Two Dogmas of Belief Revision

The paper attacks the widely held view that belief revison theories, as they have been studied in the past two decades, are founded on the Principle of Informational Economy. The principle comes in two versions. According to the rst, an agent should, when accepting a new piece of information, aim at a minimal change of his previously held beliefs. If there are di erent ways to e ect the belief change, then the agent should, according to he second version, give up those beliefs that are least entrenched. Although widely proclaimed by belief revision theorists, I argue that both versions of the principle are dogmas that are not (and perhaps should not be) adhered to. I substantiate this claim with two simple mathematical observations, and I defend it against four possible objections that involve contractions, reconstructions, dispositions, and truths.