History has had many affairs with psychology. Its longest marriage, to psychoanalysis, produced a camel called “psychohistory,” typically consisting of post-hoc analyzing of major historical figures, usually involving their mothers, to explain wars, invasions, and revolutions. The result was sometimes preposterous and sometimes interesting, but it usually was neither good history nor good psychology.
But at last, history has gotten into bed with psychological science, and it’s a happy match. History gives us the data of, in Barbara Tuchman’s splendid words, our march of folly -- repeated examples of human beings unable and unwilling to learn from mistakes, let alone to admit them. Cognitive science shows us why. Its evidence has put a stake through the heart of any remaining arrogance we might have as a species that we are Homo “sapiens.” Our brains, which have allowed us to travel into outer space, have a whole bunch of design flaws, which is why we have so much breathtaking bumbling here on Earth.
Of the many built-in biases in human thought, three have perhaps the greatest consequences for our own history and that of nations: the belief that we see things as they really are, rather than as we wish them to be; the belief that we are better, kinder, smarter, and more ethical than average; and the confirmation bias, which sees to it that we notice, remember, and accept information that confirms our beliefs -- and overlook, forget, and discount information that disconfirms our beliefs.