A Theory of Justice

In undergrad, reading these two books really changed my outlook. I went in skeptical and a little conspiratorial and these helped bring me closer to reality and even a little hopeful. - The Cost of Rights (1999) by Stephen Holmes and Cass Sunstein - A Theory of Justice (1971) by John Rawls

Check out A Theory of Justice by John Rawls. Best challenge to Utilitarian thinking I know of. (E.g. slavery is wrong not because bad outweighs good, but rather because it is inherently wrong when seen from the perspective of the original position)

Most of the "eye-opening or incredibly interesting" philosophical material that I've read has been in individual articles rather than books. That said, here are a few favourites from various areas. It's a bit heavily weighted towards recent material; Kant and Plato ought to be on there, but I can't stand Kant as a writer, even if his ideas are profound, and Plato's style has always irritated me for some reason I can't quite put my finger on. I could probably keep tying titles all day, so I'll stop with those that first popped into my head. Aristotle, Nicomachean Ethics David Chalmers, The Conscious Mind: In Search of a Fundamental Theory Gottlob Frege, Die Grundlagen der Arithmetik Thomas Hobbes, Leviathan David Hume, An Enquiry Concerning Human Understanding J.S. Mill, On Liberty John Rawls, A Theory of Justice Stewart Shapiro, Philosophy of Mathematics: Structure and Ontology

A couple by Stanley Cavell: Must We Mean What We Say? (1969) The Claim of Reason: Wittgenstein, Skepticism, Morality, and Tragedy (1979) New York: Oxford University Press. I would also second Russell's A Brief History of Western Philosophy. It's biased and weirdly shallow in some places, but written by a philosopher, so not a toothless compilation. Obscure but made an impression on me: Ways of Worldmaking by Nelson Goodman. If you can get through it: John Rawls's A Theory of Justice...an important book with a few very important ideas. Stuff by Amartya Sen. On philosophy of science, the historical narratives do the job I think, like The Sleepwalkers by Arthur Koestler (a great read once you get through the Greeks). You could read Thomas Kuhn, Feyerabend's autobiography "Killing Time" which is great, and if you're really serious read Peter Galison's stuff. Finally, again, more history that pure philosophy but I really liked Wittgenstein's Vienna by Toulmin.