Why is it believed that what pictures you can make in your head, and what is true or necessarily true, are terribly well connected? If there is not a substantial connection between the (necessarily) true and your conception of the (necessarily) true, then Hume's argument goes up in smoke.

-- Aretae

This is the moment that matters, and I refuse to look back on this day and say "maybe if I hadn't..."

-- Hybrid Theory

I've never seen a UFO. When I went to places that were rumored to be haunted, nothing showed up. Two hours of intense staring didn't make my pencil move a single millimeter, and glaring at my classmate's head didn't reveal his thoughts to me, either. I couldn't help but get depressed at how normal the laws of physics were.

-- Kyon, The Melancholy of Suzumiya Haruhi

Moral language persuades best when opinions are not yet formed, which is why writers of children’s literature can get away with saying things like, “Mr. Billings was an awful, horrible man with a heart of stone.” This sounds like a line from a children’s book because it employs persuasive methods that, though appropriate for children, would insult the intelligence of most adult readers.

Most moral discourse is the conversational equivalent of children’s literature. Disputants speak to one another—or, rather, at one another—as if their interlocutors failed to pay adequate attention on the day elementary morality was explained. Unaware of the projective nature of value, they marvel at their opponents’ blindness, their utter failure to see what is so perfectly obvious. Not knowing what else to do, they scold their opponents as if they were children, and scold them as if they were belligerent children when they fail to respond the first time.

What to do about this? Take a cue from good writers. Stick to the facts. Keep evaluative language to a minimum, and get rid of the most overtly judgmental, moralistic language.

-- Joshua Greene, The Terrible, Horrible, No Good, Very Bad Truth About Morality And What To Do About It

In volunteer organizations, when someone was allowed to fail to teach them a lesson about their responsibilities, I do not ever remember them learning that lesson.

-- Matt Arnold

Nothing sucks more than that moment during an argument when you realize you're wrong.

-- Unknown

[I]n my opinion nothing occurs contrary to nature except the impossible, and that never occurs.

-- Sagredo, "Two New Sciences" (1914 translation), Galileo Galilei

There is an unfortunate optical illusion - a variant on the Doppler effect - that besets all frauds. It's unfortunate, because it has the effect of exacerbating the pecuniary losses that fraud victims endure, by unfairly leaving them, like many rape victims, irrationally ashamed of themselves.

The Doppler principle we posit holds that as a victim approaches a swindler, he sees nothing but green lights. But as soon as he realizes that his money is gone, he spins around and beholds, as if by magic, bright red flags as far as the eye can see.

-- Roger Parloff, senior editor, "More brazen than Madoff?", Fortune, 2009-03-31

The only man I know who behaves sensibly is my tailor; he takes my measurements anew each time he sees me. The rest go on with their old measurements and expect me to fit them.

-- George Bernard Shaw, writer, Nobel laureate (1856-1950)

Edit: The full citation is to his 1903 play Man and superman: a comedy and a philosophy, where the character John Tanner ("M.I.R.C., Member of the Idle Rich Class") says:

Yes, because to be treated as a boy was to be taken on the old footing. I had become a new person ; and those who knew the old person laughed at me. The only man who behaved sensibly was my tailor : he took my measure anew every time he saw me, whilst all the rest went on with their old measurements and expected them to fit me.

You got to have a dream,

If you don't have a dream,

How you gonna have a dream come true?

• Bloody Mary, South Pacific

All that glitters is not gold

Unknown Origin

Perfecting oneself is as much unlearning as it is learning.

-- Edsger Dijkstra

You want to learn from experience, but you want to learn from other people’s experience when you can.

Warren Buffett

However beautiful the strategy, you should occasionally look at the results.

-- Winston Churchill

Dear Meg,

Please don't try to trisect the angle. . . It's not a matter of being clever.

Ian Stewart, Letters to a Young Mathematician

People often lack the discipline to adhere to a superior strategy that doesn't "feel" right. Reasoning in a way that sometimes "feels" wrong takes discipline.

-- Michael Bishop, Epistemology and the psychology of human judgement

Our minds are like inmates, captive to our biology, unless we manage a cunning escape.

-- Nassim Taleb

Mathematics is rational, not reasonable.

-- Terry Padden, in "Ultimately, in Physics the Rational shall become Reasonable!"

"Why then 'tis none to you; for there is nothing either good or bad, but thinking makes it so."

Hamlet Act 2, scene 2, 239–251

A behavioral policy based on an inside strategy permits the alcoholic to sit at the bar and rehearse the reasons to abstain. An outside strategy identifies a principle or rule of conduct that produces the most accurate or desirable available outcome, and sticks to that rule despite the subjective pull to abandon the principle. A behavioral policy based on an outside strategy recommends that you avoid the bar in the first place.

