Rationality Quotes May 2013

"The spatial anomaly has interacted with the tachyonic radiation in the nebula, it's interfering with our sensors. It's impossible to get a reading."

"There's no time - we'll have to take the ship straight through it!"

"Captain, I advise against this course of action. I have calculated the odds against our surviving such an action at three thousand, seven hundred and forty-five to one."

"Damn the odds, we've got to try... wait a second. Where, exactly, did you get that number from?"

"I hardly think this is the time for-"

"No. No, fuck you, this is exactly the time. The fate of the galaxy is at stake. Trillions of lives are hanging in the balance. You just pulled four significant digits out of your ass, I want to see you show your goddamn work."

"Well, I used the actuarial data from the past fifty years, relating to known cases of ships passing through nebulae that are interacting with spatial anomalies. There have been approximately two million such incidents reported, with only five hundred and forty-two incidents in which the ship in question survived intact."

"And did you at all take into account that ship building technology has improved over the past fifty years, and that ours is not necessarily an average ship?"

"Indeed I did, Captain. I weighted the cases differently based on how recent they were, and how close the ship in question was in build to our own. For example, one of the incidents with a happy ending was forty-seven years ago, but their ship was a model roughly five times our size. As such, I counted the incident as having twenty-four percent of the relevance of a standard case."

"But what of our ship's moxie? Can you take determination and drive and the human spirit into account?"

"As a matter of fact I can, Captain. In our three-year history together, I have observed that both you and this ship manage to beat the odds with a measurable regularity. To be exact, we tend to succeed twenty-four point five percent more often than the statistics would otherwise indicate - and, in fact, that number jumps to twenty-nine point two percent specifically in cases where I state the odds against our success to three significant digits or greater. I have already taken that supposedly 'unknowable' factor into account with my calculations."

"And you expect me to believe that you've memorized all these case studies and performed this ridiculously complicated calculation in your head within the course of a normal conversation?"

"Yes. With all due respect to your species, I am not human. While I freely admit that you do have greater insight into fields such as emotion, interpersonal relations, and spirituality than I do, in the fields of memory and calculation, I am capable of feats that would be quite simply impossible for you. Furthermore, if I may be perfectly frank, the entire purpose of my presence on the bridge is to provide insights such as these to help facilitate your command decisions. If you're not going to heed my advice, why am I even here?"

"Mm. And we're still sitting at three thousand seven hundred to one against?"

"Three thousand, seven hundred and forty five to one."

"Well, shit. Well, let's go around, then."

The Vulcan your Vulcan could sound like if he wasn't made of straw, I guess? Link

‘Hasn’t it ever occurred to you that in your promiscuous pursuit of women you are merely trying to assuage your subconscious fears of sexual impotence?’

‘Yes, sir, it has.’

‘Then why do you do it?’

‘To assuage my fears of sexual impotence.’

Joseph Heller, Catch-22

explaining /= explaining away

A lot of people gave very selflessly to build this warship so we can go out and battle the vikings, but the time has come to admit that hard work and hope are no substitute for actual knowledge and that we've made a really shitty ship. If we sail this ship against the vikings, we'll be massacred immediately.

Oglaf webcomic, "Bilge"

(Oglaf is usually NSFW, so I'm not linking, even if this particular comic has nothing worse than coarse language.)

Unless challenged to think otherwise, people quickly move from "Phew! Dodged a bullet on that one!" to "I'm a great bullet-dodger."

Discussing the "Near-miss bias" which they define as a tendency to "take more risk after an event in which luck played a critical role in deciding the event's [favorable] outcome."

Top Dog: The Science of Winning and Losing by Po Bronson and Ashley Merryman, page 150.

Noriko: Wow, you must have a real knack for it!

Kazumi: That's not it, Miss Takaya! It takes hard work in order to achieve that.

Noriko: Hard work? You must have a knack for hard work, then!

- Gunbuster

When I was at Cornell, I often talked to the people in the psychology department. One of the students told me she wanted to do an experiment that went something like this -- it had been found by others that under certain circumstances, X, rats did something, A. She was curious as to whether, if she changed the circumstances to Y, they would still do A. So her proposal was to do the experiment under circumstances Y and see if they still did A.

I explained to her that it was necessary first to repeat in her laboratory the experiment of the other person -- to do it under condition X to see if she could also get result A, and then change to Y and see if A changed. Then she would know that the real difference was the thing she thought she had under control.

