Implicatures of Irrelevant Answers and the Principle of Optimal Completion

In this paper, we present a game theoretic account of a subclass of ‘relevance’ implicatures arising from irrelevant answers. We show that these phenomena can be explained if we assume that interlocutors agree on production and interpretation strategies that are robust against small ‘trembles’ in the speaker’s production strategy. In this context, we argue for a new pragmatic principle which we call the principle of optimal completion. We als show that our model provides a parallel account of scalar implicatures which removes some limitations of previous accounts.