Reasoning without Minimality

Various forms of non-monotonic reasoning thrive on minimal change in some form or other. In general, the principle of minimal change prescribes choosing the best from a given set of alternatives. A dual of this principle, which has not drawn much attention from the researchers in the field, is to reject the worst from a given set of alternatives instead. This paper explores the use of this principle in the context of belief revision, which has known connections with plausible reasoning. Apart from arguing that the suggested operation is not excessively weak, we provide a set of “revision postulates” that demonstrably characterises this “non minimal” belief revision operation.