Opacity and the double life of singular propositions

In this paper I analyze David Kaplan’s essay “Opacity”. In “Opacity” Kaplan attempts to dismiss Quine’s concerns about quantification across intensional (modal and intentional) operators. I argue that Kaplan succeeds in showing that quantification across intensional operators is logically coherent and that quantified modal logic is strictly speaking not committed to essentialism. However, I also argue that this is not in and of itself sufficient to support Kaplan’s more ambitious attempt to move beyond purely logical results and provide unified, uncontroversial interpretations of both “believes” and “necessarily”. In the paper I raise several questions about the subject matter of logic and the role of semantics, with special focus on singular propositions.