语用学 预设The problematic properties.pptxVIP

4.3 The problematic properties Constancy under negation is not in fact a rich enough definition to pick out a coherent, homogeneous set of inferences. Actually presuppositions do exhibit a further set of distinguishing characteristics:(i) They are defeasible in (a) certain discourse contexts, (b) certain intra-sentential contexts;(ii) They are apparently tied to particular aspects of surface structureThe first property will prove to be the undoing of any possible semantic theory of presupposition, while the second property may serve to distinguish presuppositions from conversational implicatures. Defeasibility （可取消性） turns out to be one of the crucial properties of presuppositional behaviour, and one of the touchstones against which all theories of presupposition have to be assessed. 4.3.1Defeasibility One of the peculiar things about presuppositions is that they are liable to evaporate in certain contexts, either immediate linguistic context or the less immediate discourse context, or in circumstances where contrary assumptions are made. In sentences where the factive verb (叙实性动词) know has second or third person subjects, the complement is presupposed to be true, as in (80):(80) John doesnt know that Bill came Bill cameBut where the subject is first person and the verb is negated, the presupposition clearly fails; thus (81) does not presuppose (82):(81) I dont know that Bill came(82) Bill cameThe reason of course is that the presupposition that the speaker knows (82) is precisely what the sentence (81) denies, and such denials override contradictory presuppositionsSimilarly, when it is mutually known that certain facts do not obtain, we can use sentences that might otherwise presuppose those facts, with no consequent presuppositions arising.预设如果与语境冲突，则会被取消 (83) At least John wont have to regret that he did a Ph.D. He (John) did a Ph.D.? John has just finally got a job after finishing a Ph.D., the normal presupposition will hold.John获得博士学位后找到了工作, “He did