He is best known for his investigations of linguistic meanings, or semantics. He advocates the view that the meaning of an expression is fixed by how it is used in inferences (see inferential role semantics). This project is developed at length in his influential 1994 book "Making It Explicit", and more briefly in "Articulating Reasons: An Introduction to Inferentialism" (2000); a chapter of that latter work, "Semantic Inferentialism and Logical Expressivism", outlines the main themes of representationalism (the tradition of basing semantics on the concept of representation) vs. inferentialism (the conviction for an expression to be meaningful is to be governed by a certain kind of inferential rules) and inferentialism's relationship to logical expressivism (the conviction that "logic is expressive in the sense that it makes explicit or codifies certain aspects of the inferential structure of our discursive practice").