Robert Nozick, Arthur Kingsley Porter Professor of Philosophy at Harvard, was one of America's most original, insightful, controversial, and thorough modern philosophers(read him and you'll see what I mean). He first became known with his foundational text on Libertarianism, Anarchy, State, and Utopia (1974), which won the National Book Award in 1975. In it, Nozick describes why the minimal state is not only the only moral society, but how it can also be inspiring to live in. He describes his minimal state as a Framework for Utopia, not a fleshed out society in and of itself, but the only infrastructure where a true utopia might arise.
He later broadened himself with Philosophical Explanations (1981), winner of the Ralph Waldo Emerson Phi Beta Kappa award, a book that tackles almost every age old philosophical dilemma. It focuses on asking questions, not "solving" them once and for all. The major sections of that book are:
The Identity of the self
Why is there something rather than nothing?
Knowledge and skepticism
Foundations of Ethics
PHILOSOPHY AND THE MEANING OF LIFE
Full of nifty little diagrams and astonishing insight, Philosophical Explanations is one of the best books I've ever read.
In 1989, he followed up with The Examined Life, a series of Philosophical Meditations that run from the nature of enlightenment experiences to the philosophical implications of the Holocaust. In it, Nozick tempers his libertarian views slightly when he decides that some things are some important that they must be made official through government action- which may even be more symbolic than effective.
In 1993, Nozick published The Nature of Rationality, which tries to understand the way the principles behind rational (and human) thought.
He published a collection of papers and essays in 1999 called Socratic Puzzles, and his final book, Invariances : The Structure of the Objective World, was published in October, 2001.
He died of stomach cancer on the morning of January 23, 2002.