Abstract
This paper shows how Whately’s view of presumption as a preoccupation of the ground plays an indispensable role in the study of persuasive aspects of appeals to authority and deference. This is done by showing how important connections among arguments from authority, presumption, burden of proof, and deference can be precisely defined, combined, and fitted into a formal argumentation framework for responding to arguments from expert opinion and analyzing the ad verecundiam fallacy. As the inquiry into Whately’s ideas also reveals links between Aristotelian topics and dialectic later brought out by Perelman, it constitutes an illustration showing how the study of various historically important rhetorical ideas allows us to develop contemporary models of arguments.