## Posts

Suspiciously balanced evidence 2020-02-12T17:04:20.516Z · score: 47 (15 votes)
"Future of Go" summit with AlphaGo 2017-04-10T11:10:40.249Z · score: 3 (4 votes)
AlphaGo versus Lee Sedol 2016-03-09T12:22:53.237Z · score: 19 (19 votes)
[LINK] "The current state of machine intelligence" 2015-12-16T15:22:26.596Z · score: 3 (4 votes)
[LINK] Scott Aaronson: Common knowledge and Aumann's agreement theorem 2015-08-17T08:41:45.179Z · score: 15 (15 votes)
Group Rationality Diary, March 22 to April 4 2015-03-23T12:17:27.193Z · score: 6 (7 votes)
Group Rationality Diary, March 1-21 2015-03-06T15:29:01.325Z · score: 4 (5 votes)
Proportional Giving 2014-03-02T21:09:07.597Z · score: 6 (14 votes)
[Link] False memories of fabricated political events 2013-02-10T22:25:15.535Z · score: 17 (20 votes)
[LINK] Breaking the illusion of understanding 2012-10-26T23:09:25.790Z · score: 19 (20 votes)
The Problem of Thinking Too Much [LINK] 2012-04-27T14:31:26.552Z · score: 7 (11 votes)
Harry Potter and the Methods of Rationality discussion thread, part 4 2010-10-07T21:12:58.038Z · score: 5 (7 votes)
The uniquely awful example of theism 2009-04-10T00:30:08.149Z · score: 38 (48 votes)
Voting etiquette 2009-04-05T14:28:31.031Z · score: 10 (16 votes)

Comment by gjm on Open & Welcome Thread - July 2020 · 2020-07-07T09:58:35.177Z · score: 4 (2 votes) · LW · GW

It does in fact say "LessWrong Docs [Beta]" right there in the comment box. But I didn't have the wit to interpret that correctly as "you're only seeing this because you signed up to enjoy new and unstable things" rather than as "this is a new thing we're rolling out even though it might be a little flaky".

Comment by gjm on Quantifying Household Transmission of COVID-19 · 2020-07-06T19:40:31.707Z · score: 4 (2 votes) · LW · GW

Does (or could) your analysis distinguish between "someone in the household" with, say, "someone you are sleeping in the same bed as"? It's very common for relationships within a household to be highly varied in ways that seem relevant.

Comment by gjm on Open & Welcome Thread - July 2020 · 2020-07-06T19:35:57.358Z · score: 2 (1 votes) · LW · GW

Thanks. As mentioned above, I had forgotten that I'd specifically opted in to anything and assumed it was a site-wide beta. My apologies for whingeing about it in public, therefore.

Comment by gjm on Open & Welcome Thread - July 2020 · 2020-07-06T19:35:10.705Z · score: 2 (1 votes) · LW · GW

Aha. Fair enough! I'd forgotten that I explicitly opted in to beta features :-).

Comment by gjm on Open & Welcome Thread - July 2020 · 2020-07-06T01:01:13.082Z · score: 2 (1 votes) · LW · GW

Although I found the "site meta" tag, it didn't really help me answer my question. There don't seem to have been any site-update posts for ages other than the one about the tag system, which isn't obviously relevant to editor issues. I searched for "LessWrong Docs" but the most recent thing I see about it is a post from last November saying that it hadn't been released yet.

Comment by gjm on Open & Welcome Thread - July 2020 · 2020-07-06T00:53:09.747Z · score: 4 (2 votes) · LW · GW

At some point (maybe quite some time ago? I'm pretty sure it wasn't more than about a month, though) something changed (at least for me) in the LW comment editor, and not for the better. Perhaps it was when "LessWrong Docs [Beta]" became the default editor? I have no recollection of when that actually was, though. I'd try in "Draft JS", which I assume was the previous WYSIWYG-ish editor, but when I try to select that the result is that I cannot enter anything in the comment box until I switch back to a different editing mode :-).

Under certain circumstances, attempting to type a space has the result of deleting a load of the text I have just typed. This is really annoying.

The simplest such circumstance is if I do ctrl-4 to start typing some mathematics, finish by pressing Enter (I thought it used to be possible to press the right-arrow key with the same effect, by the way, but if so it has stopped working) and then press a space, which is usually what I want after a bit of inline mathematics. Result: the mathematical thing I just entered disappears.

Another situation, presumably related: I enter some mathematics, carefully remember not to press space after it (instead typing some other stuff, then moving my cursor back and then entering a space), and at some point later in that paragraph I put some text in italics. Ctrl-I, stuff-in-italics, ctrl-I, space. Boom! Everything from the start of the earlier mathematical formula gets deleted.

[EDITED to add:] Oh, quite possibly also relevant: I am using the NoScript extension to Firefox, and some of the vast number of domains that LW pages pull in have scripts blocked: googletagmanager.com, intercom.io, lr-ingest.io, sentry.io. None of those seems like it should cause this sort of thing if blocked, but who knows?

Comment by gjm on Open & Welcome Thread - July 2020 · 2020-07-06T00:40:42.383Z · score: 2 (1 votes) · LW · GW

I managed to answer part of my own question: there is indeed a "site meta" tag, which I had failed to find by following the "tags" link accessible via the hamburger menu at top left but which is found by searching for "meta". I failed to find it via the "tags" link not because it wasn't there but because it looked (to me) like a heading rather than an actual tag. Duh.

Presumably the absence of "meta" from the hamburger menu is because we are no longer supposed to find things via menus but instead by using the tag system. It is not obvious to me that this is an improvement.

Comment by gjm on Open & Welcome Thread - July 2020 · 2020-07-06T00:35:53.561Z · score: 2 (1 votes) · LW · GW

Once upon a time, clicking somewhere at the top left of the LW home page (maybe on "LESSWRONG", maybe on the hamburger to its left, probably the latter) produced a drop-down list of sections one of which was "Meta" and contained things like regular updates on Less Wrong development.

I cannot now find anything similar. I wondered whether maybe there was a "meta" tag that was being used instead, but it doesn't look that way.

I wanted to have a look at information about recent site updates (because at some point something has gone terribly wrong with the editing functionality, at least for me at the moment on this computer, and I wondered whether there was a recent change that might explain it, and whether other people had reported the same thing). I am currently failing to find any way to do that.

What am I missing?

Comment by gjm on How do you visualize the Poisson PDF? · 2020-07-06T00:28:07.556Z · score: 31 (12 votes) · LW · GW

If you have the option, it is much better to learn mathematical formulae, theorems, etc., by understanding them rather than by rote memorization. The visualization techniques you describe seem to be intended as ways to make rote memorization easier.

If you have the option, it is also much better to learn mathematical formulae, theorems, etc., by connecting them with other bits of mathematics you know. This is not the same thing as understanding them, but there's some connection between the two.

(You might not have the option. You might find whatever it is very hard to make any sense of, but need to learn it in a hurry for an examination or something. That's a bad situation to be in, and if you aren't in that situation yet you should probably try to avoid it, but that isn't always possible.)

So, for instance, one thing that jumps out at me when I look at the formula for the Poisson distribution is:  is one term in the series for  and the other factor, of , is what you need to make those terms add up to 1 instead of . (I am fairly sure this is in fact how I remember the formula for the Poisson distribution.)

