Presuppositions are pragmatically considered as the conditions of the felicity of a speech act, or discourse move; however, the decision of setting the conditions of a move, which the hearer needs to accept in order to continue the dialogue, can be thought of as a speech act of a kind. The act of presupposing depends on specific conditions and in particular on the possibility of the hearer to reconstruct and accept the propositional content. These pragmatic conditions lead to epistemic considerations: (...) How can the speaker know that the hearer can reconstruct and accept a presupposition? A possible answer can be found in an argumentative approach grounded on the notion of presumptive reasoning. On this perspective, by presupposing the speaker advances a tentative conclusion about what the hearer may accept, hold, or know proceeding from factual, linguistic, and epistemic rules of presumption. (shrink)