How Close Are Impossible Worlds? A Critique of Brogaard and Salerno's Account of Counterpossibles

Several theorists have been attracted to the idea that in order to account for counterpossibles, i.e. counterfactuals with impossible antecedents, we must appeal to impossible worlds. However, few have attempted to provide a detailed impossible worlds account of counterpossibles. Berit Brogaard and Joe Salerno's “Remarks on Counterpossibles” is one of the few attempts to fill in this theoretical gap. In this article, I critically examine their account. I prove a number of unanticipated implications of their account that end up implying a counterintuitive result. I then examine a suggested revision and point out a surprising implication of the revision.