Abstract

We are grateful for Roy T. Cook's attention to our work in his recent review of our book If A, Then B: How the World Discovered Logic. But Professor Cook leaves two misimpressions that we should like to correct. First, we have never maintained (as he phrases it) that "one's premises must be more certain than the conclusions that follow from them, ignoring the obvious logical fact that, if B logically follows from A, then B is provably at least as probable as A." Instead, we assert that one must be *initially* more certain of one's premises than the conclusions that follow from them; otherwise, we contend, no argument that relies on those premises to prove such a conclusion can be rationally persuasive. On this view, one might still be equally certain of both the premises and the conclusion after being persuaded by the argument, especially in cases where the premises entail the conclusion. By analogy, Aristotle asserts in the Posterior Analytics that the premises of demonstration must be "better known" than the conclusion—meaning, in part, that the premises must be initially more convincing. But this hardly shows that Aristotle thinks that, if A is invoked to demonstrate B, then A and B can never be regarded as equally probable…