaZ, dlthomas, thomblake
comment by saturn · 2011-10-24T23:46:44.657Z · LW(p) · GW(p)

You look at a clock and the seconds are :00, :01, or :02.

comment by JoshuaZ · 2011-10-25T00:43:39.435Z · LW(p) · GW(p)

It is a little over the chance that if you are dealt two cards from a standard deck of cards that one of them will be the ace of spaces. It is a little under the chance that if you are dealt three cards from a standard deck that one them will be the ace of spades.

It is roughly the chance that if you pick three random members of the US House of Representatives that at least two of the three will not be reelected.

If It is about half as likely as the chance that a given US soldier in Iraq over the last decade will have been killed or too badly injured to return to duty (generally estimated to be around 9%). ETA: This number is wildly off. Disregard.

It is slightly less likely than your expectation for Schrodinger's cat to be alive if you run the experiment 5 times.

It is a bit under the chance that if you put your money on two numbers on a roulette wheel that one of them will turn up.

It is slightly over the chance that if you meet two random South Koreans that their last names will both be "Kim".

ETA: Here's a depressing one: It is around the chance that if you pick two children with childhood leukemia that they will both survive five years.

Replies from: lessdazed
comment by lessdazed · 2011-10-25T00:59:46.647Z · LW(p) · GW(p)

It is about half as likely as a US soldier in Iraq over the last decade will be killed or too badly injured to return to duty (generally estimated to be around 9%).

Who exactly?

"One is always," said Bertrand, "a shirker to some one else."

"That's true; no matter what you call yourself, you'll always---always--find worse blackguards and better blackguards than yourself."

"All those that never go up to the trenches, or those who never go into the first line, and even those who only go there now and then, they're shirkers, if you like to call 'em so, and you'd see how many there are if they only gave stripes to the real fighters."

"There are two hundred and fifty to each regiment of two battalions," said Cocon.

"There are the orderlies, and a bit since there were even the servants of the adjutants."--"The cooks and the under-cooks."--"The sergeant-majors, and the quartermaster-sergeants, as often as not."--"The mess corporals and the mess fatigues."--"Some office-props and the guard of the colors."--"The baggage-masters." "The drivers, the laborers, and all the section, with all its non-coms., and even the sappers."--"The cyclists." "Not all of them."--"Nearly all the Red Cross service."--"Not the stretcher-bearers, of course; for they've not only got a devilish rotten job, but they live with the companies, and when attacks are on they charge with their stretchers; but the hospital attendants."

"Nearly all parsons, especially at the rear. For, you know, parsons with knapsacks on, I haven't seen a devil of a lot of 'em, have you?"

"Nor me either. In the papers, but not here."

"There are some, it seems."--"Ah!"

"Anyway, the common soldier's taken something on in this war."

"There are others that are in the open. We're not the only ones."

"We are!" said Tulacque, sharply; "we're almost the only ones!"

He added, "You may say--I know well enough what you'll tell me--that it was the motor lorries and the heavy artillery that brought it off at Verdun. It's true, but they've got a soft job all the same by the side of us. We're always in danger, against their once, and we've got the bullets and the bombs, too, that they haven't. The heavy artillery reared rabbits near their dug-outs, and they've been making themselves omelettes for eighteen months. We are really in danger. Those that only get a bit of it, or only once, aren't in it at all. Otherwise, everybody would be. The nursemaid strolling the streets of Paris would be, too, since there are the Taubes and the Zeppelins, as that pudding-head said that the pal was talking about just now."

"In the first expedition to the Dardanelles, there was actually a chemist wounded by a shell. You don't believe me, but it's true all the same--an officer with green facings, wounded!"

"That's chance, as I wrote to Mangouste, driver of a remount horse for the section, that got wounded--but it was done by a motor lorry."

"That's it, it's like that. After all, a bomb can tumble down on a pavement, in Paris or in Bordeaux."

"Oui, oui; so it's too easy to say, 'Don't let's make distinctions in danger!' Wait a bit. Since the beginning, there are some of those others who've got killed by an unlucky chance; among us there are some that are still alive by a lucky chance. It isn't the same thing, that, seeing that when you're dead, it's for a long time."

--Le Feu (Under Fire), translation.

Replies from: JoshuaZ
comment by JoshuaZ · 2011-10-25T01:12:15.341Z · LW(p) · GW(p)

Who exactly?

Oh. Hmm. I don't remember where I saw this but that number is my background fact set. But when I look at the actual numbers this is clearly false. There have been around 30,000 people wounded or killed. (Source) and around a million who have served. That means that the probability of being wounded or killed at all is around .03, which is much smaller, and that's even before the fact that I said wounded severely enough that one can't keep fighting. Also in retrospect my number was obviously too high. Severe failure of rationality on my part. Ugh.

Replies from: komponisto
comment by komponisto · 2011-10-25T12:44:45.276Z · LW(p) · GW(p)

I thought that number was highly suspicious, but I attributed it to the combined category (killed or too injured to return -- which of course are very different things from the perspective of the individual concerned!).

comment by dlthomas · 2011-10-25T00:09:15.531Z · LW(p) · GW(p)

It's somewhere between the chance of flipping 4 successive heads and the chance of flipping 5 successive heads with a fair coin.

comment by thomblake · 2011-10-24T23:50:23.197Z · LW(p) · GW(p)

I was going to respond for I thought I knew many such things, but the few that did not involve rolling d20s involved rolling d%.

comment by wedrifid · 2011-10-21T17:32:35.383Z · LW(p) · GW(p)

I have made some progress since a year ago on calibrating my estimates of small probabilities, but I absolutely do not think that I would be wrong approximately 1 time in 20 when making predictions to which I assign a probability of 0.95.

My guess would be more that 1 in 20 wrong for a 95% confidence.

comment by komponisto · 2011-10-21T14:16:15.373Z · LW(p) · GW(p)

Despite the fact that my opinion on the case has hardly changed at all, these posts -- and thinking about the case in general -- were a tremendous learning experience for me. Some of the lessons include:

  • Less Wrong is good at getting the right answer. Believe it or not, the strong survey consensus in favor of innocence -- prior to my second post -- came as something of a pleasant surprise to me. You don't find this in many other places, despite the fact that the case is a no-brainer. I had assumed there would be more wishy-washiness and probabilities close to 50% than there turned out to be. (There was some of this, but less than I expected.)

  • People in general are bad at getting the right answer. As shown by the original verdict, not to mention all the numerous pro-guilt commentators on internet forums and elsewhere. What's surprising about that? Not much, perhaps, but I would say that one thing that is important about it is that it shows that huge, glaring errors of judgement are not restricted to Far Mode. Even on a mundane question such as this, people are susceptible to strange cognitive biases that can severely distort their assessment of evidence.

  • Confidence should depend on how much you know. I erred twice during the original sequence of posts on the case: once when I implied that participants in my survey ought to have come up with numbers like mine (0.001), and then again when I reacted to the indignation that followed by downgrading my own confidence. In truth, because (even before the verdict) I had followed the case more than most LW readers, my level of confidence should have been higher than most readers'. For someone who spends ten minutes reading the two sites I linked to, 0.9 probability of innocence (as opposed to 0.99) is perfectly reasonable; whereas someone like me should expect to be more confident, even if only on account of the meta-information that any additional information not on those sites isn't particularly relevant.

(More comments possibly to be added later...)

Replies from: wedrifid, Jack
comment by wedrifid · 2011-10-21T14:49:13.935Z · LW(p) · GW(p)

What's surprising about that? Not much, perhaps, but I would say that one thing that is important about it is that it shows that huge, glaring errors of judgement are not restricted to Far Mode.

To the extent that I use that nomenclature I would have called this judgement to be a far mode one. It is the throwing about of far mode political abstractions to achieve perceived near mode goals. Those near mode goals have very little to do with the guilt or innocence of the victim (Amanda) and a lot to do with how your political utterance ("She's a witch! Burn her!") will be perceived by your peers.

Replies from: komponisto
comment by komponisto · 2011-10-21T15:02:20.183Z · LW(p) · GW(p)

Yes, we seem to have quite different understandings of what these terms ("near", "far", "political") mean.

An example of (erroneous) "near" reasoning in my usage would be: "Amanda is guilty because there had to be multiple attackers because there were so many wounds on the victim".

Whereas an example of (erroneous) "far" reasoning would be: "Amanda is guilty because f**ck those arrogant imperialist Americans trying to tell us how to run our country".

comment by Jack · 2011-10-21T16:17:38.440Z · LW(p) · GW(p)

In truth, because (even before the verdict) I had followed the case more than most LW readers, my level of confidence should have been higher than most readers'.

True while we're uncertain of your rationality. But at this point I find you reliable enough to think that your confidence is what mine would be if I followed the case as closely as you. And that means I'm just going to adopt your probability estimate.

Replies from: komponisto
comment by komponisto · 2011-10-21T16:38:13.774Z · LW(p) · GW(p)

Well, of course, at the time in question no one knew what my probability estimate was; I merely meant that they need not have reached 0.999 confidence from a few minutes of browsing.

(Thanks for the compliment, in any case!)

comment by Eliezer Yudkowsky (Eliezer_Yudkowsky) · 2011-10-20T19:43:30.900Z · LW(p) · GW(p)

See my added comment. I did not assign a probability of 15%. I said that if you assigned a probability higher than 15%, it meant you had a really major problem with crediting the opinions of other people and the authority of idiots. My probability that Knox and Sollecito were guilty was "that's privileging the hypothesis", i.e., "I see no real evidence in its favor so same as prior probability", i.e., "really damned' low".

Replies from: gwern
comment by gwern · 2011-10-20T22:47:35.434Z · LW(p) · GW(p)

When people gave ranges, I just used the anchoring number. You gave a range starting at 15%, so that's what I listed.

Replies from: Eliezer_Yudkowsky
comment by Eliezer Yudkowsky (Eliezer_Yudkowsky) · 2011-10-21T15:27:01.438Z · LW(p) · GW(p)

That's a neat compact algorithm but this doesn't change the fact that it produces the wrong answer.

Again, 15% isn't the maximum of a range. It's a number that's not just "wrong" but "sufficiently wrong to imply you need to adjust your emotional makeup".

If you need a number for me, put in "<0.01". I wouldn't have bet $20,000 at 99-to-1 odds over it at the time of writing that first paragraph, but I'm not quite sure anymore that this really means my probability is >0.01, it's not like I'd have taken the bet the other way.

comment by Morendil · 2011-10-20T17:00:44.920Z · LW(p) · GW(p)

The Knox thread was one of the first steps in my getting interested in predictions in general. It was a slow process and is still ongoing, but it has had me spend time on various calibration exercises, on PredictionBook, on the Crowdcast instance dedicated to the Good Judgment project, on Inkling Markets because I saw a few arbitrage opportunities there that sounded like fun. I'm not as into predictions as gwern appears to be, but they're growing on me.

All that and I'm still not very sure what to think of the Knox case. Yes, if our predictions were being scored I'd be getting a non-trivial penalty from my 50% chance of her guilt - that is, if we take the outcome of the appeals process as an arbitration of the prediction, and judge, for the purposes of scoring, that she was "in fact" innocent. (I'm not saying I have much doubt now about her innocence: I'm saying that we won't ever know for sure, and part of the point of these prediction exercises is to allow us to better deal with that permanent uncertainty.)

On the other hand, some of the people listed above would be taking a much more serious hit. One thing I've learned from my various exercises is that you can't expect to be right all the time - sometimes, with minimal knowledge of the relevant facts, a 50% prediction is in fact not so bad.

Then again, some of us were also apparently very confident in the answer that "in fact" turned out to be the correct one. Then again, we all get lucky from time to time - that too is the nature of the beast...

My intention is to continue to learn, to continue to get better at predicting, to become better calibrated and more discriminating over time.

Replies from: gwern
comment by gwern · 2011-10-20T17:12:02.496Z · LW(p) · GW(p)

(I'm not saying I have much doubt now about her innocence: I'm saying that we won't ever know for sure, and part of the point of these prediction exercises is to allow us to better deal with that permanent uncertainty.)

One of the unfortunate things about living when we do is that it seems unlikely there will be any future oracles developed which reveal definitive answers to ancient crimes.

I refer, of course, to DNA evidence, which gave us an astonishing oracle to ask questions about old crimes, revealing a shockingly high lower bound on the justice system's error rates. If we had been around and recorded predictions about various death row inmates, then the Innocence Project's &etc. results would've been an assessment of our calibration worth writing home about!

Replies from: NancyLebovitz
comment by NancyLebovitz · 2011-10-20T18:58:59.312Z · LW(p) · GW(p)

One of the unfortunate things about living when we do is that it seems unlikely there will be any future oracles developed which reveal definitive answers to ancient crimes.

I wouldn't give that an extremely high probability. One of the trends in science is getting surprising amounts of information from tiny amounts of input-- DNA is one example, and finding extrasolar planets is another. I don't have specifics in mind, but I wouldn't be surprised if another method or two which are at least as powerful are developed.

Replies from: gwern
comment by gwern · 2011-10-20T19:13:53.104Z · LW(p) · GW(p)

My reasoning goes along the lines of fingerprints and then DNA are highly precise near unique identifiers, which are also pretty sturdy and accurate. I don't know of any more biological traces which could significantly improve, much less be orders of magnitude superior to what went before like fingerprints & then DNA were.

There are plenty of future improvements in crime-solving, sure - lifelogging and pervasive surveillance comes to mind as the most obvious improvement. But none of the ones I can think of will be oracles in the sense I mean here of giving us the correct answers for cases we already 'solved', none of them will be retrospective. (Lifelogging will be employed as soon as available, witness the Canadian thing with stitching together hundreds of photos online to identify & arrest scores of rioters; I would be surprised if huge archives of recording built up and then only decades later are suddenly made public and cold case units began cracking cases with them, for example.)

Replies from: NancyLebovitz
comment by NancyLebovitz · 2011-10-20T20:16:08.161Z · LW(p) · GW(p)

Brain scans which can retrieve memories accurately? Admittedly, this would be limited to crimes with living witnesses.

The thing is, I think science leads to weird, surprising discoveries. I'm not going to predict what's impossible a century from now.

Replies from: Desrtopa, Jack
comment by Desrtopa · 2011-10-20T22:37:39.107Z · LW(p) · GW(p)

Brain scans which can retrieve memories accurately?

I believe that the current understanding is that memory encoding, not just retrieval, is pretty unreliable, so even if you can read exactly what's in people's brains, it may not be much help.

Replies from: gwern, satt
comment by gwern · 2011-10-20T22:46:33.376Z · LW(p) · GW(p)

And then there's the problem of locating the right person to interrogate - a task equivalent to and as hard as locating the hypothesis. :) But I probably shouldn't be too dismissive: brain-scanning is one of the better contenders for the next oracle.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-20T22:54:46.709Z · LW(p) · GW(p)

Well, having the right technologies can certainly make locating the hypothesis a lot easier; think how much harder it would have been to locate Guede as a suspect without DNA testing.

If we had a reliable way of determining self perceived truth value, nearly all interrogation could be narrowed down to "Do you know who did it?" "Who did it?" and "Did you do it?"

On second thought, given a device that were capable of doing that with a negligible failure rate, it might be simpler to just replace policing with occasional checkups.

"So, committed any crimes this month?"

Replies from: NancyLebovitz, dbaupp, gwern
comment by NancyLebovitz · 2011-10-21T06:51:05.788Z · LW(p) · GW(p)

Self-perceived truth value sounds like a subtle problem.

I'd settle for memory testing for eye-witnesses, though memory testing under stress is probably too much to ask.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T17:05:57.404Z · LW(p) · GW(p)

My high school psychology teacher gave my class an interesting demonstration on the usefulness of eyewitnesses.

For one class, we found a notice on the door saying that the class had been relocated to another room. We went to that room, and shortly after our teacher arrived, followed by another teacher. He complained that she had not gotten proper clearance to move her class to that room, and he needed it for an exercise for his own class. They spent a couple minutes arguing, and harsh words were exchanged, after which he left the room.

Almost immediately after he left, our teacher asked us to create profiles of his physical description. Estimates of his height ranged from 5'6 to 6'3, his hair was variously described as being brown, black, or red, and his weight was somewhere from 140 pounds to 230.

The information that the students retrieved from their short term memory, which had not yet been encoded as long term memory, was already profoundly unreliable.

comment by dbaupp · 2011-10-21T06:12:25.494Z · LW(p) · GW(p)

"So, committed any crimes this month?"

This would probably only work if the person knew activity X was a crime. There are probably ways of becoming convinced that X wasn't a crime (or vice versa).

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T06:27:07.445Z · LW(p) · GW(p)

This occurred to me, but I suspect that it would still be easier to catch more people this way than with active policing, particularly for the crimes you most care about catching people at, which most people will already know are wrong and probably if not definitely illegal.

And you could always ask them, "Are you cultivating deliberate unawareness?"

Replies from: NancyLebovitz, dbaupp
comment by NancyLebovitz · 2011-10-31T09:37:36.277Z · LW(p) · GW(p)

The whole point of deliberate unawareness is that it's unaware-- the deliberate part gets hidden in mental fog.

comment by dbaupp · 2011-10-21T07:25:06.842Z · LW(p) · GW(p)

I agree with that this method seems far easier to catch the majority of people committing those crimes, since the cultivation process would most likely be non-trivial, so the "casual" criminal wouldn't have access to it.

There is still the problem of someone else doing the cultivation, so one mastermind could create a militia of people immune to the checkups. (I'm not quite sure if this is actually possible though, although, superficially at least, hypnosis seems to do this sort of thing)

(Thanks for the "cultivating deliberate unawareness" term)

comment by gwern · 2011-10-21T02:14:31.947Z · LW(p) · GW(p)

Such a system would be far from most current Western legal systems and hence is of not much interest to me in the context of discovering bounds on error rates in current Western legal systems.

comment by satt · 2011-10-20T23:16:36.845Z · LW(p) · GW(p)

I thought the same thing.

It also occurred to me that (although it's unlikely) we might discover a neural signature distinguishing spurious memories from accurate ones. Or some less powerful but still useful signature, such as one that distinguishes memories that have been accessed after creation (and so potentially overwritten) from memories that have never been accessed (which are presumably more reliable).

Replies from: falenas108
comment by falenas108 · 2011-10-21T01:52:57.619Z · LW(p) · GW(p)

There is weak evidence that the memories you make during the day are reviewed during REM sleep, which would mean every memory is gone over at least once.

comment by Jack · 2011-10-20T20:19:30.138Z · LW(p) · GW(p)

Even just reliable brain-scan based lie detectors...

comment by PhilGoetz · 2011-10-21T04:12:12.757Z · LW(p) · GW(p)

I want to see the regression of LW karma (or the log of LW karma) on probability-Amanda-is-guilty!

You ought to leave Eliezer out of the equation, or assign him a Karma value equal to Yvain's, or else he'll dominate the regression.

Replies from: Jack, dbaupp
comment by Jack · 2011-10-21T06:20:07.276Z · LW(p) · GW(p)

Feel free to try and make something fit

Replies from: MinibearRex, PhilGoetz
comment by MinibearRex · 2011-10-21T14:40:13.754Z · LW(p) · GW(p)

Doesn't look like there's any sort of function you can use, but there are almost no points in the top right corner of your graph. Almost nobody with high karma on LW assigned a substantial probability that Knox was guilty.

comment by PhilGoetz · 2011-10-21T22:25:16.645Z · LW(p) · GW(p)

Neat! It appears the shared version is writable. How can I make a copy of a Google doc, so I can mess around with it myself? I entered this into OpenOffice, and it also gave me a slope of -.02, an intercept of .4, and an R-squared of .02. Weird that the R-squared is so low, since 8 people with log(karma) < .7 gave p > .5, and no people with log(karma) > .7 did.

Also, Eliezer gave p=.15, and that doesn't appear on the graph.

Replies from: komponisto, Jack, Jack
comment by komponisto · 2011-10-22T12:36:08.044Z · LW(p) · GW(p)

Also, Eliezer gave p=.15, and that doesn't appear on the graph.

No he didn't.

comment by Jack · 2011-10-24T06:05:17.602Z · LW(p) · GW(p)

Left Eliezer off since we don't have a firm probability for him and his karma is a huge outlier.

comment by Jack · 2011-10-21T23:12:59.925Z · LW(p) · GW(p)

There is a copy option under the file tab. You're welcome to add to mine though.

Weird that the R-squared is so low, since 8 people with log(karma) < .7 gave p > .5, and no people with log(karma) > .7 did.

For users with Ln(karma) > 7 no answer was > 0.5. But within that range people were about as attracted to 0.5 as they were to 0.01. For further investigation I'd want like to see residuals and the log10 of the prediction.

comment by dbaupp · 2011-10-21T06:15:24.548Z · LW(p) · GW(p)

Do you want it enough to do it yourself?

comment by Jack · 2011-10-20T16:45:35.235Z · LW(p) · GW(p)

Amazing job putting this together.

I had remembered LW as being a hive of Amanda fans, but either I’m succumbing to hindsight bias or people updated significantly after those articles.

My .13 probability in the first thread definitely went down following further discussion and, in particular, komponisto's second post. In the last year I've been comfortable using "She's definitely innocent" talking about the case with non-LWers.

comment by bigjeff5 · 2011-11-07T21:14:07.301Z · LW(p) · GW(p)

I updated my 60% guilt for Knox/Sollecito almost immediately after reading the follow-up article. As I noted on that page, my 60% judgement was a clear case of anchoring. I started with the pro-guilt evidence and only managed an 80% guilt after reading only their evidence. That I was then only able to re-adjust down to 60% was absurd. Since I was (and still am) fairly weak as a rationalist, I probably should have withheld any kind of assessment until after I had read the pro-innocence website, rather than try to make an early assessment and update it with the evidence I knew would be coming.

I didn't put a number on my update at the time, I just went from "There isn't enough evidence to convict" to "Why were they still suspects?". If I had to put a number on it, I'd say this was a <5% chance of guilt.

Since the acquittal, given the judge's statements about the DNA evidence and the handling thereof (I didn't read the full assessment by the independent expert), I'd have to adjust it now to <1%.

ETA: I just went through the independent analysis, and the conclusions were even stronger than I thought they were.

I thought that the conclusions were of the nature: "this DNA cannot be conclusively matched to anyone".

In fact, they were of the nature: "There is no organic material present."

They did find a few grains of starch on the bra clasp, but that was it. How did the Scientific Police screw it up that badly? They got a shakey DNA match where no DNA existed!

I have to update my assessment yet again, to the lowest I'm willing to put a number on, and that's <0.1% chance that either of them are guilty. There is literally zero evidence that either of them were involved.

comment by APMason · 2011-10-20T17:16:22.526Z · LW(p) · GW(p)

Strange thing about this is, if I've calculated it right, the average probability estimate of Guede's guilt is only ~87%. It seems to me that if this were your real probability estimate of his guilt, and you were on the jury at the guy's trial, you would be obligated to vote innocent. If you operate on the basis that a 13% chance of innocence is not a reasonable doubt, about thirteen out of every hundred people who go to jail will be innocent. That is (let me check) more than one in ten, which strikes me as rather a lot. I think my own estimate of Guede's guilt is above 99%, so I would vote guilty, but I'm surprised the average here is so low.

Replies from: steven0461, Nornagest, billswift, AlexSchell
comment by steven0461 · 2011-10-20T18:44:27.999Z · LW(p) · GW(p)

If you operate on the basis that a 13% chance of innocence is not a reasonable doubt, about thirteen out of every hundred people who go to jail will be innocent.

That's if everyone who went to jail had a 13% chance of innocence. Presumably much of the time it would be lower.

Replies from: APMason
comment by APMason · 2011-10-20T19:03:11.154Z · LW(p) · GW(p)

Yes indeed. My mistake.

Replies from: byrnema
comment by byrnema · 2011-10-20T23:35:48.768Z · LW(p) · GW(p)

Not 13 out of every 100 people in jail, but still 13 out of every 100 people sentenced by the jury as guilty in the case of a probability estimate of only ~87%. ....The argument still works to show that the probability of guilt at 87% is too low to vote guilty.

Replies from: Peter_de_Blanc
comment by Peter_de_Blanc · 2011-10-21T07:04:34.198Z · LW(p) · GW(p)

This argument does not show that.

Replies from: byrnema
comment by byrnema · 2011-10-21T11:12:57.949Z · LW(p) · GW(p)

Which argument? I meant the argument loosely defined as the one where you count which fraction of innocent people are jailed to determine if the probability of guilt at 87% is appropriate. Steven0641 correctly pointed out that the target space for the fraction isn't all people in jail, but then you modify the target space to all people judged guilty with probability 87% and the argument 'works'.

Replies from: steven0461
comment by steven0461 · 2011-10-21T19:43:21.729Z · LW(p) · GW(p)

The argument works if adding a 13% innocent population to jail is clearly wrong even though sending an individual with 13% probability of innocence to jail is not clearly wrong. Peter's point, I think, is that we don't have that "if".

Replies from: komponisto, byrnema
comment by komponisto · 2011-10-21T20:00:12.289Z · LW(p) · GW(p)

I thought that "13% innocent population in jail is wrong" was a premise, and "individual with 13% probability of innocence in jail in wrong" was the conclusion.

Which seems perfectly reasonable to me: if you have an 87% certainty threshold for conviction, it means you're willing to tolerate up to 13% of convicts being innocent, an unacceptably high number by my lights.

Replies from: Luke_A_Somers, steven0461
comment by Luke_A_Somers · 2011-10-21T20:50:17.188Z · LW(p) · GW(p)

It gets worse - the most severe crimes face the strongest pro-conviction biases.

Replies from: komponisto
comment by komponisto · 2011-10-21T21:29:03.450Z · LW(p) · GW(p)

...which is of course exactly the opposite of how it should work.

Replies from: FAWS
comment by FAWS · 2011-10-21T22:40:45.815Z · LW(p) · GW(p)

I agree if you mean that the damage from an irrational bias is higher when the stakes are higher, but disagree if you mean that rational marginal certainty levels needed for conviction would be higher for severe crimes. The risks from letting a thief go free (more thefts) seem lower than the risks from letting a murderer go free (more murders) even compared to the damage done to a potential convicted innocent (assuming no death penalty, and also assuming higher conviction rates would actually result in fewer of the real culprits going free, which often does not seem to be the case).

comment by steven0461 · 2011-10-21T20:24:39.720Z · LW(p) · GW(p)

So it sounds like you're saying we do have the "if". But are you sure the number is not just unacceptably high because in any realistic example of a 13% innocent population of convicts, many of them would have to have been seen as having substantially greater than 13% chances of innocence? If not for some biasing effect like that, it's hard for me to see why the moral question would suddenly be clear once it was stated in population frequencies rather than in individual probabilities.

Replies from: komponisto, Nornagest
comment by komponisto · 2011-10-21T21:17:57.941Z · LW(p) · GW(p)

So it sounds like you're saying we do have the "if".

Actually, no, because the equivalence of the two formulations is obvious to me.

But it might not be for everyone; it's well known that many people find thinking in terms of frequencies more intuitive than thinking in terms of bare probabilities. For such people, a statement about probabilities may simply not have any moral force unless and until it is translated into a statement about frequencies.

comment by Nornagest · 2011-10-21T20:56:08.713Z · LW(p) · GW(p)

But are you sure the number is not just unacceptably high because [...] many of them would have to have been seen as having substantially greater than 13% chances of innocence? If not for some biasing effect like that, it's hard for me to see why the moral question would suddenly be clear once it was stated in population frequencies rather than in individual probabilities.

Well, people's intuitions about justice aren't all that consistent, so I don't think this particular moral question is going to suddenly become clear to all observers no matter how it's stated. That being said, though, I don't think we have any particular reason to think that Guede was convicted on unusually shaky evidence, so it seems reasonable -- given certain assumptions -- to take our estimates of his case as representative of murder cases in general.

A 13% innocence threshold for each particular case won't give you a 13% innocent prison population (assuming good estimates, which is probably generous in this context), but if we adopt that criterion and Guede's in the middle of the probability distribution for murder defendants, it seems likely that the resulting population-level incidence would still land on the bad side of 8 or 10%. Which doesn't look much better.

Replies from: komponisto
comment by komponisto · 2011-10-21T21:27:52.175Z · LW(p) · GW(p)

By the way, I should probably clarify that I don't think the LW average of 87% probability of guilt for Guede at all means that he should have been acquitted. I attribute the low number to a lack of confidence due to not having delved sufficiently deeply into the case, as per the third point in my earlier comment.

One should only believe that a miscarriage of justice has occurred in his case if one believes that the jury should not have had more than (say) 87% confidence. But in order to believe that one would presumably have to be highly confident in one's belief about what information the jury had.

Replies from: Nornagest
comment by Nornagest · 2011-10-21T21:35:34.556Z · LW(p) · GW(p)

I agree, for reasons outlined here. Like you, I'm speaking hypothetically.

comment by byrnema · 2011-10-21T20:38:06.362Z · LW(p) · GW(p)

I would say that sending an individual with 13% probability of innocence to jail is clearly wrong, because 1 out of 10 of them would be innocent.

So the premise instead is: adding a 13% innocent population of any subset or category of individuals to jail is clearly wrong

leading to the conclusion: sending an individual with only 87% probability of guilt to jail is wrong

Replies from: lessdazed, steven0461
comment by lessdazed · 2011-10-22T02:53:21.844Z · LW(p) · GW(p)

I would say that sending an individual with 13% probability of innocence to jail is clearly wrong, because 1 out of 10 of them would be innocent.

One wonders how many of those are people the jury correctly thinks have done other crimes, or subjectively think deserve more punishment for past crimes. That would be a different malfunction from the expressed intent of the system and would imply the system otherwise does much better than the 87/13 ratio.

comment by steven0461 · 2011-10-21T20:58:30.385Z · LW(p) · GW(p)

Yes, that's what I meant by what I said. But the problem is that, at least to me, the premise is no more obvious than the conclusion.

Replies from: byrnema
comment by byrnema · 2011-10-21T21:17:35.399Z · LW(p) · GW(p)

I see. It's a little more obvious to spell out "more than 1 out of 10 innocent" instead of "only 87% probablity of guilt" but if you see them as immediately equivalent then indeed the argument will do nothing for you.

comment by Nornagest · 2011-10-20T17:55:56.879Z · LW(p) · GW(p)

Well, I haven't looked at those estimates for a few months, but I'd imagine that a lot of the margin in the outside view of Guede's case comes from uncertainties introduced by the media handling of the case or by an imperfect view of the evidence. Neither of those factors would, presumably, apply to a jury.

That being said, I wouldn't be all that surprised if thirteen out of a hundred prisoners in Europe and the US were innocent of some of the charges that put them in jail. It's higher than my own estimate would be, but within the same order of magnitude.

Replies from: APMason
comment by APMason · 2011-10-20T18:03:45.657Z · LW(p) · GW(p)

I agree that it wouldn't be hugely surprising. I meant it strikes me as higher than acceptable.

comment by billswift · 2011-10-20T17:59:29.637Z · LW(p) · GW(p)

In a situation like a trial, where I would be limited to just those "facts" presented by the lawyers, it would be extraordinarily unlikely for me to give better than 90% probability of anything.

comment by AlexSchell · 2011-10-20T19:16:04.121Z · LW(p) · GW(p)

I would think that hypothetical juror judgments of guilt or innocence may be a lot more prone to bias than a more "dispassionate" look at the evidence generating a probabilty estimate. Even if one should count one's own hypothetical guilt/innocence judgment as a small bit of evidence in the right direction, explicitly trying to calibrate this judgment with one's prior probability estimate is going to make one over-correct one's estimate.

comment by komponisto · 2011-10-22T21:02:04.486Z · LW(p) · GW(p)

One person whose reflections would be particularly welcome, of course, is Rolf Nelson.

Our debate (which is currently stalled due to my fault -- it's my turn to reply) has dealt with one of the few important pieces of evidence to emerge after the original verdict: the incompatibility of the digestive evidence with the prosecution's hypothesized time of death. (This was covered during the original trial, but was never a focus of discussion among outside commentators until the folks at the JREF forum brought it to attention last year.)

comment by Psychohistorian · 2011-10-31T05:16:54.553Z · LW(p) · GW(p)

Since I was randomly chosen to comment on this, I'll throw in my two cents. I haven't thought about too much and my first instinct was to trust whatever value judgements I had made at the time, which I thought were something like 5-5-95, but were actually 1-1-99. Since me-at-the-time was much more familiar than me-right-now, I'd still probably defer to his judgement; if anything, her exoneration and other evidence should move those numbers slightly closer to the extremes.

comment by Matt_Simpson · 2011-10-22T23:49:35.319Z · LW(p) · GW(p)

I assigned a relatively high probability of guilt for Amanda Knox because of a combination of ignorance and over-correction. I read material on the website of the innocent side first, and felt fairly convinced largely because of their assessment of the DNA evidence. The other website had a conflicting assessment of the DNA evidence, which I didn't know how to adjudicate without trying to learn more about how DNA evidence works. I didn't do this, and so remained uncertain but still thought that Knox was innocent with fairly high probability.

Additionally, I recall at the time that I was afraid of being "wrong." The original post had the feel of setting up a "gotcha" and my instinct was to avoid being gotcha'd, so I started to hedge. I realized this wasn't a good reason to change my assessment of the situation, but I discovered something else to blame it on: my own personal biases. I used to be a pretty hardcore libertarian and am wary of politics hijacking my mind (again), so I blamed the hedging on a correction of my own biases - I think I even mentioned this bias in my original comment. I also probably overweighted the fact that Knox was accused in the first place in my assessment.

In any case, I also recall changing my mind after reading the followup article and comments - partially because more research was put into that article than I put into my own assessment, but also partially because they considered the relevant data more honestly than I had. I don't really recall the details of this update or, for that matter, the real reason why I now think Amanda Knox is innocent - it's all cached thoughts at this point.

comment by jimmy · 2011-10-22T18:53:44.643Z · LW(p) · GW(p)

My high estimate came from spending insufficient mental energy to come to a stable estimate as well as, as Eliezer said "if you assigned a probability higher than 15%, it meant you had a really major problem with crediting the opinions of other people and the authority of idiots."

comment by kodos96 · 2012-01-20T00:02:24.756Z · LW(p) · GW(p)

So I'm a few months late to the game here, but I was one of the people selected to give my retrospective on this, so here goes:

My original estimates were .01, .01 and .99. I realize now that my calibration was off in the same way Komponisto has conceded his was: those numbers are way too strong to be rational estimates for something you read about on the internet for an hour or two. If I had it to do over again with benefit of hindsight, I'd probably say something more like .1 .1 .9.

The thing is though, in the time since then I've done quite a bit more reading on the topic, to the point where I now feel much more justifiably confident in my conclusions... so if I had to choose probabilities TODAY, I'd probably pick something pretty similar to my original .01 .01 .99.... ORIGINALLY those numbers were too strong to be justified based on the state of my knowledge at the time, but that's no longer the case.

So basically in the last two years I've come full circle back to my original estimates.

Of the 3 new pieces of evidence you mentioned, #1 is the only one that you might say I updated on. I didn't see any reason to update on the expert report, since I assume it just contains all the same evidence that I'd already updated on.

comment by JQuinton · 2011-10-26T15:06:09.754Z · LW(p) · GW(p)

Hmm... I'm a bit confused about what was supposed to be predicted here. Were we supposed to predict whether Knox would be convicted, or predict whether Knox actually committed a murder? If I had been involved in the original conversations, I would have assigned a very low probability to Knox's actual guilt, but a higher probability to her being found guilty. One is a question that specifically pertains to Knox herself, and the other is a commentary on the state of the Italian justice system.

Replies from: gwern
comment by gwern · 2011-10-26T17:06:07.585Z · LW(p) · GW(p)

predict whether Knox actually committed a murder

Short of a new oracle (like DNA was previously), we will never have any judgement which is reliable enough to convince both sides that the judgement is correct. So, this was not a case of predicting the legal outcome - you will notice I mentioned I got the appeal wrong - but rather a question of how and whether people have changed their probability since then. Did they increase their belief in her guilt? Decrease it? Leave it unchanged due to a complicated convergence of pro and anti evidence? This wasn't an exercise 'you guys made these predictions, they have been vindicated or falsified, please check your new calibration and ponder how to do better in the future' but 'so, what do you guys think now?'

The discussion has been a little more aggressive than I hoped for, but I still see changing opinions, which is healthy: it'd be strange if the passage of time didn't change one's belief at all!

Replies from: thomblake
comment by thomblake · 2011-10-26T17:11:45.676Z · LW(p) · GW(p)

Leave it unchanged due to a complicated convergence of pro and anti evidence?

For anyone who actually worked out figures before and after, this seems like it would be the least likely scenario.

Replies from: gwern
comment by gwern · 2011-10-26T17:28:42.143Z · LW(p) · GW(p)

Yes, it is extremely improbable that the evidences would approximately or exactly counterbalance but in fairness I had to mention it, else it wasn't a complete breakdown (greater, less, equal).

comment by brazil84 · 2011-10-20T19:47:27.884Z · LW(p) · GW(p)

I can't remember exactly what I said in the last thread, but I think my opinion is basically the same now. I am reasonably confident that Knox and Sollecito were involved in the murder and very confident that Guede was.

Replies from: TrE
comment by TrE · 2011-10-20T20:28:12.944Z · LW(p) · GW(p)

What evidence did you collect since that last post, and how shifted it your views (rather, how did it fail to shift them)?

Replies from: brazil84
comment by brazil84 · 2011-10-20T21:10:05.547Z · LW(p) · GW(p)

The main evidence was that the appeals court in Italy reversed the convictions of Knox and Sollecito. This undermined my confidence a bit. On the other hand, arguing that Knox and Sollecito were involved in the murder has made me a bit more confident in my beliefs. I hope that this is because arguing has given me the opportunity to think more carefully about the case, but it may also be the false confidence which comes from emotional investment in a position. Either way, I doubt it's made much of a difference since I was pretty confident from the beginning.

Replies from: Jack
comment by Jack · 2011-10-20T21:16:15.867Z · LW(p) · GW(p)

Did you at any point update on your fellow Less Wrong posters' estimates?

Replies from: brazil84
comment by brazil84 · 2011-10-20T21:49:40.656Z · LW(p) · GW(p)

I'm not sure what you are asking, but the opinions of other posters here has not had much of an impact on my own.

Replies from: wedrifid, Jack
comment by wedrifid · 2011-10-21T01:33:53.382Z · LW(p) · GW(p)

And here we have a case study on what not to do and why.

Replies from: brazil84
comment by brazil84 · 2011-10-21T01:39:20.969Z · LW(p) · GW(p)

If you want to make an argument for why I should put more weight on other posters' opinions about Knox and Sollecito, I'm happy to consider it.

Replies from: wedrifid
comment by wedrifid · 2011-10-21T01:44:55.267Z · LW(p) · GW(p)

I'm afraid this is a lesson for others to learn by observation and not one which you can learn yourself (without changing your mind). The reasoning goes along the lines:

  • brazil84 didn't learn from the opinions and reasoning of other fairly rational and intelligent people.
  • brazil84 expended sufficient energy on the topic in question to be able to arrive at a sane conclusion.
  • brazil84 did not arrive at a sane conclusion.
  • Don't do what brazil84 did because it makes you wrong and also makes you look silly.

Note that this is both an somewhat opposing but also complimentary lesson to the one Eliezer notes.

Replies from: brazil84
comment by brazil84 · 2011-10-21T01:54:09.119Z · LW(p) · GW(p)

I'm afraid this is a lesson for others to learn by observation and not one which you can learn yourself (without changing your mind).

I vaguely recall that you got pretty annoyed at me a year or so ago when I pointed out a contradiction in your reasoning. I suspect that your anger at me over that incident is informing your commentary.

But anyway, if there really are any lurkers reading this, feel free to look back at the actual arguments I made concerning Knox and draw whatever you conclusion you like. Also pay specific attention to my exchange with wedrifid.

Replies from: Desrtopa, magfrump, wedrifid, pedanterrific
comment by Desrtopa · 2011-10-21T02:25:56.747Z · LW(p) · GW(p)

I vaguely recall that you got pretty annoyed at me a year or so ago when I pointed out a contradiction in your reasoning. I suspect that your anger at me over that incident is informing your commentary.

I've had no interaction with you on this site at all, but I have read your posts on the previous Amanda Knox threads, and while I believe I have a far greater aversion than wedrifid to making statements so likely to antagonize others, I have to say I find your judgment in this case in conjunction with your position as a lawyer downright frightening.

Replies from: brazil84
comment by brazil84 · 2011-10-21T02:39:40.968Z · LW(p) · GW(p)

Well what exactly frightens you? I'm not a judge.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T02:50:30.157Z · LW(p) · GW(p)

Judges are mostly selected from among lawyers, so that would be a lot more comforting if I were confident that the selection process were a genuinely good filter for people of exceptional judgment. But I would have a lot more trust in our justice system if I thought that lawyers tended to be people who would not readily become convinced of and argue strongly for positions in the absence of good reasons for believing them true.

Replies from: Prismattic, wedrifid, brazil84
comment by Prismattic · 2011-10-21T03:04:03.221Z · LW(p) · GW(p)

Judges are mostly selected from among lawyers...

At least in the United States, judges are mostly selected from among prosecutors. Defense attorneys, including public defenders, aren't very well represented on the bench. General judgment aside, this a serious systemic bias of the system.

