Abstract The paper provides evidence that linguistic strategies based on the implicit encoding of information are effective means of deceptive argumentation and manipulation, as they can ease the acceptance of doubtful arguments by distracting addressees’ attention and by encouraging shallow processing of doubtful contents. The persuasive and manipulative functions of these rhetorical strategies are observed in commercial and political propaganda. Linguistic implicit strategies are divided into two main categories: the implicit encoding of content, mainly represented by implicatures and vague expressions, and the implicit encoding of responsibility, mainly represented by presuppositions and topics. The paper also suggests that the amount of persuasive implicitness contained in texts can be measured. For this purpose, a measuring model is proposed and applied to some Italian political speeches. The possible social usefulness of this approach is showed by sketching the operation of a website in which the measuring model is used to monitor contemporary political speeches.