That's a connection with other things but doesn't in itself convey any understanding: it doesn't give us a way of working out what the formula is if we happen to forget some detail. But suppose we look at the series for  instead of that for just ; then the coefficient of  is (aside from that factor of ) exactly the probability of getting  events; in other words, the formula says that  is the generating function for those probabilities. (The "-1" comes from that factor of .)

Now, that's the same thing as saying that  is equal to the expectation of  where  is Poisson-distributed with rate . (If it isn't obvious why, try writing down what that expectation is as a sum of probabilities times values.) Perhaps that's obvious if you look at it the right way? Well, saying that  is Poisson-distributed with rate  means that it's the limit for large  of what you get by having  opportunities for events to happen, each independently with probability . So  is (the limit of) the product of  independent things that are either  (with probability ) or 1 (otherwise). The expectation of a product of independent things is the product of their expectations. The expectation of one of those things is . So we're looking at the limit of , and that sort of limit is famously one way of defining . So we also have an (admittedly slightly clumsy) way of seeing why the formula has to be right.

None of this is an answer to the question you actually asked: how can you visualize this formula, so you can memorize it without any understanding? If you really truly need to do that, then you should ignore everything I just wrote. But if what you need is to be able to remember and use the formula, then I think this sort of thing will be much better for you. Why? Because it scales better. The more things you learn by understanding them and/or by making connections to other bits of mathematics, the easier it is to learn the next thing you need to remember, because you have more tools for understanding and more things to connect to.

Comment by gjm on How to Find Sources in an Unreliable World · 2020-07-03T10:24:21.882Z · score: 4 (2 votes) · LW · GW

I assume your two "N best books" examples are intended as bad examples. Since your other links are to good examples and the whole bullet-list block is introduced by offering "heuristics for finding good starting places", I think it would be worth making it even more explicit that they are intended as examples of what not to do (rather than e.g. a couple of rare counterexamples to the general pattern you've just mentioned).

Comment by gjm on Self-sacrifice is a scarce resource · 2020-06-30T14:13:09.532Z · score: 2 (1 votes) · LW · GW

Mandatory? It's not mandatory. But if you don't specify then you're making an argument with vital bits missing.

I agree that utilitarian decision making (or indeed any decision making) is harder when you don't have all the information about e.g. how much effort something takes.

I also agree that in practice we likely get more efficiency if people care more about themselves and others near to them than about random people further away.

Comment by gjm on Self-sacrifice is a scarce resource · 2020-06-30T10:44:57.510Z · score: 3 (2 votes) · LW · GW

Your last paragraph doesn't make much sense to me. I think you need to specify how much needs to be done in order to resolve that one shared issue. If it requires the same investment from all 1000 people as they'd have put into saving those single individual lives, then it's 1000 people versus 100 people and they should do the individual thing. If it requires just one person to do it, then (provided there's some way of selecting that person) it's 1 person versus 100 people and someone should do the shared thing. If it requires 100 people to do it, then as you say it's a choice of 100 versus 100 and other considerations besides "how many people saved?" will dominate. But none of this is really about private versus public, and whether someone's being efficient or inefficient in making a particular choice depends completely on that how-much-needs-to-be-done question that you left unspecified.

(There are public-versus-private issues, and once you nail down how much public effort it takes to resolve the shared issue then they become relevant. Coordination is hard! Public work is more visible and may motivate others! People care more about people close to them! Etc., etc.)

Comment by gjm on Gödel's Legacy: A game without end · 2020-06-30T08:57:18.153Z · score: 2 (1 votes) · LW · GW

Nitpick: Borges's library is of Babel, not of Babble. (Though I think "babble" is derived from "Babel", via the biblical story.)

Comment by gjm on Gödel's Legacy: A game without end · 2020-06-30T08:51:54.534Z · score: 2 (1 votes) · LW · GW

Nitpick: Wittgenstein's book is actually rather short, and that quotation is from the very end, not the start.

Comment by gjm on [deleted post] 2020-06-17T14:25:44.099Z

Entropy is not perfectly uniformly distributed in space, which means that "time is the direction orthogonal to the change in entropy" is problematic, no?

(I'm not sure you can localize entropy enough to make statements about what direction it's pointing in have much precision, either. But maybe I'm missing something.)

Comment by gjm on [Link] "Will He Go?" book review (Scott Aaronson) · 2020-06-13T15:41:08.080Z · score: 7 (5 votes) · LW · GW

I think you may be conflating two very different meanings of "not accepting". On the one hand, there's "X shouldn't have won"; on the other, "X didn't really win". The things you quote seem like they're much more about the first, and the book here is speculating about a claim of the second.

• "Not my president" generally means "I don't think X is in any way on my side and I strongly disapprove of him", not "I think X didn't really win the election and the nation's institutions should refuse to obey his executive orders etc.". So, e.g., here is a NYT opinion piece entitled "Not my president, not now, not ever", whose key claim is: "Mr. Trump has no intention of representing me, my family, the people I care about, or the majority of Americans, from the imperiled to the comfortable. It is a stretch to call him anyone’s president but his own." There were "Not my Presidents Day" rallies on 2017-02-20; according to the Wikipedia article about them) "Organizers of the protest stated that although Trump was the president, they wanted to show that he did not represent their values."
• It's maybe worth adding that in the run-up to the election, Mr Trump repeatedly refused to say that he'd accept the results of the election; he was playing the "not really president" card in advance, just in case he lost. And even when he did win, he repeatedly claimed that he'd really won the popular vote and appearances to the contrary were because of (nonexistent) millions of fraudulent Clinton votes.
• I'm not sure what "disbelief that Trump could possibly have won" actually refers to, so can't comment on it. For sure, some people were very surprised that he won, but being very surprised that someone won an election is not remotely the same as denying that they actually did win it.
• "Denial that Trump even had a chance" seems like it's the same thing as "disbelief that Trump could possibly have won", so I'm not sure why this needs a separate bullet point. In any case, the article you link to (1) was before the election, and hence can't possibly be evidence of anyone refusing to accept that Trump won the election after it happened, and (2) says "almost certain". The earliest thing I could quickly find by the same author after the election is this, from 2016-11-11, which so far as I can tell doesn't have the least hint of a suggestion that Trump's election was illegitimate. (It also claims that "[i]n some ways, [Clinton's] defeat was pre-ordained", which is pretty rich given that a few weeks before the author had been saying Clinton's victory was almost inevitable, but I'm not claiming that Abramson is impressive or intelligent, only that she wasn't denying that Trump really won.)
• There was no '"Russian collusion" hoax'. There were credible claims of Russian collusion, they were investigated (which is exactly what should have been done), and the conclusion of the investigators was not, at all, that there was nothing to the claims. They found (1) that Russia had "interfered in the 2016 presidential election in sweeping and systematic fashion", (2) that what they did "favoured ... Trump and disparaged ... Clinton" ("disparaged" is a weird choice of word, but no matter), (3) that the Trump campaign "expected" that the Russian interference would benefit them and "welcomed" that help, (4) that "the social media campaign and the GRU hacking operations coincided with a series of contacts between Trump Campaign officials and individuals with ties to the Russian government", but (5) that they were unable to find sufficient concrete evidence to accuse the Trump campaign of criminal collusion. (Not least because, as the report documented, Mr Trump and his associates repeatedly refused to cooperate with the investigation.) You may form your own opinion as to whether (a) there was no collusion or (b) there was collusion but Mr Trump and his associates were able to put up enough smoke to prevent anything being concluded beyond reasonable doubt; but there's plenty here to make it clear that this was no hoax.
• It's not at all clear to me what would have happened if Muller had found clear evidence of collusion between the Trump campaign and Russia. That certainly wouldn't have been enough to invalidate the election and make Trump no longer president. Perhaps it would have led to an impeachment, but the results of that would likely have been the same as the results of the impeachment that actually happened.