Replies from: lessdazed
comment by lessdazed · 2011-10-21T03:13:47.647Z · LW(p) · GW(p)

serious systemic bias of the system.

What mechanism makes it a problem? I can see why it would perhaps be most fair for an individual to have one of a former prosecutor and former public defender presiding over the individual's original trial and appeal. The more judges make binding rules for the system, rather than in their courtroom, the more of a problem this would be (though I am under the impression this is not the case).

But why are individual differences in judicial bias OK?

Replies from: Prismattic
comment by Prismattic · 2011-10-21T03:24:49.998Z · LW(p) · GW(p)

I see it as a problem in the sense that prosecutors and defenders are conditioned to view the judicial process in somewhat different ways, and I don't think that judges can simply wave away years of conditioning to see things from a prosecutorial point of view.

Individual bias isn't great either, but at least there the bias isn't necessarily going to be in the same direction at each step of the process. The fact that the trial judge and all the appeals court judges are all likely to be former prosecutors, on the other hand, cuts the same direction at every step.

Replies from: lessdazed
comment by lessdazed · 2011-10-21T03:39:01.432Z · LW(p) · GW(p)

Individual bias isn't great either, but at least...

I think this is a legitimate but small concern.

If half of all judges at each level were former prosecutors and half former defense attorneys, half of those who had a trial and one level of appeal would face the same bias at each step (assuming even promotion, and unless this was specifically corrected for).

A more fair system than evening out representation would be embracing a type of bias and having formal rules counteracting that, e.g. have all judges be former prosecutors and have a set of judicial ruels favoring defendants.

I think it likely you are being blinded to the gross unfairness of having an individual tried under a former defense attorney when the rules are written with no regard for bias or assuming the average judicial bias is in favor of the prosecutor, or under a former prosecutor even if half of all judges are former defense attorneys, by the legitimate point that fairness would be increased if each defendant had at most one of each type between trial and appeal.

This is especially true considering how much less important appeal is than an original trial.

comment by wedrifid · 2011-10-21T03:07:23.002Z · LW(p) · GW(p)

Judges are mostly selected from among lawyers

Only mostly? I had assumed it was an actual legal requirement. That's interesting. Where you come from how many judges have ever not been lawyers and how on earth do they know what they are doing?

EDIT: From the looks of it some (40) states in the US allow non-lawyers to be low level judges, usually for small towns doing straightforward cases. From what I can tell in Australia (and most comparable countries) a law qualification of some sort is required.

Replies from: Desrtopa, Vladimir_M, Jack
comment by Desrtopa · 2011-10-21T03:22:39.177Z · LW(p) · GW(p)

I don't know if there are any, but given the sheer number of judges, I would suspect that there have been judges who have never served as lawyers; there is no requirement that a federal judge have ever served as an attorney, and requirements for state judgeship vary by jurisdiction.

The Bureau of Labor Statistics states that a bachelor's degree and work experience are the minimum requirements for judgeship or a magistrate position, but most workers have law degrees, so I'd take it as implied that some do not, and are thus exceedingly unlikely to have been lawyers.

Replies from: Prismattic
comment by Prismattic · 2011-10-21T03:29:22.210Z · LW(p) · GW(p)

It's rare now, but used to be common, for prospective lawyers to pursue an apprenticeship rather than a law degree. You can still use either as a qualification to take the bar exam.

comment by Vladimir_M · 2011-10-21T03:20:39.932Z · LW(p) · GW(p)

That depends on the jurisdiction, and also on how exactly you define "lawyer." (Do you mean someone with a law degree, or a member of the local bar association or some equivalent guild? The former is usually, but not quite always, a requirement for the latter.)

If anything, in many state and local jurisdictions within the U.S., judges are elected by popular vote, and I would guess that in some of those there are no such requirements for candidates, at least in theory.

Interestingly, for a U.S. Supreme Court appointment, a law degree from a top 14 law school (and at least one academic degree from Harvard or Yale) has been a de facto requirement for decades, but as recently as the 1930s and 1940s, there have been occasional SCOTUS justices appointed without a law degree at all.

Replies from: wedrifid
comment by wedrifid · 2011-10-21T03:29:52.888Z · LW(p) · GW(p)

Apparently the last United States Supreme Court Justice without a law qualification was Robert H. Jackson - although he passed the bar exam without official training and was a prominent practicing lawyer. I haven't found the last time someone was appointed to that role without passing the bar but research so far does seem to suggest it is an entirely political position, without qualifications required.

Replies from: Jack
comment by Jack · 2011-10-21T03:37:58.237Z · LW(p) · GW(p)

They've all been lawyers, it's just not an official requirement.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T03:41:15.623Z · LW(p) · GW(p)

Presumably for the same reason there's technically no official requirement that they be human, either.

Replies from: wedrifid
comment by wedrifid · 2011-10-21T05:42:49.677Z · LW(p) · GW(p)

That is, those with the power to appoint such judges would look like tools if they voted in non-lawyers or non-humans so they will not do either.

(It occurs to me there is a mutual exclusion joke in there somewhere.)

comment by Jack · 2011-10-21T03:14:21.471Z · LW(p) · GW(p)

It actually isn't a requirement for Supreme Court justices -- I'm not sure about other cases.

comment by brazil84 · 2011-10-21T03:06:47.202Z · LW(p) · GW(p)

I would have a lot more trust in our justice system if I thought that lawyers tended to be people who would not readily become convinced of and strongly for positions in the absence of good reasons for believing them true.

I see your point, but I suspect the problem is more in your own judgment than in mine. Consider that I have had the experience of being wrong on these sorts of issues -- and having to face it -- many many times.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T15:03:22.265Z · LW(p) · GW(p)

In this case, knowing that you persist in your assignment of a high likelihood of guilt for Knox and Sollecito given the data that's now available to you, I feel confident in saying that your ability to say oops is too poor.

After the advent of DNA testing, retrospective analysis of many crimes exonerated people who had previously been convicted. Had this case occurred before DNA testing was available, Knox and Sollecito would most likely have been convicted, but a DNA test should have been sufficient to exonerate them.

Replies from: brazil84
comment by brazil84 · 2011-10-21T15:29:00.525Z · LW(p) · GW(p)

In this case, knowing that you persist in your assignment of a high likelihood of guilt for Knox and Sollecito given the data that's now available to you, I feel confident in saying that your ability to say oops is too poor.

FWIW that assessment happens to be incorrect. I say "oops" regularly. And even in my professional life where there is a lot of money at stake, I occasionally have to withdraw a case and apologize. Or ask for leave to amend a paper.

Had this case occurred before DNA testing was available, Knox and Sollecito would most likely have been convicted, but a DNA test should have been sufficient to exonerate them.

Exactly what DNA evidence do you believe exonerates them? I am not aware of any, but I am happy to consider it in good faith. And yes, revise my probability estimates accordingly.

My understanding is that some doubt has been cast on the DNA evidence against the two. Which isn't the same thing as being exonerated. But I really would like to hear about such evidence.

Replies from: komponisto, Desrtopa
comment by komponisto · 2011-10-21T15:35:35.185Z · LW(p) · GW(p)

Exactly what DNA evidence do you believe exonerates them?

The DNA evidence showing that Guede was the killer.

This is exactly the sort of thing that gets people exonerated under the Innocence Project. The only difference is, in most cases, the authorities don't usually go back to the scene desperately looking for new evidence to incriminate the original suspect.

Replies from: brazil84
comment by brazil84 · 2011-10-23T10:39:01.400Z · LW(p) · GW(p)

The DNA evidence showing that Guede was the killer.

This is exactly the sort of thing that gets people exonerated under the Innocence Project.

I completely disagree. As far as I know, Guede's fingerprints were found at the scene of the crime. So that if years later, his DNA was found to have been there, it should not have much of an effect of peoples' assessment of the case. It would be a surprise if his DNA were NOT found at the crime scene.

Replies from: komponisto
comment by komponisto · 2011-10-23T11:32:41.302Z · LW(p) · GW(p)

Wait, what? You're saying that the case against Guede is even stronger than I implied, and yet you're disagreeing with me?

The evidence against Guede -- of whatever type -- is what exonerates Knox and Sollecito. The more evidence against him, the more exonerated they are.

If, years later, DNA and fingerprints were found from someone other than the person convicted, that would make it even more likely for the conviction to be overturned.

Replies from: brazil84
comment by brazil84 · 2011-10-23T11:42:16.135Z · LW(p) · GW(p)

The evidence against Guede -- of whatever type -- is what exonerates Knox and Sollecito.

Only if you substantially rule out the possibility that all 3 were involved in the murder.

ETA: Besides, the claim on the table seems to be that if you look at the case without DNA evidence; and then ADD DNA evidence, it would substantially reduce, basically to zero, the assessed chances that Knox and Sollecito were involved in the murder. Agreed?

Replies from: komponisto
comment by komponisto · 2011-10-23T11:53:29.185Z · LW(p) · GW(p)

Only if you substantially rule out the possibility that all 3 were involved in the murder.

Why should we privilege that hypothesis?

ETA: Besides, the claim on the table seems to be that if you look at the case without DNA evidence; and then ADD DNA evidence, it would substantially reduce, basically to zero, the assessed chances that Knox and Sollecito were involved in the murder. Agreed?

No. Or at any rate, that's not an interesting claim, so I don't see why it should be on the table.

Replies from: brazil84
comment by brazil84 · 2011-10-23T12:11:14.821Z · LW(p) · GW(p)

Why should we privilege that hypothesis?

So you are saying that there are only two choices: (1) privileging the hypothesis; and (2) substantially ruling it out?

No. Or at any rate, that's not an interesting claim,

If it's not interesting to you, then probably you should not have tried to answer my question. Here is the claim which was made:

Had this case occurred before DNA testing was available, Knox and Sollecito would most likely have been convicted, but a DNA test should have been sufficient to exonerate them.

I asked this:

Exactly what DNA evidence do you believe exonerates them?

And you said this:

The DNA evidence showing that Guede was the killer.

Since Guede's fingerprints were (apparently) found at the scene, extra DNA evidence which confirms his presence at the scene should not have much of an effect on anyone's assessments of the likelihood of any conclusion.

Replies from: komponisto
comment by komponisto · 2011-10-23T12:52:57.536Z · LW(p) · GW(p)

So you are saying that there are only two choices: (1) privileging the hypothesis; and (2) substantially ruling it out?

In a word: yes.

The hypothesis in question has low prior probability, and hence is "substantially ruled out" by default, unless there is strong evidence pointing to it. In this case, there isn't; people who think there is are, almost invariably, anchoring on the probability that they assigned (or that the investigators assigned) to Knox and Sollecito's guilt before Guede was discovered.

If it's not interesting to you, then probably you should not have tried to answer my question.

On the contrary, I inferred from your question (correctly) that you didn't understand the point about the evidence against Guede exonerating Knox and Sollecito.

Here is the claim which was made:

Had this case occurred before DNA testing was available, Knox and Sollecito would most likely have been convicted, but a DNA test should have been sufficient to exonerate them.

[...]

Since Guede's fingerprints were (apparently) found at the scene, extra DNA evidence which confirms his presence at the scene should not have much of an effect on anyone's assessments of the likelihood of any conclusion.

Most likely, the person who made the above claim simply wasn't aware of the fingerprint evidence (or, possibly, the difference between fingerprint evidence and DNA evidence). By the principle of charity, that shouldn't have stopped you from understanding and addressing their real point, which was that Knox and Sollecito should have been dropped as suspects as soon as the physical evidence turned out to implicate Guede and not them.

Replies from: Desrtopa, brazil84
comment by Desrtopa · 2011-10-23T14:38:51.110Z · LW(p) · GW(p)

Most likely, the person who made the above claim simply wasn't aware of the fingerprint evidence (or, possibly, the difference between fingerprint evidence and DNA evidence).

I had, in fact, forgotten about the fingerprint evidence, but I stand by my claim that Knox and Sollecito would probably have been convicted prior to DNA testing, given that even with DNA testing they were only released on appeal, and with DNA testing we have a much higher burden of expectation of evidence to meet. To say that they probably would have been convicted does not and was not intended to mean that they should have been convicted given the state of evidence that would have been available in that case.

comment by brazil84 · 2011-10-23T18:13:41.630Z · LW(p) · GW(p)

The hypothesis in question has low prior probability,

Prior to what? Prior to finding the evidence against Guede or prior to considering any evidence at all?

I inferred from your question (correctly) that you didn't understand the point about the evidence against Guede exonerating Knox and Sollecito.

I do understand the point, I simply happen to disagree with you at the moment. Anyway, if you want to address a different issue from the one under discussion, it would be helpful if you made it clear from the beginning.

By the principle of charity, that shouldn't have stopped you from understanding and addressing their real point, which was that Knox and Sollecito should have been dropped as suspects as soon as the physical evidence turned out to implicate Guede and not them.

I think that's too much of a leap. Charity must be balanced with the principle that it's often a mistake to try to put words in peoples' mouths.

comment by Desrtopa · 2011-10-21T15:32:14.145Z · LW(p) · GW(p)

Did you read the independent experts' report that Komponisto linked to?

Replies from: komponisto, brazil84
comment by komponisto · 2011-10-21T16:03:19.899Z · LW(p) · GW(p)

(Er, not to sound vain, but my collaborator and I did a bit more than link to the report! ;-) )

comment by brazil84 · 2011-10-21T15:37:00.507Z · LW(p) · GW(p)

No I did not. As noted above, the main new evidence I have is the fact that the convictions were thrown out.

Would you mind quoting the part of the report which talks about the exonerating DNA evidence?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T15:50:22.958Z · LW(p) · GW(p)

Each component of the report in which they retested the samples (knife and bra clasp) for biological evidence of Knox and Sollecito returned negative results, as detailed in the conclusion. Having found specific reasons to doubt the results of the Italian crime labs' testing, the retest found no positive evidence associating Knox or Sollecito with the crime, and this is a case where absence of evidence is significant evidence of absence.

Replies from: brazil84
comment by brazil84 · 2011-10-23T10:23:02.952Z · LW(p) · GW(p)

Each component of the report in which they retested the samples (knife and bra clasp) for biological evidence of Knox and Sollecito returned negative results,

Let's make sure I understand your argument: You seem to be saying that the (apparent) lack of DNA evidence on the knife and bra clasp is convincing evidence that Knox and Sollecito were NOT involved in the murder.

Do I understand you correctly?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-23T14:33:10.214Z · LW(p) · GW(p)

There was an abundance of physical evidence of Rudy Guede on the scene. If Knox and Sollecito had any physical involvement with the crime, they should have left biological evidence on a similar order, but in fact tests for evidence of their involvement did not return positive results except when corrupted by serious mishandling and poor testing procedures. The knife and bra clasp were major pieces of the prosecution's case because they alleged that they held genetic evidence implicating Knox and Sollecito, but in fact they did not, and even if they had carried evidence of Knox and Sollecito, it would have been a suspiciously small amount of evidence compared to what one would reasonably expect had they actually been involved.

Think of the allegation of Knox and Sollecito's involvement in the murder as a claim that there is an elephant in a room. Another party examines the room and finds...

X: Well, there does seem to be an elephantish sort of smell in the room, but it's otherwise devoid of large mammals.

Y: But you agree that it's a distinctly elephantish sort of smell?

X: Yes, it does smell much more like an elephant than anything else I can think of.

Y: In that case, the presence of an elephant makes it far more likely for you to observe this smell than the non-presence of an elephant, therefore it meets the bayesian definition of evidence, so you must revise your belief in the presence of an elephant upwards!

X: But hiding an elephant in a room is very difficult. If there were actually an elephant in this room, I would expect a lot more evidence than that. I can't think of any plausible way that you could get an elephant in here and hide every sign of its presence but its smell, only very implausible ones. Your claim was sufficient evidence to promote the hypothesis of an elephant in this room to my attention in the first place, so this is less evidence than I need to maintain my prior uncertainty. To maintain my prior uncertainty, I would need to observe evidence that gave significant reason for suspecting the presence of an elephant, such as this smell, while finding some sort of arrangement that could plausibly hide an elephant. This, on the other hand, is a small enough amount of evidence that I must revise my confidence to near certainty against.

It is reflective of a suspiciously poor case that the prosecution brought so little biological evidence against Knox and Sollecito compared to the one person we can be almost certain was actually involved. The pieces of evidence were mishandled, making them suspect to begin with. This provided an opportunity for us to make our beliefs pay rent. Given the state of the evidence against them, most of us on this site concluded that Knox and Sollecito were probably not involved in the murder, so the biological evidence brought forward by the police was probably not contingent on their presence at the crime, but due to subsequent corruption and mishandling of the evidence. Thus, we could predict that the independent experts' review of the evidence would find that when properly processed, it did not point to Knox and Sollecito's presence at the crime. If the evidence were contingent on their presence at the crime, we would not expect to observe this.

So do you concede that your high confidence in their involvement did not predict observations as well as our belief that they were probably not involved?

Replies from: brazil84
comment by brazil84 · 2011-10-23T18:04:55.067Z · LW(p) · GW(p)

There was an abundance of physical evidence of Rudy Guede on the scene. If Knox and Sollecito had any physical involvement with the crime, they should have left biological evidence on a similar order.

Well I'll consider this argument, but let's make sure we are on the same page about biological evidence. According to one web site I found, Guede's DNA was found (1) on a swab of Kercher's privates; (2) mixed with Kercher's blood on Kercher's handbag and the left cuff of her sweatshirt; and (3) on toilet paper in one of the bathrooms in the house.

Do you agree with that?

So do you concede that your high confidence in their involvement did not predict observations as well as our belief that they were probably not involved?

Not yet as I am skeptical of your argument that involvement by Knox or Sollecito would have most likely resulted in the same kind of biological evidence as there was implicating Guede. But I'm willing to consider your argument and I admit that I have not heard it before today.

Let's start by making sure we agree about the DNA evidence against Guede.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-23T19:29:45.131Z · LW(p) · GW(p)

That reflects my understanding of the state of the DNA evidence against Guede.

Keep in mind that that does not imply that this is the sum of all DNA evidence Guede left on the scene; when you have already found this much biological evidence, there is no reason to continue searching in order to obtain a comprehensive inventory of every trace left by the suspect.

Replies from: brazil84
comment by brazil84 · 2011-10-23T20:19:44.054Z · LW(p) · GW(p)

That reflects my understanding of the state of the DNA evidence against Guede.

Well, I'm not an expert on DNA evidence but just based on common sense, it seems to me that if playing the primary role in a murder and sexual assault reasonably leaves 2 DNA traces in a person's blood stains a 1 trace in the person's privates, it's plausible that playing a secondary role might very well leave no DNA traces in the person's blood and none in their privates.

Of course the DNA traces in other parts of the house are far less interesting since Knox and Sollecito can be expected to have left DNA biological evidence there regardless of whether they played some role in the murder.

So I remain skeptical of your argument but I am happy to consider an authoritative source which says that even someone who plays a secondary role in a murder with a knife is very likely to leave biological traces behind. Do you have such an authority? Or are you just going by your own general knowledge and common sense?

Keep in mind that that does not imply that this is the sum of all DNA evidence Guede left on the scene; when you have already found this much biological evidence, there is no reason to continue searching in order to obtain a comprehensive inventory of every trace left by the suspect.

I disagree. The authorities had every reason to continue searching for DNA evidence since they suspected others besides Guede.

Replies from: Desrtopa, brazil84
comment by Desrtopa · 2011-10-23T23:05:26.167Z · LW(p) · GW(p)

Well, I'm not an expert on DNA evidence but just based on common sense, it seems to me that if playing the primary role in a murder and sexual assault reasonably leaves 2 DNA traces in a person's blood stains a 1 trace in the person's privates, it's plausible that playing a secondary role might very well leave no DNA traces in the person's blood and none in their privates.

The prosecution claimed that more than one person must have been involved in the murder because, they alleged, Kercher was stabbed more times than was likely by a single assailant, and the wounds were consistent with the use of more than one knife. However, the latter part has been challenged, and I am myself aware of murders known to be committed by a single person in which the victim was stabbed more times than Kercher was. The allegation was a particularly ignorant one in the first place. However, assuming that it was true that more than one person was involved in stabbing Kercher, then even if he was the only one who sexually assaulted her, then from my own knowledge of forensics I can say that it is extremely unlikely that only one person would have left biological traces on her unless everyone else was wearing extensive protection. Keep in mind that the contrast is not 3 traces versus zero traces, but three distinct samples which have considerably more than the threshold needed to be detectable by the forensic processes versus no traces above threshold level; if anyone else was involved in physically stabbing Ms. Kercher to death, as the prosecution claimed, they would have to have done so while leaving behind no traces within orders of magnitude of what Guede left.

I have studied enough of forensics and biological labwork to make more than a common sense guess in this matter, but if my say so isn't enough for you, I could email a forensics specialist, although you could do the same. I'm not aware of any website that explains this, although that doesn't mean that that there are none.

I disagree. The authorities had every reason to continue searching for DNA evidence since they suspected others besides Guede.

The traces of Guede's DNA were acquired by a simple procedure; find a spot likely to yield biological evidence, take a sample, test it. A swab from Kercher's genitals, for example, contained DNA from Guede. They did not test to see "let's see how many swabs we can take which register positive for Guede's DNA," because it's unnecessary.

You seem to be treating the distinct samples as if they were individual hairs, where a person could plausibly leave behind a few or none at all, but that simply isn't an accurate model.

Replies from: komponisto, brazil84
comment by komponisto · 2011-10-23T23:26:51.915Z · LW(p) · GW(p)

The prosecution claimed that more than one person must have been involved in the murder because, they alleged, Kercher was stabbed more times than was likely by a single assailant, and the wounds were consistent with the use of more than one knife.

None of that, of course, was the real reason. The real reason was that they had initially arrested Knox, Sollecito, and Lumumba on the basis of crackpot psychological theories, and had egg on their face after having to release Lumumba when he turned out to have an unimpeachable alibi; so they needed Knox and Sollecito to still be guilty in order not to look like the complete morons that they, in fact, were. The bottom line was already written, and it was motivated searching from that point on.

comment by brazil84 · 2011-10-24T00:42:25.216Z · LW(p) · GW(p)

The prosecution claimed that more than one person must have been involved in the murder because, they alleged, Kercher was stabbed more times than was likely by a single assailant, and the wounds were consistent with the use of more than one knife.

For what it may be worth, I don't think this is a completely accurate summary of the prosecution's argument. For example, it seems that the prosecution argued that the lack of defensive wounds suggests multiple attackers. Also, the fact that she was (allegedly) stabbed on both sides of her neck.

but three distinct samples which have considerably more than the threshold needed to be detectable by the forensic processes versus no traces above threshold level;

How much above the threshhold were each of the 3 samples which matched Guede?

I have studied enough of forensics and biological labwork to make more than a common sense guess in this matter

Well what's your job; educational background, etc?

find a spot likely to yield biological evidence, take a sample, test it

I'm not sure I understand your point. Do you agree with me that this sampling would have been done in batches? Do you agree that Knox and Sollecito were suspects almost from the very beginning? Do you agree that therefore the authorities would have had reason to continue collecting DNA evidence even after they found crime scene samples which clearly matched Guede?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-24T05:07:32.821Z · LW(p) · GW(p)

For what it may be worth, I don't think this is a completely accurate summary of the prosecution's argument. For example, it seems that the prosecution argued that the lack of defensive wounds suggests multiple attackers. Also, the fact that she was (allegedly) stabbed on both sides of her neck.

Had she been physically restrained by anyone else, we should strongly expect that person to have left biological traces. Besides, it's easy to stab someone in both sides of the neck without switching hands. Like the claim that she was stabbed too many times for one person to account for, this sounds a great deal like reaching to rationalize a story.

How much above the threshhold were each of the 3 samples which matched Guede?

I don't know, although from the fact that all sources, including the Massei-Cristiani report, agree that there was an "abundance" of genetic evidence, I can infer that the traces were well above the limit of quantification, whereas the alleged genetic material from Sollecito, when tested by the police, was amplified by a procedure which increases sensitivity by more than an order of magnitude above the base level of detection. This places a ceiling for the amount of genetic material attributed to Sollecito of about one thirtieth of what was contained in any of the samples from Guede, but that's assuming that Guede's samples were only slightly over the limit of quantification. To be described as an "abundance", there was probably many times more. And the independent experts' report determined that the DNA from Sollecito, along with three other people on the sample, was probably due to corruption of the evidence well after the crime was committed.

Amanda Knox's DNA was found in easily measurable levels on a knife that, independent report determined, had no traces of blood on it and could not have been used in the murder at all; it was improperly flagged as a piece of evidence in the first place.

Well what's your job; educational background, etc?

I have a Bachelor's in Environmental Science, currently pursuing credentials to become a high school chemistry teacher. In the meantime, I tutor.

I'm not sure I understand your point. Do you agree with me that this sampling would have been done in batches? Do you agree that Knox and Sollecito were suspects almost from the very beginning? Do you agree that therefore the authorities would have had reason to continue collecting DNA evidence even after they found crime scene samples which clearly matched Guede?

Yes, yes, no. The sampling was done in batches, but not in a comprehensive "let's test everything in the room at once" sweep. Knox and Sollecito were suspects from near the beginning, but it was on the basis of a scenario that was quickly proven to be wrong. Once it was proven that the person who they concluded that Knox's testimony had implicated could not possibly have been involved, they had practically no case for suspecting Knox and Sollecito at all. What they did have was a great deal of motivation to find evidence implicating Knox and Sollecito, because otherwise they would look and feel like idiots.

When they did the initial sampling and found multiple traces of evidence from Guede, they had already reached a state where it was unlikely that if someone else had been physically involved, they would have missed the evidence of them. They should have revised downwards from the prior likelihood that any randomly selected murder would be committed by multiple people. They had obtained evidence such that the hypothesis of Knox and Sollecito's involvement should have been discarded, given that under interrogation they had failed to implicate the one person who was definitely involved, the other person "implicated" by their testimony had been conclusively proven not to be there, and they had not found biological evidence of their involvement under an initial search that would probably have found it if there were any. At this point, their initial scenario was effectively disproven beyond reasonable doubt, but still they insisted on continuing to search for evidence implicating two people they now had every reason to believe were innocent.

Replies from: brazil84
comment by brazil84 · 2011-10-24T06:24:41.662Z · LW(p) · GW(p)

Had she been physically restrained by anyone else, we should strongly expect that person to have left biological traces. Besides, it's easy to stab someone in both sides of the neck without switching hands. Like the claim that she was stabbed too many times for one person to account for, this sounds a great deal like reaching to rationalize a story.

So you agree then, that you mischaracterized the prosecution's argument?

I don't know, although from the fact that all sources, including the Massei-Cristiani report, agree that there was an "abundance" of genetic evidence, I can infer that the traces were well above the limit of quantification, whereas the alleged genetic material from Sollecito, when tested by the police, was amplified by a procedure which increases sensitivity by more than an order of magnitude above the base level of detection.

I'm not sure I understand your point. You seemed to be arguing that the amount of DNA traces left by Guede were "orders of magnitude" above the detection threshhold, i.e. at least a hundred times higher. And that if Knox or Sollecito had been in physical contact with Kercher, they would have left at least a hundredth of the DNA left by Guede -- enough to have been unambiguously detected.

Did I misunderstand your argument?

What they did have was a great deal of motivation to find evidence implicating Knox and Sollecito, because otherwise they would look and feel like idiots.

Ok, and assuming that's true, they would have had a strong motive to do more swabs right? And if they in fact did so, then under your hypothesis, they should have found additional Guede DNA material, right?

I have a Bachelor's in Environmental Science, currently pursuing credentials to become a high school chemistry teacher. In the meantime, I tutor.

And what classes did you take which gave you your expertise in forensics?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-24T07:45:06.753Z · LW(p) · GW(p)

So you agree then, that you mischaracterized the prosecution's argument?

Not in any way that makes their case seem weaker than it actually was.

I'm not sure I understand your point. You seemed to be arguing that the amount of DNA traces left by Guede were "orders of magnitude" above the detection threshhold, i.e. at least a hundred times higher. And that if Knox or Sollecito had been in physical contact with Kercher, they would have left at least a hundredth of the DNA left by Guede -- enough to have been unambiguously detected.

The traces left by Guede were all above the limit of quantification. The only piece of evidence on the scene that contained traces above the limit of detection for anyone other than Kercher or Guede was the bra clasp, which contained DNA from Kercher as the major contributor, and DNA above the limit of detection but below the limit of quantification for several other people, according to the independent experts' report, DNA which they claim was most likely due to mishandling and contamination. That leaves no traces above the limit of detection from any uncontaminated source for any potential perpetrator other than Guede, so if we are to posit that anyone else was involved, we must suppose that they did it while shedding orders of magnitude less biological material.

Ok, and assuming that's true, they would have had a strong motive to do more swabs right? And if they in fact did so, then under your hypothesis, they should have found additional Guede DNA material, right?

By the time they went to retrieve further evidence, Meredith Kercher had already been buried. Her body, along with the objects on which they had found traces of Guede's DNA, had already been removed. They did not re-swab her body to see if they could get more of Guede's DNA off of it, nor did they attempt to see if they could get more traces from any of the other articles on which they had already found his DNA. Had they scoured the scene for more traces of Guede, I would be surprised if they did not find any, but they weren't looking for more traces of Guede, they were looking for traces of Knox and Sollecito. Further traces of Guede found on the scene 47 days later might not even have been kept due to their lesser value as evidence since there was already plenty of opportunity for corruption and the case against him was rock solid; if they found, say, small traces of his DNA on the floor on the reexamination, they'd have no particular reason to make note of it.

And what classes did you take which gave you your expertise in forensics?

Two semesters of biology labs covered forensics. My labs in atmospheric and environmental chemistry also dealt with collection and analysis of trace chemicals from a scene.

Replies from: brazil84
comment by brazil84 · 2011-10-24T11:18:59.322Z · LW(p) · GW(p)

Not in any way that makes their case seem weaker than it actually was.

Umm, does that mean yes or no?

The traces left by Guede were all above the limit of quantification.

Umm, does that mean yes or no? And what are the numerical limits for quantification and detection?

By the time they went to retrieve further evidence, Meredith Kercher had already been buried.

Umm, does that mean yes or no?

Had they scoured the scene for more traces of Guede, I would be surprised if they did not find any, but they weren't looking for more traces of Guede, they were looking for traces of Knox and Sollecito.

But when you "scour the scene," there's no way to narrow your search to DNA of a particular individual. Because the matching is determined back at the lab. Agree?

Further traces of Guede found on the scene 47 days later might not even have been kept due to their lesser value as evidence since there was already plenty of opportunity for corruption and the case against him was rock solid; if they found, say, small traces of his DNA on the floor on the reexamination, they'd have no particular reason to make note of it.

If you claim that there is likely other DNA evidence against Guede which was discarded, then I will need a cite. I have an extremely hard time believing that the lab would have tested a sample; realized it was Guede DNA; and not made a note of it in the record which would have come into the trial materials.

Two semesters of biology labs covered forensics. My labs in atmospheric and environmental chemistry also dealt with collection and analysis of trace chemicals from a scene.

I don't think that's enough for your opinion to simply be accepted on the basis of authority. Is there no reference online for your claim that secondary participation by Knox or Sollecito -- such as grabbing or holding -- would have left plenty of DNA material which the Italian authorities would have been very likely to find?

At a minimum, if what you are is saying is true, then surely one of the defense experts would have testified at trial that Knox could not have been a participant because none of her DNA traces were on or about Kercher's person. Agreed?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-24T15:39:14.740Z · LW(p) · GW(p)

Umm, does that mean yes or no?

For practical purposes, no.

Umm, does that mean yes or no?

It means that I do not strongly expect that there would be anything left on the scene which they would file as further evidence against Guede.

But when you "scour the scene," there's no way to narrow your search to DNA of a particular individual. Because the matching is determined back at the lab. Agree?

Yes and no. If they already have already established previously that person X has come into contact with objects X Y and Z, further testing of objects X Y and Z is likely to reveal further traces.

For the latter last two points, I do not have a strong expectation that further evidence against Guede would have been brought to court given that later retrieval would have been less reliable, and the case against him was already watertight, nor do I have a strong expectation that the defense would have claimed that Amanda Knox could not have been involved based on the weakness of the evidence of her involvement.

If we're going to go on though, let's review.

Meredith Kercher is killed. Knox and Sollecito are waiting outside when the police arrive to investigate the residence, and Edgargo Giobbi tags Amanda Knox as a suspect within hours of the crime's report because he thought the way she swiveled her hips while putting on her protective shoes at the crime scene was unusual. Edgardo Giobbi claimed in a later interview

We were able to establish guilt by closely observing the suspect's psychological and behavioural reaction during the interrogation. We don't need to rely on other kinds of investigation.

Having established suspicion, Giobbi now had motivation to find more reasons to suspect her. On the basis of her mannerisms being judged unusual, she was brought in for interrogation, along with Sollecito, who she had claimed to be with that night. She alleges that she was badly mistreated, which the police deny. She was not told her legal rights, provided with a lawyer, or given an official interpreter. The police told Knox that Sollecito had changed his story and no longer said that he was with her that night at the presumed time of the murder. She was persuaded to sign a statement implicating her boss Lumumba as the killer.

After giving her statement implicating Lumumba, Amanda Knox was allowed a break to receive coffee and food, and then retracted her statement within hours, saying that she had been with Sollecito as she originally claimed, and had no knowledge of the killing.

Lumumba was arrested and held for two weeks, but produced a solid alibi. Crime labs matched the print found at the scene to Rudy Guede, police substitute Guede for Lumumba in their crime scenario, while retaining Knox and Sollecito as suspects, still purely on the basis of psychological profiling (keep in mind that they did not observe everybody else Kercher had known to see if anyone else also had suspicious mannerisms, with blinding to the hypothesis so the investigating police did not know whom they were supposed to find suspicious.)

Meanwhile, Guede, the only person with hard physical evidence placing him at the scene of the crime, fails to implicate either Knox or Sollecito in his testimony.

The police continued to search for evidence against Knox and Sollecito (and I will emphasize again, did not search to see if a comparable degree of evidence could be raised against anyone else Kercher had known) and produced a knife found in Sollecito's kitchen, which they claimed contained traces of Kercher's DNA despite her never having been in his kitchen. The evidence was improperly tested, and the independent experts' report found that the knife could not have been used in a murder at all.

The police returned to the scene 47 days after the murder, and searched for items which could produce evidence against Knox and Sollecito. They claimed to have found evidence on a bra clasp which had been cut from Kercher in the attack. Since the date of the first investigation, the investigators had moved the clasp four feet across the room and left it under a rug with a collection of other items. The independent experts' report found that the clasp predominantly contained traces from Kercher, but had small traces of DNA from four other people, one of whom was Sollecito. The report found that the evidence had been mishandled and probably corrupted and that the police did not follow proper testing procedures.

At this point, what probability do you assign to the proposition that Knox and Sollecito were involved in Kercher's murder? Do you still think that focusing a search for evidence against Knox and Sollecito in particular, beyond everyone else who could potentially have been involved in the crime scene, after they and the only person with forensic evidence placing him at the scene had mutually failed to implicate each other, was reasonable?

Replies from: Jack, brazil84
comment by Jack · 2011-10-24T16:11:36.664Z · LW(p) · GW(p)

I'd like to hear people's probabilities for Brazil revising his estimate down below 50% in the next year.

Replies from: JoshuaZ
comment by JoshuaZ · 2011-10-25T02:54:19.337Z · LW(p) · GW(p)

This is interesting. But I can see someone seeing it as rude to speculate on the chance that someone else is going to change their mind. In some contexts this could come across as condescending and can easily make worse feelings that a discussion involves others who are opponents rather than people mutually trying to get a better understanding of reality.

With that disclaimer out of the way: I'm estimate an 8% chance that Brazil will reduce his estimate below 50% in the next year and publicly say so on Less Wrong.

Replies from: Jack
comment by Jack · 2011-10-25T14:22:28.923Z · LW(p) · GW(p)

Mine is 2%.

Replies from: komponisto
comment by komponisto · 2011-10-25T14:42:58.111Z · LW(p) · GW(p)

Hmm, from the look of things, it might be time to update the model...

Replies from: Jack
comment by Jack · 2011-10-25T14:45:51.045Z · LW(p) · GW(p)

Whoa! Indeed :-(

Edit: In fact not my prediction stands.

comment by brazil84 · 2011-10-24T19:38:08.418Z · LW(p) · GW(p)

For practical purposes, no.

I think you are the one who has a bit of a problem saying "oops." Please just admit that you misstated the prosecution's argument. I promise you the sky won't fall as a result.

It means that I do not strongly expect that there would be anything left on the scene which they would file as further evidence against Guede.

I do not understand what your point is here. Maybe it will help if we quantify your argument:

First, what are the numerical thresholds involved for the amount of DNA required for detection and identification.

Second, how far above that threshold was Guede. Please answer the question with a rough percentage.

Third, what is the minimum amount of DNA one would reasonably expect to be left by Knox had she participated secondarily in the murder?

If they already have already established previously that person X has come into contact with objects X Y and Z, further testing of objects X Y and Z is likely to reveal further traces.

Further traces of Person X, right?

Anyway, please give me a cite for your (apparent) claim that other DNA evidence against Guede is likely to have been discarded. Or are you just speculating?

I have a strong expectation that the defense would have claimed that Amanda Knox could not have been involved based on the weakness of the evidence of her involvement.

Again, does this mean yes or no?

Look, you are presenting what is clearly a very solid argument for Knox's innocence if your assumptions are correct.

Your argument is as follows:

(1) If Knox had been involved in the murder, there would have been DNA traces of Knox on or about Kercher's person which the authorities would have been very likely to find.

(2) There were no such traces found.

(3) Therefore Knox was very likely NOT involved in the murder.

If (1) and (2) are true, (3) clearly follows. And there doesn't seem to be any dispute about (2). Further, you assert (1) based on your expertise with forensic DNA testing. Surely Knox's experts are at least as expert as you. So if (1) is true, then Knox's experts would have almost certainly made the this point..

Agreed?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-24T20:39:11.508Z · LW(p) · GW(p)

I think you are the one who has a bit of a problem saying "oops." Please just admit that you misstated the prosecution's argument. I promise you the sky won't fall as a result.

I agree that the prosecution made claims that I did not relay. I also did not relay that Giobbi originally flagged Amanda Knox as a suspect based on what he considered to be unusual mannerisms while putting on her safety shoes. I am happy to admit that I misstated the prosecution's argument, absent the implication that I omitted only information that strengthened their case. I do not agree that I understated the strength of the prosecution's case.

I do not know how far above the threshold for detection of DNA Guede's samples were; I can make inferences from the characterizations of the evidence, both from the prosecution and defense, that they were above the limit of quantification (which as a general rule is about three times higher than the limit of detection,) without using the same amplification procedure that was used on the bra clasp, which would further increase the sensitivity of that test. However, the reports which would give the quantitative values for the traces he left relative to the limit of detection, if they are available to the public at all, are in Italian.

I am prepared to accept if you do not consider my judgment in this case sufficiently authoritative; I can respect your suspicion on that count. We could suspend this discussion in order to contact a forensics expert and ask for an estimate of the likelihood that a person could be involved in physically grappling and stabbing a victim with a knife without leaving identifiable biological traces on the scene.

However, I think you would be guilty of motivated continuing, demanding evidence far in excess of what you need to alter your decision.

I affirm that I agree with statements 1, 2 and 3. However, I am not sure of the level of forensics expertise of Knox's defense; the independent commision certainly possesses greater expertise in forensics than I, and they affirmed that there was no reason based on the forensic data to suspect Knox and Sollecito's involvement. As for her defense, I know that they were able to take issue with the handling of the evidence by the police, but they could have done this by investigating "what are the procedures that a forensics specialist is supposed to take in such a situation, and did the police follow them? The case of the prosecution sets a low floor on how much familiarity I must assume that a trial team in a case dealing with forensics would have to have, so I have a high degree of uncertainty regarding the expertise of the defense. Further, despite being simply wrong, "absence of evidence is not evidence of absence" is a sufficiently pervasive truism (what do you call it when people treat something false as a truism?) that I do not have a very strong expectation that, even given a high level of expertise in forensics, the defense would present an absence of evidence as evidence of absence, rather than simply arguing that there was no reason to believe in their guilt (which the defense did.)

Will you provide your current judgment of the case based on the information I provided in my previous post? That information I can provide citations for, so we won't have to stall waiting on further expert input.

Replies from: brazil84
comment by brazil84 · 2011-10-24T21:09:29.307Z · LW(p) · GW(p)

Will you provide your current judgment of the case based on the information I provided in my previous post?

I have considered your argument in good faith and I reject it. You have not been able to answer simple, reasonable questions to let me understand and evaluate your argument. You have also evaded and ignored simple, reasonable questions.

Most importantly, you have not been able to provide an authoritative cite for your implicit claim that secondary involvement by Knox would have very likely resulted in Knox leaving DNA evidence which would very likely have been found. It's also strange to me that I have not found prominent mention of your argument anywhere, especially since it would have been available to Knox's defense (more specifically her experts) from the get-go.

In short, your argument has not stood up to mild scrutiny. However, if you can provide answers to my questions I will reconsider.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-24T21:26:39.921Z · LW(p) · GW(p)

It is my general experience that people provide arguments of the form "if X, we should strongly expect evidence Y, we do not observe Y, therefore we should strongly disbelieve X" far less often than they are applicable, which is why I do not have a strong expectation that it would have been used in this case contingent on its applicability.

