Add to ORKGPresumptions come into play in argumentation when the evidence needed to prove or disprove a position is incomplete, allowing the investigation to move forward to meet a standard of proof. Presumptions simply disappear, like bats in the twilight, once enough evidence comes to be known to dispense with them. In this paper presumption is defined at the inferential and the dialectical level. At the inferential level, a presumption is defined as an inference to the acceptance of a proposition from two other propositions called a fact and a rule. At the dialectical level, a presumption is defined in terms of its use or function in a context of dialogue. This function is to shift an evidential burden from one side to the other in a dialogue, wher...