The current literature on presupposition fo cuses ahno st exclusively on the projection problem: the question of how and why the presuppositions of atomic clauses are projected to complex sentences which embed them Very little attention has been paid to the question of how and why these presuppositions arise at all . As Kay (1992, p.335) observes, "treatments of the presupposition inheritance problem ahno st never deal with the reasons that individual words and constructions give rise, in the

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... rst place, to the particular presuppositions that they do." l This is the question on which this paper will fo cus. There are two kinds of answer that one might give to the question of how presuppositions arise. One type of answer is that presuppositions are conventional properties of lexical items, as in the conventional implicature view of Karttunen and Peters (1979) . On this view, certain lexical items have, in addition to their truth conditional content, a special presuppositional content, which is carried through the compositional process to produce a propositional presupposition. Although the Karttunen and Peters mo del fo r treating presupposition has been rejected by most current researchers, our ta1k about presupposition seems at least implicitly to take their view of the sources of presuppositions fo r granted: we ta1k about the presuppositions of know, of too, and so on, as if assuming that the presuppositions are properties of these items. 2