A stoic sage is one who turns fear into prudence, pain into information, mistakes into initiation, and desire into undertaking.

Nasim Taleb

It doesn't matter whether a cat is white or black, as long as it catches mice.

-- Deng Xioaping

It’s not a good idea for members of the faith-based community like Hitchens to proclaim things like: Science proves we’re all genetically equal, so therefore you shouldn’t be beastly toward people of other races. The obvious flaw in this strategy is that eventually people will figure out that you are lying about what the science of genetics says, and therefore, by your own logic, that discredits the perfectly valid second half of your assertion.

--Steve Sailer

I do not pretend to start with precise questions. I do not think you can start with anything precise. You have to achieve such precision as you can, as you go along.

Bertrand Russell

Being right in the sense of being correct is not sufficient to win. Political technology determines political success. Learn how to organize and how to communicate. Most political technology is philosophically neutral. You owe it to your philosophy to study how to win.

Morton Blackwell

Ninety per cent of most magic merely consists of knowing one extra fact.

Terry Pratchett

There are two ways to slide easily through life: to believe everything or to doubt everything; both ways save us from thinking.

--Alfred Korzybski

Nemo iudex in causa sua.

A latin proverb, and I think part of Roman law, it means no-one should be a judge in their own cause.

We should venture on the study of every kind of animal without distaste; for each and all will reveal to us something natural and something beautiful.

--Aristotle

Men ... are easily induced to believe that in some wonderful manner everybody will become everybody's friend, especially when some one is heard denouncing the evils now existing in states, suits about contracts, convictions for perjury, flatteries of rich men and the like, which are said to arise out of the possession of private property. These evils, however, are due to a very different cause—the wickedness of human nature.

--Aristotle

Idealism is fine, but as it approaches reality, the costs become prohibitive.

--William F. Buckley

What we perceive today as elegant, natural selection created as simply as gravity creates a river. The water will flow downhill, every other parameter is free.

John Hawks

Part of the reason atheism looks the way it does now, and is so lacking in warm fuzzies like "Love and Completeness are Your Spiritual Right," is because it is a refuge for people who think warm fuzzies are bullshit.

-- Dave Gottlieb

Most people are theists not because they were "reasoned into" believing in God, but because they applied Occam's razor at too early an age. Their simplest explanation for the reason that their parents, not to mention everyone else in the world, believed in God, was that God actually existed. The same could be said for, say, Australia.

--Mencius Moldbug

If only the dead people who god did not save, could return and give their opinion of a god.

-Gene Ray, The Wisest Human

http://www.timecube.com/timecube2.html

No matter if it is a white cat or a black cat; as long as it can catch mice, it is a good cat.

--Deng Xiaoping

Thinking about thinking makes thinking thoughtful.

-Cleverbot

http://cleverbot.com/cleverness

I am often wrong. My prejudices are innumerable, and often idiotic.

--H.L. Mencken

Beauty is no quality in things themselves. It exists merely in the mind which contemplates them.

-- David Hume

And now my labor is over. I have had my lecture. I have no sense of fatherhood. If my genetic and personal histories had been different, I should come into possession of a different lecture. If I deserve any credit at all, it is simply for having served as a place where certain processes could take place. I shall interpret your polite applause in that light.

--B.F. Skinner

"People are stupid; given proper motivation, almost anyone will believe almost anything. Because people are stupid, they will believe a lie because they want to believe it's true, or because they are afraid it might be true. People's heads are full of knowledge, facts, and beliefs, and most of it is false, yet they think it all true. People are stupid; they can only rarely tell the difference between a lie and the truth, and yet they are confident they can, and so are all the easier to fool." -- Zeddicus Zu'l Zorander from the book "Wizard's first rule" by Terry Goodkind.

Each age would do better if it studied its own faults and endeavoured to mend them instead of comparing itself with others to its own advantage.

--James Anthony Froude

We shape our buildings, and afterwards our buildings shape us.

