As great oaks from little acorns spring, a single mistake can sometimes generate a large amount of erroneous theory. Mill's misreading of a logical fact about implication as an epistemic condition on the acceptability of universal propositions not only prevented his seeing the potential of his conception of inducto-deductive methodology to vindicate suasive syllogism against the charges of triviality and petitio; it also led him to construct an elaborate account of the nature of inference and the role of the syllogism which, though in many ways intriguing, is ultimately both wrong-headed and unnecessary. While occasionally he seems to have come close to seeing this, the powerful undertow created by his basic confusion always managed to draw him back to the view that inference cannot be syllogistic, and that to syllogise must be to do something other than to infer.