She was very delighted with this new idea, and went to her professor. And his reply was, no, you cannot do that, because the experiment has already been done and you would be wasting time. This was in about 1947 or so, and it seems to have been the general policy then to not try to repeat psychological experiments, but only to change the conditions and see what happens. Nowadays there's a certain danger of the same thing happening, even in the famous field of physics. ...

-- Richard Feynman's Surely You're Joking, Mr Feynman!

Anybody can become angry - that is easy, but to be angry with the right person and to the right degree and at the right time and for the right purpose, and in the right way - that is not within everybody's power and is not easy.

Aristotle

.

One interesting thing about Ms. Dowd’s description of “hardball” political tactics is just how dainty and genteel her brass knuckle suggestions actually are. A speech, an appeal to reason: there is nothing here about lucrative contracts for political supporters, promises of sinecure jobs for politicians who lose their seats, a “blank check” for administrative backing on some obscure tax loophole that a particular politician could award to a favored client; there’s not even a delicate hint about grand jury investigations that can be stopped in their tracks or compromising photographs or wiretaps that need never see the light of day. Far be it from Ms Dowd to speak of or even hint at the kind of strategy that actual politicians think about when words like ‘hardball’ come to mind. Ms Dowd speaks of brass knuckles and then shows us a doily; at some level it speaks well of Ms. Dowd as a human being that even when she tries she seems unable to come up with an offer someone can’t refuse.

-- Walter Russell Mead, describing someone else's failure to understand what a desperate effort actually looks like.

When a problem comes along / You must whip it / Before the cream sets out too long / You must whip it / When something's goin' wrong / You must whip it

Now whip it / Into shape / Shape it up / Get straight / Go forward / Move ahead / Try to detect it / It's not too late / To whip it / Whip it good

-- Devo, on the value of confronting problems rather than letting them fester

Philosophy... is what you have to do until you figure out what questions you should have been asking in the first place.

Daniel Dennett

But if the question is "Has this caused you to revise downward your estimate of the value of health insurance?" the answer has to obviously be yes. Anyone who answers differently is looking deep into their intestinal loops, not the Oregon study. You don't have to revise the estimate to zero, or even a low number. But if you'd asked folks before the results dropped what we'd expect to see if insurance made people a lot healthier, they'd have said "statistically significant improvement on basic markers for the most common chronic diseases. The fact that we didn't see that means that we should now say that health insurance, or at least Medicaid, probably doesn't make as big a difference in health as we thought.

-- Megan McArdle, trying to explain Bayesian updates and the importance of making predictions in advance, without referring to any mathematics.

For one mistake made for not knowing, ten mistakes are made for not looking.

– James Alexander Lindsay

Nowadays many educated people treat reinforcement theory as if it were something not terribly important that they have known and understood all along. In fact most people don't understand it, or they would not behave so badly to the people around them.

-- Karen Pryor, Don't Shoot the Dog!: The New Art of Teaching and Training

it is often better to pull numbers out of your arse and use them to make a decision, than to pull a decision out of your arse.

-- Paul Crowley

With numbers you can do anything you like. Suppose I have the sacred number 9 and I want to get a number 1314, date of the execution of Jaques de Molay - a date dear to anyone who, like me, professes devotion ot the Templar tradition of knighthood. What do I do? I multiply 9 by one hundred and forty-six, the fateful day of the destruction of Carthage. How did I arrive at this? I divided thirteen hundred and fourteen by two, three, et cetera, until I found a satisfying date. I could also have divided thirteen hundred and fourteen by 6.28, the double of 3.14 and I would have got two hundred and nine. That is the year Attulus I, king of Pergamon, ascended the throne. You see?

Umberto Eco, Foucault's Pendulum (1989)

I was pleasantly surprised to see this elegant phrasing of a (Machian?) rationalist principle in popular culture:

"There's an axiom in my business [i.e. law]: 'A difference that makes no difference is no difference.'"

