Ludwig Wittgenstein is arguably the most important philosopher of the twentieth-century. In "On Certainty" he discusses central issues in epistemology concerning the nature of knowledge and scepticism. "The Routledge Philosophy Guidebook to Wittgenstein and On Certainty" introduces and assesses: Wittgenstein's life and the background to his later philosophy the central ideas and text of "On Certainty," including its links with the arguments of G.E. Moore and its discussion of some fundamental issues in the theory of knowledge Wittgenstein's continuing importance and influence on contemporary philosophy. This "GuideBook" is essential reading for all students of Wittgenstein, as well as those studying epistemology and philosophy of language. It considers the place of "On Certainty," Wittgenstein's final work, in his late philosophy. "On Certainty" addresses a neglected category of propositions discovered by G.

E. Moore; for Wittgenstein they make up a "world-picture," and challenge his career-long view that there is a clearly-defined category of empirical propositions. The "GuideBook "offers a dynamic interpretation of world-picture propositions, as subject to transformation and yielding alternative world-pictures. It relates them to "On Certainty"'s critique of scepticism, developing Wittgenstein's critique of the sceptic's challenge as self-undermining. Its combative yet therapeutic interpretation of "On Certainty" locates within an opposition between Kantian and Humean naturalistic standpoints. It offers a critique of quietism, and of the "resolute reading" of nonsense, and concludes by showing how "On Certainty" is a classic within a humanistic conception of philosophy, essentially open to a range of interpretations.".