Why a Gricean-style defense of the vacuous truth of counterpossibles won’t work, but a defense based on heuristics just might

Abstract

AbstractCounterpossibles are counterfactuals with an impossible antecedent. According to the orthodox view of counterfactuals, all counterpossibles are vacuously true. This is puzzling because some counterpossible statements seem to be false. The paper analyzes two approaches to explaining why certain counterpossibles, though perhaps true, may appear to be false. The first, which appeals to the Gricean mechanism of conversational implicatures, asserts that some counterpossibles appear to be false because their assertion carries with it a false conversational implicature. However, I argue that, under a closer scrutiny, this approach collapses. I therefore turn to a second approach, proposed by Timothy Williamson. It appeals to a heuristic according to which speakers may regard a counterpossible to be false if they have previously accepted its opposite. Since the applicability of Williamson’s solution is limited, I suggest a more general account. Its underlining idea is that a counterpossible is rejected if the speaker cannot find what they regard as a universally true conditional function derivable from the counterpossible by substitutions and syntactic transformations.