 In discussion, one is normally expected to stick to the truth, at least as far as one knows it, but one is also expected to avoid denying what one has already accepted. These two expectancies can be understood as general prima facie duties or obligations for a person in a dialectical encounter: duties of honesty and coherence. The medieval theories of Obligationes, or “obligations” were a genre of logic that was concerned especially with the latter. These theories tried to explicate what is logically required for a coherent defense of one’s position. The basic setting in which this duty of coherence was studied, was to imagine or undertake disputations where explicit deviation from truth was allowed through some specific additional obligation laid down at the beginning. The simplest such additional obligation was to require the acceptance of some obviously false sentence that had to be defended in the disputation so that the respondent avoids denying it while allowing the force of logical inferences to constrain the answers. In the treatises, rules were laid out showing from a logical point of view how the defense ought to proceed in order to avoid denying what one has accepted.