“Trivers, pursuing his theory of the emotions to its logical conclusion, notes that in a world of walking lie detectors the best strategy is to believe your own lies. You can’t leak your hidden intentions if you don’t think they are your intentions. According to his theory of self-deception, the conscious mind sometimes hides the truth from itself the better to hide it from others. But the truth is useful, so it should be registered somewhere in the mind, walled off from the parts that interact with other people.”

“The more you think about and interact with other people, the more you realize that it is untenable to privilege your interests over theirs, at least not if you want them to listen to you. You can’t say that my interests are special compared to yours any more than you can say that the particular spot that I am standing on is a unique part of the universe because I happen to be standing on it that very minute.”

“Reason is up to these demands because it is an open-ended combinatorial system, an engine for generating an unlimited number of new ideas. Once it is programmed with a basic self-interest and an ability to communicate with others, its own logic will impel it, in the fullness of time, to respect the interests of ever-increasing numbers of others. It is reason too that can always take note of the shortcomings of previous exercises of reasoning, and update and improve itself in response. And if you detect a flaw in this argument, it is reason that allows you to point it out and defend an alternative.”

“Everyone has a theory of human nature. Everyone has to anticipate the behavior of others, and that means we all need theories about what makes people tick.”

“The universality of reason is a momentous realization, because it defines a place for morality. If I appeal to you do do something that affects me—to get off my foot, or not to stab me for the fun of it, or to save my child from drowning—then I can't do it in a way that privileges my interests of yours if I want you to take me seriously (say, by retaining my right to stand on your foot, or to stab you, or to let your children drown). I have to state my case in a way that would force me to treat you in kind. I can't act as if my interests are special just because I'm me and you're not, any more than I can persuade you that the spot I am standing on is a special place in the universe just because I happen to be standing on it.You and I ought to reach this moral understanding not just so we can have a logically consistent conversation but because mutual unselfishness is the only way we can simultaneously pursue our interests. You and I are both better off if we share our surpluses, rescue each other's children when they get into trouble, and refrain from knifing each other than we would be if we hoarded our surpluses while they rotted, let each other's children drown, and feuded incessantly. Granted, I might be a bit better off if I acted selfishly at your expense and you played the sucker, but the same is true for you with me, so if each of us tried for these advantages, we'd both end up worse off. Any neutral observer, and you and I if we could talk it over rationally, would have to conclude that the state we should aim for is the one where we both are unselfish.Morality, then, is not a set of arbitrary regulations dictated by a vengeful deity and written down in a book; nor is it the custom of a particular culture or tribe. It is a consequence of the interchangeability of perspectives and the opportunity the world provides for positive-sum games.”

“Though many of my arguments will be coolly analytical — that an acknowledgment of human nature does not, logically speaking, imply the negative outcomes so many people fear — I will not try to hide my belief that they have a positive thrust as well. "Man will become better when you show him what he is like," wrote Chekhov, and so the new sciences of human nature can help lead the way to a realistic, biologically informed humanism. They expose the psychological unity of our species beneath the superficial differences of physical appearance and parochial culture. They make us appreciate the wondrous complexity of the human mind, which we are apt to take for granted precisely because it works so well. They identify the moral intuitions that we can put to work in improving our lot. They promise a naturalness in human relationships, encouraging us to treat people in terms of how they do feel rather than how some theory says they ought to feel. They offer a touchstone by which we can identify suffering and oppression wherever they occur, unmasking the rationalizations of the powerful. They give us a way to see through the designs of self-appointed social reformers who would liberate us from our pleasures. They renew our appreciation for the achievements of democracy and of the rule of law. And they enhance the insights of artists and philosophers who have reflected on the human condition for millennia.”

“Thinking is computation, I claim, but that does not mean that the computer is a good metaphor for the mind. The mind is a set of modules, but the modules are not encapsulated boxes or circumscribed swatches on the surface of the brain. The organization of our mental modules comes from our genetic program, but that does not mean that there is a gene for every trait or that learning is less important than we used to think. The mind is an adaptation designed by natural selection, but that does not mean that everything we think, feel, and do is biologically adaptive. We evolved from apes, but that does not mean we have the same minds as apes. And the ultimate goal of natural selection is to propagate genes, but that does not mean that the ultimate goal of people is to propagate genes.”