Wittgenstein's On CertaintyEven Wittgensteins admirers have been puzzled by his last work, On Certainty. Some even regard it as a lapse at the end of a distinguished career, or as a late epistemological interest that remained undeveloped. Rush Rhees, a close friend of Wittgenstein and a major interpreter of his work, shows how Wittgensteins On Certainty concerns logic, language and reality topics that occupied Wittgenstein from early in his career. From his earliest work on the