Revising what an agent knows in response to new information is a central problem in formal epistemology. In doxastic logics such as KD45, belief revision proceeds by reordering plausibility: the agent simply re-ranks which worlds it considers most credible. This strategy fails for S5 knowledge. Because knowledge is factive ( K φ → φ), an agent cannot come to know phi merely by finding φ-worlds more plausible; if the actual world falsifies φ, then K φ remains unsatisfiable regardless of any reord