Counterfactuals, Accessibility, and Comparative Similarity

Berit Brogaard and Joe Salerno (2008) have defended the validity of counterfactual hypothetical syllogism (CHS) within the Stalnaker-Lewis account. Whenever the premisses of an instance of CHS are non-vacuosly true, a shift in context has occurred. Hence the standard counterexamples to CHS suffer from context failure. Charles Cross (2011) rejects this argument as irreconcilable with the Stalnaker-Lewis account. I argue against Cross that the basic Stalnaker-Lewis truth condition may be supplemented in a way that makes (CHS) valid. Yet pace Brogaard and Salerno, there are alternative ways of spelling out the basic truth condition which are standard in most debates; and given these ways, the counterexamples to CHS are successful.