Farnsworth A: You people and your slight differences disgust me. I'm going home. Where's that blue box with our universe in it?

Farnsworth 1: Oh, you'd like to get back to your evil universe, wouldn't you? And destroy your box with our universe inside it.

Farnsworth A: Nonsense! I would never do such a thing unless you were already having been going to do that!

--Futurama

Beware of finding a Jesus entirely congenial to you.

-- The Jesus Seminar

(Developed in the context of biblical interpretation, of course. But despite my nontheism, I've found the principle behind it to be widely applicable.)

The important thing is not to shout at this point, Vimes told himself. Do not ... what do they call it ... go spare? Treat this as a learning exercise. Find out why the world is not as you thought it was. Assemble the facts, digest the information, consider the implications. Then go spare. But with precision.

• Terry Pratchett, Thud!

[I have had cause to apply this one recently. It particularly resonated to see it in the book just now.]

Most of the founding Zetas members–the original 40–were trained elite soldiers who received instruction in radio communications, counter-insurgency and drug-interdiction. But the Army forgot to add a few ethics lessons into the education mix. And that was a big fucking mistake.

The Mexican Drug War in One Lesson: Know Your Zetas!

"...for we judge ourselves by what we feel capable of doing, while others judge us by what we have already done."

--Henry Wadsworth Longfellow, Kavanagh ch. 1

Scooping the Loop Snooper

an elementary proof of the undecidability of the halting problem

by Geoffrey Pullum

No program can say what another will do. Now, I won't just assert that, I'll prove it to you: I will prove that although you might work till you drop, you can't predict whether a program will stop.

Imagine we have a procedure called P that will snoop in the source code of programs to see there aren't infinite loops that round and around; and P prints the word "Fine!" if no looping is found.

You feed in your code, and the input it needs, and then P takes them both and it studies and reads and computes whether things will all end as they should (as opposed to going loopy the way that they could).

Well, the truth is that P cannot possibly be, because if you wrote it and gave it to me, I could use it to set up a logical bind that would shatter your reason and scramble your mind.

Here's the trick I would use—and it's simple to do. I'd define a procedure—we'll name the thing Q— that would take any program and call P (of course!) to tell if it looped, by reading the source;

And if so, Q would simply print "Loop!" and then stop; but if no, Q would go right back up to the top, and start off again, looping endlessly back, till the universe dies and is frozen and black.

And this program called Q wouldn't stay on the shelf; I would run it, and (fiendishly) feed it itself. What behavior results when I do this with Q? When it reads its own source code, just what will it do?

If P warns of loops, Q will print "Loop!" and quit; yet P is supposed to speak truly of it. So if Q's going to quit, then P should say, "Fine!"— which will make Q go back to its very first line!

No matter what P would have done, Q will scoop it: Q uses P's output to make P look stupid. If P gets things right then it lies in its tooth; and if it speaks falsely, it's telling the truth!

I've created a paradox, neat as can be— and simply by using your putative P. When you assumed P you stepped into a snare; Your assumptions have led you right into my lair.

So, how to escape from this logical mess? I don't have to tell you; I'm sure you can guess. By reductio, there cannot possibly be a procedure that acts like the mythical P.

You can never discover mechanical means for predicting the acts of computing machines. It's something that cannot be done. So we users must find our own bugs; our computers are losers!

I came across this yesterday. The blog might also be worth a look, see for example 'A Brief History of Grammar'.

From Brandon Sanderson's Mistborn series:

"Certainly, my situation is unique," Sazed said. "I would say that I arrived at it because of belief."

"Belief?" Vin asked.

"Yes," Sazed said. "Tell me, Mistress, what is it that you believe?"

Vin frowned. "What kind of question is that?"

"The most important kind, I think."

Vin thought, then shrugged. "I don't know what I believe."

"People often say that, but I find it is rarely true."

For the young who want to by Marge Piercy

The poem is mostly about not being recognized as having a magical ability to do things until after you've succeeded. I'm just posting the link because it's more trouble than it's worth to make the line breaks show up properly.

If it's a stupid idea and it works, then it isn't stupid.

-- French Ninja, Freefall

Puts me in mind of "Rationalists should win".

"Mortal danger is an effective antidote for fixed ideas."

Erwin Rommel, The Rommel Papers (1982) edited by Basil Henry Liddell Hart http://en.wikiquote.org/wiki/Erwin_Rommel#Sourced

"All of us, grave or light, get our thoughts entangled in metaphors, and act fatally on the strength of them."

---George Eliot, "Middlemarch"

I chose and my world was shaken, so what? The choice may have been mistaken; the choosing was not.