I do not evade the question of how much more of Guede's DNA was found than is necessary to meet the detection limit, I affirm that I do not know, although I maintain that I have enough information to infer that it was much more than any other potential participants must have left.

At this point, I consider you to be evading the questions of whether the evidence you already have available to you supports a belief in Knox and Sollecito's guilt, and whether you still feel that the police were justified in holding them as suspects after they received the evidence implicating Guede. I see three ways this discussion can go from here. We can suspend it, and write to an independent expert in forensics, and thus establish whether a person with acknowledged expertise in forensics would agree with my judgment. We can continue based on the information for which we already have adequate citations, and you can provide your judgment based on that information, or we can abandon it as fruitless.

Replies from: brazil84
comment by brazil84 · 2011-10-24T21:35:16.794Z · LW(p) · GW(p)

It is my general experience that people provide arguments of the form "if X, we should strongly expect evidence Y, we do not observe Y, therefore we should strongly disbelieve X" far less often than they are applicable,

That's not my experience. In fact, the pro-Knox page linked to in the very first thread explicitly makes such an argument in general terms (not specific to DNA).

At this point, I consider you to be evading the questions of whether the evidence you already have available to you supports a belief in Knox and Sollecito's guilt,

Can you please quote the question I evaded?

I see three ways this discussion can go from here

It's up to you. I've considered your argument in good faith and rejected it. But the door is still open if you want to provide the information and citations I requested.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-24T21:49:21.378Z · LW(p) · GW(p)

Can you please quote the question I evaded?

From this comment

At this point, what probability do you assign to the proposition that Knox and Sollecito were involved in Kercher's murder? Do you still think that focusing a search for evidence against Knox and Sollecito in particular, beyond everyone else who could potentially have been involved in the crime scene, after they and the only person with forensic evidence placing him at the scene had mutually failed to implicate each other, was reasonable?

If you do not trust that I have sufficient knowledge to support the argument that the state of the biological evidence in this case more or less completely rules out the possibility of Knox and Sollecito's involvement, I am prepared to accept your discounting that argument (although I find your belief that the defense would necessarily have used it if it were valid naive, if arguments of that form were used as commonly as they merit, "absence of evidence is not evidence of absence" would not have become a popular saying in the first place.) We can of course try to contact an independent expert, but is your openness to the likelihood of Knox and Sollecito's innocence contingent on that particular proof?

Replies from: brazil84
comment by brazil84 · 2011-10-24T22:11:43.243Z · LW(p) · GW(p)

From this comment

I think it's pretty clear that my assessment of the probabilities has not changed after having considered your argument, but let me make it perfectly clear: my assessment has not changed.

Do you still think that focusing a search for evidence against Knox and Sollecito in particular, beyond everyone else who could potentially have been involved in the crime scene, after they and the only person with forensic evidence placing him at the scene had mutually failed to implicate each other, was reasonable?

Yes.

but is your openness to the likelihood of Knox and Sollecito's innocence contingent on that particular proof?

I've already stated that your argument is very solid if your assumption is correct. So I am conceding in advance that if you can support your assertion, my probability assessment will change a lot.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-25T01:24:24.649Z · LW(p) · GW(p)

Can you give a numerical probability? You claimed that your assessment had shifted somewhat in light of the information that Knox and Sollecito had been found not guilty on appeal.

I'm going to do a run down of my probability estimates for Knox, Sollecito, and Guede, given the evidence available to me excluding the argument I've already given for the unlikelihood of Knox and Sollecito's presence at the scene given the state of the forensic evidence. Could you explain what, if any of it, you disagree with, and how your own analysis would differ?

Prior probabilities. Common wisdom is that most people are killed by someone they know. I'm going to go with 80% likelihood of murder by an acquaintance, although I can't actually find a single figure all sources agree on. So we'll weight the prior probability of guilt such that people Kercher knows account for 80%, and everyone else accounts for 20%. Unfortunately, I can't find a good source estimating how many people most people know, and it depends how close a standard of acquaintance you're measuring. I'm going to give a ballpark estimate of about 1000, and thus apportion an average of .00125 prior likelihood of guilt between them.

For Knox, let's adjust up for closeness of acquaintance (we'll call it a factor of 10:1) for a likelihood of .0125. She had no prior arrest record; I'll adjust down by 70 percent to .00875, and she was a woman who was neither a close family member nor an intimate partner, so I'll adjust it down by another 90%, to .000875. I don't feel that the prosecution established any good reason to suspect a motive, but I'll be charitable to their case and not revise further down for that.

I'll call Sollecito's probability .0007, adjusting upwards for his increased likelihood as a male, but downwards based on his much lesser closeness to the victim; I have to take probability mass away from slight acquaintances if I'm adding it to close ones.

Guede was male, only slightly acquainted with Kercher, had been involved in breaking and entering prior to the case, and also did not have a clear motive. People with prior criminal records account for a majority of violent crimes despite being a minority of the population. The population without a criminal record is giving up a majority of their probability mass to the minority with, so this is a pretty significant boost. I don't know the proportion of Italy's population that has a record, but if we assume similar rates to the U.S. this will increase Guede's likelihood by about 11 times. So let's call his prior probability about .0077.

There's a considerable amount of fudge factor in these numbers, and you are of course free to take issue with them, but I think they give us a reasonable ballpark order to start with.

First, we'll deal with Guede. His handprint in blood places him conclusively at the scene of the crime (I doubt that anyone has ever left a handprint in blood at a scene at which they were not present) and he does not deny having been at the scene, so we'll call the odds of his presence infinitesimally below 1. He changed his story repeatedly over the course of his interrogation, beginning with "another anonymous black man did it while I was in the bathroom after having sex with her." The prior likelihood of this is very low, and Guede left DNA traces he was unlikely to have left if he was not involved in killing her. I'd adjust Guede up from the prior by an order of about 10^7, which would leave a likelihood of guilt that approximates to 1-(10^-5).

Let's move on to Amanda Knox. Giobbi first flagged her as a suspect based on the belief that her mannerisms at the crime scene were odd. I expect that a person is significantly more likely to behave oddly at a crime scene (relative to the norm for an uninvolved person) if they were involved than if they were uninvolved. I'd put an odds ratio of maybe 15 to 1 on it, except that Knox was already known to have odd mannerisms (such as doing yoga stretches in places considered inappropriate,) so I'd revise that down to maybe 5 to 1. So that gives us a probability of involvement for Knox of about .0044. All the evidence brought forward by the police after this point is filtered evidence, because they focused their investigations on Knox and Sollecito, and put more effort into finding reasons to suspect them than anyone else who might have been involved.

In the United States in 1976-1996, 16% of murders were committed by more than one person; since I don't have any better figures I'll assume similar rates for present day Italy. Ignoring the failure of forensics to turn up evidence of anyone else, I find the arguments posed by the prosecution for believing that the murder had multiple perpetrators extremely uncompelling. Arguments such as the number of stab wounds and the fact that Kercher had wounds on both sides of her neck are extremely weak evidence; particularly taken alongside claims such as one which they offered for the break-in being staged, that the pattern of the broken glass was inconsistent with a break from outside, which was tested and found to be false, these arguments sound to me like scrambling for anything that sounds like evidence. Ignoring the failure of anyone else to leave biological traces, I'd be willing to extend perhaps a 3 to 1 odds ratio on their evidence for multiple attackers, so together with the prior unlikelihood of a murder having multiple perpetrators, that brings Knox's likelihood of guilt to about .0022.

Knox and Sollecito failed to implicate Guede, and Guede failed to implicate Knox and Sollecito; for their mutual failure to implicate each other, I'd reduce Knox and Sollecito's likelihood about 20 times, bringing Knox to about .00011.

I do not find any evidence presented by the prosecution compelling with regards to establishing a motive or likelihood of presence at the crime for Knox or Sollecito, their case seems to me to be a collection of behaviors and actions attributed to Knox with the implication "this seems more unusual for a person who was not involved than a person who was." Since this evidence is filtered, I only find it reasonable to update on it to the extent that I believe the body of evidence is stronger than what I should expect for anyone with my current assignment of guilt subject to a similar police investigation. I think if you really looked and sincerely believed you had reason to find anything, you could find a substantial body of reasons to be suspicious of anyone. One of the most common ways that people err is in believing that a false proposition must have no valid evidence, and every argument for increasing your confidence in it must be refutable. I would have to assume that people I know are generally significantly weirder and more suspicious than most of the population to assign an odds ratio of even 10 to 1 on the prosecution's evidence, but my social circle probably is fairly odd, so I'll give them that, but I think I'm being generous.

All in all, that gives approximately .001 odds of guilt for Knox. Sollecito was tagged as a suspect mainly through association with her, so I would say that he is at most as likely as she is to have been involved.

Of course, there is plenty of uncertainty in these figures, and this does not portray the entirety of the relevant evidence even ignoring the improbability of other people involved in the murder not leaving biological traces (one particular piece of evidence I even left out deliberately, you can try and guess what,) but I think it reflects a reasonable probability estimate given that omission for an amount of evidence that a person can reasonably be expected to process without a substantial time commitment.

Replies from: brazil84
comment by brazil84 · 2011-10-25T12:51:56.352Z · LW(p) · GW(p)

Can you give a numerical probability?

Perhaps about 30%.

Could you explain what, if any of it, you disagree with, and how your own analysis would differ?

I don't have the energy to do a point by point response, but I will point out what I think is the central flaw in your reasoning.

The flaw, it seems to me, is that you seem to dismiss the circumstantial evidence against Knox (and Sollecito) as "filtered evidence." There are two problems with this.

First, the evidence is not filtered in the sense that the only evidence we (or the jury) saw is that which was cherry-picked by the prosecution. Knox and Sollecito both had the opportunity to gather and present evidence which would tend to exculpate them. To be sure, they did not have the same ability to get cooperation and compel the production of evidence as the authorities, but they surely had quite a lot. And they had the advantage over the authorities of being firsthand witnesses to their own whereabouts and actions.

Second, even filtered evidence can be very probative. To take Eliezer's hypothetical a step further, imagine that a particular coin is flipped exactly 1000 times and our hypothetical advocate tells us that between 641 and 1000 of the flips resulted in heads. Even though we do not know how the actual data was filtered, and even though our advocate probably has some kind of agenda, we can be pretty confident that the coin is biased.

If we know (or can make a good guess at) the advocate's agenda, we can get an even better handle on the situation. For example, if somebody tells you that he attends a Top 6 law school, it's pretty likely that he goes to Columbia, NYU, or Chicago. And not Harvard Yale or Stanford.

Replies from: Jack, Desrtopa, JoshuaZ
comment by Jack · 2011-10-25T14:50:38.723Z · LW(p) · GW(p)

Can you give a numerical probability?

Perhaps about 30%.

Wait a second. At the top of the thread you said your opinion hadn't changed. 30% from 90% is a big drop.

Replies from: brazil84
comment by brazil84 · 2011-10-25T16:11:56.752Z · LW(p) · GW(p)

Wait a second. At the top of the thread you said your opinion hadn't changed. 30% from 90% is a big drop.

No, what I am saying is that if Desrtopa's assertion is correct, then my estimate will drop from roughly 90% to roughly 30%.

Replies from: komponisto
comment by komponisto · 2011-10-25T16:18:14.023Z · LW(p) · GW(p)

How is your probability affected by what former FBI agent Steve Moore has to say?

Replies from: brazil84
comment by brazil84 · 2011-10-26T01:49:34.518Z · LW(p) · GW(p)

How is your probability affected by what former FBI agent Steve Moore has to say?

It's not, since Moore obviously is trying to spin the case in favor of Knox's position. For example, he falsely asserts that there was not evidence of Knox's presence at or near the crime scene. So I don't put a lot of stock in his authority.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T01:56:28.620Z · LW(p) · GW(p)

Since he is a qualified expert on forensics making essentially the same claim that I was about the state of forensic evidence, I'm curious to know what you would consider to be adequate corroboration for that point.

Why do you condition strongly on the prosecution's arguments, when their evidence has been found in many points to be false, mishandled, or exaggerated, but not condition at all on the arguments of Moore?

Replies from: brazil84, brazil84
comment by brazil84 · 2011-10-26T02:13:41.577Z · LW(p) · GW(p)

Why do you condition strongly on the prosecution's arguments, when their evidence has been found in many points to be false, mishandled, or exaggerated, but not condition at all on the arguments of Moore?

I'm not sure what you mean by "condition on," but I would be similarly skeptical (probably even more skeptical) if the prosecution assured us that it's perfectly plausible for the secondary participant in a murder such as this not to have had DNA traces found on or about the victim's person. Even if the assertion were made on behalf of the prosecution by a board certified forensic investigator.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T02:28:47.231Z · LW(p) · GW(p)

By "condition on," I mean "update your probability in light of." To refuse to update at all, you must suppose that it is no more likely that Moore would claim that the state of the evidence effectively rules out Knox and Sollecito's involvement if they were not involved than if they were.

So it seems that you are claiming that it is much more likely that the prosecution would produce the evidence and arguments that they did if Knox and Guede were guilty than if they were innocent (enough to multiply the likelihood of their guilt by orders of magnitude,) but no more likely that Moore, who has neither pay nor reputation riding on the outcome of the case, would claim that there is dramatically less evidence than we would expect to see in the case of Knox and Sollecito's involvement, if they were not involved than if they were.

Would you agree with that?

You gave a probability estimate of 90% back in Komponisto's first thread, and early in this one you said that you had revised your confidence on the fact that Knox and Sollecito had been found innocent on appeal, but now you are asserting exactly the same probability that you did back then. Why is that?

Also, I would appreciate it if you would answer my question about what you would consider to be adequate corroboration for my argument that if Knox and Sollecito had been involved we would strongly expect forensic evidence that we did not see.

Replies from: brazil84
comment by brazil84 · 2011-10-26T10:00:26.643Z · LW(p) · GW(p)

Would you agree with that?

Assuming that the various evidence I am considering comes from the prosecution, yes.

You gave a probability estimate of 90% back in Komponisto's first thread, and early in this one you said that you had revised your confidence on the fact that Knox and Sollecito had been found innocent on appeal, but now you are asserting exactly the same probability that you did back then. Why is that?

Here's what I said early in the thread:

The main evidence was that the appeals court in Italy reversed the convictions of Knox and Sollecito. This undermined my confidence a bit. On the other hand, arguing that Knox and Sollecito were involved in the murder has made me a bit more confident in my beliefs. I hope that this is because arguing has given me the opportunity to think more carefully about the case, but it may also be the false confidence which comes from emotional investment in a position. Either way, I doubt it's made much of a difference since I was pretty confident from the beginning.

My probability estimate remains roughly 90% and I think that's pretty clear.

Ok, now a question for you: Why are you so eager to find a contradiction in my posts?

Also, I would appreciate it if you would answer my question about what you would consider to be adequate corroboration for my argument that if Knox and Sollecito had been involved we would strongly expect forensic evidence that we did not see.

First of all, please do not weasel, i.e. change your position without acknowledging it. Your original point was about DNA evidence.

Anyway, what would support your argument is if you can produce a quote from a textbook, police manual, or other authoritative source which says, more or less, and in general terms, that even physically restraining another person will almost always leave biological traces which can be traced back to the person who did the grabbing or holding.

comment by brazil84 · 2011-10-26T02:09:29.999Z · LW(p) · GW(p)

Since he is a qualified expert on forensics making essentially the same claim that I was about the state of forensic evidence, I'm curious to know what you would consider to be adequate corroboration for that point.

I'm not sure it's the same claim. As I recall, your claim was limited to traces of Knox and Sollecito on or about Kercher's person. Moore's point is more general.

But anyway, what I had in mind was a statement which is not specific to the case. For example, a quote from a forensics textbook or a police manual.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T02:37:35.793Z · LW(p) · GW(p)

Yes, Moore's point is more general than mine, he points to additional evidence that it had not occurred to me that we would expect. Moore's point is stronger than mine.

I do not have a forensics textbook or police manual, but Moore probably does. If I ask him for a citation, and he provides one, would you consider that adequate?

Replies from: brazil84, brazil84
comment by brazil84 · 2011-10-26T10:05:54.149Z · LW(p) · GW(p)

Yes, Moore's point is more general than mine, he points to additional evidence that it had not occurred to me that we would expect. Moore's point is stronger than mine.

Moore's point is stronger if his assumptions are correct.

I do not have a forensics textbook or police manual, but Moore probably does. If I ask him for a citation, and he provides one, would you consider that adequate?

If it says more or less, and in general terms, that even physically restraining another person will almost always leave biological traces which can be traced back to the person who did the grabbing or holding.

comment by brazil84 · 2011-10-26T12:33:42.913Z · LW(p) · GW(p)

And by the way, if you really plan to research this, what would also be helpful to me would be a cite for the proposition that the Italian forensics labs may have (or did) find additional material attributable to Guede which did not make it into the record.

comment by Desrtopa · 2011-10-25T13:46:26.896Z · LW(p) · GW(p)

What sort of odds ratio would you assign to the evidence presented by the prosecution given the knowledge that it's filtered? If your other figures are not similar to mine, it would need to be more than two orders of magnitude higher than what I assign, or about 3,000 to 1.

My low weighting of the prosecution's evidence hinges, not simply on the fact that it is filtered, but that it is not much stronger than the evidence that I would expect them to find against anyone else given a similar level of investigation. So it is not analogous to dismissal of the evidence that "coin flips between 641 and 1000 were heads" on the basis that while true, it is filtered and so can be discounted. It is more analogous to receiving the evidence "at least six of ten coin flips came up heads," and deciding "If you had stronger evidence than that, you probably would have told me, and that is not much more evidence than I would expect to see from an average unbiased coin."

The defense extensively pointed out the weakness of the evidence brought forward by the prosecution, they did not put similar resources to the prosecution in order to raise similar evidence against anyone else to show how easy it would be. If people sincerely want to produce reasons for believing something, they will tend to both find and overweight them. I would bet at 1:1 odds that had the prosecution investigated me with a similar level of prior suspicion, they would have found as much or more reason to suspect me, and I may be atypical, but I do not think I am 1 in 3,000 suspicious. Conditioned on the facts that Knox was already known to have odd mannerisms, and was a foreigner from the perspective of the police (one of the original pieces of evidence that the police used to narrow her down as a suspect, for instance, was that she texted "see you later" to her boss, whom she was not about to see,) I think you will need to provide some very strong arguments to convince me that you are not dramatically overweighting.

Replies from: brazil84
comment by brazil84 · 2011-10-26T01:43:55.631Z · LW(p) · GW(p)

What sort of odds ratio would you assign to the evidence presented by the prosecution given the knowledge that it's filtered?

I'm not sure what you mean by "odds ratio" and I don't know exactly what evidence was presented by the prosecution, so it's hard to say. My assessment of 90% is based on the evidence I am aware of.

but that it is not much stronger than the evidence that I would expect them to find against anyone else given a similar level of investigation

I disagree. I shared some of my arguments about my interpretation of the evidence in the last couple threads.

comment by JoshuaZ · 2011-10-25T14:56:51.900Z · LW(p) · GW(p)

Are you saying that you now only estimate a 30% chance of guilt?

Replies from: brazil84
comment by brazil84 · 2011-10-25T16:10:50.362Z · LW(p) · GW(p)

Are you saying that you now only estimate a 30% chance of guilt?

No, what I am saying is that if Desrtopa's assertion is correct, then my estimate will drop from roughly 90% to roughly 30%.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T03:45:03.247Z · LW(p) · GW(p)

If you accepted my assertion that an appropriate assignment of guilt not accounting for the lack of forensic evidence is about 0.1%, you would adjust your estimate to 30%?

Replies from: brazil84
comment by brazil84 · 2011-10-26T10:02:36.541Z · LW(p) · GW(p)

No, if I accepted your assertion that even grabbing or holding someone is very likely to leave biological traces which can be identified by the authorites, then I would adjust my estimate down to 30%.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T16:09:08.879Z · LW(p) · GW(p)

Can you explain why? That sounds like a claim that makes no sense in terms of probability theory, and I suspect that you either do not know enough about calculating probabilities to understand why it doesn't make sense, or you are failing to apply that understanding.

We often make inferences like that implicitly, even here, revising our beliefs much less in light of new information than actually makes sense. One of our weaknesses as humans is that we will tend to stay much closer to the first number that comes into our heads than makes sense on further information. That's why will will sometimes sanity-check our estimates by going through a numerical breakdown of what we know, like I did earlier. It gives a chance to look and see "Hey, I assigned a probability of 20%, but when I plug in the most reasonable numbers I can come up with and try and calculate a probability, I come up with .03%! To believe that the probability is really 20%, I would have to guess that this piece of evidence is a million times more probable if the belief is true than if it's false, and that seems like way too much, or that the odds of this particular other thing happening are orders of magnitude off from what this study says, or some other combination of things that all look really improbable in light of the information I have! It looks like my first instinct was not just wrong, but very wrong, so I'd better change it by a lot."

Before I put time and effort into providing more evidence, I think it's important to establish that you actually know how to process evidence in a way that makes sense mathematically, not just intuitively. You can you go through a rundown of how you arrived at your numbers? I know you said before that you didn't have the energy, but I think it will save a lot more time and energy in this conversation if you do it than if I go on trying to retrieve information for you while expecting you to update not at all or far less than makes mathematical sense.

Replies from: thomblake, brazil84
comment by thomblake · 2011-10-26T17:05:01.166Z · LW(p) · GW(p)

You sure? 90% to 30% isn't really an orders of magnitude difference. Of course, taking that into account, "beyond a reasonable doubt" should be something like "at least 99.9% probability of guilt" (or whatever incidence of innocent people you're willing to throw in prison / execute), in which case a shift from 90% to 30% would be a shift from "not guilty" to "slightly more not guilty".

Replies from: lessdazed, Desrtopa
comment by lessdazed · 2011-10-26T17:17:26.120Z · LW(p) · GW(p)

whatever incidence of innocent people you're willing to throw in prison / execute

These should really be different standards.

comment by Desrtopa · 2011-10-26T20:24:54.942Z · LW(p) · GW(p)

I don't understand what you're asking if I'm sure about. I'm saying that given the premise that brazil84 accepts the forensic argument against Knox and Sollecito's guilt, it does not make sense to update his probability by so little.

Replies from: thomblake, dlthomas
comment by thomblake · 2011-10-26T20:50:21.945Z · LW(p) · GW(p)

Aha - I'd misread you as saying that the update was too big, rather than too little.

comment by dlthomas · 2011-10-26T20:35:48.870Z · LW(p) · GW(p)

He could accept it at less than full confidence.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T20:46:44.231Z · LW(p) · GW(p)

He already stated that given that he accepts the argument, he would update to 30% confidence, which conveniently frees us from the need to consider the probability outside the argument.

It's possible that he really meant "given that I accept the argument at low confidence, as opposed to not at all, as I currently do," but that would make his statement awfully misleading, and brazil84 has demonstrated too little familiarity with Bayesian reasoning for me to read his statements with that much charity.

Replies from: dlthomas
comment by dlthomas · 2011-10-26T20:51:17.854Z · LW(p) · GW(p)

He should mean "given that I assign the argument a comparable credence to other things I would state that I accept" - which shouldn't be 1. I think this probably shouldn't be a big enough difference to matter (I missed the "given..." in the context, in my response), but it would be interesting to update the numbers to verify.

comment by brazil84 · 2011-10-26T16:22:00.901Z · LW(p) · GW(p)

Can you explain why? That sounds like a claim that makes no sense in terms of probability theory, and I suspect that you either do not know enough about calculating probabilities to understand why it doesn't make sense, or you are failing to apply that understanding.

I could try, but first please explain to me what does not make sense about my statement. If I start at 90% based on other evidence, where should I end up (in your view) if your assertion about biological traces is established, and why?

ETA: Better yet, why don't you provide your calculation which starts at 90% and ends up at some number very different from 30%.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T20:20:07.473Z · LW(p) · GW(p)

It depends on the weight of the evidence

For easy calculation, let's convert the probabilities to odds. 30% is represented by odds of .43 (3:7) and 90% is represented by odds of 9 (9:1)

9/.43 is 20.9. So if you have proposition A, which you believe with 90% confidence, but then you get some piece of evidence which Not-X makes 20.9 times more likely than X does, you should reduce your confidence to 30%. If you had evidence that Not-X made a thousand times more likely than X, then that should reduce your odds to .009, which is equivalent to a probability of slightly over .009, or .9%

So we can work backwards and figure that, given the premise that you accepted the piece of evidence and adjusted your probability from 90% to 30%, then if you did the right sort of calculations you must have decided that it was a bit more than twenty times more likely that Knox and Sollecito would have failed to leave behind the forensic evidence that would implicate them given their innocence than given their guilt.

Considering the number of pieces of evidence that Moore claims that they would almost certainly have left if they were guilty, which they did not leave, I don't think that passes a basic sanity check.

Replies from: dlthomas, brazil84
comment by dlthomas · 2011-10-26T20:34:54.306Z · LW(p) · GW(p)

Converting to log-odds, for the practice reading log-odds units...

In bits, we have:

90% initial confidence = lg(90%/10%), which is about 3.2 bits likely 30% final confidence = lg(30%/70%), which is about -1.2 bits likely, or 1.2 bits unlikely total evidence needed to shift our view that far: 4.4 bits

In decibels:

90% initial confidence = 10 log(90%/10%), which is about 9.5 decibels likely 30% initial confidence = 10 log(30%/70%), which is about -3.7 decibels likely, or 3.7 decibels unlikely total evidence needed to shift our view that far: 13.2 decibels of evidence

comment by brazil84 · 2011-10-26T20:49:49.999Z · LW(p) · GW(p)

Could you please just answer my question? I think it's very simple and reasonable.

(1) In your view, if I start at 90% based on the other evidence; and your assertion about biological traces is established, then where should I end up? 5%? 1%? 88%? 0.01%? It's a very simple question.

(2) Please show me your calculation.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-26T21:49:13.710Z · LW(p) · GW(p)

I opened my response box before you edited your comment to include the question (I actually left the house in the meantime.) I think that you do not know the necessary math well enough to believe that you can defend your assertion, and so are trying to evade the question by trying to make me answer further questions and hoping that you will find something you can take issue with.

Nevertheless, I will show you a calculation. I will use what I believe represents a reasonable lower limit on the weight one could assign to the evidence. I will not respond to requests to cite unless you agree to provide citation indicating that the weight implicit in your own estimate is more reasonable.

We start with a probability of .90. I will assume that murderers leave forensic evidence with 99.9% frequency, and non-murderers have false positives with .1% frequency.

Out of a population of 10,000 people at this confidence level of guilt, we will expect 9000 murderers and 1000 innocent people. We'll assign a 99.9% confidence that a person who is not guilty will not leave forensic evidence implicating them (with .1% chance of false positive) and a 0.1% chance that a person who is guilty will not leave forensic evidence implicating them.

Out of 9000 murderers, we will expect 9 to be false negatives (not leave forensic evidence) Out of 1000 non-murderers, we will expect 999 not to leave forensic evidence, with one false positive.

That leaves 1008 people who have not left forensic evidence, 999 of whom are innocent. So if a person has not left forensic evidence, their odds of guilt are 1-(999/1008), or about 0.9%

Edit: I actually made an embarrassing mistake in my calculations the first time around, and overestimated the posterior probability. Results now corrected.

To make myself clear, this is not the weight I assign to the evidence, I am saying that it would be unreasonable to assign less weight than this.

Replies from: brazil84
comment by brazil84 · 2011-10-26T22:20:56.913Z · LW(p) · GW(p)

I opened my response box before you edited your comment to include the question

As I recall, the original part of my post specifically asked you to give me the probability I should end up with. The addition merely asked you to provide your calculation. You provided neither.

Anyway, the main flaw in your reasoning consists in conflating the propositions that (1) Knox (and Sollecito) were physically involved in the murder (i.e. holding, grabbing, and or stabbing); and (2) that Knox and Sollecito were guilty. For example, it's possible that Knox and Sollecito encouraged Guede from a few feet away to attack Kercher but never actually touched her. And perhaps did not even intend for him to kill her.

Doing the same calculation as you, but substituting 95% for 99.9% (actually you seem to have used 99% in your calculation) gives 450 false negatives and 999 correct negatives. So out of 1449 people who have not left biological traces on or about Kercher's person, 450 are actually guilty. ETA: 31%.

Anyway, I still look forward to your cites that (1) physically participating in a knife murder (i.e. holding, grabbing or stabbing) is extremely likely to result in biological traces being left on or about the victim's person; and (2) the Italian authorities may have (or did) find additional traces from Guede on or about Kercher's person which did not end up in the record.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-27T02:20:05.256Z · LW(p) · GW(p)

Yes, I already stated before that an odds ratio of approximately 20:1 would result in a posterior probability of 30%. I have also asserted that this weight does not pass a basic sanity check. You have stated that if you accept the argument from forensic evidence, you would assign a probability of 30%. Moore, who is a forensics expert, judges that for Knox and Sollecito to have been involved in the crime, based on the state of the evidence, is nigh impossible. 5% likelihood is not a sane estimation.

I am extremely tired of looking forward to how you will attempt to evade each of my arguments and ask me to do more work in exchange for promises of "good faith consideration" which amount to looking for any possible excuse not to update. As I stated in my previous comment, I will contact an expert for citations if you agree to provide a citation for the claim that 5% likelihood of failure to leave forensic evidence is a credible assignment. One of us is asserting a confidence many orders of magnitude apart from a qualified expert,and one of us has been repeatedly demanding further evidence for the other's confidence assertion, and in a reasonable argument, these would not be the actions of two separate people.

Replies from: brazil84
comment by brazil84 · 2011-10-27T09:41:03.570Z · LW(p) · GW(p)

You have stated that if you accept the argument from forensic evidence, you would assign a probability of 30%

I'm not sure what you mean by "the argument from forensic evidence," but let me ask you this: Do you understand that the probability that Knox (and Sollecito) were physically involved in the murder (i.e. holding, grabbing or stabbing) is not necessarily the same as the probability that they were involved in the murder?

I am extremely tired of looking forward to how you will attempt to evade each of my arguments

Sorry, but you are the one who is being evasive. I explained to you EXACTLY what the flaw was in your argument, and you ignored it.

The probability that Knox (and Sollecito) were involved in the murder is necessarily greater that the probability that they were physically involved. Agreed?

And do you agree that if they were involved in the murder but did not hold, grab, or stab Kercher, then there is a good chance that they would not have left biological traces on or about Kercher's person?

These are reasonable, yes or no questions. Please do not evade them.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-27T14:46:01.601Z · LW(p) · GW(p)

I'm not sure what you mean by "the argument from forensic evidence," but let me ask you this: Do you understand that the probability that Knox (and Sollecito) were physically involved in the murder (i.e. holding, grabbing or stabbing) is not necessarily the same as the probability that they were involved in the murder?

Yes, but Moore also points out forensic evidence that we should expect to see if they were simply in the room at the time of the murder which we do not see. I agree that if they were involved in the murder, did not physically engage with Kercher, there is a good chance they would not have left biological traces on her person. However, if they were physically in the room at the time of the murder, there is still forensic evidence which we should expect but do not see. If we assume that they were conspirators in her murder, the forensic evidence doesn't rule it out, but the prosecution did not allege that Knox and Sollecito conspired with Guede but were not physically present, because they do not have the evidence of communication between them to support it.

You are consistently refusing to stick your neck out and engage with questions that will expose your analysis of the case to criticism. I have just answered your questions, yes I agree that if Knox and Sollecito did not physically engage with Kercher, we should not expect traces on her, but we still have an expectation of evidence around the room, and yes they could have been involved through conspiracy without being present and leaving physical evidence, but we don't have the evidence to support that either.

Now I am going to ask you to provide a rundown of your numbers, as I did myself, and I asked you to earlier, but you avoided with further questions. If you ask further questions without providing one, I am going to have to write you off as too logically rude to engage with.

Replies from: brazil84
comment by brazil84 · 2011-10-27T17:41:59.186Z · LW(p) · GW(p)

Yes, but Moore also points out forensic evidence that we should expect to see if they were simply in the room at the time of the murder which we do not see

That's a different issue. If you want to abandon your original claim, fine but you should acknowledge it. The question I answered was how my estimation of the chances of Knox's (and Sollecito's) guilt would change if I were very confident that physical participation in the murder would have left DNA traces of Knox (or Sollecito) on or about Kercher's person.

That's the question I answered. If you want to ask me a different question, fine, but please stop pretending that we are talking about a different question.

I have my own rules of debate, and I don't engage with people who strawman me, i.e. people who insist on attributing to me positions which I did not take. So please knock it off.

Anyway, Moore's assumption is that Knox and/or Sollecito were physically involved in the murder. Re-read his piece.

However, if they were physically in the room at the time of the murder, there is still forensic evidence which we should expect but do not see

Exactly what? If Knox and Sollecito were standing just inside the doorway, encouraging Guede to attack Kercher, and then turned and ran out when he started stabbing her, what evidence would we expect to see? Certainly not bloody footprints of Knox or Sollecito.

Now I am going to ask you to provide a rundown of your numbers, as I did myself, and I asked you to earlier

I already provided my calculation, changing your 99% to 95% to reflect the possibility that Knox and/or Sollecito were guilty but did not do anything like hold grab or stab Kercher. I think that there is a 5 to 10% chance that Knox and Sollecito were guilty but did not physically participate.

And again my question:

The probability that Knox (and Sollecito) were involved in the murder is necessarily greater that the probability that they were physically involved.

You are consistently refusing to stick your neck out and engage with questions that will expose your analysis of the case to criticism

Please quote 3 questions which you think I have avoided and I will try to answer them.

And please do not ignore or evade my question above:

If Knox and Sollecito were standing just inside the doorway, encouraging Guede to attack Kercher, and then turned and ran out when he started stabbing her, what evidence would we expect to see?


ETA: By the way, I totally concede that if Moore's assumptions are correct then the probability that the prosecution's scenario is correct is close to zero. I also concede that if your assertion about biological traces is correct, then the probability that the prosecution's scenario is correct is close to zero.

Replies from: Desrtopa, TimS
comment by Desrtopa · 2011-10-27T18:39:17.674Z · LW(p) · GW(p)

I already provided my calculation, changing your 99% to 95% to reflect the possibility that Knox and/or Sollecito were guilty but did not do anything like hold grab or stab Kercher. I think that there is a 5 to 10% chance that Knox and Sollecito were guilty but did not physically participate.

What I asked for is a run down of your numbers leading to your estimation of your probability of guilt, such as I provided here.

Please quote 3 questions which you think I have avoided and I will try to answer them.

I have asked for

A step by step analysis of your probability estimate, as I linked above.

I did not ask for your calculation of the weight of the forensic evidence, simply substituting in another number for mine, I calculated for you what weight you would have to assign the evidence, and I asked you why you thought that was a reasonable probability, and you responded with more questions instead of attempting to provide an answer.

A source for your probability assignment of the strength of the forensic evidence.

An explanation for why you revise your probability estimate strongly on the arguments of the prosecution, who have a vested interest for arguing Knox and Sollecito's guilt, when their evidence has been found in many points to be false, exaggerated or mishandled, but do not revise your probability estimate at all on the arguments of Moore, who in addition to being a qualified expert, does not have money or reputation riding on the outcome of the case, and stands to lose reputation by making assertions about it that would reflect poorly on his expertise. You have asserted that this is an accurate representation of your analysis of the evidence, but not, as I requested, given any explanation for it.

As I stated in my previous comment, I will answer further questions from you if you provide a rundown of your numbers that form the basis for your probability estimate. This would be a simple request for you to fulfill, and would save time and energy over the course of this conversation. Take as long as you want, it's not going to take as long as this conversation will if you hedge around.

Replies from: brazil84
comment by brazil84 · 2011-10-30T14:43:10.973Z · LW(p) · GW(p)

What I asked for is a run down of your numbers leading to your estimation of your probability of guilt, such as I provided here.

It didn't seem to me that you were doing that. My impression was that you were asking how I got from 90% to 30%; not how I got to 90% in the first place. The topic under discussion was whether my probability estimate had changed in light of various information and it looks to me like you are trying to play a gotcha game.

Anyway, I will give you a kind of run down with the understanding that if you ignore or evade any of my questions from now on, we are done.

The numbers I am giving you represent a rough approximation of the intuition in my thinking. At this point, 90% is not the result of an explicit mathematical calculation. Anyway, in my opinion, the prior probability that Knox is guilty is pretty low (i.e before one looks at the various circumstantial and forensic evidence). On the one hand, it's extremely rare for someone of her demographic to take part in a murder; on the other hand it's pretty common that when somebody is murdered it was someone in their household. On balance, perhaps about 1 in 500 is my prior estimate of the probability of Knox's guilt. At the same time, the chances that an innocent person would have this kind of circumstantial evidence against them (changing alibis, staged break-in, forgotten phone calls, and so forth) is much lower. Perhaps 1 in 5000. (This is including the exculpatory aspects of the evidence as well.) Of course a guilty person would be very likely to have this kind of evidence against them. So out of 100,000 hypothetical Knoxes, 200 are guilty and roughly 190 have this kind of circumstantial evidence against them. At the same time, 95,000 are innocent and about 20 of those innocent Knoxes have this kind of circumstantial evidence against them. So of 210 people who have this kind of circumstantial and forensic evidence against them, roughly 90% are guilty.

A source for your probability assignment of the strength of the forensic evidence.

I'm not sure what you are asking for here, but the source of my estimate of the strength of the forensic evidence (taking Moore's assertions as true) is the observation that Knox (and Sollecito) may have been involved in the murder but not in a way which would have put them close enough to Kercher to leave the sort of evidence Moore discusses. I have estimated this probability at about 5 to 10%. i.e. I think there is a 5 to 10% chance that IF Knox and Sollecito were involved in the murder, they were involved from at least a few feet away.

For example, it's possible that Knox and Sollecito were encouraging Guede from just inside Kercher's door, and turned and ran away shortly after he started stabbing her.

So here's a couple questions for you. (And if you ignore or evade them, we are done.)

Do you agree that in the scenario I described where Knox and Sollecito encourage Guede and then run, it's pretty likely that they would not have left any DNA traces on or about her [ETA: Kercher's] person?

Do you agree that in this scenario, it's pretty likely that Knox and Sollecito would not have left the kind of evidence described by Moore in his article?

Moore, who is a forensics expert, judges that for Knox and Sollecito to have been involved in the crime, based on the state of the evidence, is nigh impossible.

That's not what Moore says. His reasoning is based on the assumption that if they were involved, they were physically involved. Read his article again.

An explanation for why you revise your probability estimate strongly on the arguments of the prosecution, who have a vested interest for arguing Knox and Sollecito's guilt, when their evidence has been found in many points to be false, exaggerated or mishandled, but do not revise your probability estimate at all on the arguments of Moore, who in addition to being a qualified expert, does not have money or reputation riding on the outcome of the case

I am not sure what you mean by "arguments," since my probability estimate is based mainly on the evidence. Evidence is not the same thing as arguments. And neither is the same thing as an opinion. I am not basing my probability estimate on the prosecution's arguments.

Moore's actual argument is very solid. The problem is his opinion. I am skeptical of his opinion since he has an agenda. I am also skeptical of the prosecution's opinions.

And another two questions:

The probability that Knox (and Sollecito) were involved in the murder is necessarily greater that the probability that they were physically involved. Agreed?

And do you agree that if they were involved in the murder but did not hold, grab, or stab Kercher, then there is a good chance that they would not have left biological traces on or about Kercher's person?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-30T19:27:08.228Z · LW(p) · GW(p)

It didn't seem to me that you were doing that. My impression was that you were asking how I got from 90% to 30%; not how I got to 90% in the first place. The topic under discussion was whether my probability estimate had changed in light of various information and it looks to me like you are trying to play a gotcha game.

I wouldn't call it a gotcha game, but I was of course expecting to find something in your probability analysis that I would object to. My primary dispute has all along been that I think your probability estimate of Knox and Sollecito's guilt is much too high. If our posteriors disagree, then we have an implicit disagreement about what our priors should be and/or how much we should update on the available evidence. If we do a breakdown of our probability analyses, then we can determine the source of our disagreement.

At the same time, the chances that an innocent person would have this kind of circumstantial evidence against them (changing alibis, staged break-in, forgotten phone calls, and so forth)

The "staged break in" claims have been more or less discredited; all the evidence thus far has been found consistent with a real break-in. Unless you're referring to some argument presented by the prosecution that I haven't been able to find, the "forgotten phone calls" refers to a three second phone call from Knox to Kercher, which I do not think accounts for any weight as evidence at all, as I have argued here. The "changing alibis" was done,according to Knox, under extreme duress; she claims that she was treated abusively during interrogation, and encouraged to implicate Lumumba, as the police suspected him on the basis of her text message to him, until she began to imagine that perhaps she and Lumumba really had been involved after all. After she signed the statement implicating him, had a meal and some time to gather her thoughts, she went back to saying that she had no recollection of having been involved, and that the statement was collected under coercion.

A prior probability of .002 for guilt strikes me as a fairly credible starting point (I assigned a higher prior, but in retrospect I think I should have adjusted down considerably based on the fact that Knox and Sollecito meet none of the FBI dangerous individuals criteria,) but it seems that you are adjusting strongly upwards on evidence that had already been discredited, or is already very weak due to high likelihood of coercion.

That's not what Moore says. His reasoning is based on the assumption that if they were involved, they were physically involved. Read his article again.

