The linguistic tools for expressing things implicitly can be divided into two main categories: content implicitness and responsibility implicitness (Lombardi Vallauri 2016, 2019).

There are linguistic expressions that, while expressing a certain content, lead the recipient to “extract” other unexpressed contents, often with the help of context. The persuasive essence of this implicitness lies in the fact that the recipient, since they do not “see” the speaker asserting that content, and indeed they themselves construct it, is less likely to question it. The most representative examples of this type of implicitness are implicatures and vagueness.

Another aspect of a message that may remain unexpressed is the responsibility of the speaker for a portion of the transmitted content. This occurs particularly when responsibility for that content is also attributed to the recipient. The content, even if mentioned explicitly, is presented as if the recipient is already aware of it, and not as if the speaker is informing them. This gives the recipient the impression that they do not need to carefully evaluate that content because it is something they already know, or even that “everyone knows” already. As a consequence, if that content is partly questionable, the recipient may not notice it, or at least less likely than if it were introduced to them as new information proposed by the speaker. Presuppositions and topics are instances of responsibility implicitness.