Daniel Kahneman: Nothing in life is as important as you think it is, while you are thinking about it.My own answer -- since Edge somehow failed to contact me again this year -- would resemble those of the several responders who emphasized humility. John Tooby notes that we are all "error-besotted. We all start from radical ignorance in a world that is endlessly strange, vast, complex, intricate, and surprising." Kathryn Schulz wrote of "pessimistic meta-induction from the history of science," that is, the awareness that almost all ideas are either rejected or modified by future generations. I think the real contribution science has to make to other kinds of thinking is sensitivity to how strong the evidence in favor of any proposition is, along with an awareness that no knowledge is certain.
Richard Dawkins: The double-blind experiment.
Brian Eno: Ecology.
Nigel Goldenfeld: Complex systems, such as financial markets or the Earth's biosphere, do not seem to obey causality.
Gary Marcus: Cognitive humility . . . . knowing the limits of our minds can make us better reasoners.
David Pizarro: Apophenia, which is the tendency of our minds to see patterns even where there are none.
Diane Halpern: Statistical significance.
Fiery Cushman: Confabulation. We are shockingly ignorant of the causes of our own behavior. The explanations that we provide are sometimes wholly fabricated, and certainly never complete.
P.Z. Myers: The Mediocrity Principle. You aren't special. The universe does not revolve around you, this planet isn't privileged in any unique way, your country is not the perfect product of divine destiny, your existence isn't the product of directed, intentional fate, and that tuna sandwich you had for lunch was not plotting to give you indigestion. Most of what happens in the world is just a consequence of natural, universal laws — laws that apply everywhere and to everything, with no special exemptions or amplifications for your benefit — given variety by the input of chance. Everything that you as a human being consider cosmically important is an accident.
Geoffrey Miller -- To understand insanity, we have to understand personality. . . there's no clear line between "normal variation" in human personality traits and "abnormal" mental illnesses.
Matt Ridley: Human achievement is entirely a networking phenomenon.
Richard Feynman was especially insistent on this point, and he regularly said things like
We have found it of paramount importance that in order to progress, we must recognize our ignorance and leave room for doubt. Scientific knowledge is a body of statements of varying degrees of certainty — some most unsure, some nearly sure, but none absolutely certain. . . . I have approximate answers and possible beliefs in different degrees of certainty about different things, but I'm not absolutely sure of anything.I think a belief in the certainty of our own correctness is one of the banes of human life, and it is the main bane of modern politics. If I had been born 80 years ago I suppose I would have spent much of my mental life opposing Bolsheviks, who epitomized that era's commitment to ignorant certainty. In my own time this is mainly a habit of libertarians and their conservative allies, so it is mainly against them that I argue.