David Lewis tends to use the notion of knowledge in an intuitive way, and it is the burden of his contextualist relevant alternatives theory to fit this intuitive usage. The chapter begins with a review of Lewis's contribution to the theory of knowledge. This involves presenting both his elegant version of relevant alternatives theory, and his detailed version of contextualism, and then displaying the combined account and its claimed virtues. The relevance of a possibility at a context is determined by (...) all and only the rules of Actuality, Belief, Resemblance, Reliability, Method, Conservatism, and Attention. The main virtue which Lewis claims for Lewisian knowledge ascription is that of reconciling infallibilism with anti‐skepticism. It should be stressed that the intensional framework, as developed by Lewis and others, represents the best developed semantic framework to date. The relevant alternatives theory can extend very smoothly to at least some potential successor frameworks. (shrink)