 Stalnaker (1984) defends a coarse-grained account of belief contents, which individuates particular belief states in terms of a set of possible worlds that would make them true. If this project is to succeed, it must be possible to fully specify beliefs without invoking anything like Fregean senses or conceptual structure. But there is an important class of beliefs that seem to pose insuperable problems for a simple possible worlds account of their content: beliefs in necessary truths. The problem for a standard possible worlds analysis is that all necessary truths have precisely the same content (the function mapping every world to True). So the belief that Hesperus = Phosphorus will have exactly the same content as a belief that Hesperus = Hesperus &amp; Fermat’s last theorem is true. But these are clearly distinct belief states. Beliefs in identities have been particularly important in motivating theories of finer-grained thought contents.