Sunday in the Park with George, by Stephen Sondheim

“But for that matter, how do you explain the fact that the statues of Easter Island are megaliths exactly like the Celtic ones? Or that a Polynesian god called Ya is clearly the Yod of the Jews, as is the ancient Hungarian Io-v’, the great and good god? Or that an ancient Mexican manuscript shows the Earth as a square surrounded by sea, and in its center is a pyramid that has on its base the inscription Aztlan, which is close to Atlas and Atlantis? Why are pyramids found on both sides of the Atlantic?”

“Because it’s easier to build pyramids than spheres. Because the wind produces dunes in the shape of pyramids and not in the shape of the Parthenon.”

“I hate the spirit of the Enlightenment.”

Umberto Eco, Foucault's Pendulum

When I was halfway through my Ph.D. I formulated a hypothesis: The proximate challenge that keeps you from graduating is that you have to write a thesis. But the ultimate challenge to getting your Ph.D. is this: You somehow have to learn to understand, deep down, that all your romantic notions about the Ph.D. are bunk, that you will be exactly the same person on the day after you get it that you were the day before, and that you need to stop waiting for the day when you feel like a god and just write something down and get on with life.

It may take you years to accept this, and it may drive you to drink, but after you get to that point you can graduate.

Only then will you be able to live with the fact that your thesis looks like crap to you. Your thesis will always look like crap to you. Either you will have figured out absolutely everything and your thesis will look incredibly boring to you, because you've moved on, or -- vastly more likely -- your thesis will look woefully incomplete because, geez, there is so much that you couldn't figure out, and you're just so stupid!

Or, most likely of all, you will think both of these things at the same time.

Similarly: Being the world's foremost expert on a particular scientific problem is a lot less exciting in real life than it seems in the movies. In fact, being on the frontier of science feels like being totally, hopelessly lost and confused. Why this came as a surprise to me I'll never know.

--mechanical_fish on Hacker News. Emphasis mine. source

"Normal humans don't interest me. If anyone here is an alien, a time traveler, slider, or an esper, then come find me! That is all."

--The Melancholy of Haruhi Suzumiya, vol 1

Know the hair you have to get the hair you want.

-Pantene Pro-V hair care bottle

I can't keep rationalizing away everything like this, or I'm gonna die!

-- Gordon Freeman, kind of

A universe that needed someone to observe it in order to collapse it into existence would be a pretty sorry universe indeed.

— Randall Munroe, xkcd – Mutual

"But building your life's explanations around science isn't a profession. It is, at its core, an emotional contract, an agreement to only derive comfort from rationality."

-Robert Sapolsky, in a essay reply to "Does science make belief in God obsolete?"

Rationality quotes: very many from @BadDalaiLama on Twitter.

(Edit: there's also this handy archive.)

Research must contrive to do business at a profit, by which I mean it must produce more effective scientific inquiry than it expends. No doubt it already does so. But it would do well to become conscious of it's economic position and contrive ways of living upon it. -CS Peirce

The Universe behaves according to its own laws.

Talmud, Avoda Zara 54b

And should you ask yourselves, "How can we know that the oracle was not spoken by the Lord?" -- if the prophet speaks in the name of the Lord and the oracle does not come true, that oracle was not spoken by the Lord; the prophet has uttered it presumptuously: do not stand in dread of him.

Deuteronomy 18:20-22

When one person suffers from a delusion it is called insanity; when many people >suffer from a delusion it is called religion.

~ Robert M. Pirsig

Now the actual quote's out of the way, here's my version: when one person suffers from a delusion it is called insanity; when many people suffer from a delusion it is called society.

half of being smart is knowing what you're dumb at

solomon short (david gerrold's fictional character)

Overall, however, we've done better by avoiding dragons than by slaying them. -Warren E. Buffett

Q: Don't you think sire, that the TV commercials should look more like real life?

A: On the contrary! I think life should be more like TV commercials.

• Benny Hill

If you can't tell whose side someone is on, they are not on yours. -Warren E. Buffett

A horse that can count to ten is a remarkable horse, not a remarkable mathematician.
--Samuel Johnson

We are at the very beginning of time for the human race. It is not unreasonable that we grapple with problems. But there are tens of thousands of years in the future. Our responsibility is to do what we can, learn what we can, improve the solutions, and pass them on.

Richard Feynman

Kołakowski's Law, or The Law of the Infinite Cornucopia:

For any given doctrine that one wants to believe, there is never a shortage of arguments by which to support it.

Leszek Kołakowski

del

"However insistently the blind may deny the existence of the sun, they cannot annihilate it. " - D. T. Suzuki

It is a profound and necessary truth that the deep things in science are not found because they are useful, they are found because it was possible to find them. -J. Robert Oppenheimer.

