'The most common of all follies,' wrote H. L. Mencken, 'is to believe passionately in the palpably not true. It is the chief occupation of mankind.' In culture after culture, people believe that the soul lives on after death, that rituals can change the physical world and divine the truth, and that illness and misfortune are caused and alleviated by spirits, ghosts, saints . . . and gods.

Some people think that evolutionary psychology claims to have discovered that human nature is selfish and wicked. But they are flattering the researchers and anyone who would claim to have discovered the opposite. No one needs a scientist to measure whether humans are prone to knavery. The question has been answered in the history books, the newspapers, the ethnographic record, and the letters to Ann Landers. But people treat it like an open question, as if someday science might discover that it's all a bad dream and we will wake up to find that it is human nature to love one another.”

Visual thinking is often driven more strongly by the conceptual knowledge we use to organize our images than by the contents of the images themselves. Chess masters are known for their remarkable memory for the pieces on a chessboard. But it's not because people with photographic memories become chess masters. The masters are no better than beginners when remembering a board of randomly arranged pieces. Their memory captures meaningful relations among the pieces, such as threats and defenses, not just their distribution in space.

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Suppose the reasoning centers of the brain can get their hands on the mechanisms that plop shapes into the array and that read their locations out of it. Those reasoning demons can exploit the geometry of the array as a surrogate for keeping certain logical constraints in mind. Wealth, like location on a line, is transitive: if A is richer than B, and B is richer than C, then A is richer than C. By using location in an image to symbolize wealth, the thinker takes advantage of the transitivity of location built into the array, and does not have to enter it into a chain of deductive steps. The problem becomes a matter of plop down and look up. It is a fine example of how the form of a mental representation determines what is easy or hard to think.

Humans . . . entered the 'cognitive niche.' Remember the definition of intelligence from Chapter 2: using knowledge of how things work to attain goals in the face of obstacles. By learning which manipulations achieve which goals, humans have mastered the art of the surprise attack. They use novel, goal-oriented courses of action to overcome the Maginot Line defenses of other organisms, which can respond only over evolutionary time. The manipulations can be novel because human knowledge is not just couched in concrete instructions like 'how to catch a rabbit.' Humans analyze the world using intuitive theories of objects, forces, paths, places, manners, states, substances, hidden biochemical essences, and, for other animals and people, beliefs and desires. . . . People compose new knowledge and plans by mentally playing out combinatorial interactions among these laws in their mind's eye.

Stripped to its essentials, every decision in life amounts to choosing which lottery ticket to buy. . . . Most organisms don't buy lottery tickets, but they all choose between gambles every time their bodies can move in more than one way. They should be willing to 'pay' for information---in tissue, energy, and time---if the cost is lower than the expected payoff in food, safety, mating opportunities, and other resources, all ultimately valuated in the expected number of surviving offspring. In multicellular animals the information is gathered and translated into profitable decisions by the nervous system.

The human brain is an exquisitely complex organ that evolved only once. The elephant's trunk, which can stack logs, uproot trees, pick up a dime, remove thorns, powder the elephant with dust, siphon water, serve as a snorkel, and scribble with a pencil, is another complex organ that evolved only once.

Intelligence, then, is the ability to attain goals in the face of obstacles by means of decisions based on rational (truth-obeying) rules. The computer scientists Allen Newell and Herbert Simon fleshed this idea out further by noting that intelligence consists of specifying a goal, assessing the current situation to see how it differs from the goal, and applying a set of operations that reduce the difference. Perhaps reassuringly, by this definition human beings, not just aliens, are intelligent. We have desires, and we pursue them using beliefs, which, when all goes well, are at least approximately or probabilistically true.

The idea that thought is the same thing as language is an example of what can be called a conventional absurdity: a statement that goes against all common sense but that everyone believes because they dimly recall having heard it somewhere and because it is so pregnant with implications.

Evolutionary psychology was the organizing framework—the source of “explanatory adequacy” or a “theory of the computation”—that the science of psychology had been missing. Like vision and language, our emotions and cognitive faculties are complex, useful, and nonrandomly organized, which means that they must be a product of the only physical process capable of generating complex, useful, nonrandom organization, namely, natural selection. An appeal to evolution was already implicit in the metatheoretical directives of Marr and Chomsky, with their appeal to the function of a mental faculty, and evolutionary psychology simply shows how to apply that logic to the rest of the mind.

The elegant study... is consistent with the themes of modern cognitive neuroscience. Every aspect of thought and emotion is rooted in brain structure and function, including many psychological disorders and, presumably, genius. The study confirms that the brain is a modular system comprising multiple intelligences, mostly nonverbal.

To a linguist, the phenomenon is familiar: the euphemism treadmill. People invent new "polite" words to refer to emotionally laden or distasteful things, but the euphemism becomes tainted by association and the new one that must be found acquires its own negative connotations. "Water closet" becomes "toilet" (originally a term for any body care, as in "toilet kit"), which becomes "bathroom," which becomes "rest room," which becomes "lavatory." … The euphemism treadmill shows that concepts, not words, are in charge. Give a concept a new name, and the name becomes colored by the concept; the concept does not become freshened by the name. (We will know we have achieved equality and mutual respect when names for minorities stay put.)