 Stalnaker emphasizes that when we make assertions (the paradigmatic use of language, conceived as a tool for exchanging information), there is a natural division into what the speaker presupposes and what the speaker says. If Elwood says, “The Queen of England has charming grandchildren,” he presupposes that there is a unique queen of England, and says that her grandchildren are charming. In the ordinary case, the presupposition would be shared by the conversational participants, but not everyone would already know, or believe, what Elwood says about her. The presuppositions that are shared are the common ground, which is an important part of the context of an utterance. Elwood’s assertion is an attempt to add to the common ground that additional content that the queen’s grandchildren are charming. Of course, someone may deny that this is so, in which case it wouldn’t become part of the common ground. Nevertheless, we can conceptualize the meaning of a sentence, or a central part of the meaning of a sentence, in terms of the change a use of it attempts to make to the common ground.