From a BBC interview with a retiring Oxford Don:

Don: "Up until the age of 25, I believed that 'invective' was a synonym for 'urine'."

BBC: "Why ever would you have thought that?"

Don: "During my childhood, I read many of the Edgar Rice Burroughs 'Tarzan' stories, and in those books, whenever a lion wandered into a clearing, the monkeys would leap into the trees and 'cast streams of invective upon the lion's head.'"

BBC: <long pause> "But, surely sir, you now know the meaning of the word."

Don: "Yes, but I do wonder under what other misapprehensions I continue to labour."

On utility:

culturejammer: you know what pennies are AWESOME for?

culturejammer: throwing at cats

culturejammer: it only costs a single penny

culturejammer: and they'll either chase it, or get hit by it and look pissed off

culturejammer: i now use that system to value prices of things

culturejammer: for example, a thirty dollar game has to be at least as awesome as three thousand catpennies

--bash.org

Many people equate tolerance with the attitude that every belief is equally true, and that we should all simply accept this fact and go our separate ways. But I view tolerance as the willingness to come together, to face one another in the same room and hack at each other with claw hammers until the truth finally trickles out from the blood and the tears.

-- Raving Atheist, found via the Black Belt Bayesian blog (props to Steven)

"Intuition only works in situations where neurology and evolution has pre-equipped us with a good set of basic-level categories. That works for dealing with other humans, and for throwing things, and for a bunch of other things that do not, unfortunately, include constructing viable philosophies."

-- Eric S. Raymond

Education is a technology that tries to make up for what the human mind is innately bad at. Children don't have to go to school to learn how to walk, talk, recognize objects, or remember the personalities of their friends, even though these tasks are much harder than reading, adding, or remembering dates in history. They do have to go to school to learn written language, arithmetic, and science, because those bodies of knowledge and skill were invented too recently for any species-wide knack for them to have evolved.

Steven Pinker -- The Blank Slate: The Modern Denial of Human Nature

If you can't feel secure - and teach your children to feel secure - about 1-in-610,000 nightmare scenarios - the problem isn't the world. It's you.

-- Bryan Caplan

"In the matter of reforming things, as distinct from deforming them, there is one plain and simple principle; a principle which will probably be called a paradox. There exists in such a case a certain institution or law; let us say, for the sake of simplicity, a fence or gate erected across a road. The more modern type of reformer goes gaily up to it and says, "I don't see the use of this; let us clear it away." To which the more intelligent type of reformer will do well to answer: "If you don't see the use of it, I certainly won't let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it." GK Chesterton

One of my advisors will be an average five-year-old child. Any flaws in my plan that he is able to spot will be corrected before implementation.

I will maintain a realistic assessment of my strengths and weaknesses. Even though this takes some of the fun out of the job, at least I will never utter the line "No, this cannot be! I AM INVINCIBLE!!!" (After that, death is usually instantaneous.)

I will be neither chivalrous nor sporting. If I have an unstoppable superweapon, I will use it as early and as often as possible instead of keeping it in reserve.

If my advisors ask "Why are you risking everything on such a mad scheme?", I will not proceed until I have a response that satisfies them.

I will see a competent psychiatrist and get cured of all extremely unusual phobias and bizarre compulsive habits which could prove to be a disadvantage.

I will never build a sentient computer smarter than I am.

-- Peter's Evil Overlord List on how to be a less wrong fictional villain

"You don't use science to show that you're right, you use science to become right." --Randall Munroe, in the alt-text of xkcd 701

As we know,
There are known knowns.
There are things
We know we know.
We also know
There are known unknowns.
That is to say
We know there are some things
We do not know.
But there are also unknown unknowns,
The ones we don't know
We don't know.

-- Donald Rumsfeld, Feb. 12, 2002, Department of Defense news briefing

The object of opening the mind, as of opening the mouth, is to close it again on something solid.

-- G.K. Chesterton

Thinking is skilled work. It is not true that we are naturally endowed with the ability to think clearly and logically--without learning how, or without practicing.... People with untrained minds should no more expect to think clearly and logically than people who have never learned and never practiced can expect to find themselves good carpenters, golfers, bridge-players, or pianists.

Alfred Mander -- Logic for the Millions

On parsimony:

If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is.

--John von Neumann, at the first national meeting of the Association for Computing Machinery

That is not dead which can eternal lie,/ And with strange aeons even Death may die.

