Reflection: Exploiting presuppositions in discourses of power and persuasion
Presuppositions can be used to trick people into apparently accepting background assumptions which they do not have and/or would not have. Courtroom discourse is a case in point. For example, Izola Curry, on trial for the attempted murder of Dr. Martin Luther King in a restaurant in 1958, was asked:
Clearly, Curry worked out the presupposition embedded in the WH-structure (i.e. that she had found out), despite the fact that it was not common ground. Blocking this kind of presupposition is diffi cult, as one has pointedly to avoid answering the question; to do so would mean accepting what is presupposed. Cross-examination discourse from prosecutors is often designed to get a defendant or witness to accept, inadvertently or otherwise, assumptions that point towards their guilt. And presuppositions are powerful. Loftus and Palmer (1974) tested the sentence with which we began this topic: About how fast were the cars going when they smashed into each other? This is one of the questions they put to subjects about a fi lm they had been shown. The WH-structures presuppose that the cars were going “fast” and, moreover, “smashed” into each other, something which seems to explain the fact that informants were more likely to subsequently recall the presence of broken glass (though none was actually to be seen in the fi lm) than if, instead of “smashed”, the question contained “hit” or “bumped” (see also Loftus 1975).
Another kind of discourse that regularly manipulates common ground is that of advertising. Consider these advertising slogans:
One way of packing in information into the short space available in the slogan, and also of creating a dramatic and memorable slogan, is to deploy presuppositions. In addition, part of the sales pitch can be through the presupposition. Such presuppositions create the ground against which the product shines. In some cases, the presuppositions seem designed to create surreptitiously a problem or need for which the product is the solution. In the Pepsodent toothpaste advertisement, the existence of yellow on your teeth is presupposed (the yellow). In all these cases, presuppositions are part of the advertiser’s “soft sell” strategy. For more on the persuasive use of presuppositions, see Sbisà (1999).
