What projects and why
Projection is widely used as a diagnostic for presupposition, but many expression types yield projection even though they do not have standard properties of presupposition, for example appositives, expressives, and honorifics (Potts 2005). While it is possible to analyze projection piecemeal, clearly a unitary explanation is to be preferred. Yet we show that standard explanations of projective behavior (common ground based theories, anaphoric theories, and multi-dimensional theories) do not extend to the full range of triggers. Instead, we propose an alternative explanation based on the following claim, which is intended to apply to all content which occurs in embedded contexts: Meanings project IFF they are not at-issue, where at-issueness is defined in terms of the Roberts’ (1996) discourse theory. Thus, and despite their apparent heterogeneity, projective meaning triggers emerge as a natural class on the basis of the not at-issue status of their projective inference.