Among the more remarkable qualities of human beings is that they describe and explain their own minds and behavior. People are self-explainers and self-understanders. By and large, though not invariably, of course, people's efforts to understand themselves are couched in a familiar language: the language of belief, desire, intention, hope, and so forth—the language of intentional mental states. Perhaps just as remarkable is that people are "mindreaders" (Nichols and Stich 2003). In everyday commerce people attribute—sometimes unself-consciously, sometimes painfully and with great difficulty—to others intentional mental states.

Humans are social creatures—competitive and cooperative—and the practice of attributing intentional mental states is, by and large, the vehicle whereby they come to understand others and others come to understand them, and so, this practice is fundamental to efforts to navigate the social world. One is often able to anticipate or to predict what another...