Does Chance Undermine Would?

Abstract

Counterfactual scepticism holds that most ordinary counterfactuals are false. The main argument for this view appeals to a ‘chance undermines would’ principle: if ψ would have some chance of not obtaining had ϕ obtained, then $\varphi \square \to \psi$ is false. This principle seems to follow from two fairly weak principles, namely, that ‘chance ensures could’ and that $\varphi \square \to \psi$ and $\varphi \diamond \to \neg \psi$ clash. Despite their initial plausibility, I show that these principles are independently problematic: given some modest closure principles, they entail absurdities. Moreover, on the most promising strategy for saving these principles, they do not, in the relevant sense, entail the chance-undermines-would principle. Instead, they entail a principle that only supports counterfactual indeterminism, the view that most ordinary counterfactuals are chancy, that is, not settled true. I demonstrate this by developing an indeterminist semantics that vindicates the clash and chance-ensures-could principles but not the chance-undermines-would principle. This view, I argue, offers a better account of our credal and linguistic judgements than counterfactual scepticism.