So, of your four things: the first, in the actual instances I've found, is "I wish he hadn't been elected and don't think he represents me" rather than "he is not really president"; I don't know what the second means, unless it's the same as the third; the third, so far as I can tell from the specific instance you selected, says no more than "Clinton will probably win" which has nothing at all to do with your claim; the fourth might or might not imply "not legitimately elected" but was not the partisan thing you want to represent it as.

Comment by gjm on Comment on "Endogenous Epistemic Factionalization" · 2020-05-21T11:11:30.603Z · score: 6 (5 votes) · LW · GW

Relatedly, in the scenario (in some utterly absurd counterfactual world entirely unlike the real world) where agents sometimes misrepresent the evidence in a direction that favours their actual beliefs, it seems like the policy described here might well do better than the policy of updating fully on all evidence you're presented with.

Given the limitations of our ability to investigate others' honesty, it's possible that the only options are factionalism or naivety and that the latter produces worse results than factionalism; e.g., if we happen to start with more people favouring (A,A,A) than (B,B,B) then rejecting "distrust those who disagree" may end up with everyone in the (A,A,A) corner, which is probably worse than having factions in all eight corners if the reality is (B,B,B).

As Zack says, what we want is a degree of trust that matches agents' trustworthiness. But that may be extremely hard to obtain, and if all agents are somewhat untrustworthy (but some happen to be right so that their untrustworthiness does little harm) then having trust matching trustworthiness may produce exactly the sort of factional results reported here.

So I think the most interesting question is: Are there strategies that, even when agents may be untrustworthy in their reporting of the evidence, manage to converge to the truth over a reasonable portion of the space of untrustworthiness and actual-evidence-strength? My guesses: (1) yes, there kinda are, and the price they pay instead of factionalism is slowness; (2) if there is enough untrustworthiness relative to the actual strength of evidence then no strategy will give good results; (3) there are plenty of questions in the real world for which #2 holds. But I'm not terribly confident about any of those guesses.

Comment by gjm on Signaling: Why People Have Conversations · 2020-05-21T08:46:13.447Z · score: 2 (1 votes) · LW · GW

My personal theory is that not all talk is signalling, but almost all talk about signalling is. (It signals "I am smart, sophisticated, not easily fooled, and willing to face uncomfortable realities; I see below the carefully groomed surface of things to the ugliness beneath.")

In the particularly prominent case of Literal Robin Hanson, it seems possibly significant that the uncomfortable realities he uncovers are generally much more uncomfortable for one of the two major political factions in the US than for the other, and that the "other" one is the one responsible for a lot of his funding over the years (though I think he may no longer be affiliated with the Mercatus Center now?).

(Only possibly significant, and I do actually mean that. Obviously things that are politically convenient for the person saying them can also be true.)

Comment by gjm on Suspiciously balanced evidence · 2020-05-20T13:00:56.512Z · score: 5 (3 votes) · LW · GW

A probability measure is a measure (on a -algebra on a set ) such that .

A measure on a -algebra is a function with properties like "if then " etc.; the idea is that the elements of are the subsets of that are well-enough behaved to be "measurable" and then if is such a subset then says how big is.

A -algebra on a set is a set of subsets of that (1) includes all-of-, (2) whenever it includes a set also includes its complement , and (3) whenever it includes all of countably many sets also includes their union.

And now probability theory is the study of probability measures. (So the measure-theoretic definition of "probability" would be "anything satisfying the formal properties of a probability measure", just as the mathematician's definition of "vector" is "anything lying in a vector space".)

"Bayesian" probability theory doesn't disagree with any of that; it just says that one useful application for (mostly the more elementary bits of) the theory of probability measures is to reasoning under uncertainty, where it's useful to quantify an agent's beliefs as a probability measure. Here is the set of ways the world could be; is something like the set of sets of ways the world could be that can be described by propositions the agent understands, or the smallest -algebra containing all of those; , more commonly denoted or or or something of the sort, gives you for any such set of ways the world could be a number quantifying how likely the agent thinks it is that the actual state of the world is in that set.

You can work with probability measures even if you think that it's inappropriate to use them to quantify the beliefs of would-be rational agents. I guess that's PP's position?

Comment by gjm on Open & Welcome Thread—May 2020 · 2020-05-20T09:35:25.750Z · score: 2 (1 votes) · LW · GW

I assume it means an image used in the training process by which the robots learned to recognize things.

Comment by gjm on Suspiciously balanced evidence · 2020-05-20T09:33:47.857Z · score: 4 (2 votes) · LW · GW

You don't need anyone's forgiveness. But it turns out that quantifying degrees of belief is useful sometimes, and that representing them as numbers from 0 to 1 that behave like probabilities is a good way to do that. (There are theorems that kinda-sorta say it's the only way to do that, if you want various nice-sounding things to be true, but how much you care about those nice-sounding things is up to you.) So you may be missing out on some useful thinking tools.

Comment by gjm on Open & Welcome Thread—May 2020 · 2020-05-19T11:17:04.736Z · score: 6 (3 votes) · LW · GW

In the space of four frames, today's SMBC comic touches on unfriendly AI, fun theory, and overfitting in machine learning.

Comment by gjm on Studies On Slack · 2020-05-13T15:12:17.775Z · score: 6 (4 votes) · LW · GW

No one is erasing other people's comments here unless they're outright abusive.

As for the "irreducible complexity" argument, you may notice that it has convinced approximately zero percent of actual biologists. You may find "they're all brainwashed atheists so completely under Satan's thumb that they can't form rational opinions" a more convincing explanation for that than "the argument is actually not very strong", but I don't agree.

(I agree with the biologists; I think Behe's argument is bad. But I don't think arguing about that argument is particularly on topic here.)

Also, no one is claiming that Francis Bacon is anyone's moral foundation. I think you may not have been reading what Scott wrote very carefully.

Comment by gjm on Open & Welcome Thread—May 2020 · 2020-05-09T13:37:28.993Z · score: 6 (3 votes) · LW · GW

It's true that lawters aren't required to take every client who comes along, but I think generally the legal profession strongly encourages them to be willing to take unattractive cases. For instance, the ABA Model Code of Professional Responsibility has various things to say, of which I've excerpted the bits that seem to me most important (on both sides of the question):

A lawyer is under no obligation to act as adviser or advocate for every person who may wish to become his client; but in furtherance of the objective of the bar to make legal services fully available, a lawyer should not lightly decline proffered employment. The fulfillment of this objective requires acceptance by a lawyer of his share of tendered employment which may be unattractive both to him and the bar generally.
[...]
When a lawyer is appointed by a court or requested by a bar association to undertake representation of a person unable to obtain counsel, whether for financial or other reasons, he should not seek to be excused from undertaking the representation except for compelling reasons. Compelling reasons do not include such factors as the repugnance of the subject matter of the proceeding, the identity or position of a person involved in the case, the belief of the lawyer that the defendant in a criminal proceeding is guilty, or the belief of the lawyer regarding the merits of the civil case.

