This article examines the nineteenth-century debate about scientific method between John Stuart Mill and William Whewell. Contrary to standard interpretations (given, for example, by Achinstein, Buchdahl, Butts, and Laudan), I argue that their debate was not over whether to endorse an inductive methodology but rather over the nature of inductive reasoning in science and the types of conclusions yielded by it. Whewell endorses, while Mill rejects, a type of inductive reasoning in which inference is employed to find a property or (...) cause shared by the observed members of a class, which is generalized to all its members, including the unobserved ones. Because of this, Whewell’s inductivism, unlike Mill’s, is able to yield theoretical hypotheses referring to unob-servables such as molecules and light waves. This is contrary to the claims of some critics of inductivism who argue that inductivism is unable to yield such hypotheses. Moreover, I suggest that Whewell’s view of induction conforms more closely than Mill’s view to the practice of scientists such as Kepler, Newton, and Fresnel, who do attempt to discover laws involving unobservables. (shrink)