Abstract
This book addresses three kinds of readers. Academics working inside or outside philosophy should find explanations of key terms and issues in Wittgenstein's work, and be able to find out what impact it might have on their own. At the end of entries, I sometimes indicate briefly what impact it has actually had, but for detailed information one should consult the items listed in the Bibliography of Secondary Sources. Students working on Wittgenstein or related topics (Frege, Russell, philosophical logic, metaphysics, epistemology, philosophy of mind) should find an account of major exegetical and substantive problems. Wittgenstein scholars should find a state‐of‐the‐art discussion, as well as some new ideas. I have striven for a comprehensive coverage of the topics, but it is synthetic a priori that I have failed.