-- Joe Adama in the TV series Caprica

We would all like to believe that if we win something it is because of our skill, but if we lose it is because of the good luck or cheating of our opponent. This is nowhere more apparent than in the game of backgammon. A good opponent will play in such a way that the dice rolls having highest probability will be "good rolls" for them on their next turn, enabling them to take the other player's pieces, consolidate their position, etc. However, since there is an element of randomness, when these rolls actually come up it is very difficult even for me to believe that my opponent's fortune is due to their skill rather than their luck. Whenever I am being consistently beaten by an opponent I have to fight very hard to make myself believe that there is actually something wrong with my play and figure out how to correct it.

This phenomenon is nowhere more apparent than in computer backgammon. Computer backgammon is essentially a solved problem. Unlike Chess or Go, the best neural network algorithms that run even on modest hardware will consistently beat most human players, and perhaps draw with the best in the world. In fact, we have learnt rather a lot from these algorithms. Many rules of thumb that were believed for years by most decent players have been overturned by computer simulations. Computers tend to play backgammon markedly more aggressively than is natural for a human, but we can show that they are nevertheless doing the right thing. If you are not an extremely high level player, playing against a good computer algorithm feels weird if you are used to playing against humans.

One of the most annoying results of this is that it is impossible to obtain a reliable user generated rating of a backgammon program. For example, GNU Backgammon is one of the two or three best algorithms in the world and an under-appreciated gem of the GNU project as a whole. A full 50% of the user reviews on the Ubuntu software centre accuse the program of cheating by fixing the dice rolls and give it a 1 or 2 star review. It is hilarious how many of these reviews include comments like they "know how to play" or have been "playing for a long time" as if this were evidence to support their claim. The rest of the reviews are by people who know better and they all give it 4 or 5 stars (4 is reasonable due to a few user interface quirks, but the algorithm itself is worth a 5). As a result, the averaged rating is only 3 stars, even though this is widely acknowledged as one of the three best backgammon programs in the world. It doesn't cheat because it doesn't have to, and it actually gives you mechanisms for checking that it is not cheating, e.g. entering dice rolls manually and a tutor mode that will correct your bad plays.

This phenomenon is repeated absolutely everywhere that user reviews of backgammon programs are available. On the Google Play store, I have seen this even on a program with an absolutely crappy algorithm that I can consistently beat on expert level as well as on decent ones that are backed by GNUbg. As a result, it is absolutely impossible to find out which are the good backgammon programs if you don't already know, since they all get a low average rating.

-- Matthew Leifer

Ownership is not limited to material things. It can also apply to points of view. Once we take ownership of an idea—whether it’s about politics or sports—what do we do? We love it perhaps more than we should. We prize it more than it is worth. And most frequently, we have trouble letting go of it because we can’t stand the idea of its loss. What are we left with then? An ideology—rigid and unyielding.

Dan Ariely, Predictably Irrational: The Hidden Forces that Shape Our Decisions, New York, 2008, pp. 138-139

When I argue with reality, I lose -- but only 100 percent of the time.

-- Byron Katie, Loving What Is

And I told her that no matter what the org chart said, my real bosses were a bunch of mice in cages and cells in a dish, and they didn’t know what the corporate goals were and they couldn’t be “Coached For Success”, the way that poster on the wall said.

• Derek Lowe

It's often a good habit to keep track of seemingly identical concepts separately, just in case you're wrong and they're not identical.

-- aristosophy

One of the biggest tasks, according to Gardner, was tracking information and beliefs back to their roots. This is always important, but especially in a field as rich in hearsay as herbal medicine. One little piece of information, or an unsubstantiated report, can grow and become magnified, quickly becoming an unquestioned truism. She used as an example the truism that the extracts of the herb Ginkgo Biloba might cause dangerous bleeding. Everyone says it can. The journalists say it. The doctors say it. The herbalists say it. Even I say it! It's nearly impossible to read a scientific paper on Ginkgo that doesn't mention this alleged danger. But why do we say it - where did the information come from? Turns out, there was one case report - of a single person - who couldn't clot efficiently after taking Ginkgo. Another 178 papers were published that mentioned this danger, citing only this one report. Those 178 papers were cited by over 4,100 other papers. So now we have almost 4-and-a-half thousand references in the scientific literature - not to mention the tens of thousands of references in the popular press - to the dangers of Ginkgo, all traceable back to a single person whose bleeding may or may not have been attributable to the herb.

-Adam Stark

He who says "Better to go without belief forever than believe a lie!" merely shows his own... private horror of becoming a dupe... It is like a general informing his soldiers that it is better to keep out of battle forever than to risk a single wound. Not so are victories... over enemies or over nature gained.

