Rush Rhees, a close friend of Wittgenstein and a major interpreter of his work, shows how Wittgenstein's On Certainty concerns logic, language, and reality – topics that occupied Wittgenstein since early in his career.

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• Authoritative interpretation of Wittgenstein's last great work, On Certainty, by one of his closest friends.
  
• Debunks misconceptions about Wittgenstein's On Certainty and shows that it is an essay on logic.
  
• Exposes the continuity in Wittgenstein's thought, and the radical character of his conclusions.
  
• Contains a substantial and illuminating afterword discussing current scholarship surrounding On Certainty, and its relationship to Rhees's work on this subject.