How do comprehenders reason about pragmatically ambiguous scalar terms like some in complex syntactic contexts? In many pragmatic theories of conversational implicature, local exhaustification of such terms ('only some') is predicted to be difficult or impossible if the result does not entail the literal meaning, whereas grammatical accounts predict such construals to be robustly available. Recent experimental evidence supports the salience of these local enrichments, but the grammatical theories that have been argued to account for this evidence do not provide explicit mechanisms for weighting such construals against others. We propose a probabilistic model that combines previous work on pragmatic inference under 'lexical uncertainty' with a more detailed model of compositional semantics. We show that this model makes accurate predictions about new experimental data on embedded implicatures in both non-monotonic and downward-entailing semantic contexts. In addition, the model's predictions can be improved by the incorporation of neo-Gricean hypotheses about lexical alternatives. This work thus contributes to a synthesis of grammatical and probabilistic views on pragmatic inference.

We derive a probabilistic account of the vagueness and context-sensitivity of scalar adjectives from a Bayesian approach to communication and interpretation. We describe an iterated-reasoning architecture for pragmatic interpretation and illustrate it with a simple scalar implicature example. We then show how to enrich the apparatus to handle pragmatic reasoning about the values of free variables, explore its predictions about the interpretation of scalar adjectives, and show how this model implements Edgington's (Analysis 2:193-204,1992, Keefe and Smith (eds.) Vagueness: a reader, 1997) account of the sorites paradox, with variations. The Bayesian approach has a number of explanatory virtues: in particular, it does not require any special-purpose machinery for handling vagueness, and it is integrated with a promising new approach to pragmatics and other areas of cognitive science. Edgington (1992Edgington ( , 1997 proposes an attractive unified approach to the Sorites, Lottery, and Preface paradoxes. According to Edgington, these puzzles are all explained by a generalization of classical logic which has the formal structure of the probability calculus, with an accompanying generalized notion of valid reasoning. She gives a number of strong arguments to the effect that a degree-based theory of vagueness with the formal structure of probabilities is preferable to one with the structure of classical fuzzy logic. However, she explicitly disavows the idea that the degrees involved in B Daniel Lassiter

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Relative adjectives in the positive form exhibit vagueness and context-sensitivity. We suggest that these phenomena can be explained by the interaction of a free threshold variable in the meaning of the positive form with a probabilistic model of pragmatic inference. We describe a formal model of utterance interpretation as coordination, which jointly infers the value of the threshold variable and the intended meaning of the sentence. We report simulations exploring the effect of background statistical knowledge on adjective interpretation in this model. Motivated by these simulation results, we suggest that this approach can account for the correlation between scale structure and the relative/absolute distinction while also allowing for exceptions noted in previous work. Finally, we argue for a probabilistic explanation of why the sorites paradox is compelling with relative adjectives even though the second premise is false on a universal interpretation, and show that this account predicts Kennedy’s (2007) observation that the sorites paradox is more compelling with relative than with absolute adjectives.