Hyperintensionality, opacity, and counterpossibles

Series: Logic and Philosophy

Abstract: According to the orthodoxy, counterpossibles (i.e., counterfactuals with an impossible antecedent) are all vacuously true (Stalnaker 1968, Lewis 1973, Williamson 2017). However, a growing number of reformers defend the idea that some counterpossibles are false and not all true by default (Brogaard and Salerno 2013, Berto et al. 2017, among others).

One can motivate this alternative view by providing intuitive examples of false counterpossibles, but there are deeper reasons to oppose the tradition. Several metaphysicians have recently argued that important metaphysical notions behave in a hyperintensional way (Nolan 2014) and that this hyperintensional character is logically connected to the falsity of some counterpossibles (Wilson 2016).

I propose in this presentation to explore this connection further. On the one hand, I will defend at a general level the idea that philosophers who believe that there is hyperintensionality in metaphysics must abandon the traditional conception of counterpossibles. On the other hand, I will insist that there are many ways to carry out this program, and that a persistent confusion between hyperintensionality and opacity has so far prevented many reformers from doing so in a coherent way.