ABSTRACT
Communication would not be possible if speakers could not make assumptions about the background knowledge of hearers. To the extent that some of this background knowledge is shared with the speaker in an exchange, it can remain implicit as one of the presuppositions of an utterance. Presupposition is an important device that reduces the amount of explicit information that must be conveyed between speakers and hearers during communication. Its existence testifies to the fact that communicative rationality embodies certain economic constraints. This chapter examines the words and linguistic constructions that serve as triggers of presuppositions in an utterance. It also considers how presuppositions differ from the entailments of sentences, even though they may both occur in one and the same utterance.
