How Testimony Can Be a Source of Knowledge

Much of what we regard ourselves as knowing came to us from the testimony of others. But recently epistemologists have debated just how testimony can be a source of knowledge at all. Must we have some independent way to confirm what we receive through testimony, or is there perhaps some reason why we should suppose that testimony is all by itself an adequate source of knowledge? This problem, I claim, is actually a version of a much older and better known problem: the so-called problem of the criterion. I will first explain this other, older, problem, and lay out the available options for solving it. I will then show why I think the problem of testimony is simply a version of the problem of the criterion. I will conclude by arguing that the best way to solve these problems comes from a theory of justification that few epistemologists seem to support these days: holistic coherence theory. In doing so, I hope I will provide some powerful new reasons for reconsidering this theory of justification.1