The Nature of Rationality

Summary

Nozick views human rationality as an evolutionary adaptation. Its delimited purpose and function may be responsible for biases and blind spots, possibly accounting for philosophy's difficulty with perennial questions that are remote from the exigencies that drive natural selection. He offers a reformulation of the decision theory that was developed in the twentieth century to explain rational action. It should include the symbolic meaning of actions as well as a new rule of rational decision that maximizes decision value. These have implications for long-standing issues such as the Prisoner's Dilemma and for Newcomb's Problem. His proposal about rational belief has an internalist element of support by reasons that make the belief credible, and an externalist element of generation by a process that reliably produces true beliefs. Rational belief has an intellectual component, for one should not believe any statement less credible than some incompatible alternative. It also has a practical component, for one should believe a statement only if the expected utility (or decision value) of doing so is greater than that of not believing it.