In addition to the forensic evidence, Moore also lays out sixteen FBI criteria that serve as indicators of violent inclinations, out of which Knox meets zero. For a person to cheer on the attacker of a close acquaintance they had no motive to kill themselves, I would strongly expect them to show signs of a violent or sociopathic personality, which Knox and Sollecito do not.

Do you agree that in the scenario I described where Knox and Sollecito encourage Guede and then run, it's pretty likely that they would not have left any DNA traces on or about her [ETA: Kercher's] person?

Do you agree that in this scenario, it's pretty likely that Knox and Sollecito would not have left the kind of evidence described by Moore in his article?

Yes, I agree. However, I think that this scenario has a dramatically low prior probability. The calculations I've given there describe the upper limits of my confidence interval on the likelihood I would assign to such an event; I believe that even one person, who has no motive to kill the victim, is not a sociopath, and meets none of the FBI dangerous individuals criteria, witnessing a violent attack by a person they do not have strong affiliations with (if the person were, say, a fellow gang member or mobster it would be a different matter,) and cheering on or otherwise encouraging the attacker, rather than say, intervening to help the victim, calling the police, or panicking and running away, would be an event completely unprecedented in the history of criminology. For two people to do so together goes beyond incredible into downright ludicrous.

I agree that the forensic evidence does not, as far as I am aware, rule out such involvement, but the evidence of Knox and Sollecito's failure to meet any of the FBI dangerous individuals criteria does weigh heavily against it, and in my prior probability distribution for Knox and Sollecito's involvement in the murder, I would only assign such a scenario a fraction of the likelihood that I would assign to the already unlikely "Bizarre sex game goes out of control" scenario, which the forensic evidence does rule out.

The probability that Knox (and Sollecito) were involved in the murder is necessarily greater that the probability that they were physically involved. Agreed?

And do you agree that if they were involved in the murder but did not hold, grab, or stab Kercher, then there is a good chance that they would not have left biological traces on or about Kercher's person?

Agreed and agreed, but i would assign most of the prior probability mass for their being involved in the murder, but not physically, to the possibility that they were involved through conspiracy, and the lack of evidence of communication between Knox and Sollecito and Guede weighs heavily against that. The prior probability of their being involved via happening to witness the attack, and encouraging the attacker, represents such a miniscule part of my probability distribution that I would need a great deal more evidence to raise it to the point of being worthy of attention. It took me a while to realize that you were positing such a scenario because its initial plausibility was so low that it didn't occur to me that you would suggest such a thing.

Given that many of the prosecution's claims have been discredited, or simply do not constitute evidence in favor of Knox and Sollecito's involvement, I think that a 5000:1 odds ratio is much too much weight to assign to their case. However, even if we do assign that much weight, I don't think that it comes anywhere near to overcoming the prior improbability of the sort of involvement you're suggesting.

Replies from: brazil84
comment by brazil84 · 2011-10-30T19:53:40.608Z · LW(p) · GW(p)

The "staged break in" claims have been more or less discredited; all the evidence thus far has been found consistent with a real break-in.

I'm not sure what you mean by this. The fact that a piece of evidence is "consistent with" a real break-in does not mean that such a piece of evidence is not indicative of a staged break-in. For example, when Sollecito called the police, he allegedly advised them that there had been a break-in but nothing had been taken even though there was no way he could have known this if it had been a real break-in. This evidence is "consistent with" a real break-in in the sense that it's possible to come up with an innocent explanation for Sollecito's statements. But it doesn't change the fact that it's a piece of evidence which supports the staged break-in hypothesis.

the "forgotten phone calls" refers to a three second phone call from Knox to Kercher,

No, I was mainly referring to Knox's trial testimony where she claimed to have forgotten about a call she made to her mother on the day the body was discovered. The call was made extremely early in the morning, Seattle time.

The "changing alibis" was done,according to Knox, under extreme duress

So what? Look, I agree that one can look at each piece of circumstantial evidence against Knox and come up with an innocent explanation for each piece. It doesn't change the fact that when you look at all of it together, it's extremely unlikely that an innocent person would have all of that evidence against him.

For a person to cheer on the attacker of a close acquaintance they had no motive to kill themselves, I would strongly expect them to show signs of a violent or sociopathic personality, which Knox and Sollecito do not.

I'm not sure what your point is here. I agree that Knox is not a likely murderer. That's why my estimate of the probability of her guilt is only 90%. If she had been Kercher's ex-lover; or if she came from a more violent demographic, my estimate would be higher.

Yes, I agree. However, I think that this scenario has a dramatically low prior probability

Well let me ask you this: Assuming that Knox was involved in the murder, what do you think the chances are that she was not physically involved?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-30T20:43:10.645Z · LW(p) · GW(p)

I'm not sure what you mean by this. The fact that a piece of evidence is "consistent with" a real break-in does not mean that such a piece of evidence is not indicative of a staged break-in. For example, when Sollecito called the police, he allegedly advised them that there had been a break-in but nothing had been taken even though there was no way he could have known this if it had been a real break-in. This evidence is "consistent with" a real break-in in the sense that it's possible to come up with an innocent explanation for Sollecito's statements. But it doesn't change the fact that it's a piece of evidence which supports the staged break-in hypothesis.

Knox had already returned to the residence she shared with Kercher, and witnessed the signs of the break-in, but not, according to her own testimony, entered Kercher's room and seen the murder scene (if she had entered the room, she would probably have left footprints and/or gotten blood on her shoes, which the police would have been able to discover, so we can assume that she probably did not.) She returned to Sollecito's house after this, had breakfast, and made her calls. If their house had been robbed, it is probable that they would have taken things that she would not have to enter Kercher's room to find missing, so "nothing was taken" would be a reasonable inference based on the information she had available to her. I agree that the claim that nothing was taken shifts the probability in favor of a staged break-in, but I don't think that it shifts it very much.

The prosecution's case for a staged break-in also rested on arguments such as the pattern of broken glass being inconsistent with a break from outside, and it being impossible to get in through the fire escape, both of which were simply false and represent no weight as evidence at all.

No, I was mainly referring to Knox's trial testimony where she claimed to have forgotten about a call she made to her mother on the day the body was discovered. The call was made extremely early in the morning, Seattle time.

Well, this is not what I thought you had in mind, but I do not think that this is something Knox is much more likely to testify that she forgot if she was involved in the murder than if she was not. Whether she was innocent or guilty, we can assume that she was under a fair amount of stress, and the contents of the phone call weren't incriminating anyway.

So what? Look, I agree that one can look at each piece of circumstantial evidence against Knox and come up with an innocent explanation for each piece. It doesn't change the fact that when you look at all of it together, it's extremely unlikely that an innocent person would have all of that evidence against him.

I strongly disagree. I would bet in favor of police finding a body of evidence of at least equal strength against me, were I to be investigated for a murder I was uninvolved in. I forget phone calls frequently, make statements based on inference which I do not have highly certain knowledge of on a regular basis, would probably change my alibi if I were abused and exposed to strong suggestion by the police, and have unusual mannerisms. This is why I originally brought up the point about the evidence being filtered; I am unconvinced that the evidence brought forward by the prosecution is more than I would expect them to find for the average person to whom I assigned the same prior probability of guilt.

Well let me ask you this: Assuming that Knox was involved in the murder, what do you think the chances are that she was not physically involved?

I'd call 99.99999% a fair estimate. But I'd estimate about 0.00000000000001% likelihood of her being physically involved, based on my previous likelihood calculation, plus the evidence that she doesn't meet any of the FBI dangerous individuals criteria, and the lack of evidence of conspiracy with Guede, both of which I didn't account for before, and the evidence of her failure to leave forensic evidence. So if you multiply the chance that she was involved physically by the number of times more likely I think it was that she was involved non-physically, you get about 0.0000001% likelihood. Most of my probability mass for that would be that she somehow managed to conspire with Guede without producing evidence that the police would discover, rather than the even more unlikely hypothesis that she happened upon the murder and encouraged it.

My probability estimate that she and Sollecito were both involved is, of course, lower than my probability estimate that Knox alone was.

Replies from: brazil84
comment by brazil84 · 2011-10-30T23:02:28.537Z · LW(p) · GW(p)

She returned to Sollecito's house after this, had breakfast, and made her calls.

At the time Sollecito reported that there was a break-in and nothing was taken, he was aware of the broken window in Romanelli's room but Romanelli had not returned and inspected her room. Agreed?

and it being impossible to get in through the fire escape

I don't recall the prosecution making this claim. In fact, I don't recall hearing anything about a fire escape. Can you give me a link?

but I do not think that this is something Knox is much more likely to testify that she forgot if she was involved in the murder than if she was not and the contents of the phone call weren't incriminating anyway.

I disagree. The contents of the call were very inculpatory and it was extremely convenient for her to forget about it. Anyway, even if she was under stress, it seems pretty unlikely to me that she would forget the call and continue to forget the call even after she was reminded of both the call and its contents. Especially given that it was an unusual call; made at a time when she was wide awake but knew her mother would be sleeping.

I forget phone calls frequently,

I doubt you would forget an unusual phone call made to your mother at a time when you knew you would be waking her up. Especially if you were reminded about the time and contents of the call.

I would bet in favor of police finding a body of evidence of at least equal strength against me

Well in your view, what are the strongest pieces of circumstantial evidence against Knox?

I'd call 99.99999% a fair estimate

Ok, then you should not object if my probability of Knox's guilt doesn't drop much if I add the assumption that Moore's assertions are substantiated.

By the way, I am STILL waiting for cites backing up your claims about (1) trace DNA ending up on or about Kercher's person if Knox (or Sollecito) grabbed, held, or stabbed her; and (2) further evidence of Guede DNA traces being discarded and not making it into the record.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-31T00:14:18.427Z · LW(p) · GW(p)

At the time Sollecito reported that there was a break-in and nothing was taken, he was aware of the broken window in Romanelli's room but Romanelli had not returned and inspected her room. Agreed?

Agreed.

I disagree. The contents of the call were very inculpatory and it was extremely convenient for her to forget about it. Anyway, even if she was under stress, it seems pretty unlikely to me that she would forget the call and continue to forget the call even after she was reminded of both the call and its contents. Especially given that it was an unusual call; made at a time when she was wide awake but knew her mother would be sleeping.

She was a college student without a lot of experience living on her own. Her home is broken into, she's in a panic, she calls mom and asks "My home has been broken into, what do I do?"

Forgetting such a call, even repeatedly, would be entirely characteristic of me.

I don't recall the prosecution making this claim. In fact, I don't recall hearing anything about a fire escape. Can you give me a link?

I had remembered komponisto, who translated the Massei-Cristiani report, making such a statement, but applying a search function over his posts, I can't find any such claim. I suspect that someone else made a statement along those lines and I misremembered, but I don't know that they would be a credible information source, so I'm prepared to drop that claim.

Well in your view, what are the strongest pieces of circumstantial evidence against Knox?

Unusual mannerisms, and the dryer.

Ok, then you should not object if my probability of Knox's guilt doesn't drop much if I add the assumption that Moore's assertions are substantiated.

That's my estimate for the relative probability after the forensic evidence is accounted for. My likelihood estimate of Knox and Sollecito's guilt after accounting for the forensic evidence is approximately equal to my probability estimate prior to it minus all the probability mass I assigned to their physical involvement. You already acknowledged that if you accept Moore's arguments, it reduces the likelihood of Knox and Sollecito's physical involvement to near zero. If your prior estimate assigns 90% probability to Knox and Sollecito being guilty, and 85% probability to any of the prosecution's scenarios being correct, then that leaves at most 5% of your probability mass assigned to the possibility that Knox and Sollecito were involved non-physically, since the prosecution did not put forward any scenarios in which Knox and Sollecito were involved non-physically. So if you subtract nearly all of the probability mass that you assigned to Knox and Sollecito being involved physically, that should reduce your probability estimate of Knox and Sollecito's guilt to just over 5% at most, less by any overlap between "Knox and Sollecito physically involved in the murder" and "Prosecution's scenarios wrong."

By the way, I am STILL waiting for cites backing up your claims about (1) trace DNA ending up on or about Kercher's person if Knox (or Sollecito) grabbed, held, or stabbed her; and (2) further evidence of Guede DNA traces being discarded and not making it into the record.

For reasons I have already explained, this would be difficult for me to produce. I would need to contact an expert. I will agree to put in that effort if you also attempt to find a cite for your implicit premise, that 1:2 relative odds of non-physical to physical involvement is a credible distribution of probability mass in a murder with no evidence of conspiracy. You may agree to do this, and I will attempt to get a citation from an expert, you may offer some other assertion of yours that you are willing to go to the effort to acquire a citation for, and if I agree that it's a reasonable substitution, I will make the effort to get the citation. If you do neither, I will not make the effort to get the citation, and I will have to take issue with your making further requests.

Replies from: brazil84
comment by brazil84 · 2011-11-01T13:53:15.564Z · LW(p) · GW(p)

Agreed.

Ok, then I still don't understand what you mean by your claim that the evidence is "consistent with" a real break-in. This is one piece of evidence which you seem to concede supports the staged break-in hypothesis.

She was a college student without a lot of experience living on her own. Her home is broken into, she's in a panic, she calls mom and asks "My home has been broken into, what do I do?"

Assuming you are accurately summarizing the contents of the call, it's suggestive of guilt. The fact that you (seem to) have no idea why is telling.

but I don't know that they would be a credible information source, so I'm prepared to drop that claim.

You should also be prepared to confront the reality that you have very poor understanding of the case against Knox and Sollecito. This is the second time you have confidently mischaracterized the prosecution's case. You don't understand the significance of the forgotten phone call. And you seriously believe that Knox's mannerisms are among the strongest pieces of circumstantial evidence against her.

It's obvious that you are suffering from confirmation bias, i.e. you aren't paying serious attention to evidence (or argument) which contradicts your views about the case.

That's my estimate for the relative probability after the forensic evidence is accounted for.

Ok, then tell me your probability estimate ignoring the "forensic evidence."

I will agree to put in that effort if you also attempt to find a cite for your implicit premise, that 1:2 relative odds of non-physical to physical involvement

Actually the odds I have been using are roughly 1:20. You seriously think that's way off-base? (Please don't evade this question.)

Anyway, your (apparent) claim about Italian police and legal procedure is one that even you need to concede you do not have the expertise to make.

Replies from: wnoise, Desrtopa
comment by wnoise · 2011-11-01T16:55:18.969Z · LW(p) · GW(p)

Assuming you are accurately summarizing the contents of the call, it's suggestive of guilt. The fact that you (seem to) have no idea why is telling.

I too have no idea. Yes, it's something a person who has something to hide and doesn't want to involve the police might do. It's also something a confused college kid in a foreign place might do on encountering any hiccup. Completely consistent with either guilt or innocence means it sways me very little.

Replies from: brazil84
comment by brazil84 · 2011-11-01T17:08:46.133Z · LW(p) · GW(p)

I too have no idea.

Then I suggest you educate yourself about the case.

Replies from: thomblake
comment by thomblake · 2011-11-01T18:12:58.912Z · LW(p) · GW(p)

Then I suggest you educate yourself about the case.

That was a remarkably unhelpful comment. I have read quite a bit about the case and still don't have any idea why that would be suggestive of guilt.

Do you? Any hints, or are these trade secrets?

comment by Desrtopa · 2011-11-01T15:03:15.898Z · LW(p) · GW(p)

You should also be prepared to confront the reality that you have very poor understanding of the case against Knox and Sollecito. This is the second time you have confidently mischaracterized the prosecution's case. You don't understand the significance of the forgotten phone call. And you seriously believe that Knox's mannerisms are among the strongest pieces of circumstantial evidence against her.

You asserted before that you yourself do not have a great deal of familiarity with the arguments made by the prosecution, and yet you find it adequate to support 90% confidence of guilt.

I agree that this statement was probably a mischaracterization of the prosecution's argument, but can you name any other piece of evidence regarding the break in which is more probable in light of a staged break-in than a real one?

I think you are dramatically underestimating the frequency with which college students unused to living alone and exposed to frightening and unfamiliar situations will default to the action of "panic and call mom."

I am probably subject to some degree of confirmation bias in this case, but I would need to weight the evidence in favor of Knox and Sollecito's involvement many, many times more heavily for it to become a credible assertion. I think that you are yourself subject to an extremely strong confirmation bias here; weighting Knox and Sollecito's changing of their alibis under probable abuse more heavily than Knox, Sollecito and Guede's mutual failure to implicate each other, for instance, seems purely nonsensical.

Ok, then tell me your probability estimate ignoring the "forensic evidence."

Some quick googling doesn't give me any results relevant to the question of what proportion of murders involve conspiracy, but I would suggest a prior of maybe 1:100. However, the lack of evidence to support a conspiracy would weigh heavily against that, so I'd shift down to maybe 1:10,000.

"Suspects witness victim, who they have no motive to kill, being attacked, and cheer on the attacker," would approximate to zero percent of my probability mass.

If you can point to any evidence that such an event (non sociopathic, FBI zero threat rating individuals witnessing an attack on someone they have no motive to kill, by someone they do not have strong affiliation with, and cheering on the attacker,) has ever happened before, I would agree that I am underestimating the probability. Can you point to any such evidence?

Actually the odds I have been using are roughly 1:20. You seriously think that's way off-base? (Please don't evade this question.)

I think it's somewhat off base as a prior, and very very off base in light of the lack of evidence of conspiracy, and if you assign a significant fraction of that to "witnessed attack and cheered it on," I think it's positively ludicrous.

Anyway, your (apparent) claim about Italian police and legal procedure is one that even you need to concede you do not have the expertise to make.

Can you explain what this apparent claim is?

Replies from: brazil84
comment by brazil84 · 2011-11-01T16:47:00.816Z · LW(p) · GW(p)

You asserted before that you yourself do not have a great deal of familiarity with the arguments made by the prosecution, and yet you find it adequate to support 90% confidence of guilt.

Nonsense, I clearly stated that my probability assessment was based mainly on the actual facts as opposed to arguments.

I agree that this statement was probably a mischaracterization of the prosecution's argument,

Your second mischaracterization. Not only that, you seriously believe that one of the best pieces of circumstantial evidence against Knox is her "mannerisms." And not only that, you do not understand the significance of the forgotten phone call. Just admit that you don't really understand the case against Knox (or Sollecito). I promise you the sky won't fall.

I am probably subject to some degree of confirmation bias in this case, but I would need to weight the evidence in favor of Knox and Sollecito's involvement many, many times more heavily for it to become a credible assertion.

Given that you clearly don't know the strength of that evidence, you shouldn't have an opinion one way or another.

I think that you are yourself subject to an extremely strong confirmation bias here; weighting Knox and Sollecito's changing of their alibis under probable abuse more heavily than Knox, Sollecito and Guede's mutual failure to implicate each other, for instance, seems purely nonsensical.

Please show me where I made such a weighing. Please QUOTE me. Failing that, please admit that I made no such weighing and apologize.

what proportion of murders involve conspiracy,

What exactly do you mean by "conspiracy"? It seems pretty clear that if Knox and Sollecito were involved in the crime, they acted in concert with Guede.

In the scenario I describe where Knox and Sollecito encourage Guede from a few feet away and then run, would you count that as a "conspiracy"?

If you can point to any evidence that such an event (non sociopathic, FBI zero threat rating individuals witnessing an attack on someone they have no motive to kill, by someone they do not have strong affiliation with, and cheering on the attacker,) has ever happened before, I would agree that I am underestimating the probability. Can you point to any such evidence?

I think I probably could. But let's make sure I understand what you are saying.

You are claiming that Scenario A (non sociopathic, FBI zero threat rating individuals witnessing an attack on someone they have no motive to kill, by someone they do not have strong affiliation with, and cheering on the attacker) is at least a thousand times less likely than scenario B ((non sociopathic, FBI zero threat rating individuals witnessing an attack on someone they have no motive to kill, by someone they do not have strong affiliation with, and physically participating in the attack).

You are also claiming that Knox and Sollecito are known to be non-sociopathic and known not to have had a motive to harm Kercher.

Do I understand you correctly?

Can you explain what this apparent claim is?

That if additional samples taken from on or about Kercher's person matched Guede, it would not have become part of the record in the case.

ETA:

but can you name any other piece of evidence regarding the break in which is more probable in light of a staged break-in than a real one?

A single piece of evidence? Sollecito's phone call comes close, but probably not.

Replies from: Desrtopa
comment by Desrtopa · 2011-11-01T20:00:29.571Z · LW(p) · GW(p)

Your second mischaracterization. Not only that, you seriously believe that one of the best pieces of circumstantial evidence against Knox is her "mannerisms." And not only that, you do not understand the significance of the forgotten phone call. Just admit that you don't really understand the case against Knox (or Sollecito). I promise you the sky won't fall.

No, I don't concede that. If you can explain to me why it's so much more likely that Knox would make that phone call if she were guilty than if she were innocent, perhaps it will be something I failed to consider, and I will change my mind. But as-is, it seems to me like such a weak enough piece of evidence that had the police not already promoted Knox and Sollecito to attention, they would probably not have treated it as worthy of notice.

Please show me where I made such a weighing. Please QUOTE me. Failing that, please admit that I made no such weighing and apologize.

I inferred that you made such a weighting from this statement

At the same time, the chances that an innocent person would have this kind of circumstantial evidence against them (changing alibis, staged break-in, forgotten phone calls, and so forth) is much lower. Perhaps 1 in 5000. (This is including the exculpatory aspects of the evidence as well.)

If I was incorrect, then I apologize for that. But I don't see how you're getting an odds ratio of 1:5000 in favor of guilt for changed alibis (very high likelihood of coercion,) a forgotten phone call, a phone call stating that nothing had been taken in the break-in (which they could reasonably infer,) versus mutual failure to implicate, absence of evidence of motive, absence of evidence of dangerous personalities or inclinations, absence of evidence of conspiracy, and absence of evidence of physical presence at the scene.

What exactly do you mean by "conspiracy"? It seems pretty clear that if Knox and Sollecito were involved in the crime, they acted in concert with Guede.

In the scenario I describe where Knox and Sollecito encourage Guede from a few feet away and then run, would you count that as a "conspiracy"?

By conspiracy, I mean that they intended for Kercher to be murdered, and made plans to that effect in advance with her murderer.

I think I probably could. But let's make sure I understand what you are saying.

You are claiming that Scenario A (non sociopathic, FBI zero threat rating individuals witnessing an attack on someone they have no motive to kill, by someone they do not have strong affiliation with, and cheering on the attacker) is at least a thousand times less likely than scenario B ((non sociopathic, FBI zero threat rating individuals witnessing an attack on someone they have no motive to kill, by someone they do not have strong affiliation with, and physically participating in the attack).

You are also claiming that Knox and Sollecito are known to be non-sociopathic and known not to have had a motive to harm Kercher.

Do I understand you correctly?

No. I am saying that Scenario A is much less likely than the possibilities that dominate the probability mass for "Knox and Sollecito physically involved in Kercher's murder." This would include possibilities such as "violent argument over cleaning roster gone downhill," "sex game gone wrong," etc. The prior probability for "Knox and Sollecito witness Guede attacking Kercher, and proceed to assist Guede in the attack," as with the probability that they would cheer him on, is infinitesimal.

In retrospect, I think that the relative prior probability that I assigned to their involvement through conspiracy (1:100) was too low, but it's still very low in light of the absence of evidence that Knox and Sollecito conspired with Guede, and the likelihood that they would observe an attack in progress and support the attacker is infinitesimal.

Also note that if Knox and Sollecito came to the residence Knox shared with Kercher, and witnessed an attack in progress, they cannot have let Guede in. Any evidence in favor of a staged break-in is evidence against this hypothesis.

The prosecution tried quite hard to find a motive for the killing, and was unable to establish one, unless you account "crazy sex game gone wrong" or "satanic ritual" as motives, neither of which they were able to present evidence for. At this point, the notion that Knox and Sollecito had a motive to murder Kercher deserves a very low probability.

Amanda Knox was known by her acquaintances for having an low tolerance for conflict, and being uncomfortable if she and people around her were in disagreement, behavior which is highly inconsistent with Antisocial Personality Disorder. Further, if the prosecution was able to find evidence that she or Sollecito had APD, they had strong motive to make record of it, but the Massei-Cristiani report contains no such evidence. So the probability that Knox and Sollecito would witness an attack on Kercher and support the attacker may be dominated by the possibility that they were secretly sociopaths and had reason to want her dead, but we have more evidence than for the average person to suspect that neither was the case.

That if additional samples taken from on or about Kercher's person matched Guede, it would not have become part of the record in the case.

I never said that I expected that if they found additional samples implicating Guede, it would not have become part of the case, I said that I did not have strong expectation that if further evidence been found against Guede, it would have been raised in the case (or to be more precise, I do not have a strong expectation that they would have brought the evidence to the case and I would have found out about it; Guede's case was not controversial and so was not heavily reported on, and he opted for fast track trial in which he waived the right to contest any evidence against him, and all the primary documents are in Italian.)

Because I do not have a great deal of expertise regarding the Italian legal system, my model of reality would not have taken much of a hit either way.

Replies from: brazil84
comment by brazil84 · 2011-11-02T00:38:27.795Z · LW(p) · GW(p)

If you can explain to me why it's so much more likely that Knox would make that phone call if she were guilty than if she were innocent, perhaps it will be something I failed to consider, and I will change my mind.

It's not really my job to explain it to you. It's your job to do your homework to find out what the best and most important evidence is on both sides before you make your probability assessment. I have done that with both sides. On the other hand, you obviously have a very poor understanding of what the case against Knox is. As far as I can tell, you haven't even tried to defend your claim that Knox's mannerisms was among the best circumstantial evidence against her.

If I was incorrect, then I apologize for that.

Yes, you are incorrect. My statement was clearly looking at the body of evidence as a whole.

By conspiracy, I mean that they intended for Kercher to be murdered, and made plans to that effect in advance with her murderer.

Ok, then I don't see how the concept of a "conspiracy" adds much to the discussion. If there was a conspiracy, Knox and Sollecito plausibly may still have been physically involved. If there was not a conspiracy, Knox and Sollecito may plausibly not have been physically involved.

No. I am saying that Scenario A is much less likely than the possibilities that dominate the probability mass for "Knox and Sollecito physically involved in Kercher's murder."

In that case you are comparing apples and oranges, since you are comparing one narrow scenario I proposed with much bigger set.

I think that the relative prior probability that I assigned to their involvement through conspiracy (1:100) was too low, but it's still very low in light of the absence of evidence that Knox and Sollecito conspired with Guede, and the likelihood that they would observe an attack in progress and support the attacker is infinitesimal.

You are ignoring other possibilities here. A more likely scenario is that Knox and Sollecito conspired with Guede to harm Kercher in some way but did not intend for her to die.

For example, consider the murder of Janet Chandler which took place back in 1979. Her roommate and co-worker -- a girl named Laurie Swank -- apparently helped to organize a sexual attack on her. Swank admitted to cheering on the attackers who ultimately killed Chandler. There was no DNA testing back then, but if there had been, there would not have been any of Swank's DNA on or about Chandler's person.

Also note that if Knox and Sollecito came to the residence Knox shared with Kercher, and witnessed an attack in progress, they cannot have let Guede in. Any evidence in favor of a staged break-in is evidence against this hypothesis.

I agree but so what? I'm not proposing that Knox and Sollecito walked in on Guede assaulting Kercher and spontaneously decided to help him. I'm proposing that they acted in concert for some unlawful purpose (which by hypothesis pretty clearly happened) and that for whatever reason, Knox and Sollecito were not close to Kercher when Guede stabbed her to death.

So basically there are two possibilities, assuming that Knox and Sollecito were involved in the murder: (1) They acted in concert and were all physically involved; and (2) They acted in concert but only Guede was physically involved. You seem to be saying that (1) is far more likely than (2). I don't see why, since both scenarios are (a priori) pretty remote. I don't see any (a priori) reason to think that one is 100 or 1000 times more likely than the other.

But let's be specific: What do you think is the probability ratio of (1) and (2)?

I said that I did not have strong expectation that if further evidence been found against Guede, it would have been raised in the case

I don't think that's what you said, but anyway it seems to me that Knox and Sollecito (or their supporters) would have had incentive to raise this issue. If there were 100 traces of Guede on Kercher's person and none of Knox, there's a decent -- perhaps compelling -- argument that the prosecution was wrong. Certainly Moore did not make this argument even though it would have fit in nicely with the rest of his essay.

Replies from: JoshuaZ, Desrtopa, brazil84
comment by JoshuaZ · 2011-11-02T01:06:39.774Z · LW(p) · GW(p)

If you can explain to me why it's so much more likely that Knox would make that phone call if she were guilty than if she were innocent, perhaps it will be something I failed to consider, and I will change my mind.

It's not really my job to explain it to you. It's your job to do your homework to find out what the best and most important evidence is on both sides before you make your probability assessment.

Downvoted for this remark and most of the next paragraph. In this context, Derstopa is clearly aware of the phonecall and doesn't understand why one would think it is evidence of guilt. Explaining why one would think that it is non-trivial evidence of guilt (if one thinks it is) is what one should do if one trying to have an actual discussion. Refusing to explain that and telling someone to just do their homework is rude, logically rude, and generally not productive for people trying to understand your viewpoint.

Replies from: brazil84
comment by brazil84 · 2011-11-02T10:20:33.953Z · LW(p) · GW(p)

Explaining why one would think that it is non-trivial evidence of guilt (if one thinks it is) is what one should do if one trying to have an actual discussion.

I would say it depends on what is being discussed. My point in that post was not so much that Knox is probably guilty as that Derstopa is ignorant of the case against Knox. Note also that Derstopa is aware of the phone call only because I mentioned it to him.

Replies from: wnoise, JoshuaZ
comment by wnoise · 2011-11-02T17:01:42.799Z · LW(p) · GW(p)

I'm not Desrtopa, but I had heard about the call way back in 2009. I dismissed it as essentially irrelevant, because no one who has mentioned it has ever said anything convincing about how it was inculpatory. Apparently it was supposed to be obvious? But it wasn't, not to me, nor apparently to Desrtopa. At best I can make strawman arguments which I find easy to knock down. Having you respond to those would be a waste of everyone's time. So please, just tell me why you found this call suspicious.

I don't speak Italian. I have been limited to secondary sources, rather than the prosecutor's own arguments directly, but I really have looked closely at arguments by those who think Knox and Sollecito are guilty. At the time, they did not articulate any reason for me to find the phone call suspicious. I still haven't found anything after looking again.

Replies from: brazil84
comment by brazil84 · 2011-11-02T17:17:58.772Z · LW(p) · GW(p)

Apparently it was supposed to be obvious?

I don't think it's obvious at all.

but I really have looked closely at arguments by those who think Knox and Sollecito are guilty. At the time, they did not articulate any reason for me to find the phone call suspicious.

Which sites did you look at?

comment by JoshuaZ · 2011-11-02T14:58:01.390Z · LW(p) · GW(p)

My point in that post was not so much that Knox is probably guilty as that Derstopa is ignorant of the case against Knox. Note also that Derstopa is aware of the phone call only because I mentioned it to him.

The first sentence is irrelevant to my observation. The second claim (about only knowing about the phonecall from your remark) seems inaccurate to my reading of the conversation. From my skimming the thread again the only bit I see that could give you the impression that Derstopa wasn't aware of the phonecall is this exchange where Derstopa doesn't say that. In that context, Derstopa thinks you are talking about a different phonecall. Nothing in that is a useful indication that Derstopa didn't know about this phone call. Moreover, if you thought that that was the problem then telling Derstopa that he should read up on the prosecutions case would have made minimal sense as a reply at that point, not a reply three days later to where Derstopa asks about how one thinks the phonecall is relevant, especially when they've already explained why it seems only marginally relevant.

Replies from: brazil84
comment by brazil84 · 2011-11-02T17:28:14.955Z · LW(p) · GW(p)

Nothing in that is a useful indication that Derstopa didn't know about this phone call.

Here's what he said:

Unless you're referring to some argument presented by the prosecution that I haven't been able to find, the "forgotten phone calls" refers to a three second phone call from Knox to Kercher.

It seems pretty clear to me that he was not aware of the phone call I was referring to.

Moreover, if you thought that that was the problem then telling Derstopa that he should read up on the prosecutions case would have made minimal sense as a reply at that point,

As I recall, at that point, I was only just beginning to realize just how profoundly ignorant Derstopa was about the case against Knox.

comment by Desrtopa · 2011-11-02T03:47:01.569Z · LW(p) · GW(p)

It's not really my job to explain it to you. It's your job to do your homework to find out what the best and most important evidence is on both sides before you make your probability assessment. I have done that with both sides. On the other hand, you obviously have a very poor understanding of what the case against Knox is. As far as I can tell, you haven't even tried to defend your claim that Knox's mannerisms was among the best circumstantial evidence against her.

JoshuaZ's comment reflects everything I have to say about this.

You are ignoring other possibilities here. A more likely scenario is that Knox and Sollecito conspired with Guede to harm Kercher in some way but did not intend for her to die.

Then why is there no evidence of prior communications between Knox, Sollecito and Guede to support this? Knox had only met Sollecito a week before Kercher's murder, and had just started dating him, and there's no evidence that Sollecito and Guede had ever even met as of the time of the murder. The prosecution has no record of phone calls between Knox and Guede, and has no evidence or testimony of any sort to suggest that the two were more than slightly acquainted.

I agree that this scenario had greater prior likelihood, but an absence of evidence that Sollecito and Guede had ever even met is a heavy weight of evidence against it.

I agree but so what? I'm not proposing that Knox and Sollecito walked in on Guede assaulting Kercher and spontaneously decided to help him. I'm proposing that they acted in concert for some unlawful purpose (which by hypothesis pretty clearly happened) and that for whatever reason, Knox and Sollecito were not close to Kercher when Guede stabbed her to death.

You think that there's enough evidence to think that Knox and Sollecito, for whom there is an absence of evidence of any motive, and who had just recently met, deliberately collaborated with Guede, who there is no evidence that Sollecito had ever met, or that Knox had ever called or met with privately, conspired with Guede to harm Kercher? When did they do the conspiring, after 9:10 PM on the night that Kercher was killed?

The prosecution never alleged conspiracy between Knox, Sollecito and Kercher; the information they had available to them didn't render it tenable.

So basically there are two possibilities, assuming that Knox and Sollecito were involved in the murder: (1) They acted in concert and were all physically involved; and (2) They acted in concert but only Guede was physically involved. You seem to be saying that (1) is far more likely than (2). I don't see why, since both scenarios are (a priori) pretty remote. I don't see any (a priori) reason to think that one is 100 or 1000 times more likely than the other.

If Knox and Sollecito were complicit in the crime, but not participants in the crime scene, they would most likely have to have premeditated some sort of harm against Kercher, and the prosecution found no evidence at all to suggest they would have any motive for such. If they were physically involved, they could have premeditated harm against Kercher, but they could also have become involved in the heat of the moment. Most murders are not premeditated, particularly in cases with no apparent motive prior to the crime.

I would say that my previous assignment of 1:100 may have been excessive; a prior ratio of 1:20, as you assigned, might be more reasonable. But the evidence that renders any before-the-event conspiracy between the three highly unlikely weighs against it.

Just how little evidence do you expect prosecutors with a heavy dose of motivated cognition to find for an innocent person, that you think what the prosecution found weighs so heavily against Knox and Sollecito? The data from the Innocence Project suggests an error rate higher than this for average cases prior to the use of DNA evidence, and the evidence against Knox and Sollecito is far weaker than for the average suspect, let alone convict, and the evidence pointing to their innocence far stronger.

Replies from: brazil84
comment by brazil84 · 2011-11-02T10:35:02.748Z · LW(p) · GW(p)

JoshuaZ's comment reflects everything I have to say about this.

As I said to JoshuaZ, the main point of that passage was that you are ignorant of the case against Knox. Which you do not seem to deny anymore.

Then why is there no evidence of prior communications between Knox, Sollecito and Guede to support this?

The prosecution has no record of phone calls between Knox and Guede, and has no evidence or testimony of any sort to suggest that the two were more than slightly acquainted.

Not all communications result in a phone or other record. Particularly if some of those communications are between drug users and elements of the criminal underworld.

I would say that my previous assignment of 1:100 may have been excessive; a prior ratio of 1:20, as you assigned, might be more reasonable.

Ok, then it was reasonable for me to go from 90% to 30%. Unless you think there is an error in my math?

Just how little evidence do you expect prosecutors with a heavy dose of motivated cognition to find for an innocent person, that you think what the prosecution found weighs so heavily against Knox and Sollecito?

I would say a lot less than here. Maybe one or two pieces of inculpatory evidence at most.

By the way, can I take it you are conceding that Knox (and/or her supporters) would have had an incentive to introduce and publicize evidence that there were more traces of Guede on or about Kercher than the two I mentioned earlier?

Replies from: Desrtopa
comment by Desrtopa · 2011-11-02T13:26:22.195Z · LW(p) · GW(p)

As I said to JoshuaZ, the main point of that passage was that you are ignorant of the case against Knox. Which you do not seem to deny anymore.

I do deny this. You accuse me of not defending my claim that Knox's mannerisms are among the strongest evidence against her. I have defended at several points my reasons for assigning very low weight to pieces of evidence put forward by the prosecution. You, on the other hand, while asserting that the prosecution's arguments collectively deserve high weight, have not defended your reasons for assigning high weight to any of them. In response to requests for a defense of such, you've told me it's not your job to do my homework.

Ok, then it was reasonable for me to go from 90% to 30%. Unless you think there is an error in my math?

Only if you assign zero weight to the evidence rendering conspiracy between them unlikely.

Not all communications require physical meeting or result in a phone record. But when you have no evidence of private meeting, no phone records, no email records, and a very short time frame in which any sort of communication could have taken place, and you don't adjust your likelihood of communication downwards at all, then it's clear that you're desperate to come to a particular conclusion and don't want to perform any sort of update which would render it more unlikely.

I would say a lot less than here. Maybe one or two pieces of inculpatory evidence at most.

Then why are so many primary suspects and even convicts later proven to be innocent? Your estimation of the amount of evidence that it is reasonable to expect against an innocent person seems strongly contradicted given our information on false conviction rates.

By the way, can I take it you are conceding that Knox (and/or her supporters) would have had an incentive to introduce and publicize evidence that there were more traces of Guede on or about Kercher than the two I mentioned earlier?

I have stopped trying to argue that point because, in the face of a qualified expert without any professional stake in the case claiming that it is enormously unlikely for Knox and Sollecito to have left an absence of evidence if they were physically involved in the case, you insist on demanding a particular piece of evidence which I have already provided repeated and abundant explanations as to why it would be difficult for me to produce.

In fact, when I put it in words, I have to wonder I'm still arguing about any of this. Thus far you have shown a tremendous unwillingness to update in favor of any exculpatory evidence (when I think evidence from the prosecution is weak, I explain why I do not think it is much more likely if Knox and Sollecito are guilty than if they are innocent. You refuse to update on evidence entirely with an explanation of how it does not disprove all possible guilt scenarios.) You have been rude, logically rude, and I suspect you could go on arguing for Knox and Sollecito's guilt indefinitely, increasing your confidence in your probability assignment no matter how much evidence mounts against you.

You have given me every reason to believe that if exposed to further evidence against your position, you will refuse to change your assessment at all. This simply isn't worth my time.

Replies from: thomblake, brazil84
comment by thomblake · 2011-11-02T14:09:24.027Z · LW(p) · GW(p)

This simply isn't worth my time.

Indeed, for some time I've been tempted to caution you against feeding the trolls.

Replies from: Desrtopa
comment by Desrtopa · 2011-11-02T14:24:01.141Z · LW(p) · GW(p)

If brazil84 weren't a lawyer, I would have written this debate off as pointless a long time ago. It's raising a negative affect around all the time I spend on this site, but simply walking away knowing that he's going to continue practicing law without realizing that he's been making some big mistakes of judgment that demand commensurately big corrections has up till this point been even more frustrating.

Replies from: thomblake
comment by thomblake · 2011-11-02T14:34:49.652Z · LW(p) · GW(p)

Then I commend you for your efforts.

brazil84 being a lawyer, though, reduces my confidence that this will pay off. That is a person optimized for debating rather than truth-seeking.

Replies from: TimS
comment by TimS · 2011-11-02T14:44:26.052Z · LW(p) · GW(p)

As a lawyer, I feel obligated to defend the profession a little. Lawyers exist to maximize the utility of the client. But a lawyer who has no grip on what is true cannot tell the client when it makes sense to throw in the towel. And that lack of judgment is not rewarded.

That said, lawyers are relatively well trained in behavior that is orthogonal to truth but correlated with winning. But for the most part, the legal system (i.e. the judge) is trying to determine truth within the limits of its empirical system.

Replies from: thomblake
comment by thomblake · 2011-11-02T14:51:38.130Z · LW(p) · GW(p)

Well said. But note that the behavior is not entirely orthogonal to truth-seeking. Being trained to discuss a dispute through the techniques of debating will surely decrease one's ability to say "oops". (not in the sense of it being a necessary decrease, but in the sense of it being a tendency to decrease such that my prior reduced confidence is justified)

This is actually something I struggle with, being trained as a polemic philosopher.

comment by brazil84 · 2011-11-02T13:54:47.082Z · LW(p) · GW(p)

You, on the other hand, while asserting that the prosecution's arguments collectively deserve high weight

You are talking about the evidence, right?

In response to requests for a defense of such, you've told me it's not your job to do my homework.

