 The evidence provided by critically examining our natural modes of reasoning is of course defeasible—as in the case of the ‘proof’ of the principle of utility, the initiating validation is not a proof in the traditional deductive sense. But the justification provided is real nevertheless. And from here, iterative validation can increase our confidence that we are warranted in reasoning inductively: further inductions ranging over inductions can improve our reasoning abilities by establishing in more and more precise ways the circumstances in which inductive moves are good ones to make. Indeed, this process of sharpening inductive reasoning by “ulterior revision of […] spontaneous generalizations” (System, VII: 319) is, as we shall see, the very heart of the process of scientific thinking.