—H.P. Lovecraft, clearly talking about cryonic preservation

Never let your sense of morals prevent you from doing what is right.

-- Isaac Asimov via Salvor Hardin, Foundation

"If the tool you have is a hammer, make the problem look like a nail."

Steven W. Smith, The Scientist and Engineer's Guide to Digital Signal Processing

More people are killed every year by pigs than by sharks, which shows you how good people are at evaluating risk.

Bruce Schneier

In our public medical personas, we often act as though morality consisted only in following society's conventions: we do this not so much out of laziness but because we recognize that it is better that the public think of doctors as old-fashioned or stupid, than that they should think us evil.

-- The Oxford Handbook of Clinical Medicine

O Lord our Father, our young patriots, idols of our hearts, go forth to battle -- be Thou near them! With them -- in spirit -- we also go forth from the sweet peace of our beloved firesides to smite the foe. O Lord our God, help us to tear their soldiers to bloody shreds with our shells; help us to cover their smiling fields with the pale forms of their patriot dead; help us to drown the thunder of the guns with the shrieks of their wounded, writhing in pain; help us to lay waste their humble homes with a hurricane of fire; help us to wring the hearts of their unoffending widows with unavailing grief; help us to turn them out roofless with little children to wander unfriended the wastes of their desolated land in rags and hunger and thirst, sports of the sun flames of summer and the icy winds of winter, broken in spirit, worn with travail, imploring Thee for the refuge of the grave and denied it -- for our sakes who adore Thee, Lord, blast their hopes, blight their lives, protract their bitter pilgrimage, make heavy their steps, water their way with their tears, stain the white snow with the blood of their wounded feet! We ask it, in the spirit of love, of Him Who is the Source of Love, and Who is the ever-faithful refuge and friend of all that are sore beset and seek His aid with humble and contrite hearts. Amen.

-- Mark Twain, excerpt from The War Prayer

Million-to-one odds happen eight times a day in New York.

Penn Jillette

If [Ayn] Rand really wanted to build an individualist sub-culture, she would have done so in an evolutionarily informed way. If people naturally care about the opinions of others, jumping on people is a good way to get dishonest conformity, but a bad way to get an honest exchange of ideas. Instead, an individualist sub-culture must be built upon tolerance and honesty. I'd suggest three key norms:

1. Don't think less of people who sincerely disagree.
2. Do think less of people who insincerely agree.
3. Do think less of people who think less of people who sincerely disagree.

--Bryan Caplan

Reference: Guardians of Ayn Rand

'Cause it's gonna be the future soon
And I won't always be this way
When the things that make me weak and strange get engineered away

--Jonothan Coulton

The introduction of suitable abstractions is our only mental aid to organize and master complexity.

-- Edsger W. Dijkstra

"We can get very confused, because we think that words must have some secret meaning that we have to figure out. They don't. They are just noises or marks, and they mean whatever experience you have learned to mean by them. People tend to use similar words in similar situations, but unless you have specifically agreed on what the words will mean, in terms of underlying experiences, there's no way to know what another person understands when you use them. The experience you attach to a word when you say it isn't automatically the same as the experience another person attaches to the same word when hearing it."

William T. Powers

I much prefer the sharpest criticism of a single intelligent man to the thoughtless approval of the masses.

Johannes Kepler

"People are not complicated. People are really very simple. What makes them appear complicated is our continual insistence on interpreting their behavior instead of discovering their goals."

-- Bruce Gregory

It's amazing the things people would rather have than money.

-- Garfield

'Nash equilibrium strategy' is not necessarily synonymous to 'optimal play'. A Nash equilibrium can define an optimum, but only as a defensive strategy against stiff competition. More specifically: Nash equilibria are hardly ever maximally exploitive. A Nash equilibrium strategy guards against any possible competition including the fiercest, and thereby tends to fail taking advantage of sub-optimum strategies followed by competitors. Achieving maximally exploitive play generally requires deviating from the Nash strategy, and allowing for defensive leaks in ones own strategy. -- Johannes Koelman

I always saw a close kinship between the needs of "pure" mathematics and a certain hero of Greek mythology, Antaeus. The son of Earth, he had to touch the ground every so often in order to reestablish contact with his Mother; otherwise his strength waned. To strangle him, Hercules simply held him off the ground. Back to mathematics. Separation from any down-to-earth input could safely be complete for long periods — but not forever.