-Winston Churchill

He lifted a hand, his index finger pointing upward. "How many fingers am I holding up?" I paused for a moment, which was more consideration than the question seemed to warrant. "At least one," I said. "Probably no more than six"

-Kvothe, The Name of the Wind

The problem with "electability" is that it requires voters to set aside their own feelings on the basis of what they think other people will think in a general election months in the future. The problem with this is that people are generally bad at predicting what other people will think and feel and are lousy at predicting the future. As a result, voters in primaries who focus on electability either vote based on regurgitated popular wisdom of the moment, or on an assumption that other people won't respond to the same things that they respond to in a candidate. Neither is a particularly good predictor. However, since it is impossible to rerun the election after the fact with the other candidate, it is not something easily disproved.

osewalrus

"A man's gotta know his limitations." - Dirty Harry

Every age has its own outlook. It is specially good at seeing certain truths and specially liable to make certain mistakes. We all, therefore, need the books that will correct the characteristic mistakes of our own period. And that means the old books.

C.S. Lewis, Introduction to a translation of, Athanasius: On the Incarnation

"A Confucian has stolen my hairbrush! Down with Confucianism!"

-GK Chesterton (on ad hominems)

...some people requested that I be prohibited from studying. One time they achieved it through a very holy and simple mother superior who believed that studying would get me in trouble with the Inquisition and ordered me not to do it. I obeyed her for the three months that she was in office in as far as I did not touch a book, but as far as absolutely not studying, this was not in my power. [...] Even the people I spoke to, and what they said to me, gave rise to thousands of reflections. What was the source of all the variety of personality and talent I found among them, since they were all one species? [...] Sometimes I would pace in front of the fireplace in one of our large dormitories and notice that, though the lines of two sides were parallel and its ceiling level, to our vision it appears as though the lines are inclined toward each other and the ceiling is lower in the distance than it is nearby. From this it can be inferred that the lines of our vision run straight, but not parallel, to form the figure of a pyramid. And I wondered if that was the reason that the ancients questioned whether the earth was a sphere or not. Because although it seemed so, their vision might have deceived them, showing concave shapes where there were none. [...] Once I saw two girls playing with a top, and hardly had I seen the movement and the shape when I began, in my insane way, to consider the easy movement of the spherical shape and how long the momentum, once established, remained independent of its original cause, the distant hand of the girl. Not content with this I had flour brought and sprinkled on the floor in order to discover whether the spinning top would describe perfect circles or not. It turned out that they were not perfect circles but spirals that lost their circular shape to the degree that the top lost momentum.

Sister Juana Inés de la Cruz, 1691 (tr. Pamela Kirk Rappaport)

In short, they made unrealistic demands on reality and reality did not oblige them.

Cory Doctorow talking about DRM, but I think there are some wider applications.

Chu-p’ing Man studied the art of killing dragons under Crippled Yi. It cost him all the thousand pieces of gold he had in his house, and after three years he'd mastered the art, but there was no one who could use his services. - Chuang Tzu

So he decided to teach others the art of kiling dragons. - René Thom

If some persons died, and others did not die, death would indeed be a terrible affliction.

--Jean de la Bruyère

"A “lie-to-children” is a statement which is false, but which nevertheless leads the child’s mind towards a more accurate explanation, one that the child will only be able to appreciate if it has been primed with the lie." "Yes, you needed to understand that” they are told, “so that now we can tell you why it isn’t exactly true." It is for the best possible reasons, but it is still a lie".”

--(The Science of Discworld, Ebury Press edition, quotes from pp 41-42)

But, above all, it is expected that the attention of instructors to the disposition of the minds and morals of the youth under their charge will exceed every other care; well considering that though goodness without knowledge is weak and feeble, yet knowledge without goodness is dangerous, and that both united form the noblest character, and lay the surest foundation of usefulness to mankind.

John Philips, 1781

Nominal essences are all the essences that science needs, and some are better than others, because they capture more regularity in nature.