So they don't quite say that lawyers should never refuse to represent clients just because they think they're guilty. But they do say that lawyers should be willing to take "unattractive" cases, and that if a court assigns a lawyer to represent someone who can't afford to pay for his own lawyer then that lawyer shouldn't refuse just because they think the client is guilty.

So my earlier statement goes too far, but I think it's more right than wrong: in general lawyers aren't supposed to refuse to defend you just because they think you're probably guilty. Even though they are allowed to refuse to defend you.

Comment by gjm on Open & Welcome Thread—May 2020 · 2020-05-09T10:55:39.228Z · score: 3 (2 votes) · LW · GW

What do you mean by "knowing that both ways are legit"? Only one way is legit: when someone comes to you needing defence and willing to pay your fees, you defend them.

(I think the actual system is a little different: a lawyer isn't expected to defend their client if they're sure the client is guilty; in that case they would ask them to find another lawyer, or something. But that isn't because those clients don't deserve defending, it's because they deserve defending better than someone who's sure they're guilty is likely to manage.)

Comment by gjm on Reopen Protest Sign Survey · 2020-05-01T15:52:35.405Z · score: 6 (3 votes) · LW · GW

It's worth noting that what someone puts on a sign doesn't necessarily indicate what they really care most about, especially if what's on the sign is more socially acceptable than what they really care about. So I don't think the findings here are inconsistent with what annacaffeina says. (They are probably, albeit not very strong, evidence against what she says, though. Only "probably" because it could be that the other sign-slogans -- especially the more generically-political ones -- are evidence about the sort of person waving the sign; maybe some of those slogans are more characteristic of wealthier people who want the service industry serving them again than of poorer service-industry employees who want to be at work again.)

Comment by gjm on On “COVID-19 Superspreader Events in 28 Countries: Critical Patterns and Lessons” · 2020-04-29T23:41:13.929Z · score: 2 (1 votes) · LW · GW

Nature article giving some evidence for aerosol transmission. More specifically, what it gives evidence of is that in some circumstances you can find aerosolized SARS-CoV-2 where there are infected people, which doesn't seem very surprising. It doesn't say anything about how effectively that causes infection, or about the relative importance of this mode of transmission compared with others. It also has some discussion of the sizes of aerosol particles and how they got that way, and of what circumstances make it more likely for there to be non-negligible amounts of SARS-CoV-2 in the air.

The least obvious things there, to me: Toilets are pretty bad (lots of people, each there for a while, small space). In hospitals, one source of SARS-CoV-2 in the air (in smaller aerosol particles -- do these stay around longer?) may be from PPE after it's been taken off. In the public areas they looked at, only the most densely used ones had substantial amounts of SARS-CoV-2 in the air. [EDITED to add:] "Least obvious" does not mean "very not-obvious"; most of these are pretty unsurprising. I don't know that I'd have guessed the thing about discarded PPE, though.

Comment by gjm on A Book Review · 2020-04-28T22:58:17.937Z · score: 7 (4 votes) · LW · GW

I think you mean occasional weirdly out-of-place fucking cuss words.

Comment by gjm on Far-Ultraviolet Light in Public Spaces to Fight Pandemic is a Good Idea but Premature · 2020-04-20T00:51:19.681Z · score: 3 (2 votes) · LW · GW

Oops! The perils of hand-transcribing URLs.

I think I may have been unclear; I wasn't saying "let's not use blue light for anything" or anything like that, just giving a bit of context. It shouldn't be so surprising that blue light can kill some microorganisms, given that it can harm humans too.

Comment by gjm on Far-Ultraviolet Light in Public Spaces to Fight Pandemic is a Good Idea but Premature · 2020-04-17T11:32:21.209Z · score: 4 (2 votes) · LW · GW

It's not going to kill us. But high-intensity blue light will, in the long term, damage your retinas. See e.g. http://photobiology.info/Rozanowska.html .

[EDITED to fix a typo in the URL; sorry about that]

Comment by gjm on Far-Ultraviolet Light in Public Spaces to Fight Pandemic is a Good Idea but Premature · 2020-04-16T14:30:46.342Z · score: 4 (2 votes) · LW · GW

Short-wavelength blue light is harmful to humans too. In particular, it's harmful to the eyes. I would be highly unsurprised if it were slightly carcinogenic but I don't know anything about that.

Comment by gjm on The one where Quirrell is an egg · 2020-04-15T17:58:50.099Z · score: 5 (3 votes) · LW · GW

I enjoyed reading it on r/HPMOR but I confess I think it should have stayed there.

Comment by gjm on Why don't we tape surgical masks to the face to seal them airtight? · 2020-04-14T14:15:26.489Z · score: 2 (1 votes) · LW · GW

Right. Though the paper by Davies et al that Christian found suggests that at least some paper masks may not be so wretched at keeping out tiny particles.

Comment by gjm on Why don't we tape surgical masks to the face to seal them airtight? · 2020-04-14T14:14:34.906Z · score: 2 (1 votes) · LW · GW

Davies et al is encouraging as regards the benefits of surgical masks. Still, letting 10% in is a lot worse than letting 5% in, and the fact that the Wikipedia page about N95 masks says "Collection efficiency of surgical mask filters can range from less than 10% to nearly 90% for different manufacturers’ masks when measured using the test parameters for NIOSH certification" suggests that maybe Davies et al got lucky in which surgical masks they tested.

Comment by gjm on Why don't we tape surgical masks to the face to seal them airtight? · 2020-04-14T09:32:24.655Z · score: 13 (5 votes) · LW · GW

N95 masks have finer filters that keep out particles smaller than surgical masks' filters do. If you tape a surgical mask to your face in a way that seals it perfectly, then while you may be doing a better job of keeping out the particles the mask can block you're still not doing much for the smaller ones.

N95 masks are notoriously tricky to fit well, but so far as I know no one tapes those to their faces. Whatever the reasons for that, many of those reasons probably apply to surgical masks (but more so, because the benefit will be smaller, because however good the fit the surgical masks are still not keeping out all the smaller particles.) I don't know those reasons, but I guess they include the following, all of which seem like they apply to surgical masks:

• Taping a mask to your face is harder than it may sound. There isn't that much available surface between nose and eyes to tape to.
• Your face is flexible and moves around as you talk, blink, smile, etc. Tape can peel off. Especially if you have facial hair, wrinkles, damage from earlier mask-unpeelings, etc., rather than a perfect smooth surface to tape to.
• Surgical masks are also flexible and often have folds extending to their edges, making it difficult to seal them effectively using tape.
• They also have straps. It seems to me that any way of taping a mask on is going to leave a "tunnel" along the straps. You can tape the straps down but they're inevitably going to move around in ways that tend to enlarge that tunnel.
• Peeling tape off your face is painful and may do damage, especially if you are doing it repeatedly and especially if the tape is extra-sticky so as not to peel off while you're wearing the mask.
• The slow and awkward peeling-off process keeps the mask, whose outer surface might be covered in virus particles or whatever, close to your face for longer while you're removing it.