In response to your request regarding the phone call, yes. The issue there is not that you have considered the argument on this point and rejected it; the issue is that you are completely unaware of the significance of the forgotten phone call. I identified the phone call merely as an example of the body of evidence against Knox.

Only if you assign zero weight to the evidence rendering conspiracy between them unlikely.

Well, assuming for the sake of argument that (1) Knox and Sollecito were involved in the murder; and (2) there was absolutely no conspiracy as you have defined that term, are you saying that your a priori probability estimate of physical involvement by Knox and Sollecito is 1000 times higher than no physical involvement?

If not 1000, then what?

But when you have no evidence of private meeting, no phone records, no email records, and a very short time frame in which any sort of communication could have taken place, and you don't adjust your likelihood of communication downwards at all,

Are you saying that I have done so?

Then why are so many primary suspects and even convicts later proven to be innocent?

I dispute that "so many" primary suspects and even convicts are later proven to be innocent. How often do you think this happens? What is the percentage of convicts who are later completely exonerated? Surely it is far less than 10% and I have allowed a 10% chance that Knox and Sollecito are innocent.

In fact, when I put it in words, I have to wonder I'm still arguing about any of this. Thus far you have shown a tremendous unwillingness to update in favor of any exculpatory evidence

The only exculpatory evidence you have offered (which I have not already considered) is based on your non-expert opinion. I have patiently explained to you the effect it would have on my probability estimate if you were able to document your opinion.

Or is there some other piece of exculpatory evidence you think I am not considering in my probability estimate?

you insist on demanding a particular piece of evidence

Look, you are the one who is proposing that additional traces of Guede on Kercher would not have made it into the public record. I am asking for you to back up that claim.

Replies from: Desrtopa, DoubleReed
comment by Desrtopa · 2011-11-02T14:16:33.394Z · LW(p) · GW(p)

This simply isn't worth my time.

Seriously, if you want to continue this debate, show me some evidence that you will actually update in the face of more evidence against your position. In the beginning of this debate, you said that you were aware that the DNA evidence against Knox and Sollecito had been challenged. In the face of the independent experts' report indicating that there is no valid DNA evidence against them, and Moore's expert claims for all the evidence we should expect to see in the case of the sort of involvement alleged by the prosecution that we do not see, you update your probability by... nothing. You say you would update your probability were I to provide the right references, but when I offer to make the effort to obtain those references in exchange for a comparable effort on your behalf to produce evidence for your position (I offered you to substitute evidence for any of your assertions if you suggested the substitute first and I agreed that it was appropriate,) you evade. Why should I think this conversation is worth my time? You've given me every reason think that if I go to further efforts, you'll just find more excuses not to update.

Replies from: dlthomas, brazil84
comment by dlthomas · 2011-11-02T18:12:27.253Z · LW(p) · GW(p)

This simply isn't worth my time.

Why should I think this conversation is worth my time? You've given me every reason think that if I go to further efforts, you'll just find more excuses not to update.

You two agree on something!

comment by brazil84 · 2011-11-02T17:51:24.128Z · LW(p) · GW(p)

Seriously, if you want to continue this debate, show me some evidence that you will actually update in the face of more evidence against your position

I already conceded that my probability estimate would drop from roughly 90% to roughly 30% if you could substantiate your claim about transfer of DNA traces.

But anyway, I am not particularly interested in debating Knox's actual innocence with you given your ignorance of the case against Knox.

In the face of the independent experts' report indicating that there is no valid DNA evidence against them

That's not what the independent expert report said, as far as I know.

but when I offer to make the effort to obtain those references in exchange for a comparable effort on your behalf to produce evidence for your position (I offered you to substitute evidence for any of your assertions if you suggested the substitute first and I agreed that it was appropriate,) you evade

Nonsense, you are the one who is evading; since it's not even clear that you dispute my "position" on the point and you refuse to clarify your position. You demanded evidence for a strawman position you set up.

I will ask you one last time, if you evade or ignore we are done:

Assuming for the sake of argument that (1) Knox and Sollecito were involved in the murder; and (2) there was absolutely no conspiracy as you have defined that term, are you saying that your a priori probability estimate of physical involvement by Knox and Sollecito is 1000 times higher than no physical involvement?

If not 1000, then what?

ETA:

Why should I think this conversation is worth my time?

I don't know, what exactly are you trying to accomplish?

Replies from: Desrtopa, TimS
comment by Desrtopa · 2011-11-02T18:03:41.913Z · LW(p) · GW(p)

I will ask you one last time, if you evade or ignore we are done:

We are done. You've given me no more reason to think there's any point in having a conversation with you.

Replies from: Desrtopa, brazil84
comment by Desrtopa · 2011-11-02T18:51:26.176Z · LW(p) · GW(p)

I don't want to get sucked in by replying to more of brazil84's comments, but in the spirit of this quote (edit, link fixed,) in case it will help me to do better in future...

By the way, if any lurkers are reading this, I will point out the fatal flaw in Desrtopa's reasoning on the 90% to 30% issue. See, the prior probability of Knox and Sollecito being involved in the murder but not physically is quite low. But the prior probability of Knox and Sollecito being involved in the murder physically is also low. What matters for my calculation is the ratio of the two probabilities.

I suspect that's why Desrtopa had to bob and weave with my questions on this issue.

Did it look to anyone else like I was bobbing and weaving with my responses to these questions? My perception was that I answered these questions in a straightforward way, but I may have been suffering from illusions of transparency.

Replies from: thomblake, TimS, Jack
comment by thomblake · 2011-11-02T18:57:22.369Z · LW(p) · GW(p)

You definitely got somewhat sucked into "debate mode", and you often had far too many points lobbed at you to have caught all of them. It would seem to be possible for brazil84 to honestly have thought you were evading something, but I don't think an outside observer should have thought so.

That you seem to have kept your cool throughout this ridiculous exercise is a credit.

comment by TimS · 2011-11-02T18:54:49.901Z · LW(p) · GW(p)

You might want to check the link. EDIT: works now.

On the substance, all I can say is dayenu.

comment by Jack · 2011-11-02T18:54:24.682Z · LW(p) · GW(p)

No. You're fine. That's just how brazil argues.

comment by brazil84 · 2011-11-02T18:17:40.882Z · LW(p) · GW(p)

We are done. You've given me no more reason to think there's any point in having a conversation with you.

Ok bye.

By the way, if any lurkers are reading this, I will point out the fatal flaw in Desrtopa's reasoning on the 90% to 30% issue. See, the prior probability of Knox and Sollecito being involved in the murder but not physically is quite low. But the prior probability of Knox and Sollecito being involved in the murder physically is also low. What matters for my calculation is the ratio of the two probabilities.

I suspect that's why Desrtopa had to bob and weave with my questions on this issue. Because he knew deep down that there is no basis to think that this ratio is wildly lopsided. And if the ratio is not lopsided, then it's perfectly reasonable to go from 90% to 30%.

comment by TimS · 2011-11-02T18:04:20.023Z · LW(p) · GW(p)

Why should I think this conversation is worth my time?

I don't know, what exactly are you trying to accomplish?

What exactly are you trying to accomplish?

Replies from: brazil84
comment by brazil84 · 2011-11-02T18:27:52.295Z · LW(p) · GW(p)

What exactly are you trying to accomplish?

  1. I enjoy debating and I am fascinated by situations where the popular view is wrong. Also, I like debating where there isn't anything important at stake.

  2. Once in a while I learn something from debating with someone who disagrees with me.

What about you?

Replies from: TimS
comment by TimS · 2011-11-02T18:35:05.024Z · LW(p) · GW(p)

I enjoy debating and I am fascinated by situations where the popular view is wrong. Also, I like debating where there isn't anything important at stake.

I strongly suspect that you are incorrect about which side of this debate has more adherents. Neither LW nor Wikipedia are likely to be representative.


Once in a while I learn something from debating with someone who disagrees with me.

I hope to learn something in every discussion I have. Debate is for changing people's minds. Debate for its own sake is pointless (aka - I don't debate Flat-Earthers).

You don't seem interested in saying something that I can glean insight from, and you don't seem open to changing your mind.

Replies from: JoshuaZ, brazil84
comment by JoshuaZ · 2011-11-02T18:38:18.456Z · LW(p) · GW(p)

I don't debate Flat-Earthers

Actually, I've done that before. It helps a surprisingly large amount in getting one to realize how astronomy can easily pay rent. And it really tests how well one understands how much historical scientists did really careful, clever observations. That said, I can't plausibly argue that this is a good use of one's time, merely that is probably marginally better use than say playing Farmville.

comment by brazil84 · 2011-11-02T18:48:32.361Z · LW(p) · GW(p)

I strongly suspect that you are incorrect about which side of this debate has more adherents.

On this discussion board, the popular view seems to be that Knox is most likely innocent. I make no claims about what is believed in the world in general.

You don't seem interested in saying something that I can glean insight from, and you don't seem open to changing your mind.

The second part is incorrect -- I am open to changing my mind. As far as the first goes, I don't know where you are at in terms of insight so I couldn't say.

ETA:

I hope to learn something in every discussion I have.

Agree denotatively but disagree connotatively.

Replies from: None
comment by [deleted] · 2011-11-23T20:17:26.562Z · LW(p) · GW(p)

On this discussion board, the popular view seems to be that Knox is most likely innocent. I make no claims about what is believed in the world in general.

On this he is clearly correct.

In any case I don't think this particular comment deserved to be as down voted as it was.

comment by DoubleReed · 2011-11-02T14:10:03.413Z · LW(p) · GW(p)

I dispute that "so many" primary suspects and even convicts are later proven to be innocent. How often do you think this happens? What is the percentage of convicts who are later completely exonerated? Surely it is far less than 10% and I have allowed a 10% chance that Knox and Sollecito are innocent.

First of all, just because they aren't completely exonerated does not mean they are not innocent. A better question is what the percentage chance of innocence is.

Second of all, this assumes that letting a guilty person go free and sending an innocent person to get punished is of equal weight, which it is not.

Replies from: thomblake
comment by thomblake · 2011-11-02T14:17:44.879Z · LW(p) · GW(p)

Second of all, this assumes that letting a guilty person go free and sending an innocent person to get punished is of equal weight, which it is not.

The discussion is about the probability of actual guilt, not the expected utility of punishment, so that's not relevant.

ETA: Relatedly, I've commented elsewhere that a 90% probability of guilt for murder should be well within the "not guilty" verdict range.

Replies from: DoubleReed
comment by DoubleReed · 2011-11-02T14:20:53.901Z · LW(p) · GW(p)

Oh right, good point.

comment by brazil84 · 2011-11-02T00:48:30.803Z · LW(p) · GW(p)

Err that should be "what do you think is the A PRIOR ratio."

comment by TimS · 2011-10-27T17:50:51.912Z · LW(p) · GW(p)

Pardon for the digression, but isn't Knox's physical involvement in the murder the prosecutor's theory of what happened? Otherwise, why should we be interested in Knox DNA on the victim's bra?

I admit that it is conceptually possible that P(Knox is guilty) != P(prosecutor's theory is correct), but in practice they tend to converge.

ETA: I'll even agree that P(Knox is guilty) >= P(prosecutor's theory is correct). Nonetheless, P(Knox is guilty) less P(prosecutor's theory is correct) is a small number.

Replies from: brazil84
comment by brazil84 · 2011-10-27T18:08:34.507Z · LW(p) · GW(p)

Pardon for the digression, but isn't Knox's physical involvement in the murder the prosecutor's theory of what happened?

Yes, as far as I know.

Otherwise, why should we be interested in Knox DNA on the victim's bra?

Actually I think the allegation here is that Sollecito got his DNA on the bra while cleaning up the crime scene.

I admit that it is conceptually possible that P(Knox is guilty) != P(prosecutor's theory is correct), but in practice they tend to converge

I agree, but in this case there is less of a convergence than usual since the prosecution had no choice but to speculate. In any event, I'm allowing a pretty modest probability -- like 5 or 10% -- that Knox and Sollecito were guilty despite a lack of physical involvement as alleged by the prosecution.

ETA: For example, the scenario I described where Knox and Sollecito encourage Guede from just inside the doorway and then turn and run when the blood starts to spill.

Replies from: TimS
comment by TimS · 2011-10-27T18:31:18.805Z · LW(p) · GW(p)

For example, the scenario I described where Knox and Sollecito encourage Guede from just inside the doorway and then turn and run when the blood starts to spill.

This scenario you describe pushes very hard on the distinction between moral guilt and legal guilt, at least in American law. Are we debating Knox's legal culpability or moral culpability?


I agree, but in this case there is less of a convergence than usual since the prosecution had no choice but to speculate. In any event, I'm allowing a pretty modest probability -- like 5 or 10% -- that Knox and Sollecito were guilty despite a lack of physical involvement as alleged by the prosecution.

So, from your point of view:

P(Knox guilty) = .9

P(prosecutor correct) = .85

And to clarify: "Knox guilty" = knowing Knox's relevant behavior and thoughts from that time, every rational person would agree that she had committed a violation of the law that proximately caused the victim's death.


Also, I think that if P(defendant is guilty) less P(prosecutor's theory is correct) is in the range of .05, that is strong evidence that the prosecutor is utterly incompetent. After all, .05 probability is one in twenty. I confess unwillingness to believe that the prosecutor in Knox's case is that incompetent. (More rigorously, my belief in that level of incompetence approaches .001, and even that seems high).

Replies from: Desrtopa, brazil84
comment by Desrtopa · 2011-10-27T19:11:25.927Z · LW(p) · GW(p)

This scenario you describe pushes very hard on the distinction between moral guilt and legal guilt, at least in American law. Are we debating Knox's legal culpability or moral culpability?

Well, it would still be illegal, although I admit that I interpreted brazil84's meaning of "involved in the murder" more narrowly. I would have to make a different probability calculation for the the odds that they did not plan or participate in, but discovered and encouraged, the attack on Meredith Kercher. It would still contain much of the same evidence that I discussed before, and given that I have never even heard of such a thing happening, I would assign a much lower prior, particularly for someone who, as Moore points out, meets none of the FBI criteria for a dangerous personality.

It's even more unlikely when you consider that we're dealing with two people rather than one. If Knox and Sollecito did not plan to kill Kercher, and then found her being attacked in her home, the odds that one of them would be crazy enough to hang back and encourage the attacker, incredibly low as they are, are much higher than the odds that both would.

Replies from: TimS
comment by TimS · 2011-10-27T19:40:50.323Z · LW(p) · GW(p)

This scenario you describe pushes very hard on the distinction between moral guilt and legal guilt, at least in American law. Are we debating Knox's legal culpability or moral culpability?

Well, it would still be illegal.

That's why I specifically reference American law, which contains no general duty to rescue. That is one of the differences between English-descended Common Law, and French-descended Civil Code (which the common model in most of continental Europe).

Replies from: Desrtopa
comment by Desrtopa · 2011-10-27T20:25:50.446Z · LW(p) · GW(p)

I'm going to do a probability estimate for Knox and Sollecito having discovered and encouraged the attack. I'd do it in response to one of brazil84's comments, but I'm already waiting on him to respond to some other questions and don't want to sidetrack him.

Let's start with the prior probability that Knox and Sollecito would witness the murder. Knox and Kercher lived in the same apartment, and Knox and Sollecito spent a lot of time together. Let's call it .2

Neither Knox nor Sollecito meet the criteria for Antisocial Personality Disorder or any of the FBI dangerous individuals criteria. What should we call the probability that such a person, upon witnessing a violent attack on an acquaintance they have no motive to harm (the prosecution having established no motive) would stand back and encourage the attacker? I'll call it >.0001. So if you have two individuals, the chance that they'd both be the sort of person who would hang back and encourage the attacker is >10^-8. But both of them would probably expect the other person to consider this behavior crazy and horrible, much like a person is less likely to commit actual murder in front of another person who they don't know to be sympathetic, so I'll assign a probability of .1 that if both were the sort of person to encourage the attacker, either would make the first move to start doing so. So at this point we have a probability of about 2x10^-10.

Factor in the mutual failure of Knox and Sollecito and Guede to implicate each other; I'll assign this the same .05 probability that I did before. So now we have a probability of >8x10^-12.

If brazil84 assigns .85 probability to the prosecution's account being correct, and .9 probability to their involvement, (I believe he may have been simply giving this as an example rather than actually asserting this,) then let's suppose that the remainder of the probability lies in Knox and Sollecito being physically present and encouraging the attacker, but not entering the room or participating themselves. How much weight would we have to give to the prosecution's evidence against them to get from our current probability to 5%? Their evidence would have to be more than 6.2x10^9 times more likely given Knox and Sollecito's guilt than given their innocence.

As I stated in my earlier comment, I think that crediting them with a likelihood ratio of 50 times, including Knox's mannerisms at the scene, is generous to their case.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-28T11:44:55.130Z · LW(p) · GW(p)

Some additional thoughts on the arguments of the prosecution...

As I said in my first probability analysis, the arguments the prosecution put forward are mostly in the form of "This action seems more suspicious for an innocent person than a guilty person." But for much of their case, I think even that is giving them too much credit. Let's look at some examples.

The three-second phone call from Knox to Kercher. This is unusual behavior, right? Well, I've done this more than a few times myself, but I agree, it is pretty unusual. So how much weight would I assign that evidence? None. The question is not how unusual the behavior is, but how much more unusual if she's innocent than if she was involved in the murder. If I know that Amanda Knox was going, later that day, to come across Meredith Kercher being attacked, and encourage or participate in the attack, the three second phone call will not be any less confusing to me. Stalking and incessant phone calls are certainly more easily explained in light of a murder, but I know of no evidence whatsoever to suggest that murderous inclinations and unusually short phone calls are associated, nor can I think of any particular reason they would motivate one.

The time at which Amanda Knox claims to have woken up. The Massei-Cristiani report finds suspicion in the fact that Knox claimed to have gotten up at 10:00-10:30 AM that day, while her roommates characterized her as an early riser. For a person to violate their established sleep habits is unusual, although still normal enough that their say-so is generally enough to establish it as probably true absent additional reason to doubt them. I am personally not an early riser, but this morning I got up and left the house for a walk at 6:00 AM, while the stars were still bright out (which is in fact what got me thinking about the prosecution's report in the first place.) But Amanda Knox was a murder suspect, doesn't that give us additional reason to doubt her claim? Well, no. Whether she was up at 10:30 or hours earlier has no bearing on the strength of her alibi. We know that the murder didn't happen in the morning, and we know that she was in other places later in that day prior to the murder; it's not as if she failed to establish that she ever left the house. Being involved in the murder doesn't give her any additional reason to claim that she got up at 10:30.

Combined with misrepresentations and mistreatments of forensic evidence, including claims like the pattern of glass being inconsistent with a break-in, which was found to be simply false when tested, a large part of the prosecution's body of arguments does not represent any weight as evidence at all.

comment by brazil84 · 2011-10-27T19:01:48.500Z · LW(p) · GW(p)

This scenario you describe pushes very hard on the distinction between moral guilt and legal guilt, at least in American law.

Generally speaking under American law, if Knox and Sollecito intended for Guede to commit a serious crime against Kercher (such as rape or robbery), and Guede killed Kercher in the process, then Knox and Sollecito would be guilty of murder.

So, from your point of view:

P(Knox guilty) = .9

P(prosecutor correct) = .85

Basically yes, if by "prosecutor correct" you mean the prosecutor is correct that Knox and Sollecito physically participated in the murder. The prosecutor's scenario contained a lot of details; it's very likely that some of those details are wrong.

Also, I think that if P(defendant is guilty) less P(prosecutor's theory is correct) is in the range of .05, that is strong evidence that the prosecutor is utterly incompetent

I disagree, depending on how you define "incompetent." Let's suppose you are the prosecutor - you are confident that Knox and Sollecito were involved in the murder but you don't know exactly what happened. The police have brought you evidence suggesting that Knox stabbed Kercher. You know that in order to convict, you need to give the jury a plausible scenario for what happened. What choice do you have but to make your best guess and go with it?

Perhaps a better argument can be made that the prosecutors were unethical for advancing their speculations about sex games and such to the jury. It would be interesting to see a translation of the transcript of the prosecutor's opening and closing arguments.

Replies from: TimS
comment by TimS · 2011-10-27T19:37:18.759Z · LW(p) · GW(p)

Generally speaking under American law, if Knox and Sollecito intended for Guede to commit a serious crime against Kercher (such as rape or robbery), and Guede killed Kercher in the process, then Knox and Sollecito would be guilty of murder.

Regardless of what Knox and Sollecito intended, they are guilty of none of Guede's crimes unless they acted to participate in some way. But I agree that if Knox had committed conspiracy to rape (or rob, or whatever) Kercher with Guede, then she would be guilty of any murder Guede committed in furtherance or in consequence of that conspiracy. I'll agree to a similar statement about aiding and abetting, but I don't remember the technical language. (And all of this is American law, which is of limited relevance in Italy).


I disagree, depending on how you define "incompetent." Let's suppose you are the prosecutor - you are confident that Knox and Sollecito were involved in the murder but you don't know exactly what happened. The police have brought you evidence suggesting that Knox stabbed Kercher. You know that in order to convict, you need to give the jury a plausible scenario for what happened. What choice do you have but to make your best guess and go with it?

A prosecutor's theory is correct if it includes all the true, morally relevant details. Further, it contains no false, morally relevant details. Compare the a prosecutor saying:

(1) "The defendant shot the victim with a .44 caliber gun, but I don't know the model of the gun."

(2) "The defendant shot the victim, but I don't know the caliber of the gun"

Assuming the statements are true descriptions of what actually occurred, the prosecutor saying (1) is correct and the prosecutor saying (2) is pushing the envelope. Further, a prosecutor who says, "The defendant shot the victim, and the killing was planned ahead of time," when the defendant actually decided to kill during the meeting is incorrect.

As the last example shows, a defendant can be guilt of the crime charged. But I assert that prosecutors assert stories that contain morally relevant that are inconsistent with what actually happened far less than 5% of the time. And when inconsistencies happen, it suggests that the prosecutor is wrong on other morally relevant details.

The prosecutor's scenario contained a lot of details; it's very likely that some of those details are wrong.

From what I understand of the prosecutor's theory of the case, it contained many additional morally relevant details beyond simply Knox and Sollecito's physical involvement in Kercher's murder.


P(Knox guilty) = .9

P(prosecutor correct) = .85

For the reasons I just discussed, your probability distribution seems inconsistent with the evidence. Specifically, you rescue Knox and Sollecito's guilty from possible errors by the prosecutor by proposing a theory that even you think has only a 5% chance of being true.

Replies from: brazil84
comment by brazil84 · 2011-10-29T14:46:59.770Z · LW(p) · GW(p)

Regardless of what Knox and Sollecito intended, they are guilty of none of Guede's crimes unless they acted to participate in some way. But I agree that if Knox had committed conspiracy to rape (or rob, or whatever) Kercher with Guede, then she would be guilty of any murder Guede committed in furtherance or in consequence of that conspiracy. I'll agree to a similar statement about aiding and abetting, but I don't remember the technical language.

Agree.

A prosecutor's theory is correct if it includes all the true, morally relevant details. Further, it contains no false, morally relevant details. Compare the a prosecutor saying:

I'm not sure what your point is here. Are we arguing about whether the prosecutor is competent? About whether he is unethical?

Do you agree that as a practical matter, in order to have a good chance of securing a conviction, a prosecutor needs to present a coherent narrative to the jury?

Specifically, you rescue Knox and Sollecito's guilty from possible errors by the prosecutor by proposing a theory that even you think has only a 5% chance of being true.

I don't understand this sentence. I'm reluctant to guess at what you mean, but please keep in mind that "prosecutor correct" can be taken different ways. Does it mean simply that he is correct about physical involvement; or does it mean that his entire narrative is substantially correct?

Replies from: TimS
comment by TimS · 2011-10-29T16:39:20.892Z · LW(p) · GW(p)

I don't understand this sentence. I'm reluctant to guess at what you mean, but please keep in mind that "prosecutor correct" can be taken different ways. Does it mean simply that he is correct about physical involvement; or does it mean that his entire narrative is substantially correct?

My previous post was trying to define what I meant by correctness for the purpose of the probability analysis I did. In brief, a prosecutor is correct if the theory presented to the jury contains no morally relevant facts that are contradicted by what actually occurred. (To clarify what I mean by moral relevance: Did the burglar go in the unlocked front or unlocked back door? Legally relevant, but not morally relevant).

Thus, I think the answer to your question is that the prosecutor is incorrect if the narrative does not correctly describe what actually occurred. As I noted above, the prosecutor's incorrectness is not inconsistent with the defendant's legal guilt. But I assert that prosecutor's incorrectness is suggestive of legal innocence because it shows the prosecutor doesn't know what happened.


Do you agree that as a practical matter, in order to have a good chance of securing a conviction, a prosecutor needs to present a coherent narrative to the jury?

Sure, juries like stories. That isn't precisely a rationalist feature of juries.

In the Kercher case, the prosecutor's case was filled with morally relevant facts (e.g. the sex cult/orgy thing) that were wildly implausible and not supported by any evidence that I'm aware of. Then, more plausible assertions (i.e. it was impossible to enter the apartment via the fire escape) were contradicted. Since I independently believe that (P(defendant guilty of charged crime) & P(prosecutor incorrect)) is small, I'm left to estimate a very small likelihood that Knox is guilty.

Replies from: brazil84
comment by brazil84 · 2011-10-29T17:46:46.891Z · LW(p) · GW(p)

Thus, I think the answer to your question is that the prosecutor is incorrect if the narrative does not correctly describe what actually occurred. As I noted above, the prosecutor's incorrectness is not inconsistent with the defendant's legal guilt. But I assert that prosecutor's incorrectness is suggestive of legal innocence because it shows the prosecutor doesn't know what happened.

Fine, but you don't get to redefine the terms I used and then use your different definition to conclude that my probability estimate doesn't make sense. That would be a fancy way of strawmanning me.

When I basically agreed that I believe that P (prosecutor correct) is 85%, I was careful to make clear what I meant by "prosecutor correct." Please do not pretend that I meant (or that we were discussing) something different.

Replies from: TimS
comment by TimS · 2011-10-31T15:35:05.762Z · LW(p) · GW(p)

It was not my intent to strawman you. I seem to have misunderstood your position. Let's return to basics.

Let's define "no orgy, but guilty" as the state in which Knox and Sollecito are legally guilty of Kercher's murder, but many of the prosecutor's asserted morally relevant facts are false. By definition:

P(guilty) = P(prosecutor correct) + P(no orgy, but guilty)

P(no orgy, but guilty) = P(prosecutor incorrect) & P(guilty) [If I understand the terminology correctly]


Since you seem to agree that the prosecutor made incorrect assertions of morally relevant facts, your value of P(prosecutor correct) is negligibly small. Why do you think that the prosecutor made the assertions? Before you say "narrative," let me assert that many of the prosecutor's assertions could have been replaced with "I don't know" with limited loss of coherence to the narrative.

Replies from: brazil84
comment by brazil84 · 2011-11-01T13:22:37.717Z · LW(p) · GW(p)

Why do you think that the prosecutor made the assertions?

Can you give me a specific example?

Before you say "narrative," let me assert that many of the prosecutor's assertions could have been replaced with "I don't know" with limited loss of coherence to the narrative

Ok, you've said it. And now my answer:

Narrative. I do agree that the prosecutor could have omitted a few things and still had a somewhat coherent narrative. But if he got rid of all the speculation, what he would be left without any motive or explanation for why Knox and Sollecito acted in concert with Guede.

Replies from: TimS
comment by TimS · 2011-11-01T15:54:52.289Z · LW(p) · GW(p)

Why do you think that the prosecutor made the assertions?

Can you give me a specific example?

Quoting wikipedia: "[The prosecutor alleged] that the murder was part of a Satanic ritual; that it was a sex game gone wrong; or that Kercher had refused to take part in an orgy."

Honestly, a substantial part of my doubt of Knox and Sollecito's guilt is the utter ridiculousness of those allegations. They were not necessary to provide narrative to the jury and could easily have been omitted, since there was apparently no evidence suggesting they were true.

Further, they are the type of allegations I would expect when the prosecutor is seeking to inflame, rather than rationally presenting the evidence.

Replies from: brazil84
comment by brazil84 · 2011-11-01T16:24:45.150Z · LW(p) · GW(p)

Quoting wikipedia: "[The prosecutor alleged] that the murder was part of a Satanic ritual; that it was a sex game gone wrong; or that Kercher had refused to take part in an orgy."

Ok, to answer your question, I believe that the prosecutor made these assertions because he felt pressure to answer the question of Knox and Sollecito's motives.

Replies from: TimS
comment by TimS · 2011-11-01T16:39:27.763Z · LW(p) · GW(p)

Satanic ritual? The prosecutor could have just said, "The roommates had a big fight." In terms of evidence of guilt, there are two major problems in the "satanic ritual" theory that are not present in a more mundane theory. The satanic ritual theory proves too much, in that there is almost no evidence that could possibly be inconsistent with it. Second, the theory functions to demonize the defendants, which is not consistent with strong actual evidence of guilt.

And those theoretical arguments ignore the practical fact that there was no evidence suggesting interest in satanic ritual by either defendant, which I consider important given the general implausibility of the theory given what I know about society (There are practically no murderous satanists in real life).

Replies from: brazil84
comment by brazil84 · 2011-11-01T17:06:55.628Z · LW(p) · GW(p)

The prosecutor could have just said, "The roommates had a big fight."

Apparently he did also propose more mundane motives. Here's the full quote from Wikipedia:

The prosecutors proposed a number of possible motives for the murder, for which they produced no evidence, including that Kercher and Knox had fallen out over issues such as the cleaning roster in their home; that the murder was part of a Satanic ritual; that it was a sex game gone wrong; or that Kercher had refused to take part in an orgy.

When you quoted Wikipedia, why did you omit the part about the cleaning roster?

Replies from: TimS
comment by TimS · 2011-11-01T17:08:54.965Z · LW(p) · GW(p)

When you quoted Wikipedia, why did you omit the part about the cleaning roster?

Because I'm interested in why the prosecutor kept talking after he articulated that theory.

Replies from: brazil84
comment by brazil84 · 2011-11-01T17:32:30.921Z · LW(p) · GW(p)

Because I'm interested in why the prosecutor kept talking after he articulated that theory.

Either theory is just speculation, agreed? I mean, if it's unethical for the prosecutor to argue that there was a satanic ritual, it's also unethical for him to argue that it's a dispute over who should clean the apartment. Agreed?

Replies from: TimS, TheOtherDave
comment by TimS · 2011-11-01T17:44:50.891Z · LW(p) · GW(p)

I'm not trying to say the prosecutor is unethical. I'm saying that outlandish claims from the prosecutor are evidence of innocence. It's just a Big Lie


And if the prosecutor really has no idea why defendant committed a crime, that's also evidence of innocence, right?


One could rationalize the prosecutor's behavior by saying that lower standards apply to statements to the media than statements in court. But the reason that it's unethical to try cases in the media is that this reduces the likelihood that the trial will be correlated with the truth. I attribute knowledge of that principle to the prosecutor, so his decision to try the case in the media suggests that the defendants are innocent.

Replies from: brazil84
comment by brazil84 · 2011-11-01T17:58:38.586Z · LW(p) · GW(p)

I'm not trying to say the prosecutor is unethical

Ok, I thought we were discussing whether the prosecutor was ethical.

I'm saying that outlandish claims from the prosecutor are evidence of innocence.

I agree. And the decision to arrest Knox is evidence of guilt.

Replies from: TimS
comment by TimS · 2011-11-01T18:18:20.467Z · LW(p) · GW(p)

Ok, I thought we were discussing whether the prosecutor was ethical.

We were discussing whether the prosecutor is competent.


the decision to arrest Knox is evidence of guilt.

No, it isn't. The decision to arrest is evidence that the authorities think they have evidence of guilt. But the arrest is not independent of the underlying evidence and does not make the underlying evidence stronger.

Replies from: brazil84
comment by brazil84 · 2011-11-01T18:24:58.176Z · LW(p) · GW(p)

We were discussing whether the prosecutor is competent.

Ok, then why are you bringing up the question of whether the prosecutor's assertions are evidentiary?

The decision to arrest is evidence that the authorities think they have evidence of guilt. But the arrest is not independent of the underlying evidence and does not make the underlying evidence stronger.

Similarly, the prosecutor's proposal that there may have been a Satanic ritual involved is not independent of the underlying (lack of) evidence of motive and does not make the underlying evidence weaker.

Replies from: TimS
comment by TimS · 2011-11-01T18:35:51.729Z · LW(p) · GW(p)

The prosecutor's theory is not evidence of the same type as DNA. But it tells us something about how strong the prosecutor thinks the legally relevant evidence is.

The reference to satanic ritual and sex games is an appeal to applause lights. It is political machinations, not an empirically based search for truth. The fact that the prosecutor made that appeal, rather than sticking with a plausible story, shows that the prosecutor doesn't think the facts support guilt or doesn't care.

As an observer, I'm allowed to give weight to the fact that one side of a dispute doesn't seem to be trying to determine the facts.

Replies from: dlthomas, brazil84
comment by dlthomas · 2011-11-01T18:51:13.266Z · LW(p) · GW(p)

A prosecutor will always make the strongest case they think they can, and juries do not comprise perfect rationalists.

comment by brazil84 · 2011-11-01T19:04:27.261Z · LW(p) · GW(p)

The prosecutor's theory is not evidence of the same type as DNA. But it tells us something about how strong the prosecutor thinks the legally relevant evidence is.

The decision to arrest the defendant is not the same type as DNA. But it tells us something about how strong the authorities think the legally relevant evidence is.

As an observer, I'm allowed to give weight to the fact that one side of a dispute doesn't seem to be trying to determine the facts

I would say the amount of weight depends on the extent you are relying on unsupported assertions of that side. For example, if we knew nothing at all about the case except the prosecutor saying "Trust me, I have reviewed the evidence and I am satisfied that the Defendant is guilty, it would be very important that the prosecutor is proposing a seemingly outlandish hypothesis.

Replies from: TimS
comment by TimS · 2011-11-01T19:47:23.920Z · LW(p) · GW(p)

This is the expertise problem. You and I do not have access to all the evidence, so we look to the experts. If anyone is an expert on the strength of the case, it is the prosecutor. And a prosecutor referencing satanic rituals and sex cults is like a psychologist referencing the "Niceness Gene" to explain some behavior. It isn't impossibly wrong, but it strongly suggests the expert doesn't know what he is talking about.

Replies from: brazil84
comment by brazil84 · 2011-11-01T19:58:08.549Z · LW(p) · GW(p)

This is the expertise problem. You and I do not have access to all the evidence, so we look to the experts. If anyone is an expert on the strength of the case, it is the prosecutor.

So in your view, any probability assessment of Knox's guilt which does not put a lot of weight on the prosecutor's credibility is deeply flawed. Agreed?

Replies from: TimS
comment by TimS · 2011-11-01T20:10:13.271Z · LW(p) · GW(p)

No. The physical evidence does not support Knox's guilt. But the fact is that the prosecutor and other Italian authorities are engaging in a lot of motivated cognition to support the theory of guilt even when the evidence doesn't support it.

The motivated cognition is so blatant that it persuaded me that Knox was probably not guilty even before I looked at the evidence. I suspect that if the world were more rational, my reasoning would be less likely to provide useful insight.

Replies from: brazil84
comment by brazil84 · 2011-11-02T00:05:38.554Z · LW(p) · GW(p)

No. The physical evidence does not support Knox's guilt.

How do you know this if you do not have access to all of the evidence and therefore must "look to the experts"?

It seems to me that you and I both have access to enough of the evidence to make a decent estimate of the probability of Knox's guilt without relying on someone who has superior access to the evidence.

comment by TheOtherDave · 2011-11-01T18:12:04.164Z · LW(p) · GW(p)

I'm not sure I would agree with this, FWIW.

My estimate of how ethical it is for a prosecutor to propose theory X about a defendant's motive increases with how common X is, and decreases with how sensational X is. Roommates arguing over cleaning an apartment is both more common and less sensational than satanic rituals, so my estimates of how ethical it is to propose those theories differs.

Of course, maybe there's some particularly salient threshold that both examples exceed. If so, it's worth articulating that threshold explicitly... when it comes to propounding theories about motive, it's not clear to me what that threshold is or ought to be.

comment by brazil84 · 2011-10-23T21:38:43.152Z · LW(p) · GW(p)

Err, that should be "very likely to leave biological traces behind in sufficient amounts that investigators are likely to find and match them."

comment by magfrump · 2011-10-21T04:57:44.145Z · LW(p) · GW(p)

I suspect that your anger at me over that incident is informing your commentary.

Wedrifid is just like that. All the time.

Replies from: brazil84
comment by brazil84 · 2011-10-21T05:08:06.983Z · LW(p) · GW(p)

Ok, then perhaps my suspicions are unwarranted.

comment by wedrifid · 2011-10-21T02:54:48.993Z · LW(p) · GW(p)

I vaguely recall that you got pretty annoyed at me a year or so ago when I pointed out a contradiction in your reasoning.

I don't recall any conversations with you. (Mind you I expect I would have if I believed you then. Actually being wrong is embarrassing.)

No, from the premise "brazil84 is blatantly and obviously wrong despite paying attention to the topic" "don't do what brazil84 did" is a reasonably good inference to make. But as I noted you don't share that premise so naturally you should not be expected to believe it. This is why you were not the intended audience.

Replies from: lessdazed, brazil84
comment by lessdazed · 2011-10-21T02:55:59.946Z · LW(p) · GW(p)

Actually being wrong is embarrassing.

Usually, it depends.

Replies from: wedrifid
comment by wedrifid · 2011-10-21T03:03:09.727Z · LW(p) · GW(p)

Oh, true. For example your correction here gives somewhat less than 0 embarrassment points. Let me clarify that to "In cases where someone is attempting to criticize me regarding a substantial assertion I have made in a manner that makes the situation highly status relevant actually being wrong is embarrassing".

comment by brazil84 · 2011-10-21T03:18:27.474Z · LW(p) · GW(p)

I don't recall any conversations with you.

I'm pretty sure we had a lengthy exchange. But I suppose I will give you the benefit of the doubt and assume that your public claim -- in essence -- that my conclusions are insane was purely from the desire to help other posters and not in any way related to our history.

ETA: I just was looking back and I realized that I do not engage with you anymore. I had forgotten about that. Anyway, bye again.

comment by pedanterrific · 2011-10-21T02:46:36.273Z · LW(p) · GW(p)

I vaguely recall that you got pretty annoyed at me a year or so ago when I pointed out a contradiction in your reasoning.

... Also pay specific attention to my exchange with wedrifid.

Are you referring to the 'exchange' that starts around here and continues from there? If so... I'm not so sure bringing this to people's attention is in your best interests.

Replies from: brazil84
comment by brazil84 · 2011-10-21T02:53:51.381Z · LW(p) · GW(p)

Are you referring to the 'exchange' that starts around here and continues from there?

No, I was referring to the exchange in the earlier Knox thread.

I'm not so sure bringing this to people's attention is in your best interests.

For me, this is not a competition to see how many people I can win over or how many karma points I can accumulate.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T03:10:59.133Z · LW(p) · GW(p)

If it's this you're referring to, I have to wonder how you got from there to "I suspect that your anger at me over that incident is informing your commentary". That seems like blowing it way out of proportion.

Replies from: brazil84, brazil84
comment by brazil84 · 2011-10-21T03:34:42.335Z · LW(p) · GW(p)

Ok, I think I found it:

http://lesswrong.com/lw/1j7/the_amanda_knox_test_how_an_hour_on_the_internet/1c6t?context=9#comments

And here's an exchange between me and him which got pretty personal:

http://lesswrong.com/lw/1ph/youre_entitled_to_arguments_but_not_that/1njx?context=1#1njx

He's apparently deleted some of his comments, but I wouldn't have asked him to stop making things personal if he hadn't done so.

Here's one thing which he said (and later deleted, it seems):

I think you could sincerely assert six mutually contradictory things before breakfast.

Clearly he and I have some history here, to put it politely.

Anyway, was reading over the thread and now I remember I banned the guy.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T03:38:34.709Z · LW(p) · GW(p)

Ok, I think I found it:

Yes, that's the third link I suggested.

an exchange between me and him which got pretty personal

And that was the first.

Here's one thing which he said (and later deleted, it seems):

Dude, that was in the post you linked directly to.

Replies from: brazil84
comment by brazil84 · 2011-10-21T03:45:46.213Z · LW(p) · GW(p)

Ok, so you can see that he and I have a history here. It seems pretty likely to me that his most recent comments were motivated by personal animus. Feel free to draw your own conclusions.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T03:51:20.782Z · LW(p) · GW(p)

Okay, looking back, wedrifid lays out his point as:

  • brazil84 didn't learn from the opinions and reasoning of other fairly rational and intelligent people.
  • brazil84 expended sufficient energy on the topic in question to be able to arrive at a sane conclusion.
  • brazil84 did not arrive at a sane conclusion.
  • Don't do what brazil84 did because it makes you wrong and also makes you look silly.

And you respond with... an ad hominem in the form of an appeal to motive.

Hm.

Replies from: brazil84
comment by brazil84 · 2011-10-21T03:58:55.085Z · LW(p) · GW(p)

And you respond with... an ad hominem in the form of an appeal to motive.

Yes I did. What's wrong with that? My actual arguments on the merits are in the original thread. People can read them and decide if my conclusions are sane or not.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T04:03:29.787Z · LW(p) · GW(p)

What's wrong with that?