William James

This debate brings to mind one of the more interesting differences between the hard sciences and other fields. This occurs when you firmly believe A, someone makes a compelling argument, and within a few seconds you firmly believe not-A, to the point of arguing for not-A with even more vigor that you used for A just a few seconds ago.

-- Lou Scheffer

(Most recent example from my own life that springs to mind: "It seems incredibly improbable that any Turing machine of size 100 could encode a complete solution to the halting problem for all Turing machines of size up to almost 100... oh. Nevermind.")

One of the most impressive features of brains – especially human brains — is the flexibility to learn almost any kind of task that comes its way. Give an apprentice the desire to impress his master and a chicken-sexing task, and his brain devotes its massive resources to distinguishing males from females. Give an unemployed aviation enthusiast a chance to be a national hero, and his brain learns to distinguish enemy aircraft from local flyboys. This flexibility of learning accounts for a large part of what we consider human intelligence. While many animals are properly called intelligent, humans distinguish themselves in that they are so flexibly intelligent, fashioning their neural circuits to match the task at hand. It is for this reason that we can colonize every region on the planet, learn the local language we’re born into, and master skills as diverse as playing the violin, high-jumping and operating space shuttle cockpits.

David Eagleman, Incognito, p. 71

PROF. PLUM: What are you afraid of, a fate worse than death?
MRS. PEACOCK: No, just death; isn't that enough?

--Clue (1985)

"I don't really understand metaphysics or why it's needed." -- Matt Simpson

"Sketch version: There is no "no metaphysics" anwser, there is only "metaphysics I just unconsciously accept" and "metaphysics I've actually thought about". You can do it well or you can do it badly but you can't not do metaphysics." -- Andrew Summitt

But consider: Newton has thought things that no man before has ever thought. A great accomplishment to be sure. Perhaps the greatest achievement any human mind has ever made. Very well - what does that say of Newton, and of us? Why, that his mind is framed in such a way that it can out-think anyone else's. So all hail Isaac Newton! Let us give him his due, and glorify and worship whatever generative force can frame such a mind.

Now consider Hooke. Hooke has perceived things that no man before us has ever perceived. What does that say of Hooke, and of us? That Hooke was framed in some special way? No, for just look at you, Robert - by your leave, you are stooped, asthmatic, fitful, beset by aches and ills, your eyes and ears are no better than those of men who've not perceived a thousandth part of what you have.

Newton makes his discoveries in geometrical realms, where our minds cannot go, he strolls in a walled garden filled with wonders, to which he has the only key. But you Hooke, are cheek-by-jowl with all of humanity in the streets of London. Anyone can look at the things you have looked at. But in those things you see what no one else has. You are the millionth human to look at a spark, a flea, a raindrop, the moon, and the first to see it. For anyone to say that this is less remarkable than what Newton has done, is to understand things in but a hollow and jejune way, 'tis like going to a Shakespeare play and remembering only the sword fights.

Daniel Waterhouse says to Hooke in Neal Stephenson's Quicksilver

Don't you understand anything about commitment, about being a pro, about sticking with what you say you wanna be? You don't do it just when you feel good. You don't do it just when you're not tired. You don't do it just when it's sunny. You do it every day of your life. You do it when it hurts to do it, when it's the last thing in the world that you wanna do, when there are a million reasons not to do it. You do it because you're a professional.

-- Teddy Atlas

The chief trick to making good mistakes is not to hide them — especially not from yourself. Instead of turning away in denial when you make a mistake, you should become a connoisseur of your own mistakes, turning them over in your mind...

Daniel Dennett

If we think of an intuition pump as a carefully design persuasion tool, we can see that it might repay us to reverse engineer the tool, checking out all the moving parts to see what they are doing... consider the intuition pump to be a tool with many settings, and "turn all the knobs" to see if the same intuitions still get pumped when you consider different variations.

Daniel Dennett

You can't do much carpentry with your bare hands, and you can't do much thinking with your bare brain.

Bo Dahlbom

If you find it strange that I make no use of the qualities one calls heat, cold, moistness, and dryness…, as the philosophers [of the schools] do, I tell you that these qualities appear to me to be in need of explanation, and if I am not mistaken, not only these four qualities, but also all the others, and even all of the forms of inanimate bodies can be explained without having to assume anything else for this in their matter but motion, size, shape, and the arrangement of their parts.

