Implicitness impact: Measuring texts

•Implicit information can be assigned different values on a scale of implicitness impact.•Extension and intensity of implicit strategies in persuasive discourse can be measured.•Questionable content in a text can be more or less “disguised” as implicit information.•Different political discourses are assigned different ratings of information disguise.

Implicitness, besides being an indispensable feature of language whose primary function is economic in nature, also plays a major role in persuasive communication. Contents are conveyed as implicit mainly by means of implicatures, while the responsibility of the speaker is kept implicit mainly by means of presuppositions and topicalisations. We propose a system of quantification indexes to measure the intensity and the extent to which each of these strategies conceals some part of a message. This makes it possible to assess the implicitness impact of each single occurrence in a text, and of the text as a whole. The mentioned measurement system is applied to a sample of political propaganda (a discourse by Rick Santorum and one by Mitt Romney). Presuppositions and Topics hiding the speaker's responsibility seem to achieve a higher implicitness impact as compared to implicatures hiding notional contents. One of the two discourses receives a significantly higher implicitness score than the other, which signals it as more tendentious communication.