None of this means that taping down a surgical mask won't provide any benefit. My guess is that it does. But I suspect the benefit is small enough, and the pain and inconvenience large enough, that most people won't consider it a good tradeoff.

As to whether that's right in any given case, I don't know. It would be interesting to have some actual numbers on this, but my guess is that no one's done the studies.

Comment by gjm on Law school taught me nothing · 2020-04-13T01:09:24.544Z · score: 5 (2 votes) · LW · GW

Are you now working as a lawyer?

I think I can still remember a lot of what I learned when studying mathematics at university. But (to whatever extent it's actually true; I haven't tested myself) that may be because after studying mathematics at university I did a PhD in mathematics, and then some mathematics research, and I now work in the allegedly-real world as a mathematician (though in practice that work uses very very little of what I studied at university). If I'd finished my mathematics degree and then gone off to become a painter or bricklayer or chef or something, I would probably now remember a lot less of the mathematics.

(The comparison may be unfair; my impression is that learning law and learning mathematics are quite different, and that one way they're different is that learning law involves a much larger proportion of memorizing brute facts that one couldn't deduce from other things one knows. Whereas in principle a sufficiently hyperintelligent being wouldn't need to learn anything in mathematics other than definitions, terminology and notation; the actual theorems could all be deduced from first principles. It seems plausible to me that the first kind of knowledge decays faster when not in active use than the second.)

Comment by gjm on Would 2014-2016 Ebola ring the alarm bell? · 2020-04-08T13:20:20.580Z · score: 2 (1 votes) · LW · GW

... But it's possible that the Black Death was actually mostly pneumonic plague rather than bubonic (same bacterium but in the lungs), in which case I think those first two questions would have had "yes" rather than "no" answers and the checklist comes out looking better.

Comment by gjm on Would 2014-2016 Ebola ring the alarm bell? · 2020-04-08T13:17:47.159Z · score: 7 (4 votes) · LW · GW

I am concerned that your checklist may be overfit to the current pandemic, in which case the fact that it doesn't trigger for substantially different past events like an ebola outbreak isn't necessarily such a good sign.

Consider, for instance, the 14th-century "Black Death". That was a real biggie; it killed something on the order of half the population of Europe. Let's see how the checklist does for that.

Transmissibility: no, it doesn't spread from human to human, it goes via fleas and the like; no, it isn't spread by coughing and sneezing; I don't know whether it can spread before symptoms appear but I'll guess it can; obviously there were no academic papers at the time. 1/3.

Harm: yes, very high mortality rate; no, I don't think it lasts more than two weeks (when it kills you it usually takes ~10d); yes, had there been actual hospitals >5% of patients would have needed them; there were no vaccines or effective treatments at the time. 3/4.

Spread: yes, well over 2000 people; yes, found in many countries (though at the time nowhere was "industrialized"!); yes, present in places with strong travel links; yes, spread despite attempts at lockdown. 4/4.

Institutional response: yes, lockdowns were attempted; there were no WHO-like organizations (but I wonder what the Church had to say); there weren't newspapers; I'm not sure to what extent "medical supplies" were really a thing at the time. Let's say 3/3 here.

So the Black Death gets 11/14. That's a smaller fraction than your 13/16, so at best it passes marginally. Given that the Black Death was much worse than COVID-19 is likely to be, that seems like cause for a little concern.

(I've attempted to answer the questions on the basis of modern knowledge; perhaps in the 14th century they would have said it does seem to spread from human to human, and that it spreads by coughing and sneezing. Dunno what the fairest thing to do is.)

Comment by gjm on REVISED: A drowning child is hard to find · 2020-03-22T22:54:36.676Z · score: 5 (3 votes) · LW · GW

Your claim, as I understood it -- which maybe I didn't, because you have been frustratingly vague about your own argument at the same time as demanding ever-increasing amounts of detail from anyone who questions it -- was that if the $5k-per-life-equivalent figure were real then there "should" be some experiment that could be done "in a well-defined area like Madagascar" that would be convincing enough to be a good use of the (large) resources it would cost. I suggest that the scenario I described above is obviously consistent with a$5k-per-life-equivalent figure in the places where bednets are most effective per unit spent. I assume you picked Madagascar because (being isolated, fairly small, etc.) it would be a good place for an experiment.

If you think it is not credible that any global picture makes the $5k figure "true and meaningful" then it is up to you to give a good argument for that. So far, it seems to me that you have not done so; you have asserted that if it were true then EA organizations should be running large-scale experiments to prove it, but you haven't offered any credible calculations or anything to show that if the$5k figure were right then doing such experiments would be a good use of the available resources, and my back-of-envelope calculations above suggest that in the specific place you proposed, namely Madagascar, they quite likely wouldn't be.