-- Michael Bishop, 50 Years of Successful Predictive Modeling Should Be Enough: Lessons for Philosophy of Science

A great many years ago, a couple of Jehovah Witnesses bit off more than they could chew with my grandmother. During the unsolicited conversation one of them remarked, "Only God can make a rainbow". To which my grandmother-who was watering her plants at the time-said, "Nonsense!", and created her own rainbow with a spray of water from the hose. Family lore has it that was the end of the conversation.

-- seen on Livejournal

The master mathematician sat in his private room and pushed the papers from him. His calculations were already finished. In a small white phial there still remained a little of the drug that had kept him awake and active for four long nights. Each day, serene, explicit, patient as ever, he had given his lecture to his students, and then had come back at once to this momentous calculation. His face was grave, a little drawn and hectic from his drugged activity. For some time he seemed lost in thought. Then he went to the window, and the blind went up with a click. Half way up the sky, over the clustering roofs, chimneys and steeples of the city, hung the star.

He looked at it as one might look into the eyes of a brave enemy. "You may kill me," he said after a silence. "But I can hold you--and all the universe for that matter--in the grip of this little brain. I would not change. Even now."

-- H.G. Wells, "The Star", 1897

"Now I'll never know if I was right."

-- final words of Adric, in Dr. Who, "Earthshock", on realizing that he's about to crash into the Earth

The statement that all of us are purportedly able to coherently conceive or imagine a certain situation - for instance, an imitation man or a zombie - is rather trivial from a philosophical point of view because ultimately it is just an empirical claim about the history of the brain and its functional architecture. It is a statement about a world that is phenomenally possible for human beings. It is not a statement about the modal strength of the relationship between physical and phenomenal properties; logical possibility (or necessity) is not implied by phenomenological possibility (or necessity). From the simple fact that beings like ourselves are able to phenomenally simulate a certain apparently possible world, it does not follow that a consistent or even only an empirically plausible description of this world exists. -- Thomas Metzinger

The unwillingness to tolerate or respect any social forces which are not recognizable as the product of intelligent design, which is so important a cause of the present desire for comprehensive economic planning, is indeed only one aspect of a more general movement. We meet the same tendency in the field of morals and conventions, in the desire to substitute an artificial for the existing languages, and in the whole modern attitude toward processes which govern the growth of knowledge. The belief that only a synthetic system of morals, an artificial language, or even an artificial society can be justified in an age of science, as well as the increasing unwillingness to bow before any moral rules whose utility is not rationally demonstrated, or to conform with conventions whose rationale is not known, are all manifestations of the same basic view which wants all social activity to be recognizably part of a single coherent plan. They are the results of that same rationalistic "individualism" which wants to see in everything the product of conscious individual reason.

Friedrich Hayek, Individualism: True and False

I won’t teach a man who is not eager to learn, nor will I explain to one incapable of forming his own ideas. Nor have I anything more to say to those who, after I have made clear one corner of the subject, cannot deduce the other three.

Confucius

Besides porking (really) hot babes, flipping out, wailing on guitars, and cutting off heads, a ninja has to train. They have to meditate ALL THE TIME. But most importantly, each morning a ninja should think about going a little crazier than the day before. Beyond thinking about going berserk, a ninja must, by definition, actually go berserk.

Robert Hamburger, REAL Ultimate Power, The Official Ninja Book

"My interest is in the future because I am going to spend the rest of my life there."

Charles F. Kettering

"Experience does not ever err, it is only your judgement that errs in promising itself results which are not caused by your experiments."

Leonardo Da Vinci

"A theory which cannot be mortally endangered cannot be alive."

W. A. H. Rushton, quoted in J.R. Platt, "Strong Inference", Science vol.146, n.3642, 1964.

"There is a superstition in avoiding superstition, when men think to do best if they go furthest from the superstition formerly received."

-- Francis Bacon

"Everything is open to questioning. That does not mean all answers are equally valid."

-- Kelvin Throop

Ph.D. comics no.1173

The script:

A grad student in humanities has been called before a hearing to justify his existence.

Student: "It's hard to explain monetarily, but how can you put a price tag on the human soul?"

Student: "The humanities help us appreciate beauty and grow as individuals."

Student: "What good are science and technology if we don't ask ourselves the question, what does it mean to be a human being?"

Chair: "So how's the answer coming along?"

Student: "Oh no, we just ask the question, not actually answer it."

(approximate, my translation)

Blessed are those who believe without seeing. Who wants to be blessed when they could see.

-- Esa Lappi, my high school math teacher when showing us the proof of some theorem.

"Thus Aristotle laid it down that a heavy object falls faster than a light one does. The important thing about this idea is not that he was wrong, but that it never occurred to Aristotle to check it." Albert Szent-Györgyi de Nagyrápolt, winner of the Nobel Prize in Physiology or Medicine.