There's this thing, it's called 'logical fallacies'. We try to avoid them here. It's kinda the point.

Edit: Let me put it this way: the fact that you reached an incorrect conclusion and acted like you didn't get what was wrong with that was sufficient reason for wedrifid to act as he did. To impute other motives for no apparent reason is... well, it's rude.

Replies from: Desrtopa, brazil84, brazil84, brazil84
comment by Desrtopa · 2011-10-21T04:11:36.392Z · LW(p) · GW(p)

Well, if someone has motives for making a statement aside from its truth, then it will tend to decrease the degree to which the statement is conditional on the truth, and thus its weight as evidence. So while "A has ulterior motives for saying X, therefore X is false" is certainly fallacious, "A has ulterior motives for saying X, therefore decrease the weight of evidence you assign to X" is not. It can, however, be such an insignificant presentation of evidence as to be distracting and logically rude.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T04:19:11.735Z · LW(p) · GW(p)

Yes, this is what I'm getting at.

And when X = [the sky is blue], you shouldn't decrease the weight of evidence you assign to X at all, because the statement was never evidence of that in the first place: it's just remarking on something obvious.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T04:32:04.817Z · LW(p) · GW(p)

And when X = [the sky is blue], you shouldn't decrease the weight of evidence you assign to X at all, because the statement was never evidence of that in the first place: it's just remarking on something obvious.

It's still evidence; it's more likely conditional on the sky being blue than conditional on the sky not being blue. But the weight of one remark is very weak evidence compared to that which is already available to you.

If everyone started asserting that the sky was green, that it had always been green, and that you must be delusional for remembering otherwise, you might be wiser to doubt the input of your own senses.

Although if you're questioning your own sanity, I suppose it might be likelier that you're imagining that everyone has started claiming that the sky is green than that you're imagining that it's blue and that people ever used to say so.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T04:41:44.392Z · LW(p) · GW(p)

Okay, maybe "at all" was an exaggeration.

And this reminds me of a post a while back about the reliability of peer-reviewed science journals over your own senses. (The catch being that you can't extract information from science journals without using your senses.)

comment by brazil84 · 2011-10-21T04:27:57.248Z · LW(p) · GW(p)

By the way, can you explain to me what you think it is that I am (or should be) trying to accomplish here?

I'm not so sure bringing this to people's attention is in your best interests.

What interests are you referring to?

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T04:36:43.336Z · LW(p) · GW(p)

I assumed you were playing a status game; all "oh woe is me, wedrifid is unfairly persecuting me for besting him in an argument (which is blurred by the passage of time and to which I will not provide a link)". In which case, bringing up that specific argument - in which you are clearly in the wrong - would seem to work at cross-purposes.

That's just the impression I was operating under when I wrote that comment, mind.

Replies from: brazil84
comment by brazil84 · 2011-10-21T04:42:18.673Z · LW(p) · GW(p)

I assumed you were playing a status game;

Lol, thanks for your concern about my motivations.

Anyway, I'm pretty confident that I was in the right in my previous exchange but I prefer to discuss it in the previous thread. If you see a flaw in an argument I presented, feel free to present it (preferably there). I promise to consider it in good faith.

comment by brazil84 · 2011-10-21T04:24:12.234Z · LW(p) · GW(p)

Let me put it this way: the fact that you reached an incorrect conclusion and acted like you didn't get what was wrong with that was sufficient reason for wedrifid to act as he did. To impute other motives for no apparent reason is... well, it's rude.

I'm not sure what your point is here. Wedrifid seemed to be saying that it was necessarily wrong for me to put little weight on the opinions of other posters. In essence, I asked him to spell out his argument. At that point, he got pretty nasty. And as noted, he didn't actually make an argument on the merit's of Knox's guilt or innocence. Nor did he make an actual argument for why I should have put more weight on the opinions of other posters. He asserted his conclusion.

When somebody makes a statement like that, as if it's from authority, it's reasonable to point it out if they have an agenda.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T04:48:56.617Z · LW(p) · GW(p)

And as noted, he didn't actually make an argument on the merit's of Knox's guilt or innocence.

For one thing, he wasn't really talking to you, but to people already convinced of her innocence.

Nor did he make an actual argument for why I should have put more weight on the opinions of other posters.

Once you accept the implications of Aumann's Agreement Theorem, the only reason not to would seem to be extremely low opinions of their intelligence and rationality.

It's a combination of having little respect for the opinions of anonymous internet posters

Well, guess that answers that.

Replies from: brazil84
comment by brazil84 · 2011-10-21T05:06:09.645Z · LW(p) · GW(p)

For one thing, he wasn't really talking to you, but to people already convinced of her innocence.

I'm not sure what difference this makes. He publicly pronounced my earlier conclusion to be insane, in response to a post I made. When somebody behaves like that, it's reasonable to point out that there may be some personal animus involved.

Well, guess that answers that.

FWIW, the only person here whose opinion I have some degree of respect for is Eliezer and even he has lost a lot of his edge over the years. Not that it matters, since I mainly go by peoples' actual arguments on the merits and not their opinions.

Replies from: bigjeff5
comment by bigjeff5 · 2011-11-07T23:33:00.147Z · LW(p) · GW(p)

I really think you aught to start reading through the sequences on rationality and biases, but you might need to start with basic logic first.

If you've read them already, then I'm just shocked. Maybe read them again? I don't know what else to suggest.

The fact that you can continue to argue that Knox and Sollecito are guilty with a 90% confidence, after it has been proven within the limits if modern science's ability to prove anything, that there is not one trace of physical evidence that Knox and Sollecito were involved in the murder, is just mind blowing to me.

All of the arguments presented to you are going to fail, because they are based on critical thinking and logic, and you don't seem to be capable of these.

To repeat a previous poster, the fact that you are a lawyer and show such a complete inability to reason (to the point that you think logical fallacies are reasonable arguments in some cases*) is downright scary.

*Motive is reasonable evidence for adjusting credibility, but it is always weak and often insignificant. It should never, ever be used to claim an argument is false. The most you can claim is uncertainty of the truth of an argument if the motive is sufficiently strong.

Replies from: dlthomas, brazil84
comment by dlthomas · 2011-11-10T21:01:44.574Z · LW(p) · GW(p)

[I]t has been proven within the limits if modern science's ability to prove anything, that there is not one trace of physical evidence that [some specific facts about a specific event].

This seems like ridiculous hyperbole - science has far more ability to "prove" things that are repeatable than unrepeatable.

Replies from: bigjeff5, PhilosophyTutor, DoubleReed
comment by bigjeff5 · 2011-11-11T01:03:15.846Z · LW(p) · GW(p)

You are absolutely correct.

I should have said "anything of this nature", my mistake.

comment by PhilosophyTutor · 2011-11-10T22:46:54.632Z · LW(p) · GW(p)

This seems like ridiculous hyperbole - science has far more ability to "prove" things that are repeatable than unrepeatable.

You are completely correct.

In the spirit of constructing the best possible argument to engage with, I think we should run as if bigjeff5 had actually said exactly what he said, but appended to it "and the prior probability of the alleged crime having occurred as per the police theory is so incredibly low that nothing but physical evidence that Knox and Sollecito were involved in the murder should push our posterior probability into the >1% range", or something similar.

Replies from: Desrtopa, dlthomas
comment by Desrtopa · 2011-11-10T23:42:14.347Z · LW(p) · GW(p)

I'd say there's all sorts of non-physical evidence that would be sufficient to push our posterior probability of their guilt higher than that (insofar as any evidence in a materialistic universe can be said to be non-physical.) Email records between Knox, Sollecito and Guede discussing their plans to kill Kercher, for instance. Or if Knox or Sollecito had made statements about the circumstances of Kercher's death which forensics corroborated which they could not plausibly have made without knowledge that would require them to have been there. Even just evidence of private meetings between Knox, Sollecito and Guede, combined with enough of the warning signs for a person likely to commit murder ought to boost the likelihood that they were complicit well over 1%.

It's not that there aren't possible forms of non physical evidence that would be adequate to establish a high likelihood for their guilt, it's that such evidence is conspicuous in its absence.

Replies from: PhilosophyTutor
comment by PhilosophyTutor · 2011-11-11T01:09:32.006Z · LW(p) · GW(p)

I'd say there's all sorts of non-physical evidence that would be sufficient to push our posterior probability of their guilt higher than that (insofar as any evidence in a materialistic universe can be said to be non-physical.) Email records between Knox, Sollecito and Guede discussing their plans to kill Kercher, for instance. Or if Knox or Sollecito had made statements about the circumstances of Kercher's death which forensics corroborated which they could not plausibly have made without knowledge that would require them to have been there. Even just evidence of private meetings between Knox, Sollecito and Guede, combined with enough of the warning signs for a person likely to commit murder ought to boost the likelihood that they were complicit well over 1%

My intention was certainly to have recordings of Knox and Sollecito plotting to kill Meredith Kercher, email records of such an exchange, mobile phone calls placed to Rudy Guede and so on as physical evidence if any of them had existed. I class ones and zeroes on a hard drive or a magnetic imprint on a tape as physical evidence just as I count DNA as physical evidence.

Eyewitness evidence or police claims unsupported by physical evidence would be the kind of thing I intended to exclude by specifying physical evidence.

comment by dlthomas · 2011-11-10T22:52:10.307Z · LW(p) · GW(p)

I agree that the argument should proceed that way. I was only weighing in tangentially on the rhetoric.

comment by DoubleReed · 2011-11-10T21:15:11.823Z · LW(p) · GW(p)

Nonetheless, the absence of any scientific evidence at all pointing towards guilt (when there was lots of scientific evidence taken) would still be significant evidence of absence of guilt, correct?

It's not a proof but it is evidence. He's challenging the 90%, which is perfectly fair under Bayesian reasoning. Because that evidence of absence of guilt is very significant, it would should shift your probabilities far more downward.

Replies from: dlthomas
comment by dlthomas · 2011-11-10T21:21:35.819Z · LW(p) · GW(p)

I did not mean to say, "there is no evidence of absence of guilt", or even "there is not overwhelming evidence of absence of guilt" - not really having looked directly at evidence myself, it would be silly for me to weigh in either way. I was just objecting to the hyperbole: science's ability to "prove" (or provide evidence for) the premise that Newtonian gravity approximately holds for speeds and masses typically involved in human activity on the surface of the earth seems much, much greater than sciences ability to "prove" (or provide evidence for) anything particular feature of a past event.

comment by brazil84 · 2011-11-08T10:31:51.228Z · LW(p) · GW(p)

I really think you aught to start reading through the sequences on rationality and biases, but you might need to start with basic logic first. If you've read them already, then I'm just shocked. Maybe read them again? I don't know what else to suggest.

I've already read most of that stuff, and I would suggest to you that the problem is with your thinking -- not mine. If you are in the wrong, then it would naturally seem to you like my thinking is completely irrational.

Perhaps it will help if I ask you this question: What do you think are some of the best pieces of evidence against Knox and Sollecito?

P.S. It's likely that for many people, most of the articles on bias will actually make them stupider because they will become better at results-oriented or motivated reasoning.

Replies from: wedrifid, bigjeff5, TimS
comment by wedrifid · 2011-11-10T20:28:25.612Z · LW(p) · GW(p)

I want to print this comment out and frame it. This is for real, not tongue in cheek irony?

comment by bigjeff5 · 2011-11-08T19:12:21.533Z · LW(p) · GW(p)

Since the elimination of the faulty DNA evidence (which was previously the best evidence against them), the best evidence against Knox and Sollecito come from the police interrogation, specifically Knox's confession, and the fact that they knew the victim.

The strongest bit here is the confession, as knowing the victim is, at best, a pointer for where to look for a suspect - it is incredibly weak evidence on its own (in fact, there are dozens of people who fit better based on just knowing the victim) and does not in any way eliminate the possibility of a random stranger committing the crime. By all accounts the three got along reasonably well, if not particularly friendly to each other.

There are some interesting facts about the confession that I think you're missing:

1.) It is factually incorrect. The statements in the confession do not fit the facts of the crime. This severely damages the validity of the confession.

2.) The confession came after 24 hours of non-stop interrogation by the Italian police. There have been a number of studies that have shown that suspects become highly confused after long, intense interrogation sessions - particularly those that include sleep deprivation as was the case here. Suspects can be coerced into making whatever statements the interrogators want. In fact, in the US we have laws against this kind of treatment, including things like the right to silence and the right to have an attorney present during an interrogation to prevent exactly these scenarios. As an attorney I'd expect to know this.

Taken together, by far the most likely scenario is that the police coerced the confession out of Knox. Just on the facts relating to the interrogation alone, I'd put the likelihood that the confession was genuine at 10% at the very highest.

If the confession were genuine, we would expect some physical evidence of Knox and Sollecito at the crime scene. Given the fact that there is literally zero physical evidence of Knox and Sollecito's involvement, the likelihood that the confession is genuine must drop even further, to below 1%.

Considering the confession is about the only evidence for their involvement, I have to place the likelihood of their guilt at <1%. (There was a homeless man who claimed he saw them enter the apartment, but this is so weak as to be irrelevant given the poor track record of eyewitness accounts even immediately after a highly memorable event, the credibility of a detailed recollection of a mundane event over a year after it occurred is virtually non-existent, particularly without any evidence to back it up of any kind.)

Also, the reason I suggested you re-read the sequences is because you stated that you were 90% certain that all three were guilty, yet 90% that Guide was guilty even if the other two were not. This is a major failure in probability (and is actually a pretty common bias), as the options are Guide acted alone, or Guide acted with accomplices. Eliminating Knox and Sollecito from the equation eliminates a point of uncertainty, no matter how certain you are of Knox and Sollecito's guilt, and aught to increase your confidence in the individual assessment of Guide's guilt. Being 99% certain that Guide is guilty, and 90% certain that Guide, Knox, and Sollecito are guilty is logically consistent. Being 90% certain that Guide is guilty, yet 90% certain that all three are guilty is not logically consistent. You have to either lower you confidence in the guilt of all three, or raise your confidence in the guilt of Guide.

I may have phrased that last paragraph poorly, but most people should be able to understand it. I may edit for clarity later.

Edited to add: Here is a good article on coerced confessions, written by a forensic scientist.

Second edit, sorry, pertinent quote from the article:

When a confession is admitted and later retracted and claimed to have been made under duress, an additional question is whether the jury can understand the pressures that led up to the confession. Milgram's (1963, 1964) obedience studies suggest that, although most people may believe they personally would never succumb to pressure, their behavior in a coercive environment is to conform. Jury members may be unable to perceive how an innocent person could actually confess to something he did not do. Widespread overconfidence in personal ability to resist coercion may lead jurors to give undue and erroneous weight to a coerced confession. Expert testimony may be necessary to help jurors understand the circumstances that lead to nonvoluntary confessions, but trial courts have not always admitted such testimony.

Replies from: brazil84
comment by brazil84 · 2011-11-10T16:01:30.008Z · LW(p) · GW(p)

There are some interesting facts about the confession that I think you're missing:

Not really, since I put little weight on what Knox said under interrogation. I have no problem believing that an innocent person would buckle under the pressure and point the finger at someone else. To me, what's most interesting about this "confession" was that the authorities arrested another person (the wrong person) based on Knox's statements. This is evidence that the authorities had something of an open mind about the situation.

Anyway, I disagree with you that this is the strongest piece of evidence against Knox and I think I can demonstrate it to you if you will indulge me by answering (or trying to answer) a few questions:

(1) When did Knox first become concerned about Kercher's absence?

(2) When did Sollecito and Knox first call the police and why?

(3) If it turns out that the ransacking of Romanelli's room was a staged burglary, do you agree that this is decent evidence against Knox?

Also, the reason I suggested you re-read the sequences is because you stated that you were 90% certain that all three were guilty, yet 90% that Guide was guilty even if the other two were not.

Can you show me where I did that? My recollection is I estimated roughly 99% for Guede's guilt.

I agree that it would not make sense to estimate 90% for Knox, Sollecito, and Guede to all be involved in the murder and 90% for Guede alone.

Replies from: bigjeff5, komponisto
comment by bigjeff5 · 2011-11-11T02:18:28.971Z · LW(p) · GW(p)

Can you show me where I did that? My recollection is I estimated roughly 99% for Guede's guilt.

I agree that it would not make sense to estimate 90% for Knox, Sollecito, and Guede to all be involved in the murder and 90% for Guede alone.

My apologies, I misread/misremembered your original assessment. I should have double checked before posting; you can ignore that whole portion of my post.

(1) When did Knox first become concerned about Kercher's absence?

(2) When did Sollecito and Knox first call the police and why?

These circumstances are enough to drive suspicion toward Knox and Sollecito, but without any sort of physical evidence to back up the suspicions they are insignificant. There are a lot of possible explanations for their behavior and the vast majority don't include murder.

(3) If it turns out that the ransacking of Romanelli's room was a staged burglary, do you agree that this is decent evidence against Knox?

If it is proven that it was staged by Knox/Sollecito, then absolutely. The inverse is also true, however: if Knox/Sollecito are innocent, then they didn't fake the break-in. The evidence that the break-in was staged is very weak, which is exactly what you expect to see if they are innocent.

This is the part, I think, that you are missing: the physical evidence (including reliable electronic evidence) is extremely strong evidence. It is "trumps everything" kind of strong. Slightly odd behavior is incredibly weak evidence. There is a huge amount of physical evidence in this case, and none of it points to Knox or Sollecito. The likelihood that they could be guilty of murder without leaving any evidence behind is incredibly small. Without evidence of any sort of link between Guide and Knox/Sollecito the complete lack of physical evidence of their involvement trumps the little bit of circumstantial evidence by a wide margin.

Replies from: brazil84
comment by brazil84 · 2011-11-11T02:51:35.818Z · LW(p) · GW(p)

These circumstances are enough to drive suspicion toward Knox and Sollecito, but without any sort of physical evidence to back up the suspicions they are insignificant. There are a lot of possible explanations for their behavior and the vast majority don't include murder.

It seems you are unable to answer two questions which would have been pretty easy if you understood the case against Knox and Sollecito and were still satisfied of their innocence. To be sure, they are komponisto-disingenuous questions. But still, why not simply try to answer them anyway?

This is the part, I think, that you are missing: the physical evidence (including reliable electronic evidence) is extremely strong evidence. It is "trumps everything" kind of strong. Slightly odd behavior is incredibly weak evidence.

Again, it seems pretty clear to me that you do not understand the case against Knox and Sollecito, which is far more than "slightly odd behavior."

Without evidence of any sort of link between Guide and Knox/Sollecito

By the way, did you know that there was in fact evidence of such a link presented? I was surprised myself to learn about it.

Replies from: wnoise, PhilosophyTutor
comment by wnoise · 2011-11-11T18:39:48.375Z · LW(p) · GW(p)

Again, it seems pretty clear to me that you do not understand the case against Knox and Sollecito, which is far more than "slightly odd behavior."

You act as if there is one unified "case against Knox and Sollecito". There is not. There are many, as different people who believe Knox and Sollecito did it find different aspects to be more convincing. We understand plenty of cases against Knox and Sollecito just fine -- the ones we have read that have been made clearly. What is true is that we don't understand the case you have in mind. This is because you have never made that case, nor pointed us to someone clearly making that case. Yet you do expect us to miraculously understand the details of it. If we guess, unsurprisingly, it is counted as evidence that we don't understand, yet you never attempt to correct that understanding. It is your responsibility to say why some bit evidence actually means anything. I'm disinclined to continue unless this is rectified.

Stop trolling and put up or if that's too hard, at least shut up.

Replies from: brazil84
comment by brazil84 · 2011-11-14T12:44:26.330Z · LW(p) · GW(p)

You act as if there is one unified "case against Knox and Sollecito". There is not. There are many, as different people who believe Knox and Sollecito did it find different aspects to be more convincing.

Perhaps reasonable people can differ on fine gradations of significance among the more important pieces of evidence, but, for example, anyone who seriously believes that Knox's "mannerisms" are among the best pieces of evidence against her has seriously missed the boat.

Anyway, if I have the time I will put together a blog post laying out what I think are the most important pieces of evidence and Knox (and Sollecito).

Replies from: wnoise
comment by wnoise · 2011-11-14T19:53:03.149Z · LW(p) · GW(p)

I await with bated breath.

Replies from: brazil84
comment by brazil84 · 2011-11-16T17:49:05.159Z · LW(p) · GW(p)

I'm glad to know you are so interested in what I have to say.

ETA: My blog post is up as of today (11/17/11)

Replies from: wnoise
comment by wnoise · 2011-11-18T20:55:35.086Z · LW(p) · GW(p)

A link to said post would help.

Replies from: brazil84
comment by brazil84 · 2011-11-18T21:20:30.429Z · LW(p) · GW(p)

http://fortaleza84.wordpress.com/2011/11/17/is-amanda-knox-guilty/

Replies from: JoshuaZ
comment by JoshuaZ · 2011-11-18T23:12:25.510Z · LW(p) · GW(p)

I'm happy that you've finally posted this. However, much of this piece makes me cringe. I don't know if it is the style, an actual failure of logic or something else. Parts like:

It’s interesting that in this case, Sollecito had taken a strong interest in deviant pornography. I think he would have been really turned on by the idea of setting up a pretty white girl to be raped by a black thug.

Really doesn't help your case more than simply inflame issues. Moreover, "deviant pornography", seriously? What fraction of the population watches BDSM themed porn or other forms of non-standard porn? The fraction is orders of magnitude larger than the set of people who murder or arrange for murders. It isn't even obvious to me that that's even more common among murderers.

Replies from: brazil84
comment by brazil84 · 2011-11-19T01:12:17.852Z · LW(p) · GW(p)

I'm happy that you've finally posted this. However, much of this piece makes me cringe. I don't know if it is the style, an actual failure of logic or something else. Parts like:

It’s interesting that in this case, Sollecito had taken a strong interest in deviant pornography. I think he would have been really turned on by the idea of setting up a pretty white girl to be raped by a black thug.

Really doesn't help your case more than simply inflame issues. Moreover, "deviant pornography", seriously? What fraction of the population watches BDSM themed porn or other forms of non-standard porn? The fraction is orders of magnitude larger than the set of people who murder or arrange form murders. It isn't even obvious to me that that's even more common among murderers.

Frankly, I would guess a big part of the problem is that you did not read my post very carefully. Because you seem to be under the impression that I argued that Sollecito's (alleged) interest in deviant pornography was evidence of guilt.

I even went so far as to put the following at the bottom the post:

Second, please try to respond to the arguments I actually make. I can already imagine some joker saying “Sollecito’s interest in deviant pornography is not evidence that he was a murder!!!” Dude, that’s not the argument I am making. I have no tolerance for people who strawman me.

Replies from: gwern, JoshuaZ
comment by gwern · 2011-11-19T01:36:16.017Z · LW(p) · GW(p)

If the porn is not relevant either way, then it should not be mentioned. Mentioning it in a short piece invites the viewer to interpret it that way or, if they read it so carefully as to (non-)interpret it as you say, it comes off as sheer rhetoric and an attempt to contaminate the reader's mind with unfounded assertions.

("Ladies and gentleman of the jury, I would like you to imagine the defendant late one night holding down his daughter and raping her repeatedly in every orifice in defiance of every law of God and man. There is of course no evidence he has actually done this and we are here to discuss his tax evasion, but I simply wanted you to imagine it for a little bit. Moving on to the first tax filing exhibit...")

Replies from: Desrtopa, brazil84
comment by Desrtopa · 2011-11-19T17:59:43.398Z · LW(p) · GW(p)

If anything, I would say that the porn is evidence against Sollecito's guilt. After all, considering how common "black guy rapes white girl" porn is, if that's something he was interested in seeing and his porn viewing is indicative of his interests, then it would be more reasonable to expect him to have it than not.

Anyway, the idea that the porn could be not evidence, but something to show a plausible scenario, is simply nonsense. The prior probability for Sollecito's guilt reflects all possible scenarios in which Sollecito could have been involved, and is based on our best available knowledge of how often people in his circumstances commit the sort of crime attributed to him. Any meaningful information must either show that our prior was inappropriate (people in Sollecito's reference class commit this sort of crime more often than we thought) or show that Sollecito in particular was more likely to have committed this particular crime. Brazil disavowed its relevance in the latter respect, and it's obviously not relevant in the former.

comment by brazil84 · 2011-11-19T02:07:23.776Z · LW(p) · GW(p)

If the porn is not relevant either way, then it should not be mentioned.

I think it's relevant because it helps to show that there is a remotely plausible scenario in which Knox murders her roommate; that it's not like asserting that Elvis was actually an extra-terrestrial.

It's the same reason I mentioned the Janet Chandler murder. The fact that one white girl took part in the rape and murder of another white girl in Michigan in the 70s is not evidence that Knox is guilty either. Again, it just helps to show that such a scenario is remotely plausible.

I would hope and expect that many of the posters on this board will accept this point about remote plausibility without any narrative. Such people should feel free to ignore that part of my blog post.

Replies from: PhilosophyTutor
comment by PhilosophyTutor · 2011-11-19T03:57:26.896Z · LW(p) · GW(p)

I think you've run afoul of the principle of charity here, in that your piece was taken as an argumentative essay and thus it was charitable to assume that each part of it was intended to support your stated conclusion. In future it would help a lot if you made your conclusions explicit at each stage of the argument rather than leaving them implicit because otherwise readers are forced to guess at what you think the evidence means.

Having read your piece I also think that you're reasoning from some false premises. If you read enough of the popular material on the internet about this case it becomes evident fairly quickly that in pro-guilt circles the evidence has taken on a life of its own and grown in the telling.

There is no actual evidence that Sollecito had " a strong interest in deviant pornography", although plenty of sites would claim that. There is evidence he was once in possession of one film clip involving bestiality in his university years, which is not proof of a strong interest, and evidence he was in possession of a mainstream and unremarkable manga book, but that's the extent of the evidence that he had any deviant sexual tendencies.

Similarly there was no evidence Amanda Knox had a promiscuous lifestyle by student standards nor that Knox had numerous male visitors. Knox gave a complete list of her lifetime sexual partners to the police when they (falsely) told her she had tested HIV+, and she wasn't any more promiscuous than your average student.

It's simply not true that Knox and Sollecito called the police after the police had already arrived. That misconception arose due to incorrect police testimony but it was later cleared up.

There was never any evidence that the break-in at the house was staged and the appeal court exonerated Knox and Sollecito of those charges on the grounds that particular crime had never in fact happened.

To your credit you state clearly that you are basing your opinion on popular sources and that you are open to the possibility that your evidence is faulty, and it's no sin to reason rigorously from false premises and get to a false conclusion.

(By contrast the evidence of egregious police misconduct in the Knox case is very strong indeed. Italy is a curiosity in that it has no meaningful police oversight body and hence the police can get away with virtually anything. In every other First World country the relevant misconduct investigation body would have their metaphorical foot right up the Perugian authorities' collective metaphorical posterior by now).

Replies from: brazil84
comment by brazil84 · 2011-11-19T12:14:26.240Z · LW(p) · GW(p)

I think you've run afoul of the principle of charity here, in that your piece was taken as an argumentative essay and thus it was charitable to assume that each part of it was intended to support your stated conclusion. In future it would help a lot if you made your conclusions explicit at each stage of the argument rather than leaving them implicit because otherwise readers are forced to guess at what you think the evidence means.

I would say it doesn't get much more explicit than this:

Of course, none of the above is proof or even evidence that Knox was involved, it’s pure speculation and I would write it off if there weren’t such compelling evidence against Knox.

In fact, I would go so far as to suspect that some folks here are going on the principle of anti-charity, i.e. looking for the easiest way to attack my post while ignoring the core argument.

Having read your piece I also think that you're reasoning from some false premises.

Well let's discuss them then.

There is no actual evidence that Sollecito had " a strong interest in deviant pornography",

I would say that having been in possession of a bestiality film as well as "comic books that 'mixed pornography and horror‛" is pretty good evidence of a strong interest in deviant pornography. I'm not sure that it matters, since Sollecito's alleged interest in deviant pornography is not central to my argument. But perhaps it's worth discussing.

You seem to dispute that Sollecito was in the possession of such comic books (plural.) Do you happen to have a cite and a link? I am going by the police report as quoted on page 103 of the sentencing report.

Similarly there was no evidence Amanda Knox had a promiscuous lifestyle by student standards nor that Knox had numerous male visitors

I'm not sure what "promiscuous lifestyle by student standards" means. According to one report I read (ETA: this morning), Knox had sex with 3 men after her arrival in Italy and 4 prior. Disagree?

As far as male visitors goes I was able to find this quote:

"Another friend, Robyn Butterworth talked about how their friend Meredith felt awkward because Knox didn't flush the toilet. All of the girls recalled Meredith talking about how Knox brought strange men home and how she kept in the bathroom a transparent tote bag with condoms and a pink vibrator shaped like a rabbit.

I'm not sure what "numerous" means to you, but it seems clear to me that at a minimum, there is evidence to believe that Knox engaged in sexual activities which Kercher would have resented and perceived as slutty. Agreed?

It's simply not true that Knox and Sollecito called the police after the police had already arrived. That misconception arose due to incorrect police testimony but it was later cleared up.

Well in your view, when did the police arrive? And more importantly, at the time the police arrived, were Knox and Sollecito concerned about Kercher's absence? If you look at the evidence carefully, you will see that there is no good answer for this question which is consistent with Knox being innocent.

Also, do you agree that Sollecito at one point stated to police that he had not called the police at the time the police showed up?

There was never any evidence that the break-in at the house was staged

That's simply not true. For example, Romanelli apparently testified to finding glass on top of her dislodged belongings. She also testified that nothing was taken. And Sollecito told the police that nothing was taken before he should have known it. Now, you may want to debate the strength of this evidence, but it's still evidence that the break-in was staged.

and it's no sin to reason rigorously from false premises and get to a false conclusion.

I agree. Could you please share your own sources? Maybe we can figure out which of us (perhaps both) are reasoning from false premises.

Replies from: PhilosophyTutor
comment by PhilosophyTutor · 2011-11-20T01:20:35.113Z · LW(p) · GW(p)

As far as sources go, it's just a fact that so far you have provided few sources and those were vague. I'm happy to take part in a conversation where we each cite our sources properly, or where neither do, but not an asymmetrical one where I am obliged to cite sources and you are not.

I would say that having been in possession of a bestiality film as well as "comic books that 'mixed pornography and horror‛" is pretty good evidence of a strong interest in deviant pornography.

I wouldn't say that at all. Potential alternative reasons for being in possession of a bestiality film clip include curiosity, desire to shock, or an interest in deviant pornography which does not rise to the level of "strong". The comic book in question was 'Blood: The Last Vampire' which is such a mainstream affair that the animated movie shows regularly on the public broadcasting channel SBS where I live in Australia.

If Sollecito had been found to have a few gigabytes of rape and BDSM porn on his hard drive I would take that to be evidence of a strong interest in deviant pornography. One clip he possessed once in the past and a mundane comic book do not to my mind constitute strong evidence.

I'm not sure what "numerous" means to you, but it seems clear to me that at a minimum, there is evidence to believe that Knox engaged in sexual activities which Kercher would have resented and perceived as slutty. Agreed?

Well no, not based on that evidence. To begin with this was court testimony from long after the murder, from people who have had over a year to cherry-pick anything Meredith could have said at any time which could be taken as evidence of friction between Knox and Kercher. You have to avoid the base rate fallacy here: What are the odds that we would hear testimony like this if there was no serious animosity between the two, under these circumstances? I'd say pretty good.

Bear in mind that if the two had ever, say, had a nasty argument or one had stolen the other's clothes or anything more serious had ever occurred we would be hearing about that instead. For students living together if the worst instances of friction anyone can recall are complaints about monotonous guitar practice, a transparent toiletries bag and (as I recall) a single instance of Knox bringing a strange man home, who she did not (as far as we can ascertain from her list of sexual contacts) sleep with, then they probably got along quite well.

By all accounts dating from before the murder the two got on well, went on outings together and were friends.

Well in your view, when did the police arrive? And more importantly, at the time the police arrived, were Knox and Sollecito concerned about Kercher's absence? If you look at the evidence carefully, you will see that there is no good answer for this question which is consistent with Knox being innocent.

The postal police arrived at 13:00 as established by security camera evidence. The carabinieri arrived at 13:34. Raffaele called the police at 12:51. Knox and Sollecito had been trying to find out where Meredith was and whether she was okay from 12:07 onwards as established by phone records.

The postal police incorrectly claimed they had arrived at 12:35 but this was based on their unassisted recollection and was falsified by the security camera nearby.

That's simply not true. For example, Romanelli apparently testified to finding glass on top of her dislodged belongings. She also testified that nothing was taken. And Sollecito told the police that nothing was taken before he should have known it.

She also testified to finding glass under some of her belongings and mixed through them, and since some things were in fact taken (money and mobile phones) the fact that some things were not taken is not evidence for staging over a real break-in. Sollecito did state that nothing was taken but at that stage he did not know anything had been taken, and while an ideal rationalist with time to think would have said "I am aware of no evidence anything was taken" a university student under stress being imprecise is not more consistent with guilt than innocence.

There were also scuff marks on the wall outside consistent with someone climbing in, freshly exposed brickwork consistent with someone chipping the wall while climbing in, white powdery deposits in Filomena's room consistent with someone having scuffed their feet on the white wall outside while climbing in, and several large chunks of glass on the outside windowsill consistent with someone positioned on the window sill manually enlarging the hole in the glass to access the window's latch. This is all evident from photographs of the crime scene yet the police inexplicably testified that there was no evidence of a break-in.

Replies from: gwern, shokwave, brazil84
comment by gwern · 2011-11-20T02:07:16.330Z · LW(p) · GW(p)

The comic book in question was 'Blood: The Last Vampire' which is such a mainstream affair that the animated movie shows regularly on the public broadcasting channel SBS where I live in Australia.

Wait, that was what was being referenced when Brazil quoted

"comic books that 'mixed pornography and horror‛"

‽ My high school anime club showed the movie of that twice (we ran under schedule one day) so I remember it well... Good grief. And Brazil is still arguing. I don't know why you guys are still bothering - I'm not going to, even if it seems tempting.

Replies from: wedrifid, Vladimir_Nesov
comment by wedrifid · 2011-11-20T02:49:27.862Z · LW(p) · GW(p)

I have considered arguing with brazil about Knox to be troll feeding for some time.

comment by Vladimir_Nesov · 2011-11-20T02:23:14.580Z · LW(p) · GW(p)

(Note that brazil84 earned –208 Karma in the last 30 days, with most of the recent comments having moderately negative rating.)

comment by shokwave · 2011-11-20T02:00:58.922Z · LW(p) · GW(p)

This is all evident from photographs of the crime scene yet the police inexplicably testified that there was no evidence of a break-in.

Outside view explication: a break-in reliably leaves more evidence than what the police found.

comment by brazil84 · 2011-11-20T13:41:19.429Z · LW(p) · GW(p)

I'm happy to take part in a conversation where we each cite our sources properly, or where neither do, but not an asymmetrical one where I am obliged to cite sources and you are not.

The way I do things with sources is that if somebody represents to me that he is seriously skeptical of a claim I have made, I will normally try to find a source. Similarly, I will not ask for a source (or cite) unless I am seriously skeptical of a claim which has been made. The reason I do things this way is because I do think in general people should provide sources (or cites) to back up their claims, but at the same time I have encountered problems in online debate with people who demand cites for claims which they don't seriously dispute, presumably just to distract the discussion from the critical issues. (Also, keep in mind that for some claims, general knowledge, simple observation, and common sense are potentially reasonable or adequate sources. )

So the upshot is that I will try to find and provide a cite or source for any claim I make if you represent to me that you are seriously skeptical of the claim.

With that out of the way, I am seriously skeptical of your apparent claim that Sollecito was in the possession of a "mainstream and unremarkable manga book" and not multiple "comic books that mixed pornography and horror." I have provided a cite for my position, now please provide a cite for yours.

Well no, not based on that evidence.

I'm not sure I understand your point.

Do you agree that there was testimony that Kercher advised her friends that Knox had brought "strange men [plural]" over?

Do you agree that such testimony is evidence (although perhaps not proof) that Knox did in fact bring multiple men to the residence?

Based on your knowledge of human nature, do you agree that there is a pretty good chance that Kercher would have resented such behavior?

The postal police arrived at 13:00 as established by security camera evidence.

Can you give me a cite for this please? (I am seriously skeptical)

Raffaele called the police at 12:51. Knox and Sollecito had been trying to find out where Meredith was and whether she was okay from 12:07 onwards as established by phone records.

Ok, then here's a couple questions for you:

  1. If Knox and Sollecito were concerned about Kercher's absence when the postal police arrived, why did Knox (apparently) advise them that Kercher normally kept her door locked?

  2. Why did Sollecito (apparently) later admit to the authorities that he had not yet called the police with the postal police showed up?

(And yes, I will provide sources for this stuff if you represent to me that you are seriously skeptical.)

She also testified to finding glass under some of her belongings

I'm not sure what your point is here. Do you dispute that she testified to finding glass on top of some of her belongings? Do you dispute that this is evidence (evidence, not conclusive proof) of a staged break-in?

some things were in fact taken (money and mobile phones) the fact that some things were not taken

Well do you agree that (1) the evidence seems to indicate that nothing was taken from Romenelli's room; and (2) according to Sollecito's story, he had seen Romanelli's room but not Kercher's room at that point?

a university student under stress being imprecise is not more consistent with guilt than innocence.

Well was he asked about it or did he volunteer it? As far as I know, he first volunteered that there was no theft and then when asked if anything was taken, he said "no." I could understand him giving an imprecise answer if asked about it, but why would he volunteer that nothing was taken?

There were also scuff marks on the wall outside consistent with someone climbing in,

Again, I am seriously skeptical of this claim. Please back it up with a quote, link, and cite.

comment by JoshuaZ · 2011-11-19T01:39:00.633Z · LW(p) · GW(p)

Yes, I saw that, but I found it to be as either disingenuous or at best unhelpful. If it is irrelevant then it shouldn't be mentioned. In context if you are using it for evidence then claiming you aren't isn't helpful and simply brings up something that will make people annoyed.

Replies from: brazil84
comment by brazil84 · 2011-11-19T02:29:43.669Z · LW(p) · GW(p)

The same thing could be said about my mention of the Janet Chandler murder. The fact that one white girl helped to rape and murder another white girl (who was her roommate) back in the 70s in Michigan is not evidence of Knox's guilt.

But as I mentioned in the blog post, I think both are helpful to show a remotely plausible scenario in which Knox is guilty.

If you disagree, then I think that under the "principle of charity," you should simply ignore paragraphs 2 through 7 (which you apparently consider to be irrelevant, inflammatory fluff) and consider the core of my argument.

Replies from: JoshuaZ
comment by JoshuaZ · 2011-11-19T22:06:00.402Z · LW(p) · GW(p)

Yes, and the mention of the Chandler case also falls into the same category.

both are helpful to show a remotely plausible scenario in which Knox is guilty.

Does something increase plausibility or show a plausible scenario? Then it is evidence. If it doesn't increase plausibility then it isn't evidence. You can't have it both ways.

Replies from: brazil84, Desrtopa
comment by brazil84 · 2011-11-19T22:51:42.648Z · LW(p) · GW(p)

Does something increase plausibility or show a plausible scenario? Then it is evidence.

Well sure if you want to take a broad view of what constitutes "evidence," then everything in my scenario constitutes "evidence." (ETA: I would take a slightly narrower view, but perhaps it makes sense to agree on a definition.)

Similarly, by your standard the fact that had had sex with at least 7 men by the age of 20 is "evidence." Why? First, because it raises the probability that she suffers from borderline personality disorder and therefore is lacking in empathy. Someone lacking in empathy is more likely to take part in a serious crime against another person. Second, because it raises the probability that she had male visitors which would have increased tension between her and Kercher, increasing the chances that she had a motive.

Anyway, I have a question for you: Why do you continue to ignore my core argument for Knox's guilt?

Replies from: Tyrrell_McAllister
comment by Tyrrell_McAllister · 2011-11-20T23:16:00.095Z · LW(p) · GW(p)

Similarly, by your standard the fact that had had sex with at least 7 men by the age of 20 is "evidence." Why? First, because it raises the probability that she suffers from borderline personality disorder and therefore is lacking in empathy.

Yes, this is all evidence according to the Bayesian definition. Calling E evidence (with respect to prior knowledge X) for a proposition H just means that p(H | E & X) > p(H | X). That is why quantifying evidence is so important. Just how much evidence is it? If all the evidence you offer raises the probability of H by only a few percent from a very low prior, then it should have practically no effect on how we treat Knox.

Replies from: brazil84
comment by brazil84 · 2011-11-21T02:08:02.695Z · LW(p) · GW(p)

Yes, this is all evidence according to the Bayesian definition. Calling E evidence (with respect to prior knowledge X) for a proposition H just means that p(H | E & X) > p(H | X). That is why quantifying evidence is so important. Just how much evidence is it? If all the evidence you offer raises the probability of H by only a few percent from a very low prior, then it should have practically no effect on how we treat Knox.

I basically agree, but sometimes it's helpful to have a story or narrative or illustration before jumping in to look at the important evidence. That's just how the human mind works, or at least most peoples' minds. I realize this can be dangerous, for example it can lead to a "conjunction fallacy," but I was careful to lable my narrative as speculation.

