In clear, precise, and non-technical language, Chomsky elaborates on fifty years of scientific development in the study of language, sketching how his own work has implications for the origins of language, the close relations that language bears to thought, and its eventual biological basis. He expounds and criticizes many alternative theories, such as those that emphasize the social, the communicative, and the referential aspects of language. Chomsky reviews how new discoveries about language overcome what seemed to be highly problematic assumptions in the past. He also investigates the apparent scope and limits of human cognitive capacities and what the human mind can seriously investigate, in the light of history of science and philosophical reflection and current understanding. Moving from language and mind to society and politics, he concludes with a searching exploration and philosophical defense of a position he describes as "libertarian socialism," tracing its links to anarchism and the ideas of John Dewey, and even briefly to the ideas of Marx and Mill, demonstrating its conceptual growth out of our historical past and urgent relation to matters of the present.