Probabilistic Might and the Free Choice Effect ∗ Paolo Santorio University of Leeds Jacopo Romoli University of Ulster Draft of September 3, 2014 Synopsis This paper brings together two strands of literature about epistemic modality. The first concerns the relation between probability and the semantics of modal verbs like might. The second concerns the pragmatic effects associated to modals like might, and in particular the so-called free choice effect. These two debates have proceeded independently so far. We show that they shouldn’t: a probabilistic semantics for modals like might yields an elegant and straightforward account of the free choice effect. On the one hand, this gives us a new way to explain a very recalcitrant phenomenon. On the other, it provides (as far as we know, for the first time) a straightforward argument for a probabilistic semantics for might—or at least, for a semantics that yields an equivalent logic. Despite the widespread use of probability throughout philosophy, the idea that probability might be involved in the semantics for modal expressions like might, must, or even probably, is relatively recent. Classical work in the semantics for modality (for example Kratzer 1981, 1991, 2012) treats all modals with standard quantificational tools, often supplemented with a closeness relation analogous to the one that Stalnaker (1968) and Lewis (1973) employed for the semantics of conditionals. Recently, several writers have argued that this account fails for the case of probably and likely, and that we need rather an account involving probability measures. The evidence for a probabilistic treatment of probably is (perhaps unsurprisingly) pretty strong. But it’s controversial whether this evidence has any bearing on other epistemic modal expressions like might and must. The free choice effect is a meaning effect associated to all existential modals, including epistemic might. Here is a basic illustration. (1) is naturally heard as entailing (1-a) and (1-b): (1) Mary might be at the beach or at the movies. a.  Mary might be at the beach. b.  Mary might be at the movies. ∗ to be added. 1