Abstract

In the nineteenth century, William Whewell claimed that his confirmation criterion of consilience was a truth-guarantor: we could, he believed, be certain that a consilient theory was true. Since that time Whewell has been much ridiculed for this claim by critics such as J. S. Mill and Bas van Fraassen. I have argued elsewhere that, while Whewell's claim that consilience can guarantee the truth of a theory is clearly wrong, consilience is indeed quite useful as a confirmation criterion (Snyder 2005). Here I will show that, even when consilience gives evidence for a theory that turns out to be false, there is an important sense in which consilience shows that the theory has captured something correct about the natural-kind structure of the physical world. Whewell was therefore correct to claim that consilience provides a "criterion of reality" (Whewell [1847] 1967, vol. 2, 68). Consilience provides this by giving justification for the claim that we have really `cut nature at its causal joints', to adapt Plato's famous phrase. Because of this, consilience can play a role in an argument for scientific realism.