-- René Descartes

All knowledge, every empirical statement about the real world, is an "if..., then..." proposition; there is no "fact" without "theory". But we buy knowledge with the assumptions we make - the more assumptions made, the more knowledge obtained. ...all knowledge is paid for; if the assumptions are correct, we have a bargain.

--Clyde Coombs, A theory of data 1964, pg284,488

He who is firm in will molds the world to himself.

Johann Wolfgang von Goethe, Hermann und Dorothea, IX. 303.

if you have to choose between two explanations and one gives you an excuse for being lazy, choose the other one.

-Paul Graham

In Germany in 1911 the minimum requirement for a professor was a head circumference of 52 centimeters. This was used to discriminate against women; [one] leading medical physicist of the time stated: "We do not have to ask for the head circumference of women of genius — they do not exist." At the same time... a French scientist of note pointed out that, on average, women had brains which were closer in size to gorillas than they were to those of men! These serve as good examples of trying to use some sort of measure to come to the conclusion that was wanted... in the first place.

Kevin Warwick

I am also thankful that, once I had an appetite for philosophy, I did not fall into the hands of some so-called wise man, and that I did not waste my time publishing or attempting to solve logical puzzles, or busy myself with observing the sky.

-Marcus Aurelius

“Monads and atoms both are infinitely small, yet everything is made out of them; and in considering how such a paradox is possible, we must look to the interactions among them <...> But either way, we’re obliged to explain the things we see — like the church-tower — solely in terms of those interactions. ”

“Solely, Doctor? ”

“Solely, your highness. For if God made the world according to understandable, consistent laws <...> then it must be consistent through and through, top to bottom. If it is made of atoms, then it is made of atoms, and must be explained in terms of atoms; when we get into a difficulty, we cannot suddenly wave our hands and say, "At this point there is a miracle," or "Here I invoke a wholly new thing called Force which has nothing to do with atoms. " ”

Leibniz in Neal Stephenson's The Confusion

Reality, for me, is what is true. The truth is whatever is in front of you, whatever is really happening. Whether you like it or not, it's raining now. "It shouldn't be raining" is just a thought. In reality, there is no such thing as a "should" or a "shouldn't." These are only thoughts that we impose onto reality. The mind is like a carpenter's level. When the bubble is off to one side -- "It shouldn't be raining" -- we can know that the mind is caught in its thinking. When the bubble is right in the middle -- "It's raining" -- we can know that the surface is level and the mind is accepting reality as it is. Without the "should" and "shouldn't," we can see reality as it is, and this leaves us free to act efficiently, clearly, and sanely.

-- Byron Katie, Loving What Is

The most common mistake that people make in this regard is believing other people. For instance, a testimonial— whether it comes to you from a friend or blares out at you from a TV screen—is a poor criterion for determining truth.

A case in point is the experience of a writer for a popular fitness magazine who once wrote a facetious article about a “miracle supplement.” At the bottom of the page on which the article appeared, he had the magazine’s art department create a perforated square roughly the size of a postage stamp, next to which appeared the following recommendation: “For optimal muscle gains, cut out this little piece of paper and place it in a glass of water overnight. It contains a special mix of amino acids that are released in water over several hours. In the morning, remove the paper and place it on your tongue to allow the amino acids to enter your body.” He intended it as a joke, a last-minute bit of whimsy to fill a page where an advertisement had been withdrawn. His intention, however, was not communicated very well to the readers, as, within days of the magazine’s hitting the stands, the publisher was inundated with requests for “more of that awesome paper.” Many readers honestly believed that placing it on their tongues as instructed made their muscles bigger and stronger. This response is characteristic of the placebo effect, a demonstration of the power of suggestion, which impels people to buy all manner of things. If one of your friends or relatives happened to number among those who believed in this “miracle supplement,” he or she likely would have told you how “great” this product was, and you— if you put stock in testimonials—would probably have tried it.

-- Doug McDuff, M.D., and John Little, Body by Science, pp. ix-x

We are enormously indebted to those academics; what could be more advantageous in an intellectual contest--whether it be bridge, chess, or stock selection--than to have opponents who have been taught thinking is a waste of energy?

