 Most epistemologists accepted Harman’s appeal to defeaters. Some have tried to make it more precise with details about updating indicative conditionals (Sorensen 1988b). This may vindicate and generalize Harman’s prediction that the future evidence will change your mind about what is misleading evidence. Knowledge of such conditionals is useless for a future modus ponens. The dogmatist correctly says we know the conditional “If I know that \(p\), then any evidence conflicting with \(p\) is misleading evidence”. Indeed, it is a tautology! But the dogmatist fails to recognize this known tautology is useless knowledge. Acquiring the misleading evidence will make me stop knowing p. If an auditor foresees being presented with a biased list of facts, he may utter the tautology to his assistant to convey another proposition for which he has empirical support. That empirical proposition need not be useless knowledge. When the predicted list is presented, the forearmed auditor ignores the facts. But the basis is not his a priori knowledge of the dogmatist’s tautology.