||Defeat in epistemology focuses on the idea that one's justification or evidence or reasons for believing, and thus one's knowledge, may be defeated in some way by "defeaters." Views diverge over what defeaters are (whether they are mental states, or propositions, or facts, or some combination thereof). Views also diverge over how defeat works (e.g. whether they are what Pollock called "undercutting" or "rebutting," or whether defeaters attack one's reasons, one's evidence, or simply whether one knows or is justified in believing). The debate over defeat extends to issues surrounding the rationality of belief that p in the face of higher-order belief or evidence concerning whether one's belief (or credence) in p is reliable or rational; to the conditions, if any, under which one may be dogmatic toward information one regards as misleading; and to formal epistemology's interest in capturing how one's credence ought to change given incoming evidence.