Standard and Non-standard Suppositions and Presuppositions

In this paper, I argue that the distinction between standard and non-standard pragmatic implications, originally used to differentiate among types of conversational implicatures, applies to the family of contents—traditionally referred to as ‘presuppositions’—that exhibit projective behaviour. Following the scholars working within the Question Under Discussion model of communication, I distinguish between two types of projective implications: suppositions and presuppositions narrowly construed. Next, I identify two rules of appropriateness that govern the use of, respectively, supposition-triggering and presupposition-triggering expressions. Finally, I argue that the ostentatious violation of the rules in question gives rise to non-standard projective implications, whereas their observance results in standard suppositions and presuppositions; I also use the idea of discourse coherence to develop a sketchy account of the mechanisms underlying the functioning of non-standard projective implications.