-Benoit Mandelbrot

There's no mystical energy field that controls my destiny.

-- Han Solo

I'll start incorporating crazy counter-intuitive notions about the nature of the universe when the cold implacable hand of the universe starts shoving them down my throat, not before!

-- PZ Myers

So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for every thing one has a mind to do.

-- Benjamin Franklin

Margaret Mead made a world-wide reputation for herself with her book Coming of Age in Samoa. After visiting the island of Samoa and talking to some teenage girls, she came away convinced that the Puritanism of the American sexual code was cultural artifact. In Samoa, by contrast, sex was freely practiced, with little attention to any niceties. Unfortunately, she was wrong about this, as we learned almost a half a century later, when Derek Freeman, who actually spoke Samoan, went to Samoa and interviewed the now grown women who had been interviewed by Margaret Mead many years earlier. He discovered that they had been putting her on. Decency and sexual restraint were as important to Samoans as to Americans.

• James Q. Wilson, Moral Intuitions

Organizations don’t suffer pathologies; they are intrinsically pathological constructs. Idealized organizations are not perfect. They are perfectly pathological.

-- http://www.ribbonfarm.com/2009/10/07/the-gervais-principle-or-the-office-according-to-the-office/

Ce que l'on conçoit bien s'énonce clairement / Et les mots pour le dire arrivent aisément

-- Nicolas Boileau

Rough translation: "What is well understood can be told clearly, and words to express it should come easily."

ETA: it is worth pondering the converse; just because something rolls off the tongue doesn't mean it's well understood. It could be that it's only well-rehearsed.

What the quote is aimed at is work of a supposedly high intellectual caliber, which just so happens to be couched in impenetrable jargon. Far more often, that is in fact evidence of muddled thought, not that the material is "beyond me".

"Seeing is believing, but seeing isn't knowing." -- AronRa

The activist is not the man who says the river is dirty. The activist is the man who cleans up the river.

-- H. Ross Perot

A black cat crossing your path signifies that the animal is going somewhere.

-- Groucho Marx

During a conversation with a Christian friend, during which my apostasy was challenged sincerely and politely but with the usual arguments and style...

Christian: And the Bible tells us that if we have Faith as small as a mustard seed...
Me: Yeah, we can move mountains. Matthew 17:20. So, tell me. Could God make an argument so circular that even He couldn't believe it?
Christian: Of course! He's God, God can do anything.

'Made in His Image' seems to apply all too well.

If you think of losing as “not winning,” then when you try to work out why you’ve lost, or (God forbid) why you’re a loser, you’ll tend to focus on the things you didn’t do and the qualities you don’t have. So it goes with any “negative” concept, one that is defined by what it isn’t (think of how “background” = “everything but the foreground” or how valleys are made by the mountains around them).

I think it’s worthwhile to occasionally invert the picture, to see “being a winner” as “not being a loser.” That way you attend to those habits of mind that are hurting you, instead of the ones that might be helping.

-- Jsomers.net, How to be a loser (Relevance)

What is it about us, the public, and what is it about conformity itself that causes us all to require it of our neighbors and of our artists and then, with consummate fickleness, to forget those who fall into line and eternally celebrate those who do not?

-- Ben Shahn, "The Shape of Content"

"If we were bees, ants, or Lacedaemonian warriors, to whom personal fear does not exist and cowardice is the most shameful thing in the world, warring would go on forever.
But luckily we are only men - and cowards."

--Erwin Schrodinger, Mind and Matter

"In my experience, the most staunchly held views are based on ignorance or accepted dogma, not carefully considered accumulations of facts. The more you expose the intricacies and realities of the situation, the less clear-cut things become."

Mary Roach - from her book Spook

The secret of what anything means to us depends on how we've connected it to all the other things we know. That's why it's almost always wrong to seek the "real meaning" of anything. A thing with just one meaning has scarcely any meaning at all.

Marvin Minsky -- The Society of Mind

Karl Marx's writings glorifying communism (though Western capitalists regard it as grim and joyless) may well have reflected merely his alienation from society due to a lifelong series of excruciatingly painful boils, according to a recent British Journal of Dermatology article. In an 1867 letter, Marx wrote, "The bourgeoisie will remember my carbuncles until their dying day." [Reuters, 10-30-07]

-- News of the Weird (relevance)

The difficulty lies, not in the new ideas, but in escaping the old ones, which ramify, for those brought up as most of us have been, into every corner of our minds.

