This book revives the study of conventional implicatures in natural language semantics. Since H. Paul Grice first defined the concept, his definition has seen much use and many redefinitions, but it has never enjoyed a stable place in linguistic theory. Christopher Potts returns to the original and uses it as a key into two presently under-studied areas of natural language: supplements (appositives, parentheticals) and expressives (e.g. honorifics, epithets).