Warren Buffet on proponents of the efficient market hypothesis

If you attempt to make sense of the world of ideas and meanings, free will and morality, art and science and even philosophy itself without a sound and quite detailed knowledge of evolution, you have one hand tied behind your back.

Daniel Dennett

When you have spoken the word, it reigns over you. When it is unspoken you reign over it.

-Arabian proverb

An objection that can be brought against everything ought not to be brought against anything.

Lee Kelly.

Rodger Cotes defending Newton from the charge that his theory treats gravity as an occult cause:

I can hear some people disagreeing with this conclusion and muttering something or other about occult qualities. They are always prattling on and on to the effect that gravity is something occult, and that occult causes are to be banished completely from philosophy. But it is easy to answer them: occult causes are not those causes whose existence is very clearly demonstrated by observations, but only those whose existence is occult, imagined, and not yet proved.

Therefore gravity is not an occult cause of celestial motions, since it has been shown from phenomena that this force really exists. Rather, occult causes are the refuge of those who assign the governing of these motions to some sort of vortices of a certain matter utterly fictitious and completely imperceptible to the senses.

The stony path to truth is competing with seductive, easier paths that turn out to be dead ends.

Marcel Kinsbourne, quoted in Dennett (2013)

-We can't go back. We don't understand everything yet.

-"Everything" is a little ambitious. We barely understand anything.

-Yeah. But that's what the first part of understanding everything looks like.

--from the ongoing animation xkcd: Time, dialogue transcript found here

Time is a created thing. To say "I don't have time" is to say "I don't want to"

• Lao Tzu

To recognize that some of the things our culture believes are not true imposes on us the duty of finding out which are true and which are not.

--Allan Bloom, Giants and Dwarfs, "Western Civ"

Rationality is not the gold standard against which all other forms of thought are to be judged. Adaptation is the gold standard against which rationality must be judged, along with all other forms of thought.

• D. S. Wilson.

"If someone tells you their results before the results are gathered, be suspicious."

• I Fucking Love Science

I've never seen the Icarus story as a lesson about the limitations of humans. I see it as a lesson about the limitations of wax as an adhesive, - Randall Munroe.

The sad truth is that most evil is done by people who never make up their minds to be good or evil.

• Hannah Arendt

"People don't pay much attention to anything unless you give them reason to"

--The Night Circus

Illustration of availability bias:

Baldrick: But then I will go to Hell forever for stealing.

Blackadder: Believe me, Baldrick, eternity in the company of Beelzebub, and all his hellish instruments of death, will be a picnic compared to five minutes with me... and this pencil.

http://www.youtube.com/watch?v=LVM4jR3TZsU

"Take a step back. Look at the bigger picture. That's how you devour a whale. One bite at a time."

-Congressman Frank Underwood in the TV series House of Cards

Suppose that, unlike in the “stone soup” scenario I outlined above, it eventually becomes clear that quantum annealing can be made to work on thousands of qubits, but that it’s a dead end as far as getting a quantum speedup is concerned. Suppose the evidence piles up that simulated annealing on a conventional computer will continue to beat quantum annealing, if even the slightest effort is put into optimizing the classical annealing code. If that happens, then I predict that the very same people now hyping D-Wave will turn around and—without the slightest acknowledgment of error on their part—declare that the entire field of quantum computing has now been unmasked as a mirage, a scam, and a chimera. The same pointy-haired bosses who now flock toward quantum computing, will flock away from it just as quickly and as uncomprehendingly. Academic QC programs will be decimated, despite the slow but genuine progress that they’d been making the entire time in a “parallel universe” from D-Wave. People’s contempt for academia is such that, while a D-Wave success would be trumpeted as its alone, a D-Wave failure would be blamed on the entire QC community.

--Scott Aaronson, D-Wave: Truth finally starts to emerge

Absolute faith corrupts as absolutely as absolute power.

-- Eric Hoffer

The Spanish flu of 1918 killed 25-50 million people. World War II killed 60 million people; 107 is the order of the largest catastrophes in humanity’s written history. Substantially larger numbers, such as 500 million deaths, and especially qualitatively different scenarios such as the extinction of the entire human species, seem to trigger a different mode of thinking—enter into a ‘separate magisterium’. People who would never dream of hurting a child hear of an existential risk, and say, ‘Well, maybe the human species doesn’t really deserve to survive.’