John Maynard Keynes

"Love God?" you're in an abusive relationship.

DLC, commenter at Pharyngula.

"I waste many hours each day being efficient."

--Emanuel Derman

As the mind learns to understand more complicated combinations of ideas, simpler formulae soon reduce their complexity; so truths that were discovered only by great effort, that could at first only be understood by men capable of profound thought, are soon developed and proved by methods that are not beyond the reach of common intelligence.

Marquis de Condorcet, 1794

If we take in our hand any volume; of divinity or school metaphysics, for instance: let us ask, "Does it contain any abstract reasoning concerning quantity or number?" No. "Does it contain any experimental reasoning concerning matter of fact and existence?" No. Commit it then to the flames: for it can contain nothing but sophistry and illusion. --- David Hume

(quoted in Beyond AI by JoSH Hall)

"Most people are more complicated than they seem, but less complicated than they think"

• BS

For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much - the wheel, New York, wars and so on - whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man - for precisely the same reasons.

-- Douglas Adams, The Hitchhiker's Guide to the Galaxy

Who am I to judge myself?

-- Karp

“He was a dreamer, a thinker, a speculative philosopher...or, as his wife would have it, an idiot.”

A bit of a meta-quote:

But in choosing a chair we follow the dictates of our eyes, for better or for worse, more often than those of our "ischial tuberosities," and the hammocklike Hardoy looks comfortable. [Joseph] Rykwert correctly assumes that "the buyers of Hardoy chairs, like many other customers for design goods, are guided in their choice by promptings quite different from the dictates of reason." And he adds a conclusion worth remembering: "The very fact that they do so should be a matter of interest to the designer: nothing human should be alien to him."

A Philosophy of Interior Design (1990) by Stanley Abercrombie, quoting "The Sitting Position - A Question of Method" (1958) by Joseph Rykwert.

ETA: It would seem that rationality quotes are no longer desired. After several days this thread stands voted into the negatives. Wolud whoever chose to to downvote this below 0 would care to express their disapproval of the regular quotes tradition more explicitly?

For the record, I didn't downvote this below zero, but it did at one point downvote this back to zero (and did the same for the Open Thread). Not because I'd disagree with the tradition in any way, but because I don't think the first person to get around posting the month's thread should get tens of points of karma for simply being quick.

"What is written without effort is in general read without pleasure."

--Dr. Samuel Johnson

JANEWAY: I understand you grew up on Vico Five. No wonder you became a cosmologist.
HARREN: Wildest sky in the Alpha quadrant.
JANEWAY: So they say. I've never been there.
HARREN: Do you really believe that childhood environment is more important than genetically driven behaviour patterns?
JANEWAY: Just making conversation.
HARREN: Conversation filled with unspoken assumptions, which I don't agree with. I'm a product of my nucleic acids. Where and how I was raised are beside the point. So if you're trying to understand me better, questions about my home planet are irrelevant.

---Star Trek: Voyager, "Good Shepherd"

"In madness all sounds become articulate." -- "Language of the Shadows", Nile

Shamisen deserves an honorable mention. Although he only has one speech, he's a good enough philosopher that upon being introduced he manages to sidetrack the brigade members into a debate over the nature of conversation and away from the fact that, you know, he's a talking cat. - TV Tropes, "The Philosopher"

[Connections to rationality: Focus, taking action, and conversation style.]

TELFER: At least I have a friend. Don't you ever get lonely down there?
HARREN: In the company of my own thoughts? Never.
TELFER: I don't believe that. Spend some time with us when we get back. You might enjoy yourself.
HARREN: A hypothesis that would require testing. I'm a theoretician, remember?

---Star Trek: Voyager, "Good Shepherd"

"To know something is to make this something that I know myself; but to avail myself of it, to dominate it, it has to remain distinct from myself." -- Miguel de Unamuno

There's no scientific reason to believe that we have free will. There's no buffer zone that we've found in any of the physical laws of how the universe works to make room for free will. There's non-determinism; but there's not choice. Choice is the introduction of something, dare I say it, supernatural: some influence that isn't part of the physical interaction, which allows some clusters of matter and energy to decide how they'll collapse a probabilistic waveform into a particular reality.

-- Mark Chu-Carroll