Formal Dialogue Systems (FDSs) model rule-based interaction between agents. Their conceptual roots go back to Hamblin's [11,12], which cites the medieval theory of obligationes as inspiration for his development of a formal system of argumentation. In an obligatio, two agents, Opponent and Respondent, engage in an alternating-move dialogue, where Respondent's actions are governed by certain rules, and the goal of the dialogue is establishing the consistency of a proposition. We implement obligationes in the formal dialogue system framework of [20] using Dynamic Epistemic Logic [26]. The result is a new type of inter-agent dialogue, consistency-checking, and analyzing obligationes in this way also sheds light on interpretational and historical questions concerning their use and purpose in medieval academia.