Clothes, shoes, hairstyles, ideas and activities may be more or less fashionable. But what is it to be fashionable? What do fashionable things have in common? It seems that if something is fashionable – clothes, shoes, hairstyles, ideas or activities – then those things must stand in relation to people who think certain things about them or experience them or engage with them in certain ways. Being fashionable seems like being famous in that it is what philosophers call a “relational property.” If something is famous then it stands in a certain relation to people who know of it. And, similarly, if something is fashionable, then it stands in relation to people who think certain things about it or experience or engage with it in certain ways. Thus understood, both the notions of fame and fashion refer to social relations, and there are facts about what is and what is not fashionable. These facts are relative facts, but facts nonetheless. Presumably if a person...