Belief revision revised

I outline a novel counterexample to the principle of belief revision, Anticipation : if both learning and learning not‐ would render belief in unjustified, you cannot now be justified in believing . If I am right, not only is the leading theory of belief revision false, so are various recently proposed weakenings. I develop and defend a new theory that correctly predicts the failures of Anticipation I argue for, predicated on the simple idea that one is justified in ruling out possibility just in case that possibility is sufficiently improbable.