Proceedings of the Annual Meeting of the Cognitive Science Society

A positive disjunction (A or B) in natural language typically receives two logical interpretations: inclusive disjunction vs. exclusive disjunction. Within the Gricean paradigm, the inclusive interpretation of disjunction is considered its basic meaning while the exclusive interpretation is caused by Gricean pragmatic reasoning, called exclusivity implicatures. However, pragmatic reasoning is not the only source of exclusivity. In this paper we quantify the role of prior beliefs regarding the compatibility of the two propositions (A, B) in a disjunction (A or B). In two experiments, we tested the impact of prior compatibility on exclusivity implication generation using examples from the literature. Our results show that prior beliefs about compatibility influence the overall exclusivity of a disjunction, but that significant exclusivity remains to be explained by other sources. We conclude that most exclusivity implications are composite implications that feed from minimally two sources: prior beliefs about compatibility and Gricean pragmatic reasoning.