This book consists of fifteen dialogues between Bryan Magee and some of the outstanding thinkers of the twentieth century. It is based on a highly successful BBC television series which had enormous impact. The informality and clarity of the conversational form makes even the most difficult ideas accessible to the general reader. Isaiah Berlin opens by considering the fundamental question ''What is philosophy?'' Subsequent conversations examine such widely different schools as Marxism and existentialism. Chomsky, Quine, Marcuse, and others discuss their own work; A. J. Ayer reviews logical positivism; Iris Murdoch talks about the relation between philosophy and literature. Moral philosophy, political philosophy, the philosophy of language, and the philosophy of science are all treated in depth by the thinkers whose work has shaped the fields.