 Maher’s (1988) makes the simplifying assumption that any method of prediction used by a predictor is either completely reliable (this is the claim abbreviated by ‘R’) or is no better than a random method (\(\neg R\)). (Maher [1990] shows that this assumption can be surrendered and a continuum of degrees of reliability of scientific methods assumed; the predictivist result is still generated.) In qualitative terms, where M generates T (and thus predicts E) without input of evidence E, we should infer that it is much more likely that the method that generated E is reliable than that E just happened to turn out true though R was no better than a random method. In other words, we judge that we are much more likely to stumble on a subject using a reliable method M of coin flip prediction than we are to stumble on a sequence of 99 true flip predictions that were merely lucky guesses—because