No serious philosopher or student of philosophy can afford to neglect Wittgenstein's work. Professor Fogelin provides an authoritative critical evaluation of both the Tractatus Logico-Philosophicus and Philosophical Investigations , enabling the reader to come to grips with these difficult yet key works. Fogelin explains Wittgenstein's attempt in the Tractatus to combine a picture theory of propositional structure, and also explores Wittgenstein's own criticisms of the Tractarian synthesis. He gives particular attention to topics in the philosophy of language, logic, psychology and the foundations of mathematics, examining Wittgenstein's work on these fields and arguing that Wittgenstein's criticisms in these areas form the basis for a radically new standpoint in philosophy.