What is a convention?

Ever since David Lewis’s publication of Convention: A Philosophical Study (1969) his definition of a convention has been widely accepted and marginally challenged. Andrei Marmor’s book Social Conventions: From Language to Law (2009) is both a continuation and a critical response to Lewis’s work. “Convention”, alongside “rule” and “norm”, is one of the most important and fundamental philosophical concepts. We tend to think of our behavior as human beings, of our linguistic and social actions, as largely conditioned by conventions. Marmor examines the role and significance of conventions in language, in the moral sphere, and in the legal system. His definition of convention renders language less conventional than we had thought it is and morality more so. In this review article I present Marmor’s concept of convention and follow the book’s main arguments. I then point to what I think is amiss in his account of convention, namely, the idea that some norms are conventional, which yields a conflation of norms and conventions.