Just today I was browsing this web site and I came across an article called "Existential Risk" which was complete with (1) a picture of the Earth; (2) a likely apocryphal story about a man who singlehandedly prevented nuclear war; and (3) a picture of a Stanford torus. Is this cheap emotional manipulation? Perhaps, but again, I think this kind of story-telling can be useful to get the mind ready to focus on the meat of the argument.

One can ask what the likelihood is that we are reaching a critical juncture where the decisions and dilligence of just a few humans in the artificial intelligence community will have a massive impact on the future of humanity. Strictly speaking, the fact that some Russian dude did (or didn't) singlehandedly prevent a nuclear war shouldn't have much impact on our estimate of this probability. But I think it still might be worth mentioning to demonstrate the plausibility of the claim that one person can have a big impact.

In the same way, I think it's worth mentioning the Janet Chandler case from the 70s. But again, if you object to this approach, just ignore paragraphs 2 through 7 of my blog post.

Replies from: Tyrrell_McAllister
comment by Tyrrell_McAllister · 2011-11-21T02:42:47.226Z · LW(p) · GW(p)

In the same way, I think it's worth mentioning the Janet Chandler case from the 70s. But again, if you object to this approach, just ignore paragraphs 2 through 7 of my blog post.

I agree that it's worth mentioning Janet Chandler. It would be better to treat it seriously as evidence, rather than merely as a narrative framing device. To treat it seriously as evidence, you should use it to help establish a prior probability for Knox's guilt (like Desrtopa did).

Replies from: brazil84
comment by brazil84 · 2011-11-21T03:16:50.234Z · LW(p) · GW(p)

It would be better to treat it seriously as evidence, rather than merely as a narrative framing device. To treat it seriously as evidence, you should use it to help establish a prior probability for Knox's guilt

It seems to me that "narrative framing device" is basically a poor man's method of estimating a prior probability. Here's what I said in my blog post:

The point is that there are levels of extraordinary. Claiming that Knox participated in her roommate’s murder is not like claiming that the president is actually an extra-terrestrial from Mars.

Of course in terms of assessing probabilities, it might be better if there were a lot of precedents, for example in a situation where a husband is suspected of killing his wife. But here there's not a lot to go on.

comment by Desrtopa · 2011-11-19T22:44:02.345Z · LW(p) · GW(p)

Well, new information could suggest that you applied the wrong prior. If you're trying to calculate the likelihood of a person's guilt, and you find that the crime is more common than you originally thought, you'll have to assign a higher probability of guilt, but you could reasonably say that it's not evidence of guilt, because you're revising P(A) rather than introducing a new (B).

This could be said to apply to the mention of the Chandler case, if you don't have any information on how common such crimes are that would screen it off, but it clearly does not apply to the porn.

comment by PhilosophyTutor · 2011-11-11T03:06:28.827Z · LW(p) · GW(p)

It seems you are unable to answer two questions which would have been pretty easy if you understood the case against Knox and Sollecito and were still satisfied of their innocence. To be sure, they are komponisto-disingenuous questions. But still, why not simply try to answer them anyway?

It's a very effective rhetorical device to trick the opponent into saying a complicated thing, and then respond with a simple thing. I'm not saying this is what you are attempting, but it could well seem that you are attempting this.

For example homeopaths try to steer conversations about homeopathy so that the skeptic says a lot of complicated things about Avogadro's Number and the minute time-scale on which water molecule structures persist and the need for double-blinded, placebo-controlled trials and then the homeopath gets to say "Yes, well, it miraculously cured my cat's cataracts and that's all I need to know".

If you tried to explain what evidence you have with regard to when Knox first became concerned about Kercher's absence, and with regard to when Sollecito and Knox first called the police, and how you conclude from this evidence that they are guilty, you would be put in the position of saying the complicated thing. Other people could then respond with the simple thing, which I predict would be "none of that proves anything".

Whereas if you make the other person say the complicated thing, then you could respond with a pithy rhetorical question and gain the rhetorical advantage.

I honestly cannot see how the truth-seeking process benefits from you not presenting your evidence. You seem to be taking the discussion to the level of a status battle over who has personal authority and I think we should try to avoid that outcome.

comment by komponisto · 2011-11-10T16:22:29.586Z · LW(p) · GW(p)

(1) When did Knox first become concerned about Kercher's absence?

(2) When did Sollecito and Knox first call the police and why?

These questions are disingenuous and pointless. If you think the answers to them are incriminating to Knox and Sollecito, then you should just state (what you believe to be) the answers and explain why they are incriminating. This is what you would do if you were arguing honestly (instead of trying to "catch" your opponent in a mistake), and it would also save time.

(3) If it turns out that the ransacking of Romanelli's room was a staged burglary, do you agree that this is decent evidence against Knox?

Of course it is, which is why the staging charge carries a burden of proof equal to that of the murder charge.

I agree that it would not make sense to estimate 90% for Knox, Sollecito, and Guede to all be involved in the murder and 90% for Guede alone.

That would make perfectly good sense. What would not make sense is 90% for all three and 90% for Guede with or without the others.

Replies from: wedrifid, brazil84
comment by wedrifid · 2011-11-10T19:53:08.049Z · LW(p) · GW(p)

Preface: I disagree with brazil about basically everything he says regarding Knox and reject most of the reasoning he uses to try to argue his case. But:

These questions are disingenuous and pointless.

Disingenuous does not apply to these questions in this context. There is no feigning of naivety, ignorance or unsophistication. The questions are rhetorical, pretentious, annoying, misguided, of dubious relevance and wrapped up with a tad of snide - but not disingenuous.

Replies from: komponisto
comment by komponisto · 2011-11-10T19:58:37.369Z · LW(p) · GW(p)

There is feigning of ignorance of the answers (even if the feigning is transparent); and they aren't rhetorical. On the other qualities we agree.

Replies from: wedrifid
comment by wedrifid · 2011-11-10T20:17:58.165Z · LW(p) · GW(p)

There is feigning of ignorance of the answers (even if the feigning is transparent)

No, there isn't. Nothing in that passage in any way implies that brazil is ignorant of the answer to those questions.

Replies from: komponisto
comment by komponisto · 2011-11-10T22:22:19.264Z · LW(p) · GW(p)

I do not consider the distinction you are drawing important enough to restrict my use of the term "disingenuous". As far as I am concerned the questions themselves imply ignorance of the answers, and this is the basis on which the term was used. You are free to disapprove (and your disapproval is noted), but I shan't be drawn into a status battle over this issue.

Replies from: wedrifid, PhilosophyTutor
comment by wedrifid · 2011-11-11T01:43:48.257Z · LW(p) · GW(p)

You are free to disapprove (and your disapproval is noted), but I shan't be drawn into a status battle over this issue.

Excuse me? While there is an unfortunate and unavoidable status implication in the mere willingness to correct someone rather than being too intimidated by the potential threat they may pose I went to a lot of trouble to ameliorate that in the correction in question. I prefaced with an indication of full support for you in your status battle with brazil then offered a whole stream of applicable substitute negative labels for brazil's rheotorical ploy to show that I am not trying to subvert the core of the message "brazil should have lowered status because of what he said to kompo" - because the latter would, in fact, seem appropriate.

The above being the case it actually kind of hurts to be portrayed as trying to 'draw you into a status battle'. The opening salvo in any such battle would be the parent and I obviously wouldn't draw it out beyond this one reply. I could only stand to lose by such an engagement.

Regarding the calling of people disingenuous there probably isn't a problem here - I expect you consider the back and forth you've had with brazil over the subject to have gone on long enough. Obviously in general I am always likely to object if somewhat is falsely accused of being disingenuous. It would be outright bizarre if I didn't when I have already done so when the unjustly accused is someone I consider a troll-minus-malicious-intent. In the context of lesswrong disingenuousness is perhaps one of the most dire things you can accuse someone of!

Replies from: komponisto
comment by komponisto · 2011-11-11T02:17:40.067Z · LW(p) · GW(p)

The above being the case it actually kind of hurts to be portrayed as trying to 'draw you into a status battle'.

As it happens I gave serious consideration to rewording or dropping the last line, but didn't get to it in time. It was more heavy-handed than I intended, sorry. But, in fairness to myself, I would point out that the future tense was used, and that there was no intended implication of inappropriate aggression on your part in the preceding exchange. I was, in other words, retreating from a danger that I foresaw (for whose existence I am as surely to blame as anyone, being as I am a human).

I had intended only to communicate that I wasn't terribly interested in arguing about the meaning of "disingenuous" in this particular context at this particular moment, nothing more. (I'll mention that I had also considered the wording: "drawn into a status battle with an ally...)

Replies from: wedrifid
comment by wedrifid · 2011-11-11T02:20:09.397Z · LW(p) · GW(p)

Note that I had also considered the wording: "drawn into a status battle with an ally...

It's amazing how much difference those few words make. ;)

comment by PhilosophyTutor · 2011-11-10T22:39:55.134Z · LW(p) · GW(p)

I do not consider the distinction you are drawing important enough to restrict my use of the term "disingenuous". As far as I am concerned the questions themselves imply ignorance of the answers, and this is the basis on which the term was used.

The questions may have been posed as Socratic questions rather than disingenuous or rhetorical questions.

However the Socratic method is a pedagogical device. It's not meant to be a tactic used to get out of stating what your argument or beliefs really are when trying to arrive at the truth and it does seem to me that it would save time if brazil84just stated whatever evidence they have and what conclusions they draw from it.

Replies from: komponisto
comment by komponisto · 2011-11-10T22:45:51.774Z · LW(p) · GW(p)

The questions may have been posed as Socratic questions...However the Socratic method is a pedagogical device.

Indeed; hence using it amounts to an assertion of higher status like that of teacher over pupil. This would be another ground on which to object to brazil's questions.

comment by brazil84 · 2011-11-10T17:09:12.926Z · LW(p) · GW(p)

These questions are disingenuous and pointless.

I disagree, because I suspect that just like desrtopa, bigjeff5 does not understand the case against Knox. If he is unable to answer these questions, it will confirm my suspicions. At the moment, I am not interested in debating Knox's guilt with biggjeff5 if he hasn't bothered to study and understand the evidence against her.

Of course it is

Well do you agree that there is decent (if not compelling) evidence that the burglary was staged? For example (1) Romanelli's testimony that she found glass on top of her disturbed items; (2) Romanelli's testimony that nothing was taken from her room; and (3) Sollecito's apparent statement to the police (before Romanelli returned) that there had been a burglary but nothing was taken?

What would not make sense is 90% for all three and 90% for Guede with or without the others.

Yes, I think that's what I meant. I think I can make things simpler by laying out 4 possibilities:

(1) Guede, Knox, and Sollecito were all involved in the murder;

(2) Guede was involved in the murder but not Knox or Sollecito;

(3) Guede was not involved in the murder but Knox and Sollecito were;

(4) None of Guede, Knox, or Sollecito were involved in the murder.

I think that the probability of (1) is roughly 90%; (2) is roughly 9+%; (3) is negligible; and (4) is negligible.

Make sense?

(I also think that the chances that Knox was involved but not Sollecito or vice versa are negligible)

Replies from: komponisto
comment by komponisto · 2011-11-10T17:41:05.350Z · LW(p) · GW(p)

I disagree, because I suspect that just like desrtopa, bigjeff5 does not understand the case against Knox. If he is unable to answer these questions, it will confirm my suspicions.

Exactly. So, far from "disagreeing", you admit that your questions were disingenuous.

Well do you agree that there is decent (if not compelling) evidence that the burglary was staged?

No.

For example (1) Romanelli's testimony that she found glass on top of her disturbed items; (2) Romanelli's testimony that nothing was taken from her room; and (3) Sollecito's apparent statement to the police (before Romanelli returned) that there had been a burglary but nothing was taken?

You need evidence that is thousands of times more likely in the case of staging than in the case of an authentic burglary. The notion that any of those items comes anywhere close to meeting such a standard is simply ridiculous.

Replies from: brazil84
comment by brazil84 · 2011-11-10T17:55:33.383Z · LW(p) · GW(p)

So, far from "disagreeing", you admit that your questions were disingenuous.

I clearly prefaced my questions with the following:

Anyway, I disagree with you that this is the strongest piece of evidence against Knox and I think I can demonstrate it to you if you will indulge me by answering (or trying to answer) a few questions:

So it was pretty clear to any reasonable person that I was asking the questions not simply to improve my understanding. Agree?

You need evidence that is thousands of times more likely in the case of staging than in the case of an authentic burglary.

First, I would ask you why that is.

Second, let's break it down a bit: In your view, how much more likely is it that Romanelli would have discovered glass on top of her disturbed items in the case of a staged burglarly than in a legitimate one?

Next, how much more likely is it that nothing would be taken in the case of a staged burglary than a legitimate one?

Same question for Sollecito's phone call.

Replies from: komponisto, dlthomas
comment by komponisto · 2011-11-10T18:55:08.347Z · LW(p) · GW(p)

So it was pretty clear to any reasonable person that I was asking the questions not simply to improve my understanding.

Yes, your disingenuousness was indeed transparent.

If you thought there was some stronger piece of evidence than what your interlocutor mentioned, you should simply have stated it rather than quizzing the other person.

You need evidence that is thousands of times more likely in the case of staging than in the case of an authentic burglary.

First, I would ask you why that is.

Read the post I linked, and review Bayes' theorem if necessary.

Second, let's break it down a bit:

Sorry, no. You are the contrarian here; the onus is on you to explain your position. My view is well known by now; I've explained it in a number of posts and comments. Just for the record, my current probability of guilt for Knox and Sollecito is between 0.0001 and 0.001, updated from a prior of between 0.00001 and 0.0001; if you want numerical bounds on my likelihood ratios, you can do the arithmetic yourself.

Replies from: brazil84
comment by brazil84 · 2011-11-11T00:19:06.727Z · LW(p) · GW(p)

Yes, your disingenuousness was indeed transparent.

Let's see if I have this straight: According to you, any question which is for rhetorical, testing, or socratic purposes is "disingenuous" even if the nature of the question is made clear from the beginning? Is that what you are saying?

Read the post I linked,

I'm not sure I see your point. It seems that your "thousands of times more likely" comes from the observation that the prior probability of Knox's guilt is pretty low. But the exact same thing could be said in connection with Knox's "confession" and in any event, the unlikelihood of the various evidence resulting from a bona fide break-in would appear to counterbalance the low prior probability.

Sorry, no. You are the contrarian here; the onus is on you to explain your position.

I'm not sure it needs to go by the majority. But anyway, if you don't want to explain your position, that's fine by me. I was trying to get down to the nub of our disagreement.

Replies from: komponisto
comment by komponisto · 2011-11-11T03:39:19.934Z · LW(p) · GW(p)

I was trying to get down to the nub of our disagreement.

The nub of our disagreement is quite clearly identifiable: you apparently believe that certain testimony about the position of glass fragments (contrary to the photographic evidence, incidentally) is thousands of times less likely to occur in the case of an actual burglary than in the case of fake one. More generally, you are of the opinion that circumstantial and psychological evidence of the sort produced in this case is powerful enough to overcome not only the incredibly low prior probability of guilt for Knox and Sollecito, but also the total lack of any (significant, non-discredited) physical evidence tying them to the crime, the failure of Guede to implicate them until he knew they were suspects, and the fact that Kercher had both a full stomach and an empty duodenum at death, and thus almost certainly died before 9:30 pm, while Sollecito's computer was in use at his apartment.

Needless to say, I think this is sheer madness. In my view, you are vastly, hugely overconfident in your model of human behavior. However, in the unlikely event that you can actually produce a compelling argument for why I should (for example) regard the presence of glass on top of clothes as 30-decibel evidence in favor of the hypothesis that Knox and Sollecito staged the burglary over the hypothesis that there was an authentic burglary committed by known burglar Rudy Guede, I am all ears.

Really, however, I'm long past the point where I'm ready to write you off as an incorrigible clacker.

Replies from: brazil84
comment by brazil84 · 2011-11-14T15:11:05.031Z · LW(p) · GW(p)

you apparently believe that certain testimony about the position of glass fragments (contrary to the photographic evidence, incidentally) is thousands of times less likely to occur in the case of an actual burglary than in the case of fake one.

Actually I don't believe that. My estimate is somewhere between 10 and 100. It seems you refuse to tell me yours.

the fact that Kercher had both a full stomach and an empty duodenum at death, and thus almost certainly died before 9:30 pm, while Sollecito's computer was in use at his apartment.

Where are you getting this from?

According to my research

(1) Sollecito's computer stopped being used at 9:10pm

(2) Sollecito's own expert witness -- Professor Introna -- testified that based on the stomach and duodenum contents, the time of death was between 9:30 pm and 10:30pm.

(3) Professor Bacci, the prosecution's expert, testified (based on the same digestive issues) that the time of death was between 9:00 to 9:30 pm and 11:00pm to midnight.

Do you disagree with any of this? Because it looks to me like you are suffering from a massive case of confirmation bias. To be sure, I got items (2) and (3) from the sentencing report. But I have a really hard time believing that the report would flat out lie about peoples' testimony.

And by the way, I would still like an answer to my earlier question:

According to you, any question which is for rhetorical, testing, or socratic purposes is "disingenuous" even if the nature of the question is made clear from the beginning? Is that what you are saying?

comment by dlthomas · 2011-11-10T18:02:49.760Z · LW(p) · GW(p)

Next, how much more likely is it that nothing would be taken in the case of a staged burglary than a legitimate one?

Strictly speaking, this is not evidence we possess. The evidence we possess is that it is reported that nothing was taken. An explanation that involves things being taken but a false report otherwise still fits our observations. Whether this moves the probabilities much, I have too little knowledge of the other facts of the case to say. (Strictly speaking, the facts could even contradict my objection - if, for instance, there was an audit of the apartment conducted by a reliable third party immediately prior to the burglary. I think that unlikely enough to discount, though...)

Replies from: brazil84
comment by brazil84 · 2011-11-10T18:05:37.287Z · LW(p) · GW(p)

Strictly speaking, this is not evidence we possess.

I agree. (One could also say that strictly speaking we don't know that Knox was in Italy at the time of the murder; we don't even know if there really is a girl named Amanda Knox.)

ETA: One should of course consider the possibility that much of the evidence against Knox is simply fraudulent.

Replies from: dlthomas
comment by dlthomas · 2011-11-10T18:10:30.127Z · LW(p) · GW(p)

That's speaking a little more strictly than relevant, I think. My point was that, in the general case, there can be reasons that nothing was reported stolen other than that nothing was reported stolen. "He took my 10 lbs of cocaine" is something someone would be reluctant to tell the police, though I might expect it to nonetheless come out in a murder trial. Alternatively, something might have been taken that the person had forgotten they were in possession of. Adjudge for yourself how likely either of these explanations is, but they should be considered - along with any others that run along similar lines. Asking strictly about the probability of a real vs. staged break-in based on the fact that nothing is taken might be misleading.

Replies from: brazil84
comment by brazil84 · 2011-11-10T18:15:52.453Z · LW(p) · GW(p)

That's speaking a little more strictly than relevant, I think. My point was that, in the general case, there can be reasons that nothing was reported stolen other than that nothing was reported stolen

I agree, and one should of course take Romanelli's testimony with a grain of salt. She might be forgetful; she might have been coached to give testimony damaging to Knox; and so forth.

However, keep in mind that the question on the table is whether the strongest (piece of?) evidence against Knox is her statement to the police that she was at the apartment at the time of the murder. For these purposes, I think it's reasonable to accept Romanelli's testimony at face value.

comment by TimS · 2011-11-10T18:13:06.330Z · LW(p) · GW(p)

What do you think are some of the best pieces of evidence against Knox and Sollecito?

Honestly, given what I know about the facts, the strongest evidence of guilt is that Knox and Sollecito were roommates of Knox.

Replies from: brazil84
comment by brazil84 · 2011-11-10T18:27:26.147Z · LW(p) · GW(p)

Honestly, given what I know about the facts, the strongest evidence of guilt is that Knox and Sollecito were roommates of Knox.

Are you familiar with the case against Knox and Sollecito?

Replies from: TimS
comment by TimS · 2011-11-10T18:42:47.397Z · LW(p) · GW(p)

I would say moderately familiar. But most of my knowledge is based on gwern's posts on the case. Are there significant facts not mentioned in the posts?

Replies from: komponisto, brazil84
comment by komponisto · 2011-11-10T18:59:10.066Z · LW(p) · GW(p)

But most of my knowledge is based on gwern's posts on the case

FYI: gwern and I are not the same person.

Replies from: TimS
comment by TimS · 2011-11-10T19:17:38.074Z · LW(p) · GW(p)

Oops. I looked at the author of this post and generalized. Sorry about that.

comment by brazil84 · 2011-11-10T18:52:24.176Z · LW(p) · GW(p)

I haven't read all the posts, but my sense is that the people I have discussed the case with here are not aware of certain significant facts.

What I would suggest is studying the truejustice.org site which was linked to in the very first post. And of course looking at pro-Knox sites too.

Replies from: TimS, wedrifid
comment by TimS · 2011-11-10T19:18:34.897Z · LW(p) · GW(p)

Stick your neck out. What evidence do you believe is not well understood?

Replies from: brazil84
comment by brazil84 · 2011-11-11T00:41:30.619Z · LW(p) · GW(p)

What evidence do you believe is not well understood?

Mainly, the inconsistencies in stories and timelines and the lies to the authorities. You can learn about all of this stuff on the site I mentioned. Or, if you prefer, I think I can demonstrate it to you through a series of komponisto-disingenous questions. A kind of gentle cross examination, if you will.

Replies from: TimS
comment by TimS · 2011-11-11T01:00:03.636Z · LW(p) · GW(p)

You say you are a lawyer. When you write briefs, do you write them in rhetorical questions? Because I write briefs like this:

The law is X. Here is a case that says the law is X. Therefore, the law is X.

It just seems more persuasive that way.

Replies from: brazil84
comment by brazil84 · 2011-11-11T01:12:01.277Z · LW(p) · GW(p)

You say you are a lawyer. When you write briefs, do you write them in rhetorical questions?

Generally not. So what? This is not a brief.

(Interestingly, I cross-examine witnesses a lot more than I write briefs. When you cross-examine someone, you make your point by asking questions. Typically, the questioner is not asking the questions to get information but instead to make a point. i.e. the questions are komponisto-disingenuous. I'd love to see komponisto in the witness box, whining about the "disingenuous" questions being asked of him by the attorneys. Anyway, I think questioning someone can be a very effective way to make your point. However, if you don't feel like playing that game, I certainly cannot force you.)

Replies from: TimS, JoshuaZ
comment by TimS · 2011-11-11T01:29:21.135Z · LW(p) · GW(p)

There are several interesting characteristics of cross-examination:

1) The witness is hostile to your case, which is to say that you are not trying to persuade the witness of anything.

2) The audience is the jury (i.e. a third party to the dialogue). You might be trying to elicit facts from the witness that you can't demonstrate any other way. Or you might be trying to show that the witness is not worthy of belief, perhaps because of bias, lack of knowledge, unworthiness of belief, or suchlike.

3) The primary focus of questioning witnesses is to resolve questions of fact.

None of those characteristics are particularly parallel to a debate on a message board. We aren't hostile to your case, we are interested in your points. We are the audience, not the source of the facts. We aren't trying to act in bad faith. And we aren't trying to find out the facts. We are trying to find out the significance of the facts.

Finding the significance of the facts is applying law to fact. That's just not the purpose of cross-examination.

In short, placing us in the witness stand is the wrong move. Try treating us like opposing counsel. I'm doubtful that rhetorical questions have a major place in your settlement negotiations. If you were arguing a motion in front of a judge, disingenuous would be the nicest thing she would call to you if you answered her question with a question every time. This is not a legal brief, but it's more like a brief than questioning a witness.

Replies from: wedrifid, brazil84
comment by wedrifid · 2011-11-11T01:55:48.712Z · LW(p) · GW(p)

If you were arguing a motion in front of a judge, disingenuous would be the nicest thing she would call to you if you answered her question with a question every time.

For example, she could call you a 'contemnor'. I just learned that word yesterday. I can't remember why. Oh yes, I was wikipediaing my way from "methods of suicide" through "suicide by cop" through one jurisdiction where it can be done easily due to the applicable punishment for contempt of court.

comment by brazil84 · 2011-11-11T03:16:23.605Z · LW(p) · GW(p)

The witness is hostile to your case, which is to say that you are not trying to persuade the witness of anything.

That's not entirely true. Sometimes you get the witness to finally concede a key point. Besides which, having questioned over a thousand hostile witnesses and watched hundreds of message board debates, I can say that the level of hostility is slightly higher in message board debates.

Anyway, I am not saying that a message board debate necessarily is, or should be, like cross-examination. I am simply saying that asking questions is often a very effective way to make a point. It can also be very useful in getting to the nub of a disagreement.

Finding the significance of the facts is applying law to fact. That's just not the purpose of cross-examination.

That's not true. The main interest here is in determining Knox's actions, i.e. whether she was involved in the murder. Not the legal significance of those actions, for example whether she is guilty of the Italian equivalent of manslaughter.

Let's suppose for the sake of argument that after Knox was convicted, some procedural flaw in the proceedings is uncovered, for example they used 5 jurors instead of 6, and therefore her conviction must be thrown out. It shouldn't have much of an effect on this discussion.

In short, placing us in the witness stand is the wrong move.

Are you disputing that asking questions can be an effective way to make a point? ;)

I'm doubtful that rhetorical questions have a major place in your settlement negotiations.

I use them all the time and they are just as effective as any other logical persuasive technique. None of which works all that well on opposing attorneys. Generally speaking, I don't get people to settle cases by persuading them I am right. The kind of people who are open to this sort of persuasion don't really need it because they can do their own research and come to a reasonable conclusion. More emotional arguments work far better to persuade people to settle cases.

Replies from: TimS, JoshuaZ
comment by TimS · 2011-11-11T03:42:33.065Z · LW(p) · GW(p)

Cross-examination

You realize that cross-examination is about putting your words in the witness's mouth, right?

Questions on cross-examination are really just sentences. Isn't that correct?

Each question should articulate a point, shouldn't it?

That point should be clear. Is that a yes?

In short, you are trying to show that the witness agrees with the point that you already think is true. Isn't that correct?

So, a leading question that doesn't clearly articulate what you are asserting is a failed question, isn't it?

Moving on. Do you recall our earlier discussion about arguing motions before a judge?

Would you agree that your goal in the motion hearing is to persuade the court that your side of the argument has merit?

Regardless of the merits, being rude to the judge would probably not convince the judge to rule in your favor, right?

The judge would probably not be happy if you attempted to cross examine her, would she?

It would be rude? A little bit passive-aggressive?

No further questions.

Replies from: Desrtopa, brazil84
comment by Desrtopa · 2011-11-11T14:19:05.650Z · LW(p) · GW(p)

I think a substantial part of why brazil is getting a poor reception here is that he's trying to treat this debate as if he's cross examining witnesses in order to persuade a jury, but the question of what is liable to persuade a jury is very different from what establishes a proposition as more or less likely. In general the population of this site is well aware of the sort of rhetorical techniques which can be used to convince people more effectively without introducing more valid evidence, and have a dim view of having them used on them, particularly in a way that's so transparent as to come across as patronizing.

Also, I think I'm being passive aggressive by posting this in response to your comment when you're not the one who has any need to read it, but at this point I'd rather be passive aggressive if it means less risk of getting sucked back into a debate with brazil.

Replies from: TimS
comment by TimS · 2011-11-11T14:36:50.838Z · LW(p) · GW(p)

I agree that some part of the negative response to brazil is his reliance on Dark Arts persuasion techniques.

But I think the bigger part of the negative response is his refusal to lay out and defend what he actually thinks. It has become quite aggravating.

In law, it is always possible to create a coherent counter-argument by changing the method of analysis. Appealing to the purpose of a rule can easily lead to a more favorable result. If not, then the literal text may be more favorable. Etc. But law is seldom concerned with your true rejection because it is generally quite obvious (i.e. "I don't want to comply with that regulation" or "I don't want to go to prison").

But we genuinely want to reach better understanding, so generating coherent counter-arguments to our points gets really annoying when the speaker doesn't actually believe the counter-argument. If brazil had a theory and presented it coherently, he would not give the impression that he was trying to yank our chains.

Replies from: Desrtopa
comment by Desrtopa · 2011-11-11T14:45:05.301Z · LW(p) · GW(p)

I agree that some part of the negative response to brazil is his reliance on Dark Arts persuasion techniques.

But I think the bigger part of the negative response is his refusal to lay out and defend what he actually thinks. It has become quite aggravating.

I agree that it's aggravating, and I called him out on it earlier myself, but I think it's also a rhetorical technique. By not saying what he thinks straight out, and continually asking more questions, brazil can wait for his interlocutor to produce an answer he can hold up as damning and use that as an excuse to dismiss their whole case. It's a good way to convince a jury to discount someone's testimony, but very bad for resolving questions of evidence.

comment by brazil84 · 2011-11-14T12:34:23.545Z · LW(p) · GW(p)

You realize that cross-examination is about putting your words in the witness's mouth, right?

Not necessarily. Sometimes more open-ended questions are appropriate.

Questions on cross-examination are really just sentences. Isn't that correct?

No.

Each question should articulate a point, shouldn't it?

Not necessarily.

That point should be clear. Is that a yes? In short, you are trying to show that the witness agrees with the point that you already think is true. Isn't that correct?

Again, not necessarily.

Moving on. Do you recall our earlier discussion about arguing motions before a judge?

Yes, I think so.

Would you agree that your goal in the motion hearing is to persuade the court that your side of the argument has merit?

Yes.

Regardless of the merits, being rude to the judge would probably not convince the judge to rule in your favor, right?

Agree.

The judge would probably not be happy if you attempted to cross examine her, would she?

I would say it depends on the judge, but generally not.

It would be rude? A little bit passive-aggressive?

I'm not sure "rude" (ETA: or "passive-aggressive") is the right word, but it's usually not done.

No further questions.

Ok, my turn now:

Do you agree that it is sometimes very effective to approach a debate by using questions, or to use questions within a debate, either to get to the nub of a dispute or to highlight a critical issue which you adversary may be missing?

A simple yes or no will do :)

Replies from: TimS
comment by TimS · 2011-11-14T14:03:24.274Z · LW(p) · GW(p)

Each question should articulate a point, shouldn't it?

Not necessarily.

If you aren't trying to make a point, but only to nitpick others, we're done.

Replies from: brazil84
comment by brazil84 · 2011-11-14T14:33:44.178Z · LW(p) · GW(p)

If you aren't trying to make a point, but only to nitpick others, we're done.

If somebody is making a point, it doesn't necessarily follow that each and every question they ask articulates a point. For example, they might be nailing down the other side's position. If you want to include that in "making a point," then yes, I would agree with you that each question should make a point.

Now please answer my question:

Do you agree that it is sometimes very effective to approach a debate by using questions, or to use questions within a debate, either to get to the nub of a dispute or to highlight a critical issue which you adversary may be missing?

Replies from: TimS
comment by TimS · 2011-11-14T14:57:41.326Z · LW(p) · GW(p)

In football (American version), teams will sometimes have a change-of-pace running back. As opposes to the starting running back (A), the change-of-pace back (B) runs with a very different style. Often A is a "power" back, while B is a "speed" back.

The whole purpose of B is to go into the game and take advantage of some defensive tendency in dealing with A. Maybe B makes a huge run. Or maybe the defense over-corrects and A makes some big plays when he comes back into the game. But if your team's only backs run change-of-pace style, there are two basic possibilities. Maybe your back is an incredible talent. But more likely, your running game is not very good.


To deconstruct the metaphor, statements are A and questions are B. Questions can be incredible. But usually they barely rise to the level of nitpicking. To be clear, that's a general statement about questions, not directed at anyone in particular.

But if your debate tactics do not rely on statements, then your debate tactics are unlikely to persuade. That's the point I was making about briefs. And your questions are not incredible. In fact, they would barely function as change-of-pace even if you relied on statements. The tactics you consistently choose are unlikely to work, so it is a fair question to ask whether I correctly understand your goal.

Anyway, if I have the time I will put together a blog post laying out what I think are the most important pieces of evidence and Knox (and Sollecito).

That would be fantastic

Replies from: brazil84
comment by brazil84 · 2011-11-14T15:41:51.069Z · LW(p) · GW(p)

But if your debate tactics do not rely on statements, then your debate tactics are unlikely to persuade

Putting aside the issue of persuasion, do you agree that a simple series of questions can sometimes demonstrate that a position is contradictory; that it doesn't add up, so to speak?

Is the point you are making that even if I demonstrate something using questions, it's less persuasive since it annoys people?

Replies from: TimS
comment by TimS · 2011-11-14T16:35:08.942Z · LW(p) · GW(p)

I can't put persuasion to the side. That's the whole point.

Do you dispute that asking questions is sometimes an effective way of getting to the nub of an issue and/or focusing attention on a critical issue?

Getting to the nub of the issue is a tool in persuasion. But it is not the most important tool, and it isn't close. When you are debating the naive, getting to the nub of the issue might be most of the work, but that doesn't make it most important.

Is the point you are making that even if I demonstrate something using questions, it's less persuasive since it annoys people?

You say the purpose of asking questions is to get to the nub of the issue. I assert that we have gotten to the nub of the issue of Knox and Sollecito's guilt (i.e. the strength of the evidence). If you think that is not the nub, then you are implying that we are naive.

In other circumstances, that would be quite an insult. But here, we are trying to be Less Wrong. So show us where we are wrong. All your questions do is continue to assert that we are wrong without showing why you think that is true.

Anyway, if I have the time I will put together a blog post laying out what I think are the most important pieces of evidence and Knox (and Sollecito).

That would be fantastic because it would give me a chance to see what ways I might be wrong.

Replies from: dlthomas, brazil84
comment by dlthomas · 2011-11-14T16:46:59.185Z · LW(p) · GW(p)

I can't put persuasion to the side. That's the whole point.

Getting to the nub of the issue is a tool in persuasion.

I disagree; the point is to find truth, and getting to the nub of the issue (which can often mean "finding the most basic point of disagreement") is a valuable tool to that end.

Edited to add: In this particular case, where our beliefs on this issue have little opportunity to usefully direct our action, the whole point is to find flaws in our reasoning that drive us away from truth, so we can learn to correct them in more meaningful situations.

Replies from: TimS
comment by TimS · 2011-11-14T17:29:53.898Z · LW(p) · GW(p)

I agree that I bundled a number of concepts into "persuasion." To make it explicit, I used "persuasion" to mean trying to change another person's mind. Since I aspire to practice the Light Arts, that meant moving the other person's belief towards truth.

Edited to add: In this particular case, where our beliefs on this issue have little opportunity to usefully direct our action, the whole point is to find flaws in our reasoning that drive us away from truth, so we can learn to correct them in more meaningful situations.

Exactly. Well said. I hope to learn how I err by observing how I fail to persuade.

Replies from: dlthomas
comment by dlthomas · 2011-11-14T17:57:25.459Z · LW(p) · GW(p)

I don't mean to suggest that this is never an appropriate approach; I object to your suggestion that this is the only appropriate approach (and in particular in a situation like this, where it is that approach that seems to be breaking down).

Replies from: TimS
comment by TimS · 2011-11-14T18:04:15.466Z · LW(p) · GW(p)

It's not that I disagree with you, so much as I don't understand.

I could make lots of concessions about how the point you originally quoted is too simplistic. I suspect that you have a particular caveat in mind, and I suspect that I would agree with it.

I made the original statement in the context of explaining to brazil why he's coming off like a troll.

comment by brazil84 · 2011-11-14T17:25:47.972Z · LW(p) · GW(p)

I can't put persuasion to the side. That's the whole point.

I don't think that's necessarily true, depending on what you mean by "persuasion" Because it sounds like you might be making the argument that even if I am demonstrating my points effectively, I am not persuading anyone because I am annoying.

Anyway, my question was not komponisto-disingenous. i.e. I honestly would like an answer.

Do you dispute that asking questions is sometimes an effective way of getting to the nub of an issue and/or focusing attention on a critical issue?

It really is a simple yes or no question.

When you are debating the naive, getting to the nub of the issue might be most of the work, but that doesn't make it most important.

Even assuming that's true, so what? It's not an answer to my question.

You say the purpose of asking questions is to get to the nub of the issue.

And also to highlight critical issues.

I assert that we have gotten to the nub of the issue of Knox and Sollecito's guilt (i.e. the strength of the evidence).

That's not true at all. "the strength of the evidence" is composed of dozens of sub-issues. For example, the question of the time of death based on the state of Kercher's digestive system.

All your questions do is continue to assert that we are wrong without showing why you think that is true.

That's not true either. My questions have shown that various people are unfamiliar with the important facts concerning the case.

I do agree it would be better (in terms of arguing for Knox's guilt) if I laid out those important facts and I will do so (ETA: In a blog post) if I have the time. But there is also an issue of economy. I'm not thrilled about spending the time to educate people about the case if they have not done their basic homework. Making my case by asking questions forces people to do the same simple research I have done, such as reading a few posts from the anti-Knox site which was linked in the very first thread.

I will however lay out the case on a side issue right here and now:

komponisto asserted in another post as follows:

Kercher had both a full stomach and an empty duodenum at death, and thus almost certainly died before 9:30 pm, while Sollecito's computer was in use at his apartment.

I was a bit surprised to see such a convincing-sounding argument which I had not heard before, so I decided to look into it. What I found is this:

  1. According to various sources, Sollecito's computer use ended at 9:10 not 9:30.

  2. According to the sentencing report, Sollecito's expert testified (based on the state of Kercher's digestive system) that the time of death was between 9:30 and 10:30.

  3. According to the sentencing report, the prosecution expert testified (based on the state of Kercher's digestive system) that the time of death was as late as midnight.

It seems unlikely to me that the sentencing report would flat out lie about the expert testimony. It also seems unlikely that Sollecito's expert would testify that the time of death could have been as late as 10:30 if there was solid evidence that the time of death was almost certainly before 9:30pm.

My conclusion is that komponisto is likely the victim of serious confirmation bias.

At the same time, I myself will concede that if his underlying assertions about the computer use and time of death are correct, I will need to re-evaluate my own probability estimate.

Replies from: TimS
comment by TimS · 2011-11-14T17:58:28.680Z · LW(p) · GW(p)

I think that dlthomas made an excellent point. Specifically, there are lots of goals each of us could be trying to achieve. You could be trying to cause us to have truer beliefs. You could be trying to understand your though processes and how they might err. Or some other goal.

I do agree it would be better (in terms of arguing for Knox's guilt) if I laid out those important facts and I will do so if I have the time. But there is also an issue of economy. I'm not thrilled about spending the time to educate people about the case if they have not done their basic homework. Making my case by asking questions forces people to do the same simple research I have done, such as reading a few posts from the anti-Knox site which was linked in the very first thread.

If you cannot achieve your goals because LessWrong is incompatible with them, or the goals are incompatible with LessWrong, then it is perfectly rational for you to spend you time elsewhere. If so, I'm sorry that you were not able to achieve you goals. (As an aside, you have very high standards for an internet discussion if you expect us to do significant research beyond the posts on this site. I like high standards, but seldom live up to them).


Do you dispute that asking questions is sometimes an effective way of getting to the nub of an issue and/or focusing attention on a critical issue?

First, this isn't a simple yes or no question because you have acquired a reputation for trying to be avoid the issues. That said, lots of things help focus a discussion on the critical issues. Questions are one of those things. But your questions did not seem to have this goal.

I assert that we have gotten to the nub of the issue of Knox and Sollecito's guilt (i.e. the strength of the evidence).

That's not true at all. "the strength of the evidence" is composed of dozens of sub-issues. For example, the question of the time of death based on the state of Kercher's digestive system.

There are lots of basis of guilt articulated that have nothing to do with evidence. Like asserting that Knox's nationality, age, gender, or status as a college student living abroad have any relevance to her guilt.


Your marshaling of facts about the time of death vs. Sollecito's computer usage is excellent, in that it provides a real basis for discussion. But is it your true rejection? You pointed out it was a side issue, and even if the prosecution expert was entirely correct, it would only show the evidence was consistent with guilt and would not be [ETA: very strong] evidence of guilt.

Replies from: JoshuaZ, brazil84
comment by JoshuaZ · 2011-11-14T18:22:59.191Z · LW(p) · GW(p)

it would only show the evidence was consistent with guilt and would not be evidence of guilt.

Most of your points seem good. However, this stood out. Consistency is from a Bayesian perspective evidence (albeit weak evidence) of guilt since it is more likely to occur in the guilty situation than in the non-guilty situation.

Replies from: brazil84
comment by brazil84 · 2011-11-16T18:05:20.102Z · LW(p) · GW(p)

What stood out to me was that TimS pretty much missed the point of my argument on this issue. Which was that komponisto seems to be suffering from a serious case of confirmation bias.

The rational thing for komponisto to do would be to verify the points I made, and assuming they check out, thank me for helping him to become less wrong and then try to completely re-think the case. komponisto needs to realize that if he is dead wrong about an issue which he believes to be of central importance, it calls into question all of his thinking about the case, and in particular whether he is adequately scrutinizing the pro-Knox arguments and evidence and adequately considering the anti-Knox arguments (and evidence).

Also, TimS needs to ask himself why he missed the point of my argument. Was it just an oversight? Or is he subconsciously reluctant to go against the Captain of the Blue Team?

Replies from: TimS
comment by TimS · 2011-11-16T18:28:35.997Z · LW(p) · GW(p)

I thought you didn't believe in referencing motivated cognition to determine truth.

