Conventions without knowledge of conformity

David Lewis’s account of conventions has received substantial criticism over the years, but one aspect of it has been less controversial and thus has been retained in various forms by other authors: his requirement that members of a group in which a convention obtains must know that they and others conform. I argue that knowledge of conformity requirements wrongly exclude certain paradigmatic conventions, including some central semantic conventions. Ruth Garrett Millikan’s account of conventions accommodates these cases, but it is marred by her (as I argue) mistaken claim that most linguistic conventions involve coordination, and by complications with her central notion of reproduction. Aiming to build upon Millikan’s insights while avoiding her account’s problems, I contend that doing A is conventional in groups in which there is widespread, interconnected copying of doing A as a way of doing something further, B, where there are other equally good and accessible ways to do B.