Perhaps I'm wrong. I often am. But I think you need to provide more than handwaving here. Show us your detailed models and calculations that demonstrate that if the $5k figure is anywhere near right then EA organizations should be acting very differently from how they actually are acting. Stop making grand claims and then demanding that other people do the hard work of giving quantitative evidence that you're wrong, when you yourself haven't done the hard work of giving quantitative evidence that you're right. Once again I say: what you are doing here is not what arguing in good faith usually looks like. Comment by gjm on At what point does disease spread stop being well-modeled by an exponential function? · 2020-03-09T00:17:45.354Z · score: 4 (2 votes) · LW · GW Typo alert: you've written "tags: coronavirsus" which has an extra "s" in "coronavirus". Comment by gjm on Matrix Multiplication · 2020-03-05T12:54:28.583Z · score: 3 (2 votes) · LW · GW Matrix multiplication means multiplying matrices. A vector can be viewed as a particular sort of a matrix, with one dimension equal to 1. So matrix-vector multiplications are a special case of matrix-matrix multiplications. A tensor is a possibly-higher-dimensional generalization of a matrix. A scalar is a rank-0 tensor, a vector is a rank-1 tensor, a matrix is a rank-2 tensor, and then there are higher ranks as well. In actual mathematics, vectors and tensors are not mere arrays of numbers; they are objects that live in "vector spaces" or "tensor products of vector spaces", and the numbers are their coordinates; you can change coordinate system and the numbers will change in certain well-defined ways. But when e.g. Nvidia sell you a GPU with "tensor cores" they just mean something that can do certain kinds of matrix arithmetic quickly. In e.g. one version of Google's TPUs, there's a big systolic array of multiply-accumulate units, which is good for dot-product-like operations, and you program it with instructions that do things like an Nx256-by-256x256 matrix multiplication, for whatever value of N you choose. If you need to handle arrays of different sizes, you'd build the calculations out of those units. Comment by gjm on The Apologist and the Revolutionary · 2020-03-05T12:44:47.675Z · score: 6 (3 votes) · LW · GW A thing I am horrified not to have thought of when I first read this, or at any time in the ~11 years since (and, looking through the comments, it doesn't seem like anyone else did, which is also a bit horrifying): If reality matches fairly closely with Ramachandran's metaphor and there's an actual brain subsystem localized somewhere in the left hemipshere that acts as "apologist" and another actual brain subsystem localized somewhere in the right hemisphere that acts as "revolutionary", we should expect left-hemisphere damage sometimes to have a sort of anti-anosognosic effect by suppressing the "apologist". Since this sort of apologism is a thing most of us do all the time about everything, anapologetic syndrome should have clearly discernible effects: the patient would lose the ability to confabulate nice explanations for not-so-nice things, in a way that ought to be noticeable since if we didn't need that ability to function effectively in society it seems like it'd be evolutionarily advantageous to lose it. This might show up to some extent as depression, which Scott mentions is not uncommon in victims of left-hemisphere brain damage, but it seems much more specific. You might think: no, this won't happen, because apologism is just how the brain works; so you have a revolutionary-module and the whole rest of your brain is the apologist. Or you might think: no, this won't happen, because the relevant module isn't really an "apologist" but an "explainer" that happens to work in a positively-biased way, so if that module went offline then you'd just completely lost the ability to make sense of the world. BUT both of these seem hard to square with the cold-water trick, which sure does seem as if it's briefly disabling or shaking up a localized apologism module. Maaaaaybe the apologist is the whole left hemisphere, and damaging bits of it doesn't do much, but cold-water-squirting somehow changes the state of the whole hemisphere? (Could it instead be briefly waking up the damaged revolutionary module? No, because it's right-hemisphere damage that causes anosognosia. The damaged bit is not in the same part of the brain as you're squirting cold water near to.) I notice that I am confused. Anyone got good suggestions? Comment by gjm on Is there a better way to define groups for COVID-19 impact? · 2020-03-04T23:05:44.648Z · score: 2 (1 votes) · LW · GW That's exactly what I meant by "we hear about increased risk if ...". Those figures don't do much to distinguish between e.g. "these specific conditions make it more likely to be bad, and if you're old but don't have them then you're fine" and "age makes it more likely to be bad, and if you're young but have those conditions then you're fine". Do they do anything to distinguish those possibilities? Probably. How much depends on how strongly those various conditions correlate with age. But my feeling is that e.g. cardiovascular disease is a better indication of being old than hypertension or diabetes, which I think are more likely to crop up in middle age, so the percentages feel fairly compatible with the it's-just-age hypothesis. If it were 6% for CVD and 10% for hypertension instead then I'd be more confident that there's something specifically bad about hypertension that makes COVID-19 worse. (If I have to guess, I guess that the answer is somewhere in the middle: almost any specific health issue makes something like COVID-19 more likely to kill you, including the specific ones listed there but others too, and being older is bad because of all the ways you're likely to be less healthy if older. But who knows?) Comment by gjm on Is there a better way to define groups for COVID-19 impact? · 2020-03-04T15:04:49.348Z · score: 6 (3 votes) · LW · GW A related thing I wonder about: as well as the variation of risk with age, we hear about increased risk if you have various other conditions -- diabetes, hypertension, etc. Many of these of course are also things that tend to appear and/or worsen with age, and it's not clear to me how the various numbers should be interpreted if you want to estimate the risk to someone with known age and known other conditions (or absence thereof). Comment by gjm on How does electricity work literally? · 2020-02-28T14:37:11.793Z · score: 3 (2 votes) · LW · GW It's not a big amount. (For, e.g., a typical mains cable.) And cabling, especially if the currents flowing in it are at high frequencies (which means more radiation), is often designed to reduce that radiation. That's one reason why we have coaxial cables and twisted pairs. For a 50Hz or 60Hz power cable, though, the radiative losses are tiny. You can power devices wirelessly -- using "those cordless chargers". They are designed to maximize the extent to which these effects happen, and of course the devices need to be designed to work that way. Ordinary mains cables don't radiate a lot and it isn't practical to power anything nontrivial by putting it near a mains cable. But the most effective way of getting energy from the field around a pair of wires is ... to connect the wires into an electric circuit. Indeed, it's only when they're connected in such a circuit that the current will flow through the wires and the energy will flow around them. Comment by gjm on How does electricity work literally? · 2020-02-27T13:49:24.676Z · score: 3 (2 votes) · LW · GW Yes, water and electricity are different in important ways even though the analogy is informative sometimes. The energy in the electromagnetic field really truly is different from the kinetic energy of the electrons. (This is one of the important differences from water in a pipe, in fact.) You can see this fairly easily in a "static" case: if I use electricity to charge up a big capacitor, I've stored lots of energy in the capacitor but it's potential not kinetic energy. (There's a lot of potential energy there because there's extra positive charge in one place and extra negative charge in another, and energy will be released if they are allowed to move together so that the net charge everywhere becomes approximately zero.) You might want to describe this situation by saying that the electrons involved have a certain amount of potential energy, just as you might say that when you lift a heavy object from the surface of the earth that object has acquired (gravitational) potential energy. That point of view works fine for this sort of static situation, but once your charges start moving around it turns out to be more insightful to think of the energy as located in the electromagnetic fields rather than in the particles that interact with those fields. So, for instance, suppose you arrange for an alternating current to flow in a conductor. Then it will radiate, transmitting energy outward in the form of electromagnetic waves. (Radio waves, at the sort of frequencies you can readily generate in a wire. At much higher frequencies you get e.g. light waves, but you typically need different hardware for that.) This energy is carried by the electromagnetic field. It will propagate just fine in a vacuum: no need for any charged particles in between. When you have an actual electrical circuit, things are more complicated, but it turns out that the electrical energy is not flowing through the wires, it's flowing through the field around the wires. And, again, this energy is not the kinetic energy of the electrons. Comment by gjm on How does electricity work literally? · 2020-02-25T15:14:31.112Z · score: 3 (2 votes) · LW · GW The water (or, rather, the electricity) sloshes to and fro 50 times a second, so there's