Abstract

Proponents of conditional logics such as David Lewis and Robert Stalnaker reject inferences containing counterfactuals from "if A, B" and "if B, C" to "if A, C" due to ordinary language counterexamples. Contextualists defend this inference rule called "hypothetical syllogism" or "transitivity" on the basis of a possible word semantics, which, however, assigns implausible truth values to certain counterfactuals. My defence of hypothetical syllogism avoids this problem, as it rests on Nelson Goodman's uncontroversial, metaphysically parsimonious assumption that we accept counterfactuals as true only under certain conditions from which, in conjunction with the antecedent, the consequent can be inferred. The counterexamples to hypothetical syllogism can be rebutted because their premises are doxastically noncotenable; that is, there is no set of conditions under which the premises can be accepted as jointly true.