The Coat Problem. Counterfactuals, Truth-makers, and Temporal specification

Standard semantic treatments of counterfactuals appeal to a relation of similarity between possible worlds. Similarity, however, is a vague notion. Lewis suggests reducing the vagueness of similarity by adopting a principle known as 'late departure' (LD): the more the past two worlds share, the more they are similar. LD has several virtues. However, as Bennett points out, a standard semantics based on LD suffers from the so-called coat problem. In a nutshell, we are led to assign counterintuitive truth-values to counterfactuals whose antecedent time is left underspecified. In the present paper, we argue that the coat problem may be solved by defining a time-sensitive notion of similarity. To illustrate, we assume a Priorean, tensed language, interpreted on branching-time frames in the usual, 'Ockhamist' way, and we enrich it with a counterfactual connective. Within this framework, we define a time-sensitive relation of similarity, based on Yablo's work on truth-makers and partial truth. In the resulting semantics, which has independent interest, the coat problem does not arise.