Hilary Putnam is one of Americas most important and influential contemporary philosophers. He has made considerable contributions to the philosophy of mind, philosophy of language, philosophy of science, philosophy of mathematics, logic, metaphysics and ethics. In many of these areas he has been not only an active participant, but a foundational thinker. This book offers an overview of Putnam's ideas, his key writings and his contributions to the various fields of philosophy. Thematically organized, the book begins with Putnam's work in the philosophy of language and shows how his theory of semantic externalism serves as a lynchpin for understanding his thought as a whole. Crucially, the author also examines the ways in which Putnam has shifted his position on some key philosophical issues and argues that there is in fact more unity to Putnam's thought than is widely believed. An entire chapter is devoted to Putnams pragmatism and the possibilities this provides for revitalizing contemporary philosophy. This is the ideal companion to study of this hugely influential thinker.