Eliezer Yudkowsky, ‘Cognitive Biases Potentially Affecting Judgement of Global Risks’, in Nick Bostrom and Milan M. Ćirković (eds.), Global Catastrophic Risks, Oxford, 2008, p. 114

Retracted because it violates the spirit of one of the section rules.

"Is this real? Or has this been happening inside my head?" "Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?"

• Harry Potter and the Deathly Hallows, Part 2

From Richard Feynman one last letter to his first wife, over a year after her death from TB (incidentally, antibiotics had been discovered and were being tested on humans a few months before her death; a year sooner, and she would have had a good chance of recovery):

My darling wife, I do adore you.
I love my wife. My wife is dead.
Rich.

P.S. Please excuse my not mailing this -- but I don't know your new address.

Perfectly Reasonable Deviations from the Beaten Track: The Letters of Richard P. Feynman.

The whole letter and the rest of the book is well worth reading.

(I found this interesting, given that Feynman was likely the most instrumentally rational physicist ever, and definitely did not believe in any kind of afterlife -- he surely knew he was writing it for himself.)

When it comes to understanding how our universe evolves, religion and theology have been at best irrelevant. They often muddy the waters, for example, by focusing on questions of nothingness without providing any definition of the term based on empirical evidence. While we do not yet fully understand the origin of our universe, there is no reason to expect things to change in this regard. Moreover, I expect that ultimately the same will be true for understanding of areas that religion now considers its own territory, such as human morality.

Science has been effective at furthering our understanding of nature because the scientific ethos is based on three key principles: (1) follow the evidence wherever it leads; (2) if one has a theory, one needs to be willing to try to prove it wrong as much as one tries to prove that it is right; (3) the ultimate arbiter of truth is experiment, not the comfort one derives from one's a priori beliefs, nor the beauty or elegance one ascribes to one's theoretical models.

Lawrence M. Krauss, A Universe from Nothing, xvi

More from Scott Aaronson:

maybe there’s a yet-undiscovered law of physics implying that every Earth-like planet must eventually contain at least one kangaroo!

Replying to a many-world-like question

Even more from the same source:

OK, now I’ll try to address free will.

Like consciousness, free will has an aspect that seems outside the scope of scientific investigation almost by definition. Are “you” the author of your choices? Well, what exactly do we mean by “you”? No matter what sequence of physical causes, random events, or even supernatural interventions led up to your making a particular choice, a skeptic could always claim that the choice wasn’t really made by “you,” but only by an impersonating demon that looks and acts like you.

On the other hand, there’s another aspect of free will that’s perfectly within the scope of science. Namely, to what extent can your choices actually be predicted by an external entity constrained by the laws of physics? Obviously they’re at least partly predictable: advertisers, seducers, and demagogues have always known as much, and modern fMRI scans confirm it! But is there any limit to the accuracy of prediction? If there isn’t, then can at least the probabilities be predicted to arbitrary accuracy, as they can in (say) the case of radioactive decay? Or are they subject to Knightian uncertainty?

Of course, even supposing your choices were unpredictable in the strongest sense imaginable, a philosopher could always say that that’s just a practical problem, and still doesn’t mean that your choices are in any sense “free.” Well, fine—but let’s at least try to answer the “straightforward empirical question,” of whether your choices are predictable or they aren’t!

Now, it’s on this latter, predictability question that quantum mechanics might finally become relevant. Or it might not—we don’t know yet. But it’s at least conceivable that the No-Cloning Theorem puts some fundamental limit on how well you can learn the state of a chaotic dynamical system, like (say) a human brain, and that it might forbid you from making a second copy accurately enough to “instantiate a new copy of the person, with the same will” (whatever that means!). Again, I stress that I have no idea whether this is true or not; many people feel confident that the “classical, macroscopic, non-invasively measurable” degrees of freedom should already contain all the relevant information. If it were true, though, then as many others have pointed out, it could have all sorts of “applications” to resolving classic philosophical paradoxes involving brain-copying, by simply explaining what goes wrong when you try to set up the paradox.

http://www.youtube.com/watch?v=rMXs1C434B8

"Stats are so f**\ng stupid, ya know? Not that they’re stupid, its the way people apply them. You already have your mind made up, and then you go to imright.com and you start memorizing a bunch of s\t and just throw it up at people." -Bill Burr

The 3^^^3th virtue of rationality is "Relinquish Princess Celestia."