You can leave your dog outside, but do you have to?: An RSA approach

Abstract

A deontic possibility utterance can have a necessity interpretation in some contexts. For example, a café owner’s utterance of “You can leave your dog outside.” to a dog owner who is about to enter can be taken to mean that the dog owner has to leave their dog outside.This phenomenon, where a logically weaker item (possibility) implies a stronger item (necessity) on a scale, is not straightforwardly explained through standard theories of scalar implicature that predict that the assertion of a logically weaker item implies the negation of a stronger item. I attempt to account for this phenomenon of possibility-to-necessity inference using a theory of graded modality (Lassiter, 2011, 2017; Chung and Mascarenhas 2023) and the Rational Speech Act (RSA) framework (Frank and Goodman, 2012; Goodman and Stuhlmüller, 2013). I construct an RSA model where the pragmatic listener jointly infers about the state of the world and the value of the semantic variable as in Lassiter and Goodman (2013, 2017). The speaker utility includes social utility along epistemic utility, after Yoon et al. (2017). I consider two situations which differ in terms of whether explicit deontic necessity utterances are available to the speaker. The RSA model predicts a high probability of necessity interpretation in both. I further compare these results to the ones I obtain by controlling for components of the RSA model such as utterance cost and social utility, examining the effect that each has on the final result. The present study thus offers a way of systematically investigating a previously understudied phenomenon of deontic necessity inference arising from a deontic possibility utterance.