Relations of epistemic proximity for belief change

摘要

Relations of epistemic proximity are closely related to relations of epistemic entrenchment, but contrary to the latter they do not refer to sentences but to belief patterns that are expressed with a metalinguistic belief predicate B. Hence ¬Bp≻B¬q means that disbelief in p is more close at hand (obtainable with less far-reaching changes in belief) than belief in not-q. The logic of epistemic proximity is investigated, and it is used to construct a uniform operation of belief change that has the standard operations as special cases, specified with success conditions such as Bp for revision and {¬Bp1,…,¬Bpn} for multiple contraction. Standard entrenchment relations are obtained by defining p to be less entrenched than q if and only if ¬Bp≻¬Bq.