How to Disbelieve p—>q: Resolving contradictions

This study discusses belief-change as the problem of deciding which previously-accepted belief, or premise, to abandon, when an inference from an initial belief set is subsequently contradicted. The data concern how "disbelieving" a previously-accepted conditional premise is realized as a particular modification to that premise. The types of revisions that are made are influenced by the kind of knowledge expressed in the conditional. The results and the broader issues of beliefrevision are related to other concerns that have emerged in the literature on propositional inference, such as the reported reluctance of people to make simple valid modus ponens inferences in some circumstances and the general interest in incorporating subjective belief into accounts of deductive inference.