It is still an unending source of surprise for me how a few scribbles on a blackboard or on a piece of paper can change the course of human affairs. -Stanislaw Ulam

Many a man has cherished for years as his hobby some vague shadow of an idea, too meaningless to be positively false; he has, nevertheless, passionately loved it, has made it his companion by day and by night, and has given to it his strength and his life, leaving all other occupations for its sake, and in short has lived with it and for it, until it has become, as it were, flesh of his flesh and bone of his bone; and then he has waked up some bright morning to find it gone, clean vanished away like the beautiful Melusina of the fable, and the essence of his life gone with it. I have myself known such a man; and who can tell how many histories of circle-squarers, metaphysicians, astrologers, and what not, may not be told in the old German story?

Charles Sanders Peirce

Man, I'm amazing! I'm a machine that turns FOOD into IDEAS!

-- T-Rex, Dinosaur Comics #539

The course of human progress staggers like a drunk; its steps are quick and heavy but its mind is slow and blunt

-Jesse Michaels of Operation Ivy

Posted because it's a useful and evocative metaphor: the drunk feels himself leaning or falling in one direction, and puts his foot down in that direction to steady himself. If he doesn't step far enough, he is still leaning in the same direction, and he steps again. In this way we can make fantastic progress in directions we don't like while getting further away from the ways we did want to go.

I just came across this and thought it was a pretty funny dialogue: "Reality is that which does not go away upon reprogramming." (Check the first 4 comments here: Chatbot Debates Climate Change Deniers on Twitter so You Don’t Have to)

This is of course a paraphrase borrowed from Philip K. Dick's famous statement:

Reality is that which, when you stop believing in it, doesn't go away.

This is a bit long for a rationality quote and isn't really a quote but short enough and worth the read: The most poetic and convincing argument for striving for posthumanity (via aleph.se).

All my confidence comes from knowing God's laws.

-- Talib Kweli (substitute "nature" for "God")

There are more fools than knaves in the world, else the knaves would not have enough to live upon.

-Samuel Butler

"The best thing for being sad," replied Merlin, beginning to puff and blow, "is to learn something. That's the only thing that never fails. You may grow old and trembling in your anatomies, you may lie awake at night listening to the disorder of your veins, you may miss your only love, you may see the world about you devastated by evil lunatics, or know your honour trampled in the sewers of baser minds. There is only one thing for it then — to learn. Learn why the world wags and what wags it. That is the only thing which the mind can never exhaust, never alienate, never be tortured by, never fear or distrust, and never dream of regretting. Learning is the only thing for you. Look what a lot of things there are to learn."

— T.H. White (The Once and Future King)

Isaac Newton's argument for intelligent design:

Were all the planets as swift as Mercury or as slow as Saturn or his satellites; or were the several velocities otherwise much greater or less than they are (as they might have been had they arose from any other cause than their gravities); or had the distances from the centers about which they move been greater or less than they are (as they might have been had they arose from any other cause than their gravities); or had the quantity of matter in the sun or in Saturn, Jupiter, and the earth (and by consequence their gravitating power) been greater or less than it is; the primary planets could not have revolved about the sun nor the secondary ones about Saturn, Jupiter, and the earth, in concentric circles as they do, but would have moved in hyperbolas or parabolas or in ellipses very eccentric. To make this system, therefore, with all its motions, required a cause which understood and compared together the quantities of matter in the several bodies of the sun and planets and the gravitating powers resulting from thence.... And to compare and adjust all these things together in so great a variety of bodies, argues that cause to be, not blind and fortuitous, but very well skilled in mechanics and geometry.

-- Letter to Richard Bentley

We're all puppets, Laurie. I'm just a puppet who can see the strings.

Dr. Manhattan (Watchmen)

If oxen and horses and lions had hands and were able to draw with their hands and do the same things as men, horses would draw the shapes of gods to look like horses and oxen to look like oxen, and each would make the gods’ bodies have the same shape as they themselves had.

Xenophanes

Out-of-sample error equals in-sample error plus a penalty for model complexity

Y.S. Abu-Mostafa, in explaining the VC inequality of PAC learning.

Go down deep enough into anything and you will find mathematics.

Dean Schlicter

If you haven’t found something strange during the day, it hasn’t been much of a day.

John Archibald Wheeler

If you are in a shipwreck and all the boats are gone, a piano top … that comes along makes a fortuitous life preserver. But this is not to say that the best way to design a life preserver is in the form of a piano top. I think that we are clinging to a great many piano tops in accepting yesterday’s fortuitous contrivings.

