Saying the Same Thing

Against hyperintensional accounts of propositional contents, such as truthmaker semantics, impossible worlds semantics, structured propositions, and Fregean senses, Williamson has defended the Claim that such contents are to be taken as sets of possible worlds, resorting to guises while explaining away putative counterexamples as by-products of fallible cognitive heuristics. The workings of same-saying raise issues for the general applicability of the strategy: one can multiply ad libitum examples of co-intensional sentences saying different things, where guises won’t help the Claim, because they make no relevant cognitive difference. Besides, this is not even a catastrophe for possible worlds semantics.