Ideas can, and do, change the world. Just as Marxism, existentialism, and feminism shaped the last century, so are fundamentalism, globalization, and bioethics transforming our world now. In Ideas That Matter, renowned philosopher A. C. Grayling provides a personal and heartfelt guide to the ideas—past and present—that will shape our future. With customary wit, fire, and erudition, Grayling ranges across the gamut of essential theories, movements, and philosophies—from animal rights to neurophilosophy to war crimes—to deliver a rich, elucidating book intended both to arm readers with vital knowledge and to engage them in provocative philosophical debate.