Puzzling Data, Beautiful Computations: A New Analysis of When ‘or’ Means ‘and’

In this contribution, we offer some new insights on the sources and nature of the free-choice (FC) reading found in disjunctive sentences containing a (deontic) modal. Notoriously, interpreting the sentence ‘You can speak to Bill or John’ with the meaning that you are free to speak to either of them involves a logical entailment that cannot be derived by any current version of Standard Deontic Logic: ⋄(p∨q) → ⋄p∧⋄q. We argue that the FC reading is the result of a non-Gricean process of pragmatic intrusion that slightly affects the interpretation of propositional operators to ensure that two distinct scope assignments be associated with distinct truth conditions. We further show that the attempt to derive the FC reading from an enriched version of scalar implicature computation (based on Grice’s Maxim of Quantity) meets important empirical and theoretical objections, besides not being confirmed by some relevant experimental results in language processing and language acquisition. We propose that the key to FC computation is local compositional semantics and, more particularly, the availability, within the same sentence, of two competing construals of relative scope assignment.