never enough delay between flicking the switch and getting usable power that a human being would notice. Typically other things are slower; e.g., if you're turning on an incandescent lightbulb then it may take longer than that for the filament to get hot enough that it starts glowing. For many devices (e.g., your phone) there is a converter device, and when you attach your phone to its USB wall-plug it's getting DC electricity from it. It would be possible to have some sort of converter for every household, but every such converter has some losses, and many devices are perfectly happy just running off AC, and ones that aren't don't necessarily all want the same operating voltage. Again, if we were doing everything from scratch now it might be worth considering something like that (or it might not; the details matter and I'm not an electrical engineer myself), but we have a basically-working system and replacing it wholesale with something new would need to be a big improvement to be worth the tremendous cost and inconvenience. It would be more accurate to say that devices use the energy in the electromagnetic field rather than the kinetic energy of electrons, as such. (There isn't a clear distinction between using the electric field and using the magnetic field; the two are very intimately linked and, e.g., if two observers are moving rapidly relative to one another, then what one sees as the electric field the other may see as the magnetic field.) The motor in an electric fan works something like this. (Unfortunately it involves effects that don't have a close analogue in terms of flowing water.) There are coils of wire. You pass an alternating current through these coils; changing currents generate a magnetic field. (This isn't meant to be obvious. It was one of the big discoveries of 19th-century physics.) There's a lump of iron placed so that this magnetic field pulls on it. A bit of engineering ingenuity lets you arrange these elements so that the effect is to make a shaft keep turning in a consistent direction. You mount your fan blades on that shaft. (Don't take my description too literally. An actual design might e.g. have the wires on the shaft and the big lumps of iron on the outside, not moving.) In terms of individual electrons: a moving electron produces a magnetic field that "curls around" its path; a whole lot of electrons moving along a conductor produce a magnetic field that curls around those conductors; if you wind that conductor into a coil, you get a magnetic field running along the length of the coil. The details of how energy flows from place to place in all this are subtle and I will probably get them wrong if I try to go into details. As an example: suppose you supply electricity to some system by means of a pair of parallel wires with opposite currents flowing in them; then the energy flow in the system happens outside the wires, not inside them. (It happens near to the wires, and the energy flows parallel to the wires.) (Just to reiterate: this isn't a matter of electrons flowing into the device and being consumed, just as a hydraulically powered system that works by having water turn turbine blades doesn't work by consuming the water.) I think most of the power consumption in (the processing parts of) a computer is resistive losses -- i.e., the thing where energy from the electric field gets transferred to kinetic energy in the electrons and/or atoms and heats things up. In an idealized maximally-efficient computing device, it turns out that the one thing that unavoidably costs energy is disposing of information, and some people have speculated about "reversible computing" that never erases bits or otherwise throws information away; but real computing devices are several orders of magnitude away from being limited by these considerations. I believe a fridge uses electrical energy mostly in motors, which work in much the same way as the motor in a fan. These motors then drive other interesting systems that e.g. compress fluids and pump them around and so forth -- I don't know any of the details offhand -- but electricity is not directly involved in those mechanisms. As I hope I've already made clear, I'm not really an expert on this, and quite possibly no other LW regulars are either. You might do better to find e.g. a textbook on electromagnetism. (But be warned: if you read a textbook on electromagnetism that goes deep enough to answer your questions, you will end up having to do quite a lot of maths.) Comment by gjm on How does electricity work literally? · 2020-02-24T16:13:45.401Z · score: 18 (10 votes) · LW · GW The speed at which electrical signals propagate is much faster than the speed at which electrons move in an electrical conductor. (Possibly helpful metaphor: suppose I take a broomstick and poke you with it. You feel the poke very soon after I start shoving the stick, even though the stick is moving slowly. You don't need to wait until the very same bit of wood I shoved reaches your body.) The speed at which electrical signals propagate is slower than the speed of light, but it's a substantial fraction of the speed of light and it doesn't depend on the speed at which the electrons move. (It may correlate with it -- e.g., both may be a consequence of how the electrons interact with the atoms in the conductor. Understanding this right is one of the quantum-mechanical subtleties I mention below.) When current flows through a conductor with some resistance, some of the energy in the flow of the electrons gets turned into random-ish motion in the material, i.e., heat. This will indeed make the electrons move more slowly but (see above) this doesn't make much difference to the speed at which electrical effects propagate through the conductor. (What actually happens in electrical conductors is more complicated than individual electrons moving around, and understanding it well involves quantum-mechanical subtleties, of most of which I know nothing to speak of.) It is not usual to convert AC to DC using relays. It is true that if you take AC power, rectify it using the simplest possible circuit, and use that to supply a DC device then it will alternate between being powered and not being powered -- and also that during the "powered" periods the voltage it gets will vary. Some devices can work fine that way, some not so fine. In practice, AC-to-DC conversion doesn't use the simplest possible circuit. It's possible to smooth things out a lot so that the device being powered gets something close to a constant DC supply. But there are similar effects even when no rectification is being done. You mentioned flickering lights, and until recently they were an example of this. If you power an incandescent bulb using AC at 50Hz then the amount of current flowing in it varies and accordingly so does the light output. (At 100Hz, not 50Hz; figuring out why is left as an exercise for the reader.) However, because it takes time for the filament to heat up and cool down the actual fluctuation in light output is small. Fluorescent bulbs respond much faster and do flicker, and some people find their light very unpleasant for exactly that reason. LED lights, increasingly often used where incandescents and fluorescents used to be, are DC devices. I think there's a wide variety in the circuitry used to power them, but most will flicker at some rate. Good ones will be driven in such a way that they flicker so fast you will never notice it. (Somewhere in the kHz range.) Sometimes DC (at high voltages) is used for power transmission. I think AC is used, where it is used, because conversion between (typically very high) transmission voltage and the much lower voltages convenient for actual use is easy by means of transformers; transformers only work for AC. (Because they depend on electromagnetic induction, which works on the principle that changes in current produce magnetic fields and changes in magnetic field produce currents.) I don't know whether AC or DC would be a better choice if we were starting from scratch now, but both systems were proposed and tried very early in the history of electrical power generation and I'm pretty sure all the obvious arguments on both sides were aired right from the start. When a device "consumes" electrical energy it isn't absorbing electrons. (In that case it would have to accumulate a large electrical charge. That's usually a Bad Thing.) It's absorbing (or using in some other way) energy carried in the electric field. It might help to imagine a system that transmits energy hydraulically instead, with every household equipped with high-pressure pipes, with a constant flow of water maintained by the water-power company, and operating its equipment using turbines. These wouldn't consume water unless there were a leak; instead they would take in fast-moving water and return slower-moving water to the system. An "AC" hydraulic system would have water moving to and fro in the pipes; again, the water wouldn't be consumed, but energy would be transferred from the water-pipes to the devices being operated. Powering things with electricity is similar. Comment by gjm on REVISED: A drowning child is hard to find · 2020-02-18T15:45:13.042Z · score: 4 (2 votes) · LW · GW I'm pointing out what seem to me to be large and important holes in your argument. To an objection of the form "You have given no good reason to think Y follows from X", it is not reasonable to respond with "You need to give a specific example of how you can have X and not Y, with realistic numbers in it". I claim that you have given no reason to think that if there's a lot of good to be done at$5k per life-equivalent then there is necessarily an experiment that it's feasible for (say) GiveWell to conduct that would do something like eliminating all malaria deaths in Madagascar for a year. You've just said that obviously there must be.

