Belief revision theories standardly endorse a principle of intensionality to the effect that ideal doxastic agents do not discriminate between pieces of information that are equivalent within classical logic. I argue that this principle should be rejected. Its failure, on my view, does not require failures of logical omniscience on the part of the agent, but results from a view of the update as mighty: as encoding what the agent learns might be the case, as well as what must be. The view is motivated by consideration of a puzzle case, obtained by transposing into the context of belief revision a kind of scenario that Kit Fine has used to argue against intensionalism about counterfactuals. Employing the framework of truthmaker semantics, I go on to develop a novel account of belief revision, based on a conception of the update as mighty, which validates natural hyperintensional counterparts of the usual AGM postulates.

信念修正理论标准地认可一个内涵​​性原则，即理想的 Doxastic 代理不会区分经典逻辑中等效的信息片段。我认为这个原则应该被拒绝。在我看来，它的失败并不需要代理的逻辑全知失败，而是由于认为更新是强大的：作为编码代理学习的内容可能是这种情况，以及必须是什么。该观点的动机是考虑一个难题案例，该案例是通过将 Kit Fine 用来反对关于反事实的内涵主义的一种场景转换到信念修正的上下文中而获得的。运用真理制造者语义的框架，我继续开发一个关于信念修正的新解释，基于一个强大的更新概念，它验证了通常的 AGM 假设的自然高内涵对应物。