 What Holkot added to the discussion was an elaborate analysis of such puzzles using the rules and structure of obligational debates to explore counterfactual possibility. Debates de obligatione were a commonplace in the medieval university curriculum and involved one person, the “opponent” posing a proposition to another, the “respondent,” that, if accepted, would form the basis for a continuing exchange. The posed proposition was usually a counterfactual or a proposition whose truth status was uncertain. The opponent then proposed further propositions to the respondent, each of which might follow from, contradict or be irrelevant to the first. The respondent was to take the first proposition as true for the time of the debate (understood in Holkot’s version to take place in a single hypothetical instant of time), and to respond with agreement or rejection depending on whether the succeeding propositions followed from what had been agreed on before or contradicted the preceding concessions. If a proposed proposition was unconnected with any of the preceding propositions, the respondent would respond with agreement, rejection or doubt depending on what he understood the actual state of affairs in the world to be. The forms and rules of obligational debate suggested a rigorous format for exploring the contingent possibilities, which Holkot adopted (Gelber 2004, 171–189; Slotemaker and Witt 2015, 26–30).