Dan Dennett

To explain: a "nominal essence" is just an abstract idea that humans have decided to use to pick out a particular type of thing. This is contrasted with a more Aristotelean view of essence.

... if anyone thinks they can get an accurate picture of anyplace on the planet by reading news reports, they're sadly mistaken.

--Bruce Schneier

Imagine willpower doesn't exist. That's step 1 to a better future.

Second slide of this powerpoint by Stanford's Persuasive Tech Lab.

What interest, zest, or excitement can there be in achieving the right way, unless we are enabled to feel that the wrong way is also a possible and a natural way, — nay, more, a menacing and an imminent way? And what sense can there be in condemning ourselves for taking the wrong way, unless we need have done nothing of the sort, unless the right way was open to us as well? I cannot understand the willingness to act, no matter how we feel, without the belief that acts are really good and bad.

-William James

"This has been a good day... I haven't done a single thing that was stupid..."

"Have you done anything that was smart?"

--Peanuts (Nov. 23, 1981) by Charles Schulz

In questions of this appalling magnitude, I find the best way to "overcome bias" is often to find perspectives which seem to make each answer obvious. Once we recognize that both A and B are obviously true, and A is inconsistent with B, we are in the right mindset for actual thought.

--Mencius Moldbug

As an experimental psychologist I have been trained not to believe anything unless it can be demonstrated in the laboratory on rats or sophomores.

Steven Pinker, Words and Rules

Lack of experience diminishes our power of taking a comprehensive view of the admitted facts. Hence those who dwell in intimate association with nature and its phenomena grow more and more able to formulate, as the foundations of their theories, principles such as to admit of a wide and coherent development: while those whom devotion to abstract discussions has rendered unobservant of the facts are too ready to dogmatize on the basis of a few observations.

-Aristotle, On Generation and Corruption

A critical analysis of the present global constellation -- one which offers no clear solution, no "practical" advice on what to do, and provides no light at the end of the tunnel, since one is well aware that this light might belong to a train crashing towards us -- usually meets with reproach: "Do you mean we should do nothing? Just sit and wait?" One should gather the courage to answer: "YES, precisely that!" There are situations when the only truly "practical" thing to do is to resist the temptation to engage immediately and to "wait and see" by means of a patient, critical analysis.

Slavoj Žižek, Violence, emphasis added. Admittedly not the most clear elucidation of the subject of how urgency (fabricated or otherwise) should affect ethical deliberation, but see also his essay "Jack Bauer and the Ethics of Urgency" -- if you're into that sort of thing.

Human knowledge and human power meet in one; for where the cause is not known the effect cannot be produced. Nature to be commanded must be obeyed; and that which in contemplation is as the cause is in operation as the rule.

Francis Bacon

We made our oath to Vavilov
We'd not betray the solanum
The acres of asteraceae
To our own pangs of starvation

"When The War Came", by The Decemberists

(from memory, will fix any errors later)

Never work against Mother Nature. You only succeed when you're working with her. --Cesar Milan, quoting his grandfather in Cesar's Way, a book about rehabilitating dogs

While this quote isn't directly about rationality, it reminds me a good deal of Tsuyoku Naritai!.

It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly. So that his place shall never be with those cold and timid souls who know neither victory nor defeat.

~ Theodore Roosevelt, The Man in the Arena

(Edit: Just to clarify as some might misinterpret the posting of this to be a knock on rationality, the relevance of this quote is that what counts is trying to solve problem. While with hindsight it's easy to say how (to pick a mundane example) one might work out the area under a curve once you already know calculus, it's not so easy to do it without that knowledge.)

Prompted by Maniakes', but sufficiently different to post separately:

It cannot have escaped philosophers' attention that our fellow academics in other fields--especially in the sciences--often have difficulty suppressing their incredulous amusement when such topics as Twin Earth, Swampman, and Blockheads are posed for apparently serious consideration. Are the scientists just being philistines, betraying their tin ears for the subtleties of philosophical investigation, or have the philosophers who indulge in these exercises lost their grip on reality?

