 Linguistic pragmatics studies the context-dependent use and interpretation of expressions. Perhaps the most important notion in pragmatics is Grice’s (1967) conversational implicature. It is based on the insight that by means of general principles of rational cooperative behavior we can communicate more with the use of a sentence than the conventional semantic meaning associated with it. Grice has argued, for instance, that the exclusive interpretation of ‘or’—according to which we infer from ‘John or Mary came’ that John and Mary didn’t come both—is not due to the semantic meaning of ‘or’ but should be accounted for by a theory of conversational implicature. In this particular example,—a typical example of a so-called Quantity implicature—the hearer’s implication is taken to follow from the fact that the speaker could have used a contrasting, and informatively stronger expression, but chose not to. Other implicatures may follow from what the hearer thinks that the speaker takes to be normal states of affairs, i.e., stereotypical interpretations. For both types of implicatures, the hearer’s (pragmatic) interpretation of an expression involves what he takes to be the speaker’s reason for using this expression. But obviously, this speaker’s reason must involve assumptions about the hearer’s reasoning as well.