Because if we were just weighing the amount of motivated cognition, the Italian prosecutor has engaged in substantially more than komponisto. The low-count DNA testing is nonsense, defense investigators showed a break-in was possible after prosecutors asserted otherwise, and the prosecution theory revolved around Satanism and orgies. At this point, nothing about stomach digestion and computer use timing could persuade me that guilt was more likely that innocence. In short, komponisto could be totally wrong about it and it won't significantly affect my opinion of the ultimate issue.

Replies from: brazil84
comment by brazil84 · 2011-11-16T18:40:24.948Z · LW(p) · GW(p)

I thought you didn't believe in referencing motivated cognition to determine truth.

If you think so, then you misread my post.

Because if we were just weighing the amount of motivated cognition, the Italian prosecutor has engaged in substantially more than komponisto.

Let's assume for the moment that's true. In that case, if the Italian prosecutor were posting here, then just like komponisto, the rational thing for him to do would be to re-think the case.

ETA: Since you seem to keep missing the point of my post, I think it will be helpful to focus things with a few of those dreaded "questions."

(1) Do you agree that a few posts back, komponisto posted an argument which seems to be dead wrong?

(2) Do you agree that this argument seems to be pretty important to komponisto?

(3) Do you agree that komponisto seems to have fallen victim to confirmation bias? i.e. he failed to scrutinize a pro-Knox argument most likely because he believes so strongly in her innocence?

(4) Do you agree that this calls into question all of komponisto's thinking about the case?

(5) Do you agree that komponisto should thank me for helping to make him less wrong?

(6) And if komponisto instead writes me off as a "clack," isn't that just more of his bias at work?

(7) Finally, if the Italian prosecutor is more biased than komponisto, but in the opposite direction, do you agree it does not change the fact that komponisto himself is biased?

comment by brazil84 · 2011-11-14T18:15:36.390Z · LW(p) · GW(p)

If you cannot achieve your goals because LessWrong is incompatible with them, or the goals are incompatible with LessWrong, then it is perfectly rational for you to spend you time elsewhere.

I agree, but again, so what? Isn't what you are saying pretty much obvious? Why are you telling me this?

As an aside, you have very high standards for an internet discussion if you expect us to do significant research beyond the posts on this site

Well, the very first thread on the subject invited participants to read somewhat detailed summaries of the arguments (and evidence) for and against Knox's guilt. Anyway, if you assert a very low probability of Knox's guilt (which many people here do) (ETA: or a very high probability of Knox's guilt), then either (1) you have done the research yourself and reached some conclusion which may or may not be justified; (2) you are relying on other posts here; or (3) you are fooling yourself. If number 2 is the case, then my point about komponisto should give you serious pause.

First, this isn't a simple yes or no question because you have acquired a reputation for trying to be avoid the issues.

I don't see what my reputation has to do with it. Either my assertion about questions being useful is true or it isn't.

But your questions did not seem to have this goal.

Can you give me an example of a question I asked, and what you feel the actual goal of the question was?

There are lots of basis of guilt articulated that have nothing to do with evidence.

So what? It doesn't change the fact that "strength of the evidence" -- as a general proposition -- is not the nub of the issue. To put it metaphorically, you are missing the trees for the forest.

You pointed out it was a side issue, and even if the prosecution expert was entirely correct, it would only show the evidence was consistent with guilt and would not be evidence of guilt.

Of course, but you need to understand the point of my argument -- which is that komponisto seems to have royally screwed up. If you are basing your opinion about guilt or innocence on other peoples posts here -- that should give you a lot of pause.

comment by JoshuaZ · 2011-11-11T03:25:02.198Z · LW(p) · GW(p)

Besides which, having questioned over a thousand hostile witnesses and watched hundreds of message board debates, I can say that the level of hostility is slightly higher in message board debates.

This may be a cause for part of the problematic interactions you are having here. Less Wrong in general strives for a lower degree of hostility on average than the average message board. (Indeed, if we're not succeeding at that then we've failed rationality at so many different levels we might as well spend our time playing Robot Unicorn Attack rather than posting here.) Less Wrong is not the only internet forum that is somewhat successful in this regard. A major part of being successful about this sort of thing is as far as I can tell simply being open to the possibility that interactions on the internet with people one disagrees with don't need to be hostile. There's the important related step of realizing that people who disagree are not necessarily stupid, evil, ignorant or crazy. So, try to interact in a way that doesn't assume that being on a message board necessitates hostile interaction (if it helps imagine that the conversation is occurring over a few beers rather than a message board.)

Replies from: brazil84
comment by brazil84 · 2011-11-11T03:40:20.308Z · LW(p) · GW(p)

Less Wrong in general strives for a lower degree of hostility on average than the average message board.

I don't know about the "average message board," but I would say there is still a good deal of hostility here, both in the sense of people being resistant to evidence which contradicts their position as well as plain nastiness.

For example, a few posts back, komponisto accused me of asking questions which were "disingenuous." When I pointed out that I had made it reasonably clear from the get-go that the questions were for rhetorical purposes, he still insisted that my questions were disingenuous. (Actually, he made his comments more personal by referring to "your disingenuousness ")

I think the non-hostile thing to do would have been to say "Ok, I agree that your questions were not disingenuous but I still object to them for the following reasons . . . "

Replies from: TimS
comment by TimS · 2011-11-11T03:56:32.474Z · LW(p) · GW(p)

Now that you've seen that sentence I added late, do you have a response? Because not responding really calls into question whether you really want to persuade us at all. One might even assert ducking that point was . . . disingenuous.

Replies from: brazil84
comment by brazil84 · 2011-11-14T14:15:43.019Z · LW(p) · GW(p)

Now that you've seen that sentence I added late, do you have a response?

Sure, I think that sometimes laying things out positively is an effective way to make an argument; and sometimes a more socratic approach is better.

Since you mentioned the fact that I am an attorney, I will give you an example from my work. I have a breach of contract case pending in the general trial court of my state. My client was employed by the defendant and is alleging that she is owed a severance payment under her employment contract.

After we filed suit, the defendant served a counterclaim, i.e. they sued her back. The counterclaim alleges that my client breached her obligations to the company by deleting company information from her laptop computer before returning it. I asked my client about the allegations, and she insisted (fairly credibly) that all of the stuff she deleted was duplicative of information already in the defendant's possession, i.e the defendant didn't actually lose anything as a result of her actions.

I called up the attorney for the defendant and explained all this to him. I urged him to stop wasting everyone's time with this BS counterclaim. I explained to him that his client apparently hadn't actually lost any data or software as a result of my client's actions. After talking to his client about it (and arguing with me a few times), he refused to withdraw the counterclaim for some BS reason which didn't make a lot of sense.

My next step was to serve what's called an "interrogatory" on him. An interrogatory is a formal written question. In this case, I asked him to provide a calculation of the damages his client had suffered as a result of my client's alleged misconduct. (Note that the interrogatory was komponisto-disingenuous, i.e. I already knew the answer.)

He tried to duck the question, and at the next discovery conference, I got the court to order him to answer the question by a certain date. When that day rolled around, the attorney faxed me a letter saying that he wanted to withdraw the counterclaim.

So you see, questions are often a very effective and economical way to shine the spotlight on a critical point.

Replies from: TimS
comment by TimS · 2011-11-14T15:07:45.186Z · LW(p) · GW(p)

As I see it, there was only one important question in that story (the interrogatory).

I called up the attorney for the defendant and explained all this to him. I urged him to stop wasting everyone's time with this BS counterclaim. I explained to him that his client apparently hadn't actually lost any data or software as a result of my client's actions.

This conversation was an exchange of statements. "No merit because X" "Yes merit because "

at the next discovery conference, I got the court to order him to answer the question by a certain date.

May I speculate that your motion to compel and the judge's order were not filled with questions.

When that day rolled around, the attorney faxed me a letter saying that he wanted to withdraw the counterclaim.

Also a statement.


(Note that the interrogatory was komponisto-disingenuous, i.e. I already knew the answer.)

If you believe that this type of questioning is a virtue in debating because it is a virtue in discovery practice, you are simply mistaken. Also, many questions that are appropriate for interrogatories are not appropriate for cross-examination.

Replies from: brazil84
comment by brazil84 · 2011-11-14T15:21:33.561Z · LW(p) · GW(p)

This conversation was an exchange of statements. "No merit because X" "Yes merit because "

Well there wasn't really a pause, as best as I recall.

May I speculate that your motion to compel and the judge's order were not filled with questions.

There was no motion to compel. I simply mentioned it at the discovery conference that I would like an answer to my question. The court officer looked at my adversary and asked, in substance, what exactly the problem was in answering it [Another one of those pesky questions!!] and my adversary agreed to supply an answer.

Also a statement.

Agreed. So what? I'm not arguing that statements or assertions have no place in litigation (or internet discussions).

If you believe that this type of questioning is a virtue in debating because it is a virtue in discovery practice, you are simply mistaken.

Not because it is a virtue in discovery practice per se, but the same underlying principle is at often at work. A question is often an effective (and economical) way of getting to the nub of a dispute and/or focusing attention on a critical issue.

Also, many questions that are appropriate for interrogatories are not appropriate for cross-examination.

Agree, but so what? I'm not trying to say that internet debating is just like litigation.

Since we are talking about questions, I will ironically ask you a question:

Do you dispute that asking questions is sometimes an effective way of getting to the nub of an issue and/or focusing attention on a critical issue?

comment by JoshuaZ · 2011-11-11T01:14:58.869Z · LW(p) · GW(p)

Generally not. So what?

Did you read his final sentence?

Replies from: brazil84
comment by brazil84 · 2011-11-11T01:30:48.208Z · LW(p) · GW(p)

Did you read his final sentence?

No, I didn't notice it. Either I wasn't paying attention or he added it after I hit "reply."

Replies from: TimS
comment by TimS · 2011-11-11T01:36:07.053Z · LW(p) · GW(p)

In fairness, I did edit to add it. Didn't realize it would be read so quickly.

comment by wedrifid · 2011-11-10T20:00:55.306Z · LW(p) · GW(p)

I haven't read all the posts, but my sense is that the people I have discussed the case with here are not aware of certain significant facts.

The most obvious of these facts being the futility of trying to fix people who are wrong on the internet. After sufficient opportunity for the wrongee to get a clue further effort is more likely to hasten a transition to outright troll than to actually improve their thinking.

Replies from: brazil84
comment by brazil84 · 2011-11-11T00:29:58.419Z · LW(p) · GW(p)

By the way, I no longer engage with "wedrifid" due to his incoherent posts and personal insults.

Replies from: wedrifid
comment by wedrifid · 2011-11-11T01:28:54.628Z · LW(p) · GW(p)

(I am not one of the downvoters of the parent. While I obviously don't think my posts are often incoherent I can certainly understand the objection to my comment. It does, after all, represent proposing a motion that we start to consider arguing with brazil specifically over the Amanda Knox issue to be deprecated as troll feeding!)

comment by brazil84 · 2011-10-21T04:14:43.504Z · LW(p) · GW(p)

There's this thing, it's called 'logical fallacy'

Sure, and the fallacy does not automatically apply every time one poster comments on another poster's motivations. Note that wedrifid did not make any actual argument about Knox's guilt or innocence in his post; he did however offer his opinion that my conclusion on this issue was not sane.

comment by brazil84 · 2011-10-21T03:20:17.257Z · LW(p) · GW(p)

No, that wasn't it either.

Replies from: pedanterrific
comment by pedanterrific · 2011-10-21T03:26:23.334Z · LW(p) · GW(p)

...Maybe this one? (That's the one that ends in you saying "Lol, that's nonsense.")

Side note: I'm not sure whether to be amazed, impressed or disturbed at how many arguments you've had with wedrifid. This whole line of conversation is veering into the farcical.

Replies from: brazil84
comment by brazil84 · 2011-10-21T03:38:16.164Z · LW(p) · GW(p)

Side note: I'm not sure whether to be amazed, impressed or disturbed at how many arguments you've had with wedrifid. This whole line of conversation is veering into the farcical.

Well the bottom line is that he and I have a history here, a lot more than I realized a few minutes ago. And now he seems to be claiming he doesn't remember our exchanges; it's apparently just a coincidence that he needs to publicly announce -- in essence -- I've reached conclusions which are insane.

Replies from: pedanterrific, thomblake
comment by pedanterrific · 2011-10-21T03:43:35.696Z · LW(p) · GW(p)

To be fair, those exchanges probably wouldn't be particularly noteworthy from wedrifid's point of view.

Replies from: brazil84
comment by brazil84 · 2011-10-21T03:52:14.349Z · LW(p) · GW(p)

I concede that if he has personal exchanges like that on a regular basis, it's plausible that he really doesn't remember me.

comment by thomblake · 2011-10-24T18:50:10.938Z · LW(p) · GW(p)

he and I have a history here, a lot more than I realized a few minutes ago.

And now he seems to be claiming he doesn't remember our exchanges

Given these two statements, I'm surprised at your surprise.

Replies from: brazil84
comment by brazil84 · 2011-10-24T19:11:00.806Z · LW(p) · GW(p)

Given these two statements, I'm surprised at your surprise.

What exactly do you think I am surprised about?

Replies from: thomblake
comment by thomblake · 2011-10-24T19:26:07.703Z · LW(p) · GW(p)

Your memory of the exchanges seems to have been hazy at best, and yet you seemed incredulous that wedrifid doesn't remember them.

Replies from: brazil84
comment by brazil84 · 2011-10-24T20:36:08.482Z · LW(p) · GW(p)

I remember that there was a lot of unpleasantness. Besides, you need to keep in mind that wedrifid behaved rather antagonistically towards me in this thread. Right out of the blocks, so to speak. I have had a lot of internet exchanges and typically people don't start acting nasty until after there has been some back and forth.

Replies from: thomblake
comment by thomblake · 2011-10-24T20:49:06.629Z · LW(p) · GW(p)

Besides, you need to keep in mind that wedrifid behaved rather antagonistically towards me in this thread.

Ah, I had not actually realized you characterized wedrifid's comments that way. I just saw it as taking note of a potentially-useful object lesson.

If you don't mind my asking, in what way did you find it antagonistic? Was it merely having your actions pointed to as a good example of what not to do? Perceived tone? Claiming that you were incorrect? Use of the Lw jargon term 'insane'?

Replies from: brazil84
comment by brazil84 · 2011-10-24T21:18:21.828Z · LW(p) · GW(p)

If you don't mind my asking, in what way did you find it antagonistic?

Actually, I do mind you asking. If you don't care to invest the energy to answer my questions, I prefer not to invest the energy to answer yours.

comment by Jack · 2011-10-20T22:53:08.004Z · LW(p) · GW(p)

Well, the judgment of people here is evidence just like anything else. Lets say I initially predicted Knox's guilt with p=0.01, Since I think my beliefs track the truth and the beliefs of other Less Wrong posters track the truth I should expect other posters to agree with my assessment if my belief is accurate. The majority of posters disagreeing with me is far more likely if I'm wrong than if I'm right. So upon learning that the vast majority of posters disagree with me I should be more uncertain about my prediction.

How uncertain I should be is a difficult question-- in many cases in that thread it was resolved by discussing evidence. Many people with initially high probabilities shifted their estimates downward after evidence they missed was pointed out to them. If you think you have evidence other Less Wrong posters don't have then it makes sense to not take their opinions seriously. Alternatively, if you think Less Wrong posters are irrational or poorly calibrated and don't expect their beliefs as a group to track the truth well then it makes sense to more or less ignore their opinion. I suppose one could also ignore the opinions of the Less Wrong posters on the ground that the opinions of random people reading about the case are swamped by the opinions of people who have studied the case for months-- and thus make very little difference. But now Knox and Sollecito have been released-- if your trust in the experts was what lead you to ignore Less Wrong you should update on the new court decision.

So why didn't you update on the opinions of Less Wrong posters?

Replies from: MarkusRamikin, brazil84
comment by MarkusRamikin · 2011-10-21T12:57:11.621Z · LW(p) · GW(p)

I wonder. The opinions of members of a given community are not independent events. There's influence by high status members, and by perceived community consensus (note how in a previous post, brazil84 got downvoted just for admitting, when asked, that this consensus didn't move his own opinion much - I don't know, but to me that's ominous). So isn't there's a risk of counting the same evidence (the arguments and facts that convinced the "first movers" in forming this community consensus) multiple times?

What you say, that if others of my group disagree with me and I'm in a strong minority, then I'm probably wrong - how far does that go? The majority of humanity is probably wrong about a lot of things that we on Less Wrong are probably right about, by virtue of our greater rationality, and we don't seem to be updating in their direction, are we? Well, if brazil84 is a lawyer, then similarly, by virtue of his expertise, it seems reasonable to me that he should not easily let his opinion be influenced by that of laymen.

Replies from: komponisto
comment by komponisto · 2011-10-21T13:29:07.532Z · LW(p) · GW(p)

Well, if brazil84 is a lawyer, then similarly, by virtue of his expertise, it seems reasonable to me that he should not easily let his opinion be influenced by that of laymen.

That might make sense if the question under discussion were a legal question (e.g. how a statute is likely to be interpreted by a court). But that isn't the case here. In fact, even if the domain that brazil84 is claiming expertise in -- determining whether people are telling the truth or not -- were one in which lawyers were more likely to have expertise (and frankly I know of no reason to believe this), the fact is that it has precious little relevance to this case. This case is not about which human statements to believe. Instead, it's about applying Occam's Razor to physical evidence.

Replies from: MarkusRamikin
comment by MarkusRamikin · 2011-10-22T07:54:31.397Z · LW(p) · GW(p)

Point taken.

comment by brazil84 · 2011-10-21T00:39:23.688Z · LW(p) · GW(p)

So why didn't you update on the opinions of Less Wrong posters?

It's a combination of having little respect for the opinions of anonymous internet posters as well as faith in my own ability to look at incomplete evidence concerning real world disputes and draw reasonable conclusions. As an attorney I do this every day. In fact, my livelihood depends on doing it. All day long people call me up and spin tales and I have to guess at what happened in their case based on limited evidence. I've been wrong many times over the years, both in believing people who turned out to have been BSing me as well as being skeptical of people who turned out to have been telling the truth.

Replies from: wnoise, Prismattic, loqi, Desrtopa
comment by wnoise · 2011-10-21T17:38:21.565Z · LW(p) · GW(p)

anonymous internet posters

Pseudonymous. There are many similarities, but having a long-standing name does have significant differences, even if the name isn't tied to one's "real-life" name.

comment by Prismattic · 2011-10-21T01:12:20.448Z · LW(p) · GW(p)

There seems to be a certain disjoint between the second half of this paragraph and the first.

Replies from: RomanDavis
comment by RomanDavis · 2011-10-21T05:00:11.770Z · LW(p) · GW(p)

Confidence isn't really about evidence?

comment by loqi · 2011-10-21T06:09:07.084Z · LW(p) · GW(p)

So, to summarize why you didn't update:

  • You didn't know the names of the people commenting.
  • You have faith that you're more reliable than those people.
  • You would lose your job if you weren't so great at seeing through bullshit.
  • You have often failed to see through bullshit.

Boy was Upton Sinclair ever right.

Replies from: brazil84
comment by brazil84 · 2011-10-21T10:43:58.389Z · LW(p) · GW(p)

•You didn't know the names of the people commenting.

I'm not sure that's the way to put it, but let me ask you this: How much stock do you put in the unsupported assertion of an anonymous person on the internet?

•You have faith that you're more reliable than those people.

Please quote me where I made that assertion.

•You would lose your job if you weren't so great at seeing through bullshit.

Well I need to be decent at a minimum. But basically yeah. I assess cases day in and day out. That's a huge advantage. I know that I'm much better than I was 15 years ago, even though I was just as smart then as I am now.

•You have often failed to see through bullshit.

Sure, getting this kind of feedback is a good way to improve one's judgment. Do you seriously disagree?

Boy was Upton Sinclair ever right.

:shrug: I agree, but employment is sadly not the only motivator for self-deception. Let me ask you this:

Do you agree that the tone of your post is a bit nasty?

Replies from: Vive-ut-Vivas, Desrtopa, thomblake, loqi
comment by Vive-ut-Vivas · 2011-10-21T14:25:23.190Z · LW(p) · GW(p)

I'm not sure that's the way to put it, but let me ask you this: How much stock do you put in the unsupported assertion of an anonymous person on the internet?

How much stock do you put in the supported assertion of an anonymous person on the internet? I think that's a more relevant question here. To what degree does a poster's anonymity detract from his argument?

Replies from: brazil84
comment by brazil84 · 2011-10-21T15:06:31.749Z · LW(p) · GW(p)

How much stock do you put in the supported assertion of an anonymous person on the internet?

Quite a lot. But I don't think that's the right question. See, the basic argument being made is that even though I have considered Mr. Anonymous' arguments and decided they were without merit, I should still be significantly less certain of my position simply because a number of these anonymous people (making basically the same weak arguments) disagree with me. Did I misunderstand the argument being made?

Replies from: komponisto
comment by komponisto · 2011-10-21T15:24:12.128Z · LW(p) · GW(p)

the basic argument being made is that even though I have considered Mr. Anonymous' arguments and decided they were without merit, I should still be significantly less certain of my position simply because a number of these anonymous people (making basically the same weak arguments) disagree with me. Did I misunderstand the argument being made?

Yes. The point is that in "deciding [the arguments] were without merit", you didn't take sufficient account of the quality (not merely the quantity, by the way) of the people making them.

If a high-quality person says "X is true", you might be able to dismiss it if you have sufficient knowledge. But if they say "X is true because of A,B, and C", you can't dismiss X without also dismissing A, B, and C. And here the problem is with your judgement about A, B, and C, not (just) your judgement about X.

Replies from: brazil84
comment by brazil84 · 2011-10-21T15:31:51.209Z · LW(p) · GW(p)

you didn't take sufficient account of the quality (not merely the quantity, by the way) of the people making them.

I'm pretty confident that I did. If you see a problem with the arguments I made back in the original thread, please feel free to respond (preferably there) and I'm happy to consider your point in good faith.

comment by Desrtopa · 2011-10-21T14:46:16.355Z · LW(p) · GW(p)

Please quote me where I made that assertion.

To the extent that you don't think that you're more reliable than those people, you're engaging in a treatment of evidence that is simply wrong. The fact of someone's belief is evidence weighted according to the reliability of their mechanisms for establishing belief. That's the principle behind Aumann's Agreement Theorem.

Replies from: brazil84
comment by brazil84 · 2011-10-21T15:17:05.951Z · LW(p) · GW(p)

I'm not sure I understand your point. My belief that I have superior judgment in this area is based on actual knowledge about myself and my experiences. "Faith" implies that there is no such basis.

I don't recall claiming or implying that I was basing my assessment on "faith," but I could be wrong. Which is why I am giving loqi a chance to back up his statement.

Replies from: Desrtopa, Jack
comment by Desrtopa · 2011-10-21T15:23:01.760Z · LW(p) · GW(p)

I'm not sure I understand your point. My belief that I have superior judgment in this area is based on actual knowledge about myself and my experiences.

But not knowledge of the other commenters and their experiences, whom you seem to have lumped into the reference class of "anonymous internet commenters," which you assign a low assessment of competence.

If you want to find a lot of people with significant expertise in rendering judgment under uncertainty, I think this is a pretty good place to look.

Replies from: brazil84
comment by brazil84 · 2011-10-23T10:31:09.091Z · LW(p) · GW(p)

If you want to find a lot of people with significant expertise in rendering judgment under uncertainty, I think this is a pretty good place to look.

What evidence I have seen does not give me much confidence in the critical thinking ability of posters here as a group, to put it politely. Not much different from "anonymous internet posters" in general.

Replies from: Vive-ut-Vivas
comment by Vive-ut-Vivas · 2011-10-24T00:04:12.762Z · LW(p) · GW(p)

What evidence I have seen does not give me much confidence in the critical thinking ability of posters here as a group, to put it politely. Not much different from "anonymous internet posters" in general.

Just in this instance, or in general?

Replies from: brazil84
comment by brazil84 · 2011-10-24T00:24:45.883Z · LW(p) · GW(p)

Just in this instance, or in general?

Based on the 10 or 20 or so threads I have participated in over the last couple years here.

comment by Jack · 2011-10-21T15:21:03.560Z · LW(p) · GW(p)

If "have faith" is changed to "believe" everyone here should agree.

comment by thomblake · 2011-10-24T18:27:04.690Z · LW(p) · GW(p)

Nobody seems to have answered this question directly, though it seems easy...

•You have faith that you're more reliable than those people.

Please quote me where I made that assertion.

See the direct parent of the post you were replying to (which I think should have been obvious since it was presented as a summary):

It's a combination of having little respect for the opinions of anonymous internet posters as well as faith in my own ability to look at incomplete evidence concerning real world disputes and draw reasonable conclusions.

Also, don't you at least see the tension between:

You would lose your job if you weren't so great at seeing through bullshit.

You have often failed to see through bullshit.

It seems the logical conclusion is that you've lost your job.

Replies from: brazil84
comment by brazil84 · 2011-10-24T19:16:32.823Z · LW(p) · GW(p)

See the direct parent of the post you were replying to (which I think should have been obvious since it was presented as a summary):

Ok, so you agree that in the exact post where I used the word "faith," I summarized the factual basis for confidence in my own judgment?

It seems the logical conclusion is that you've lost your job.

That would be the case if my livelihood depended on exercising perfect judgment at all times. Which fortunately it does not.

Let me ask you basically the same question I asked the other poster:

Do you agree that getting feedback about one's judgment (including being wrong from time to time) is helpful in improving one's judgment?

Replies from: thomblake
comment by thomblake · 2011-10-24T19:33:05.902Z · LW(p) · GW(p)

Ok, so you agree that in the exact post where I used the word "faith," I summarized the factual basis for confidence in my own judgment?

No, I don't particularly care to parse all that enough to agree to anything. I was just answering your question since it seemed like nobody else had bothered to. People seem to have an odd problem answering questions with obvious-seeming answers, even though they are often helpful to people. For example, the other day on aiqus someone was asking how to type the | symbol, and the answer was straightforwardly a series of directions starting from locating the "Enter" key on a US keyboard. It turned out to be very helpful to the OP, as there was a piece of lint blocking the | symbol.. I was pleasantly surprised that the OP did not merely become the subject of ridicule, as I've often seen with 'obvious' seeming questions in other contexts.

Let me ask you basically the same question I asked the other poster:

No thanks.

Replies from: brazil84
comment by brazil84 · 2011-10-24T21:17:18.911Z · LW(p) · GW(p)

No, I don't particularly care to parse all that enough to agree to anything.

Suit yourself, but you will be missing the problem with loqi's statement.

No thanks.

Again, it's your choice. But I think that answering the question will help you to see why it's not necessarily a contradiction to (1) have one's livelihood depend on making good judgments; and (2) regularly make judgments which turn out to be wrong.

Replies from: thomblake
comment by thomblake · 2011-10-24T21:34:07.071Z · LW(p) · GW(p)

But I think that answering the question will help you to see why it's not necessarily a contradiction

I saw that. That's why I used the word 'tension' rather than the word 'contradiction'.

(Though looking for a reference for how the word 'tension' is used in the discipline of Philosophy, I can't seem to find anything online - it's used extensively on SEP, and there was a book written in 1936 on the word's proper use, but the sense used in Philosophy doesn't even make it into OED).

Replies from: brazil84
comment by brazil84 · 2011-10-24T21:55:57.542Z · LW(p) · GW(p)

That's why I used the word 'tension' rather than the word 'contradiction'.

Well you also said "It seems the logical conclusion is that you've lost your job."

Replies from: thomblake
comment by thomblake · 2011-10-24T21:57:50.872Z · LW(p) · GW(p)

Indeed, that's why I used the word "seems".

A good rule of thumb: If it looks like someone is making an obviously stupid mistake, you're probably misunderstanding them. It's a benefit of the principle of charity.

Replies from: brazil84
comment by brazil84 · 2011-10-24T22:14:09.622Z · LW(p) · GW(p)

Indeed, that's why I used the word "seems".

I don't understand your point. Are you saying that you knew all along that there wasn't contradiction; that you were simply observing that there might appear to be a contradiction to some people?

Replies from: thomblake
comment by thomblake · 2011-10-24T22:31:47.520Z · LW(p) · GW(p)

Are you saying that you knew all along that there wasn't contradiction

Yes

Are you saying that ... you were simply observing that there might appear to be a contradiction to some people?

No, I was initially pointing to the tension between the two statements, and underscoring that by noting the seeming implication. You did not acknowledge the tension when those statements were juxtaposed by loqi, so I was trying to make it clear that they are in apparent conflict. Given "S will lose his job if he could not X" and "S often makes mistakes when trying to X", it does not deductively follow that "S lost his job", but it's the result to bet on. Learning in that context that S did not lose his job, one should perform a Bayesian update to decrease the probability of the premises.

Replies from: brazil84
comment by brazil84 · 2011-10-24T22:35:39.671Z · LW(p) · GW(p)

Yes

No, I was initially pointing to the tension between the two statements

Ok, I see your point now. But using the same principle of charity, it's easy enough to read my statements so that they are not in contradiction (or tension) with eachother.

comment by loqi · 2011-10-21T17:17:35.065Z · LW(p) · GW(p)

Do you agree that the tone of your post is a bit nasty?

Yes. It's a combination of having little respect for the feelings of typically-wrong pseudonymous internet posters as well as faith in my own ability to look at incomplete justifications for sloppy reasoning and draw snarky conclusions.

Replies from: brazil84
comment by brazil84 · 2011-10-23T10:15:47.418Z · LW(p) · GW(p)

Yes

Ok, and again my questions:

•You have faith that you're more reliable than those people.

Please quote me where I made that assertion.

•You have often failed to see through bullshit.

Sure, getting this kind of feedback is a good way to improve one's judgment. Do you seriously disagree?

Replies from: loqi
comment by loqi · 2011-10-23T23:22:11.150Z · LW(p) · GW(p)

Please quote me where I accused you of having faith that you're more reliable than those people.

Replies from: brazil84
comment by brazil84 · 2011-10-24T00:23:13.667Z · LW(p) · GW(p)

Please quote me where I accused you of having faith that you're more reliable than those people.

Right here:

http://lesswrong.com/lw/84j/amanda_knox_post_mortem/52b8

You have faith that you're more reliable than those people.

By the way, I have my own rules of debate. One rule is that I will not engage with people who "strawman" me, i.e. misrepresent my position.

I also won't engage with people who refuse to answer reasonable questions to let me understand their position. So I will try one last time:

You have faith that you're more reliable than those people.

Please quote me where I made that assertion.

You have often failed to see through bullshit.

Sure, getting this kind of feedback is a good way to improve one's judgment. Do you seriously disagree?


Your choice.

Replies from: loqi
comment by loqi · 2011-10-24T17:45:07.388Z · LW(p) · GW(p)

Please quote me where I accused you of having faith that you're more reliable than those people.

Right here:

Thanks!

I also won't engage with people who refuse to answer reasonable questions to let me understand their position.

Thanks!

Replies from: brazil84
comment by brazil84 · 2011-10-24T19:17:09.446Z · LW(p) · GW(p)

Ok bye.

comment by Desrtopa · 2011-10-21T04:48:37.942Z · LW(p) · GW(p)

It's a combination of having little respect for the opinions of anonymous internet posters as well as faith in my own ability to look at incomplete evidence concerning real world disputes and draw reasonable conclusions.

Keep in mind that you are yourself an anonymous internet poster dealing with other anonymous internet posters with confidence in their ability to look at incomplete evidence concerning real world disputes and draw reasonable conclusions. I would say this is a situation where consideration of the outside view is warranted.

Replies from: brazil84
comment by brazil84 · 2011-10-21T05:13:20.245Z · LW(p) · GW(p)

Keep in mind that you are yourself an anonymous internet poster dealing with other anonymous internet posters

Well to me, I'm not anonymous. But anyway, I also try to go by peoples' actual arguments. I think this is a reasonable amount of consideration.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T05:27:05.387Z · LW(p) · GW(p)

Well to me, I'm not anonymous.

Which is a very tenuous basis on which to put yourself in a separate reference class.

You should adjust your confidence according to the strength of others' arguments relative to what you would expect given your prior confidence value, and you should also adjust your confidence according to the fact of others' belief weighted according to your confidence in their mechanisms for establishing truth.

If I believe proposition A, and someone gives me argument X for disbelieving it, and I find argument X weak, I should adjust my confidence little if at all. But if a large population of people whose judgment I have no reason to believe is less sound than my own for cases in this class tells me that proposition A is wrong on the basis of argument X, and I'm just not getting it, I should significantly decrease my confidence, on the likelihood that I really am just not getting it.

Replies from: brazil84
comment by brazil84 · 2011-10-21T10:47:19.979Z · LW(p) · GW(p)

Which is a very tenuous basis on which to put yourself in a separate reference class.

Well let me ask you this: roughly speaking how much weight do you give to the unsupported assertion of an anonymous person on the internet versus your own conclusions of which you are reasonably confident in an area where you are reasonably confident of your skill and experience?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T14:39:11.295Z · LW(p) · GW(p)

Depends on where the anonymous internet people are selected from. From Youtube comments? Very little. From here? Quite a lot more.

If I knew that it were something that the people here had put a lot of thought into, and that nearly everybody here thought that I was completely wrong, I would need tremendous prior certainty not to be reduced below .5.

Replies from: brazil84
comment by brazil84 · 2011-10-21T15:13:06.557Z · LW(p) · GW(p)

If I knew that it were something that the people here had put a lot of thought into, and that nearly everybody here thought that I was completely wrong, I would need tremendous prior certainty not to be reduced below .5.

Even if the dispute were in an area where you believed you had unusual expertise?

Replies from: Desrtopa
comment by Desrtopa · 2011-10-21T15:18:32.074Z · LW(p) · GW(p)

If the other members were aware of my assessment of my expertise and reasons for assigning it, and were not moved from high confidence that I was wrong, then yes. I would need very strong confidence in my having unique qualifications to not mostly discount on the basis of their discounting.

Replies from: Jack, brazil84
comment by Jack · 2011-10-21T15:24:55.369Z · LW(p) · GW(p)

If the other members were aware of my assessment of my expertise and reasons for assigning it, and were not moved from high confidence that I was wrong, then yes.

Quoted so it won't get missed. This is a really important point.

comment by brazil84 · 2011-10-23T10:32:21.311Z · LW(p) · GW(p)

I think the difference is that you have a lot of respect for posters here as a group. I do not.

comment by [deleted] · 2011-10-24T19:14:32.516Z · LW(p) · GW(p)

This comment is unrelated to the main article.

I take issue with your Bayes-prayer. I don't mind so much that it seems to be just a normal prayer with some replaced words, rather than being something good in its own right, though I think this would offend other LWers. However, it does violate one message on LW that I've found very important to internalize:

Never confess to me that you are just as flawed as I am unless you can tell me what you plan to do about it.

So, apparently, we're really really bad at bayescraft. What are we going to do about it?

Replies from: Normal_Anomaly, gwern, lessdazed
comment by Normal_Anomaly · 2011-10-31T01:23:00.978Z · LW(p) · GW(p)

I don't mind so much that it seems to be just a normal prayer with some replaced words, rather than being something good in its own right, though I think this would offend other LWers.

It doesn't offend me, and I don't anticipate that it would offend many other LWers. So I'm going to test this with a poll. If you were NOT offended by changing a Christian prayer to be about Bayes, upvote this comment.

EDIT: This isn't actually what eridu was talking about.

Replies from: wedrifid, None, Desrtopa, Normal_Anomaly, lessdazed
comment by wedrifid · 2011-10-31T01:47:51.521Z · LW(p) · GW(p)

Not offended but I do think it is rather lame. It did make me downvote and mentally dissociate from the post. More "ewww" than "How dare you!".

Replies from: gwern
comment by gwern · 2011-10-31T03:48:25.843Z · LW(p) · GW(p)

Was it really that lame? Man, now I'm wondering whether the Fate/Stay Night bit of http://lesswrong.com/lw/7z9/1001_predictionbook_nights/ turned off a bunch of readers who simply haven't mentioned it.

Replies from: None
comment by [deleted] · 2011-11-10T16:01:30.013Z · LW(p) · GW(p)

I really liked that, because I think it captured a good part of the essence of tsuyoku naritai. I don't think the Bayes-prayer did.

comment by [deleted] · 2011-11-10T15:57:54.205Z · LW(p) · GW(p)

I think this would offend the LW zeitgeist because to me, this seems like awful political art.

I tried to imply that because I don't like linking to the sequences every time I make some point based off of them, but I think you missed that. Taking that one line out of context didn't help.

Edit: To be as explicit as I can, I don't care that this is a christian prayer. I just think it's not well done, because it doesn't reflect tsuyoku naritai.

Replies from: komponisto, Normal_Anomaly
comment by komponisto · 2011-11-10T17:00:08.416Z · LW(p) · GW(p)

I think this would offend the LW zeitgeist because to me, this seems like awful political art.

To me it seems humorous. Which is in stark contrast to awful political art such as the poem EY describes in the linked post.

Replies from: None
comment by [deleted] · 2011-11-10T17:02:24.302Z · LW(p) · GW(p)

Why is it humorous besides pointing out that the author is on our side?

Replies from: komponisto
comment by komponisto · 2011-11-10T17:12:09.880Z · LW(p) · GW(p)

It's a combination of irreverence (mocking religion by treating non-divine entities as gods), incongruity (you don't expect a bunch of science-minded techno-nerds to sit around praying), and self-mockery (poking fun at our level of enthusiasm for Bayesian concepts).

Replies from: None
comment by [deleted] · 2011-11-10T18:39:34.094Z · LW(p) · GW(p)

None of that resolves to anything more than "I'm on your team! Go team!"

comment by Normal_Anomaly · 2011-11-10T23:16:29.840Z · LW(p) · GW(p)

That makes sense. I thought you were saying that other people objected to using language originating with Christianity. Your complaint is perfectly reasonable and I slightly agree with it.

Replies from: None
comment by [deleted] · 2011-11-11T03:13:15.566Z · LW(p) · GW(p)

I apologize for not being more clear.

comment by Desrtopa · 2011-10-31T04:09:20.699Z · LW(p) · GW(p)

I wasn't offended, but I did find it a bit ridiculous, and not really in a funny way, although in a different context I might have found it funny.

comment by Normal_Anomaly · 2011-10-31T01:23:21.890Z · LW(p) · GW(p)

If you WERE offended by by changing a Christian prayer to be about Bayes, upvote this comment.

Replies from: Normal_Anomaly
comment by Normal_Anomaly · 2011-10-31T01:23:35.881Z · LW(p) · GW(p)

Karma Balance.

comment by lessdazed · 2011-10-31T01:52:45.693Z · LW(p) · GW(p)

These might be relevant.

I mean, these might be rationally Bayesian.

comment by gwern · 2012-02-27T03:05:37.658Z · LW(p) · GW(p)

What are we going to do about it?

If there's anyone here who has made more suggestions than me and tried harder than me on calibrating one's predictions, I would appreciate an introduction so I can pick their brain.

Replies from: None
comment by [deleted] · 2012-04-10T00:55:55.989Z · LW(p) · GW(p)

I'm saying it deserves mention within the prayer, to remind the reciter that it's not enough to confess one's flaws without also forming a plan to obliterate them.

comment by lessdazed · 2011-10-31T06:56:00.783Z · LW(p) · GW(p)

If Bayes is all knowing, that sort of defeats the point, doesn't it?

comment by John_Maxwell (John_Maxwell_IV) · 2011-10-27T05:42:22.594Z · LW(p) · GW(p)

I'd appreciate being removed as I don't feel like I spent much time reading or thinking before making my estimate and probably never should have commented. (Sorry for ruining your perfectly good and valid experiment...)

Edit: Actually, it doesn't look like I spent all that much less time on a log scale than other folks. It does seem like we didn't really have enough time to get a solid grip on things though.

comment by lukeprog · 2011-10-29T04:52:47.750Z · LW(p) · GW(p)

Amanda Knox vs. Troy Davis.

Replies from: Desrtopa
comment by Desrtopa · 2011-10-29T05:11:11.347Z · LW(p) · GW(p)

The family of the British girl killed in Italy expressed dismay that the original evidence was unreliable and has accepted that Amanda Knox may be innocent after all.

Is this really true? It isn't reflected in the quotes that I've read so far.

I went and did a bit more reading on the Troy Davis case, and I don't think they're that comparable. In the evidentiary hearing, the court found that several of the alleged recantations by witnesses were not recantations at all; most of the witnesses were still claiming Davis's guilt. The murder weapon was never recovered, so they have no prints.

Considering the unreliability of eyewitnesses, especially when the police are encouraging a particular response, it's a lot less confidence than I'd want before applying the death penalty, setting aside the issue of whether it's ever an appropriate punishment, but I don't think it can reasonably be compared to the Knox and Sollecito trial, where the defendants were almost certainly innocent.

Replies from: komponisto
comment by komponisto · 2011-10-29T06:15:01.628Z · LW(p) · GW(p)

The family of the British girl killed in Italy expressed dismay that the original evidence was unreliable and has accepted that Amanda Knox may be innocent after all.

Is this really true? It isn't reflected in the quotes that I've read so far.

Indeed it isn't -- what they have said is that they plan to support the prosecution's appeal of the acquittal. (In fact, as the Italian system allows, they are actually a party to the case, seeking a monetary judgement against Knox and Sollecito. [This fact should not be confused with the recent false reports that they were planning to sue Knox in another jurisdiction.])