Robert Nozick

However, Jeff Riggenbach has noted that in an interview conducted in July 2001, he stated that he had never stopped self-identifying as a libertarian. Roderick Long reported that in his last book, Invariances, "[Nozick] identified voluntary cooperation as the 'core principle' of ethics, maintaining that the duty not to interfere with another person's 'domain of choice' is '[a]ll that any society should (coercively) demand'; higher levels of ethics, involving positive benevolence, represent instead a 'personal ideal' that should be left to 'a person's own individual choice and development.' And that certainly sounds like an attempt to embrace libertarianism all over again. My own view is that Nozick's thinking about these matters evolved over time and that what he wrote at any given time was an accurate reflection of what he was thinking at that time." Furthermore, Julian Sanchez reported that "Nozick always thought of himself as a libertarian in a broad sense, right up to his final days, even as his views became somewhat less 'hardcore.'"

His last production, Invariances (2001), applies insights from physics and biology to questions of objectivity in such areas as the nature of necessity and moral value.

In his 2001 work, Invariances, Nozick introduces his theory of truth, in which he leans towards a deflationary theory of truth, but argues that objectivity arises through being invariant under various transformations. For instance, space-time is a significant objective fact because an interval involving both temporal and spatial separation is invariant, whereas no simpler interval involving only temporal or only spatial separation is invariant under Lorentz transformations. Nozick argues that invariances, and hence objectivity itself, emerged through a theory of evolutionary cosmology across possible worlds.

Socratic Puzzles (1997) is a collection of papers that range in topic from Ayn Rand and Austrian economics to animal rights. A thesis claims that "social ties are deeply interconnected with vital parts of Nozick's later philosophy", citing these two works as a development of The Examined Life.

The Nature of Rationality (1993) presents a theory of practical reason that attempts to embellish notoriously spartan classical decision theory.

The Examined Life (1989), pitched to a broader public, explores love, death, faith, reality, and the meaning of life. According to Stephen Metcalf, Nozick expresses serious misgivings about capitalist libertarianism, going so far as to reject much of the foundations of the theory on the grounds that personal freedom can sometimes only be fully actualized via a collectivist politics and that wealth is at times justly redistributed via taxation to protect the freedom of the many from the potential tyranny of an overly selfish and powerful few. Nozick suggests that citizens who are opposed to wealth redistribution which fund programs they object to, should be able to opt out by supporting alternative government approved charities with an added 5% surcharge.

In Philosophical Explanations (1981), which received the Phi Beta Kappa Society's Ralph Waldo Emerson Award, Nozick provided novel accounts of knowledge, free will, personal identity, the nature of value, and the meaning of life. He also put forward an epistemological system which attempted to deal with both the Gettier problem and those posed by skepticism. This highly influential argument eschewed justification as a necessary requirement for knowledge.

For Anarchy, State, and Utopia (1974) Nozick received a National Book Award in the category Philosophy and Religion. There, Nozick argues that only a minimal state limited to the narrow functions of protection against "force, fraud, theft, and administering courts of law" could be justified, as any more extensive state would violate people's rights. For Nozick, a distribution of goods is just if brought about by free exchange among consenting adults from a just starting position, even if large inequalities subsequently emerge from the process.

Nozick attended the public schools in Brooklyn. He was then educated at Columbia University (A.B. 1959, summa cum laude), where he studied with Sidney Morgenbesser; Princeton University (PhD 1963) under Carl Hempel; and at Oxford University as a Fulbright Scholar (1963–1964). At one point, he joined the YPSL. In addition, at Columbia he founded the local chapter of the Student League for Industrial Democracy which in 1960 changed its name to Students for a Democratic Society.

After receiving his undergraduate degree in 1959, he married Barbara Fierer. They had two children, Emily and David. The Nozicks eventually divorced; Nozick later married the poet Gjertrud Schnackenberg. Nozick died in 2002 after a prolonged struggle with stomach cancer. He was interred at Mount Auburn Cemetery in Cambridge, Massachusetts.

Robert Nozick (/ˈnoʊzɪk/; November 16, 1938 – January 23, 2002) was an American philosopher. He held the Joseph Pellegrino University Professorship at Harvard University, and was president of the American Philosophical Association. He is best known for his books Anarchy, State, and Utopia (1974), a libertarian answer to John Rawls' A Theory of Justice (1971), in which Nozick also presented his own theory of utopia as one in which people can freely choose the rules of the society they enter into, and Philosophical Explanations (1981), which included his counterfactual theory of knowledge. His other work involved ethics, decision theory, philosophy of mind, metaphysics and epistemology. His final work before his death, Invariances (2001), introduced his theory of evolutionary cosmology, by which he argues invariances, and hence objectivity itself, emerged through evolution across possible worlds.