These bizarre examples all attempt to prove one "conceptual" point or another by deliberately reducing something underappreciated to zero, so that What Really Counts can shine through. Blockheads hold peripheral behavior constant and reduce internal structural details (and--what comes to the same thing--intervening internal processes) close to zero, and provoke the intuition that then there would be no mind there; internal structure Really Counts. Manthra is more or less the mirror-image; it keeps internal processes constant and reduces control of peripheral behavior to zero, showing, presumably, that external behavior Really Doesn't Count. Swampman keeps both future peripheral dispositions and internal states constant and reduces "history" to zero. Twin Earth sets internal similarity to maximum, so that external context can be demonstrated to be responsible for whatever our intuitions tell us. Thus these thought experiments mimic empirical experiments in their design, attempting to isolate a crucial interaction between variables by holding other variables constant. In the past I have often noted that a problem with such experiments is that the dependent variable is "intuition"--they are intuition pumps--and the contribution of imagination in the generation of intuitions is harder to control than philosophers have usually acknowledged.

But there is also a deeper problem with them. It is child's play to dream up further such examples to "prove" further conceptual points. Suppose a cow gave birth to something that was atom-for-atom indiscernible from a shark. Would it be a shark? What is the truth-maker for sharkhood? If you posed that question to a biologist, the charitable reaction would be that you were making a labored attempt at a joke. Suppose an evil demon could make water turn solid at room temperature by smiling at it; would demon-water be ice? Too silly a hypothesis to deserve a response. All such intuition pumps depend on the distinction spelled out by McLaughlin and O'Leary-Hawthorne between "conceptual" and "reductive" answers to the big questions. What I hadn't sufficiently appreciated in my earlier forthright response to Jackson is that when one says that the truth-maker question requires a conceptual answer, one means an answer that holds not just in our world, or all nomologically possible worlds, but in all logically possible worlds. Smiling demons, cow-sharks, Blockheads, and Swampmen are all, some philosophers think, logically possible, even if they are not nomologically possible, and these philosophers think this is important. I do not. Why should the truth-maker question cast its net this wide? Because, I gather, otherwise its answer doesn't tell us about the essence of the topic in question. But who believes in real essences of this sort nowadays? Not I.

Daniel Dennett, "Get Real" (emphasis added).

Uncertainty, in the presence of vivid hopes and fears, is painful, but must be endured if we wish to live without the support of comforting fairy tales

— Bertrand Russell, History of Western Philosophy (from the introduction)

I replied as follows: "What would you think of someone who said, "I would like to have a cat, provided it barked"? [...] As a natural scientist, you recognize that you cannot assign characteristics at will to chemical and biological entities, cannot demand that cats bark or water burn. Why do you suppose that the situation is different in the "social sciences?"

-- Milton Friedman

An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.

-- H. L. Mencken, describing halo bias before it was named

The road to wisdom? — Well, it's plain
and simple to express:
Err
and err
and err again
but less
and less
and less.

--Piet Hein

Lesswrong!

A soldier should always seek the most desperate post that has to be filled.

--William Ransom Johnson Pegram

The ultimate theological question is: ‘Where does the Sun go at night?’.

The answer that so many civilisations agreed for so long was: ‘The Sun is driven by one of the gods, and at night it goes under the Earth to fight a battle. There is at least some risk that the god will lose this battle, and so the Sun may not rise tomorrow’. It’s something the human race understood was a cast iron fact before they knew how to cast iron. It survived as the working model twenty-five times longer than the four hundred years we’ve understood the Earth goes around the Sun.

Lance Parkin, Above us only sky

This is less a rationality quote than a "yay science" quote, but I find that impressive beyond words. For millenia that was a huge and frightening question, and then we went and answered it, and now it's too trivial to point out. We found out where the sun goes at night. I want to carve a primer on cosmology in gold letters on a mountain, entitled something in all caps along the lines of "HERE IS THE GLORY OF HUMANKIND".