Buckminster Fuller

Truth will sooner come out from error than from confusion.

Francis Bacon

Rule I

We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances.

To this purpose the philosophers say that Nature does nothing in vain, and more is in vain when less will serve; for Nature is pleased with simplicity, and affects not the pomp of superfluous causes.

Rule II

Therefore to the same natural effects we must, as far as possible, assign the same causes.

As to respiration in a man and in a beast; the descent of stones in Europe and in America; the light of our culinary fire and of the sun; the reflection of light in the earth, and in the planets.

Rule III

The qualities of bodies, which admit neither intensification nor remission of degrees, and which are found to belong to all bodies within the reach of our experiments, are to be esteemed the universal qualities of all bodies whatsoever.

For since the qualities of bodies are only known to us by experiments, we are to hold for universal all such as universally agree with experiments; and such as are not liable to diminution can never be quite taken away. We are certainly not to relinquish the evidence for the sake of dreams and vain fictions of our own devising; nor are we to recede from the analogy of Nature, which is wont to be simple, and always consonant to itself. . .

Rule IV

In experimental philosophy we are to look upon propositions inferred by general induction from phenomena as accurately or very nearly true, notwithstanding any contrary hypotheses that may be imagined, till such time as other phenomena occur, by which they may either be made more accurate, or liable to exceptions.

This rule we must follow, that the argument of induction may not be evaded by hypotheses.

Isaac Newton, Philosophiae naturalis: Rules of Reasoning in Philosophy

Getting caught up in style and throwing away victory is something for the lower ranks to do. Captains can't even think about doing such a carefree thing. Don't try to be a good guy. It doesn't matter who owes who. From the instant they enter into a war, both sides are evil.

• Shunsui Kyōraku Bleach

Related to: Politics, Protection

David Hume was right to predict that superstition would survive for hundreds of years after his death, but how could he have anticipated that his own work would inspire Kant to invent a whole new package of superstitions? Or that the incoherent system of Marx would move vast populations to engineer their own ruin? Or that the infantile rantings of the author of Mein Kampf would be capable of bringing the whole world to war?

Perhaps we will one day succeed in immunizing our societies against such bouts of collective idiocy by establishing a social contract in which each child is systematically instructed in Humean skepticism. Such a new Emile would learn about the psychological weaknesses to which Homo sapiens is prey, and so would understand the wisdom of treating all authorities - political leaders and social role-models, academics and teachers, philosophers and prophets, poets and pop stars - as so many potential rogues and knoves, each out to exploit the universal human hunger for social status. He would therefore appreciate the necessity of doing all of his own thinking for himself. He would understand why and when to trust his neighbors. Above all, he would waste no time yearning for utopias that are incompatible with human nature.

-- Ken Binmore, in Natural Justice, p56

Justice is an artefact of custom. Where customs are unsettled its dictates soon become dated. Ideas of justice are as timeless as fashions in hats.

-John Gray, Straw Dogs

Who has not experienced the chilling memory of the better things? How it creeps over the spirit of one's current dreams! Like the specter at the banquet it stands, its substanceless eyes viewing with a sad philosophy the make-shift feast.

-Theodore Dreiser, The Titan

If, instead of welcoming inquiry and criticism, the admirers of a great author accept his writings as authoritative, both in their excellences and in their defects, the most serious injury is done to truth. In matters of philosophy and science, authority has ever been the great opponent of truth. A despotic calm is usually the triumph of error. In the republic of the sciences, sedition and even anarchy are beneficial in the long run to the greatest happiness of the greatest number.

William Stanley Jevons, Theory of Political Economy, 1871: p.275-6

Not a quote about rationalism, but probably relevant to Less Wrong:

Pure Death

We looked, we loved, and therewith instantly

Death became terrible to you and me.

By love we disenthralled our natural terror

From every comfortable philosopher

Or tall, grey doctor of divinity:

Death stood at last in his true rank and order.

It happened soon, so wild of heart were we,

Exchange of gifts grew to a malady:

Their worth rose always higher on each side

Till there seemed nothing but ungivable pride

That yet remained ungiven, and this degree

Called a conclusion not to be denied.

Then we at last bethought ourselves, made shift

And simultaneously this final gift

Gave: each with shaking hands unlocks

The sinister, long, brass-bound coffin-box,

Unwraps pure death, with such bewilderment

As greeted our love's first accomplishment.

--Robert Graves

The fact that I have no remedy for all the sorrows of the world is no reason for my accepting yours. It simply supports the strong probability that yours is a fake.

H.L. Mencken, Minority Report.