Abstract

The key to an adequate account of presupposition projection is to accommodate the fact that the presuppositions of a sentence cannot always be read off the sentence but can often be identified only on the basis of prior utterances in the conversation in which the sentence is uttered. In addition, an account of presupposition requires a three-valued semantics of assertibility and deniability in a context. Presuppositions can be explicated as sentences that belong to the conversation and the assertibility of which ensures that the remaining assertibility and deniability conditions of the presupposition-bearing sentence are dual to one another. The prevailing approach to presuppositions, grounded in Heim’s context-change semantics, can be criticized both on philosophical grounds and for failing to accommodate the phenomena