Book excerpt: Based on a highly successful BBC television series, this book presents fifteen dialogues between author and broadcaster Bryan Magee and some of the most important thinkers of the twentieth century. Isaiah Berlin considers the fundamental question, "What is philosophy?," A. J. Ayer reviews logical positivism, and 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 who have shaped these fields--including Noam Chomsky, W. V. O. Quine, and Herbert Marcuse. Written in an informal, conversational style, even the most difficult philosophical ideas are made accessible to the general reader.