Lewis on Williamson: Evidence, Knowledge and Vagueness

In May 1999, David Lewis sent Timothy Williamson an intriguing letter about knowledge and vagueness. This paper has a brief discussion of Lewis on evidence, and a longer discussion of a distinctive theory of vagueness Lewis puts forward in this letter, one rather different from standard forms of supervaluationism. Lewis's theory enables him to provide distinctive responses to the challenges to supervaluationism famously offered in chapter 5 of Timothy Williamson's 1994 book Vagueness. However these responses bring out a number of very surprising features of Lewis's own view. The letter from Lewis itself is available on the blog of The Age of Metaphysical Revolution Project, University of Manchester.