The truth is common property. You can't distinguish your group by doing things that are rational, and believing things that are true.

Paul Graham, Lies We Tell Kids

Not everything that is more difficult is more meritorious.

-Saint Thomas Aquinas

I wish I would have memorized this quote before attending university.

*This comment was inspired by Will_Newsome's attempt to find rationality quotes in Summa Theologica.

Songs can be Trojan horses, taking charged ideas and sneaking past the ego's defenses and into the open mind.

John Mayer, Esquire (the magazine, not the social/occupational title)

"if we offer too much silent assent about mysticism and superstition – even when it seems to be doing a little good – we abet a general climate in which skepticism is considered impolite, science tiresome, and rigorous thinking somehow stuffy and inappropriate. Figuring out a prudent balance takes wisdom.”

– Carl Sagan

"Never interrupt your enemy while he is making a mistake." -- Napoleon Bonaparte

(This has been mentioned before on LW but not in a quote thread. I figured it was fair game.)

"Hit 'em where they ain't". --Douglas MacArthur commenting on his island-hopping strategy in WW2.

"The last enemy that shall be destroyed is death"

--1 Corinthians 15:26

(I wonder what Eliezer would've made of it - as far as I know, he never read Deathly Hallows and so never read about the tombstone.)

...when you do have a deep understanding, you have solved the problem and it is time to do something else. This makes the total time you spend in life reveling in your mastery of something quite brief. One of the main skills of research scientists of any type is knowing how to work comfortably and productively in a state of confusion.

-Anon http://www.quora.com/What-is-it-like-to-have-an-understanding-of-very-advanced-mathematics#ans873950

(emphasis mine)

As in the Roman empire age, the theoretical concepts, taken out of the theories assigning their meaning and considered instead real objects, whose existence can be apparent only to the initiated people, are used to amaze the public. In physics courses the student (now unaware of the experimental basis of heliocentrism or of atomic theory, accepted on the sole basis of the authority principle) gets addicted to a complex and mysterious mythology, with orbitals undergoing hybridization, elusive quarks, voracious and disquieting black holes and a creating Big Bang: objects introduced, all of them, in theories totally unknown to him and having no understandable relation with any phenomenon he may have access to.

Lucio Russo, The Forgotten Revolution: How Science Was Born in 300 BC and Why it Had to Be Reborn

[I]ntractable problems are not a good reason to attempt impossible "solutions".

-- Eric Raymond

Do not accept any of my words on faith,
Believing them just because I said them.
Be like an analyst buying gold, who cuts, burns,
And critically examines his product for authenticity.
Only accept what passes the test
By proving useful and beneficial in your life.

-- The Buddha, Jnanasara-samuccaya Sutra

Am I sure that there is no mind behind our existence and no mystery anywhere in the universe? I think I am. What joy, what relief it would be, if we could declare so with complete conviction. If that were so I could wish to live forever. How terrifying and glorious the role of man if, indeed, without guidance and without consolation he must create from his own vitals the meaning for his existence and write the rules whereby he lives.

Thornton Wilder, The Ides of March.

In every branch of knowledge the progress is proportional to the amount of facts on which to build, and therefore to the facility of obtaining data.

— James Clerk Maxwell

“A casual stroll through the lunatic asylum shows that faith does not prove anything.”

• Friedrich Nietzsche

Most people you know are probably weak skeptics, and I would probably fit this definition in several ways. "Strong skeptics" are the people who write The Skeptics' Encyclopedia, join the California Skeptics' League, buy the Complete Works of James Randi, and introduce themselves at parties saying "Hi, I'm Ted, and I'm a skeptic!". Of weak skeptics I approve entirely. But strong skeptics confused me for a long while. You don't believe something exists. That seems like a pretty good reason not to be too concerned with it.

• Yvain, 2004, source

Edit: authorial instance specified on popular demand.