I reject any norms that say that in that situation anyone saying that your reasoning has gaps in is obliged to show concrete counterexamples.

However, because I'm an obliging sort of chap, let's have a go at constructing one and see what happens. (But, for the avoidance of doubt, I am not conceding that if my specific counterexample turns out not to work then it means your claim is right and mine is wrong. Of course it's possible that you know ahead of time that I can't construct a working counterexample, on account of having a better understanding than mine of the situation -- but, again, in that case communicating that better understanding should be part of your argument.) I'll look at Madagascar since that's the country you mentioned specifically.

[EDITED to add:] Although the foregoing paragraph talks about "constructing a counterexample", in fact what I did in the following paragraphs is just to make some guesses about numbers and see where they lead; I wasn't trying to pick numbers that are maximally persuasive or anything.

So, first of all let's find some numbers. Madagascar has a population of about 26 million. Malaria is the 7th most common cause of death there. If I'm reading the stats correctly, about 10% of the population has malaria and they have about 6k deaths per year. Essentially the entire population is considered at risk. At present Madagascar gets about $50M/year of malaria-fighting from the rest of the world. Insecticide-treated bed nets allegedly reduce the risk of getting malaria by ~70% compared with not having them; it's not clear to me how that's defined, but let's suppose it's per year. The statistics I've seen differ somewhat in their estimates of what fraction of the Madagascan population has access to bed nets; e.g., in this document from the WHO plot E on page 85 seems to show only ~5% of the population with access to either bed nets or indoor spraying; the table on page 117 says 6%; but then another table on page 122 estimates ~80% of households have at least one net and ~44% have at least one per two people. I guess maybe most Madagascan households have a great many people? These figures are much lower in Madagascar than in most of Africa; I don't know why. It seems reasonable to guess that bed net charities expect it to be more expensive, more difficult or less effective in Madagascar than in the other places where they have distributed more nets, but again even if this is correct I don't know what the underlying reasons are. I observe that several African countries have a lot more malaria deaths per unit population; e.g., Niger has slightly fewer people than Madagascar but nearly 3x as many malaria deaths. (And also about 3x as many people with malaria.) So maybe bed net distribution focuses on those countries? So, my first observation is that this is all consistent with the possbility that the number of lives saveable in Madagascar at ~$5k/life is zero, because of some combination of { lower prevalence of malaria, higher cost of distributing nets, lower effectiveness of nets } there compared with, say, Niger or the DRC. This seems like the simplest explanation of the fact that Madagascar has surprisingly few bed nets per person, and it seems consistent with the fact that, while it certainly has a severe malaria problem, it has substantially less malaria per person than many other African countries. Let's make a handwavy guess that the effectiveness per dollar of bednets in Madagascar is half what it is in the countries with the best effectiveness-per-dollar opportunities, which conditional on that $5k/life-equivalent figure would mean$10k/life-equivalent.

Now, as to fatality: evidently the huge majority of people with malaria do not die in any given year. (~2.5M cases, ~6k deaths.) Malaria is a serious disease even when it doesn't kill you. Back of envelope: suppose deaths from malaria in Madagascar cost 40 QALYs each (life expectancy in Madagascar is ~66y, many malaria deaths are of young children but not all, there's a lot of other disease in Madagascar and I guess quality of life is often poor, handwave handwave; 40 QALYs seems like the right ballpark) and suppose having malaria but not dying costs 0.05 QALYs per year (it puts you completely out of action some of the time, makes you feel ill a lot more of the time, causes mental distress, sometimes does lasting organ damage, etc.; again I'm making handwavy estimates). Then every year Madagascar loses ~125k QALYs to nonfatal malaria and ~240k QALYs to fatal malaria. Those numbers are super-inexact and all I'm really comfortable concluding here is that the two are comparable. I guess (though I don't know) that bednets are somewhere around equally effective in keeping adults and children from getting malaria, and that there isn't any correlation between preventability-by-bednet and severity in any particular case; so I expect the benefits of bednets in death-reduction and other-illness-reduction to, again, be comparable. I believe death, when it occurs, is commonly soon after infection, but the other effects commonly persist for a long time. I'm going to guess that 3/4 of the effects of a change in bednet use happen within ~ a year, with a long tail for the rest.

So, let's put that together a bit. Most of the population is not currently protected by bednets. If they suddenly were then we might expect a ~70% reduction in new malaria cases that year, for those protected by the nets. Best case, that might mean a ~70% reduction in malaria deaths that year; presumably the actual figure is a bit less because some malaria deaths happen longer after infection. Call it 60%. Reduction in malaria harm that year would be more like 50%. Cost would be $10k per life-equivalent saved. Total cost somewhere on the order of$50M, a substantial fraction of e.g. AMF's total assets.

Another way to estimate the cost: GiveWell estimates that AMF's bednet distribution costs somewhere around $4.50 per net. So one net per person in Madagascar is$100M or so.

But that's only ~60% of the deaths; you wanted a nice clear-cut experiment that got rid of all the malaria deaths in Madagascar for one year. And indeed cutting deaths by 60% would not necessarily be conclusive, because the annual variation in malaria cases in Madagascar seems to be large and so is the uncertainty in counting those cases. In the 2010-2017 period the point estimates in the document I linked above have been as low as ~2200 and as high as ~7300; the error bars each year go from just barely above zero to nearly twice the point estimate. (These uncertainties are much larger, incidentally, than in many other African countries with similar malaria rates, which seems consistent with there being something about Madagascar that makes treatment and/or measurement harder than other African countries.)

To get rid of all (or nearly all) the deaths in one year, presumably you need to eliminate infection that happens while people aren't sleeping under their bed nets, and to deal with whatever minority of people are unwilling or unable to use bed nets. Those seem like harder problems. I think countries that have eliminated malaria have done it by eliminating the mosquitoes that spread it, which is a great long-term solution if you can do it but much harder than distributing bed nets. So my best guess is that if you want to get rid of all the malaria, even for one year, you will have to spend an awful lot more per life-equivalent saved that year; I would be unsurprised by 10x as much, not that surprised by 100x, and not altogether astonished if it turned out that no one actually knows how to do it for any amount of money. It might still be worth it if the costs are large -- the future effects are large if you can eliminate malaria from a place permanently. (Which might be easier in Madagascar than in many other African countries, since it's an island.) But it puts the costs out of the range of "things existing EA charities could easily do to prove a point". And it's a Gates Foundation sort of project, not an AMF one, and indeed as I understand it the Gates Foundation is putting a lot of money into investigating ways to eliminate malaria.

Tentative conclusion: It's not a all obvious to me that this sort of experiment would be worth while. For "only" an amount of money comparable to the total assets of the Against Malaria Foundation, it looks like it might be possible to somewhat-more-than-halve malaria deaths in Madagascar for one year (and reduce ongoing malaria a bit in subsequent years). The expected benefits of doing this would be substantially less than those of distributing bed nets in the probably-more-cost-effective other places where organizations like AMF are currently putting them. Given how variable the prevalence of malaria is in Madagascar, and how uncertain the available estimates of that prevalence seem to be, it is not clear that doing this would be anything like conclusive evidence that bednet distribution is as effective as it's claimed to be. (All of the foregoing is conditional on the assumption that it is as effective as claimed.) To get such conclusive evidence, it would be necessary to do things radically different from, and probably far more expensive than, bednet distribution; organizations like AMF would have neither the expertise nor the resources to do that.

I am not very confident about any of the numbers above (other than "easy" ones like the population of Madagascar), and all my calculations are handwavy estimates (because there's little point doing anything more careful when the underlying numbers are so doubtful). But what those calculations suggest to me is that, whether or not doing the sort of experiment you propose would be a good idea, it doesn't seem to be an obviously good idea (since, in particular, my current best estimate is that it would not be a good idea). Therefore, unless I am shown compelling evidence pointing in a different direction, I cannot take seriously the claim that EA organizations that aren't doing such experiments show thereby that they don't believe that there is large scope for doing good at a price on the order of \$5k per life-equivalent.

Comment by gjm on Why Science is slowing down, Universities and Maslow's hierarchy of needs · 2020-02-16T19:44:47.902Z · score: 2 (1 votes) · LW · GW

I can well believe that universities used to work well and worsened over time. The point of my question at the end there is that I would expect any New Improved University Replacement to suffer the same process.

(Of course it might be worth it anyway, if it works better for long enough.)