"I can't see it, so you must be wrong."

my four-year-old

It seems thus impossible that any question about the nature or character of particular sensory qualities should ever arise which is not a question about the differences from (or relations to) other sensory qualities; and the extent to which the effects of its occurrence differ from the effects of the occurrence of any other qualities determines the whole of its character.

To ask beyond this for the explanation of some absolute attribute of sensory qualities seems to be to ask for something which by definition cannot manifest itself in any differences in the consequences which will follow because this rather than any other quality has occurred. Such a factor, however, could by definition not be of relevance to any scientific problem. The 'absolute' quality seems to be unexplainable because there is nothing to explain, because absolute, if it has any meaning at all, can only mean that the attribute which is so described has no scientific significance.

--F. A. Hayek, The Sensory Order (never terse)

There are two mistakes one can make along the road to truth…not going all the way, and not starting.

Buddha

The public have an insatiable curiosity to know everything. Except what is worth knowing. Journalism, conscious of this, and having tradesman-like habits, supplies their demands. -Oscar Wilde

When things are hard to understand, people who suspect they're nonsense generally keep quiet.

-- Paul Graham

The carting of manure had to begin earlier, so that everything would be finished before the early mowing. The far field had to be ploughed continually, so as to keep it fallow. The hay was to be got in, not on half shares with the peasants, but by hired workers.

The steward listened attentively and obviously made an effort to approve of the master's suggestions; but all the same he had that hopeless and glum look, so familiar to Levin and always so irritating to him. This look said: "That's all very well, but it's as God grants."

Nothing so upset Levin as this tone. But it was a tone common to all stewards, as many of them as he had employed. They all had the same attitude toward his proposals, and therefore he now no longer got angry, but became upset and felt himself still more roused to fight this somehow elemental force for which he could find no other name than "as God grants", and which was continually opposed to him.

-- Leo Tolstoy, "Anna Karenina"

Since all things related to akrasia and self motivation are relevant here:

"As a final incentive before giving up a difficult task, try to imagine it successfully accomplished by someone you violently dislike." -K. Zenios

the human mind is trained by the knowledge imparted to it and the direction given to its ideas. Only what is great can make it great; the little can only make it little.

-Carl von Clausewitz

You must engage in these internal dialogues all the time, and you must let yourself lose the arguments gracefully. Writing may be a game of solitaire, but it isn’t a game at which you can cheat.

-Theodore Cheney, Getting the Words Right

It does not matter how frequently something succeeds if failure is too costly to bear. —Nicholas Nassim Taleb

(i.e.: don't forget to put, in your utility functions, the damn appropriate weight of those highly-improbable-but-high-negative-impact tragedies!)

You are entitled to your own opinion, but you are not entitled to your own facts. —Daniel Moyniham

Anyone who denies the law of non-contradiction should be beaten and burned until he admits that to be beaten is not the same as not to be beaten, and to be burned is not the same as not to be burned. —Avicenna (980–1037 AD)

What gets us into trouble is not what we don't know. It's what we know for sure that just ain't so. —Mark Twain

Never underestimate the difficulty of changing false beliefs by facts. —Harvard economist Henry Rosovsky

And when one goeth through fire for his teaching--what doth that prove? Verily, it is more when one's teaching cometh out of one's own burning!

-Friedrich Nietzsche, The Antichrist

I have met people who exaggerate the differences [between the morality of different cultures], because they have not distinguished between differences of morality and differences of belief about facts. For example, one man said to me, "Three hundred years ago people in England were putting witches to death. Was that what you call the Rule of Human Nature or Right Conduct?" But surely the reason we do not execute witches is that we do not believe there are such things. If we did-if we really thought that there were people going about who had sold themselves to the devil and received supernatural powers from him in return and were using these powers to kill their neighbours or drive them mad or bring bad weather, surely we would all agree that if anyone deserved the death penalty, then these filthy quislings did. There is no difference of moral principle here: the difference is simply about matter of fact. It may be a great advance in knowledge not to believe in witches: there is no moral advance in not executing them when you do not think they are there. You would not call a man humane for ceasing to set mousetraps if he did so because he believed there were no mice in the house.

-C.S. Lewis

"Although blinding with science can be used in any argument, many will recognize the special domain of this fallacy as the subjects which like to consider themselves as sciences, but are not.

Science deals with things from atoms to stars at a level where individual differences do not matter. The scientist talks of 'all' rolling bodies or whatever, and formulates general laws to test by experiment.

The trouble with human beings is that, unlike rolling bodies, the individual differences do matter. Often, again unlike rolling bodies, they want to do different things.

Although this might prevent us from being scientific about human beings, it does not stop us pretending to be so. What we do here is to add the word 'science' onto the study, giving us 'economic science', 'political science' and 'social science'. Then we dress them in that white coat of scientific language, and hope that no one will notice the difference."

-- Madsen Pirie, "How To Win Every Argument: The Use and Abuse of Logic"