The ones I find most T-shirtable are “Most haystacks do not even have a needle”, “Things are only impossible until they’re not”, “The truth will set you free. But first, it will piss you off”, “Reality is not optional”, and “The best way to escape from a problem is to solve it.”
(Note how the first two send apparently contradictory messages. The next twos seem to be variations on the Litany of Gendlin; they remind of something I’ve read somewhere, “Deal with reality or reality will deal with you.”)
I did exactly that after looking at this thread, and only spotted your comment when I wanted to post the results.
I skipped some obvious refinements as this was a 5 minute project.
55 A Bet is a Tax on Bullshit. Alex Tabarrok
45 Luck is statistics taken personally. Penn Jellete
33 Comic Quote Minus 37 -- Ryan Armand Also a favourite.
34 Nobody is smart enough to be wrong all the time.Ken Wilber
32 A problem well stated is a problem half solved.Charles Kettering
48 I will not procrastinate regarding any ritual granting immortality. --Evil Overlord List #230
29 The greatest weariness comes from work not done.-Eric Hoffer
26 “Most haystacks do not even have a needle.” -- Lorenzo
24 “I accidentally changed my mind.” my four-year-old
31 Doubt is not a pleasant condition, but certainty is absurd. Voltaire
39 People say “think outside the box,” as if the box wasn’t a fucking great idea.Sean Thomason
38 The Noah principle: predicting rain doesn’t count, building arks does. -Warren E. Buffett
37 It’s easy to lie with statistics, but it’s easier to lie without them. -Fred Mosteller
30 If one does not know to which port one is sailing, no wind is favorable.-Seneca
34 It is the mark of a truly intelligent person to be moved by statistics.George Bernard Shaw
34 “Working in mysterious ways” is the greatest euphemism for failure ever devised.TheTweetOfGod
12 Death is the gods’ crime. Unsounded
24 The most practical thing in the world is a good theory. Helmholtz
29 When the facts change, I change my mind. What do you do, sir? John Maynard Keynes
28 Writing program code is a good way of debugging your thinking. -- Bill Venables
28 It is easy to be certain....One has only to be sufficiently vague.Charles S. Peirce
30 Truth is much too complicated to allow anything but approximations. — John Von Neumann
31 There is one rule that’s very simple, but not easy: observe reality and adjust. Ran Prieur
21 Things are only impossible until they’re not. -- Jean-Luc Picard
24 Part of the potential of things is how they break. Vi Hart, How To Snakes
25 A scholar is just a library’s way of making another library. Daniel Dennett
29 We should be careful to get out of an experience only the wisdom that is in it. Mark Twain
29 The Company that needs a new machine tool is already paying for it. -old Warner Swasey ad
25 “Any sufficiently analyzed magic is indistinguishable from SCIENCE!” ~Girl Genius
26 Complex problems have simple, easy to understand wrong answers. — Grossman’s Law
22 Most people would rather die than think; many do. – Bertrand Russell
22 The only road to doing good shows, is doing bad shows.Louis C.K., on Reddit
28 My brain technically-not-a-lies to me far more than it actually lies to me.-- Aristosophy (again)
23 The truth will set you free. But first, it will piss you off. Gloria Steinem
27 Nature draws no line between living and nonliving. -- K. Eric Drexler, Engines of Creation
22 It is better to destroy one’s own errors than those of others. Democritus
12 Reality is not optional. Thomas Sowell
17 Statistics is applied philosophy of science. A. P. Dawid
22 Forget Jesus. The stars died so that you could be here today. Lawrence Krauss
23 Go down deep enough into anything and you will find mathematics. Dean Schlicter
24 We are built to be effective animals, not happy ones. -Robert Wright, The Moral Animal
19 Being right too soon is socially unacceptable. Robert A. Heinlein
14 “Anything you can do, I can do meta” -Rudolf Carnap
17 Mind is a machine for jumping to conclusions—Daniel Kahneman
26 A faith which cannot survive collision with the truth is not worth many regrets.Arthur C. Clarke
26 Nobody panics when things go “according to plan”… even if the plan is horrifying. The Joker
23 “Convictions are more dangerous enemies of truth than lies.” --Friedrich Nietzsche
20 I honestly don’t know. Let’s see what happens. -- Hans. The Troll Hunter
16 Luck is opportunity plus preparation plus luck.--Jane Espenson
20 The singularity is my retirement plan. -- tocomment, in a Hacker News post
19 Better our hypotheses die for our errors than ourselves. -- Karl Popper
22 Errors using inadequate data are much less than those using no data at all.-Charles Babbage
19 In general, we are least aware of what our minds do best. — Marvin Minsky
20 It is easier to love humanity than to love one’s neighbor.--Eric Hoffer, on Near/Far
15 Keep your solutions close, and your problems closer.afoolswisdom
18 “If God gives you lemons, you find a new God.”—Powerthirst 2: Re-Domination
17 Truth comes out of error more easily than out of confusion.-Francis Bacon
23 Opening your eyes doesn’t make a bad picture worse. http://onefte.com/2011/07/17/bully-for-you/
19 Know the hair you have to get the hair you want. -Pantene Pro-V hair care bottle
16 The best way to escape from a problem is to solve it. -Alan Saporta
16 Not to know is bad; not to wish to know is worse. — Wolof proverb
20 Those who can make you believe absurdities can make you commit atrocities. -- Voltaire
The ones I find most T-shirtable are “Most haystacks do not even have a needle”, “Things are only impossible until they’re not”, “The truth will set you free. But first, it will piss you off”, “Reality is not optional”, and “The best way to escape from a problem is to solve it.”
(Note how the first two send apparently contradictory messages. The next twos seem to be variations on the Litany of Gendlin; they remind of something I’ve read somewhere, “Deal with reality or reality will deal with you.”)