Some Pragmatic Issues in the Planning of Definite & Indefinite Noun Phrases

In this paper we examine the pragmatic knowledge an utterance-planning system must have in order to produce certain kinds of definite and indefinite noun phrases. An utterance.planning system, like other planning systems, plans actions to satisfy an agent 's goals, but allows some of the actions to consist of the utterance of sentences. This approach to language generation emphasizes the view of language as action, and hence assigns a critical role to pragmatics. The noun phrases under consideration in this paper are those that presuppose the existence of an individual that could be described by the description D. In other words, when a speaker uses a noun phrase with description P, it makes sense to ask the question "Which x is P? ~ This criterion includes more than strictly referential uses of noun phrases, because it is not necessary for the speaker or hearer to k'now what individual is described by D it is merely necessary that the existence of such an individual is presupposed. Consider the at t r ibut ive description in sentence ( l} :