Pragmatic Presupposition And Its Value In Discourse Coherence

After about two decades of debate over the semantic-or-pragmatic status of presupposition, the view generally taken now is that presupposition is a pragmatic notion. However, even if weaccept that presupposition is a part of pragmatics, there remains a further discussion as to what is meant by pragmatic presupposition and whether or not it can be described purely in linguistic terms or whether it involves non-linguistic knowledge as well. Moreover, previous research on presupposition has been conventionally confined to the sentential level of language with the discourse aspects of presupposition being greatly downplayed.This paper is an attempt to propose a new understanding of pragmatic presupposition from the discourse perspective, by which we can investigate its coherence value at the supra-sentential level of language. It is suggested that, as a pragmatic phenomenon, presupposition can be viewed as a way of expressing given information and mutual knowledge. Two types of presupposition are distinguished: conventional and non-conventional. Conventional presupposition, being closely tied to surface aspects of language, dictates the flow of information in a discourse and consequently, exerts constraint on discourse coherence. Non-conventional presupposition, involving discourse participants' knowledge about the situational context, the socio-cultural aspects and the world in general, has a great bearing on one's perception of discourse coherence and degrees of discourse coherence, depending on whether a stretch of discourse is perceived as relevant and expression clear. It is demonstrated that the examination of presupposition in ongoing discourse can provide insights into the mechanism of presupposition at discourse level and at the same time, account for the internal mechanism of discourse coherence.