The material interpretation of the conditional is motivated by attractive principles of logic. As an account of the conditional in natural language, however, it is widely thought to suffer from two major drawbacks. One is that it appears to be in conflict with speakers’ judgments about the truth-value of many conditionals. The other is that its prospects for incorporation into a unified view of indicative and subjunctive conditionals appear dimmer than those of contextualist possible-worlds views. Williamson’s book is broadly organized as a defense of the material interpretation against these two challenges.
All material conditionals with false antecedents are true; many indicative conditionals with false antecedents are naturally judged to be false. One major contribution of Williamson’s book is his account of the source of this discrepancy. In his view, it comes not from an implicature but from a psychological heuristic we use to evaluate conditionals. This heuristic is what...
