Nozick Robert (b.1938), American philosopher currently at Harvard University, best known for Anarchy, State, and Utopia (1974), which defends the libertarian position that only a minimal state (limited to protecting rights) is just. Nozick argues that a minimal state, but not a more extensive state, could arise without violating rights. Drawing on Kant’s dictum that people may not be used as mere means, Nozick says that people’s rights are inviolable, no matter how useful violations might be to the state. He criticizes principles of redistributive justice on which theorists base defenses of extensive states, such as the principle of utility, and Rawls’s principle that goods should be distributed in favor of the least well-off. Enforcing these principles requires eliminating the cumulative effects of free exchanges, which violates (permanent, bequeathable) property rights. Nozick’s own entitlement theory says that a distribution of holdings is just if people under that distribution are entitled to what they hold. Entitlements, in turn, would be clarified using principles of justice in acquisition, transfer, and rectification. Nozick’s other works include Philosophical Explanations (1981), The Examined Life (1989), The Nature of Rationality (1993), and Socratic Puzzles (1997). These are contributions to rational choice theory, epistemology, metaphysics, philosophy of mind, philosophy of religion, and ethics. Philosophical Explanations features two especially important contributions. The first is Nozick’s (reliabilist, causal) view that beliefs that constitute knowledge must track the truth. My belief that (say) a cat is on the mat tracks the truth only if (a) I would not believe this if a cat were not on the mat, and (b) I would believe this if a cat were there. The tracking account positions Nozick to reject the principle that people know all of the things they believe via deductions from things they know, and to reject versions of skepticism based on this principle of closure. The second is Nozick’s closest continuer theory of identity, according to which A’s identity at a later time can depend on facts about other existing things, for it depends on (1) what continues A closely enough to be A and (2) what continues A more closely than any other existing thing. Nozick’s 1969 essay ‘Newcomb’s Problem and Two Principles of Choice’ is another important contribution. It is the first discussion of Newcomb’s problem, a problem in decision theory, and presents many positions prominent in subsequent debate. See also CLOSURE , NEWCOMB ‘S PARADOX, POLITICAL PHILOSOPHY, RAWL. S.L.