Much of philosophy of language and linguistics is concerned with showing what is special about language. One of Grice’s (1967/1989) contributions, against this tendency, was to treat speech as a form of rational activity, subject to the same sorts of norms and expectations that apply to all such activity. This general perspective has proved very fruitful in pragmatics. However, it is rarely explicitly asked whether a particular pragmatic phenomenon should be understood entirely in terms of rational agency or whether positing special linguistic principles is necessary. This paper is concerned with evaluating the degree to which a species of simple pragmatic inferences, scalar implicatures, should be viewed as a form of rational inference. A rigorous answer to this last question requires us to use the theoretical resources of game theory. I argue that weak-dominance reasoning, a standard form of game-theoretic reasoning, allows us cash out scalar implicatures as rational inferences in a large class of communicative situations. This account of the derivation of scalar implicatures is more principled and robust than other explanations in the game theory and pragmatics literature.