Normativity in Lewis' and Bicchieri's Accounts of Conventions and Norms

Abstract Lewis [3] argues that, generally, we ought to conform to conventions because that answers (1) our own preferences, and (2) the preferences of others. While (1) is based on instrumental rationality, (2) is based on a moral principle or norm: other things being equal, we should do what answers others' preferences. Bicchieri [1] claims there is a third kind of normativity, neither rational nor moral, that applies to social norms. I argue that conventions draw their normativity from instrumental rationality and other independent moral principles or norms, and that it is unclear what further normativity could there be.