The testimony challenge against the possibility of philosophical knowledge

We access most of our most cherished beliefs via testimony. Philosophy is no exception. We treat spoken and written philosophical testimony as evidence for philosophical claims. Nonetheless, this paper argues that philosophical testimony is unable to justify philosophical beliefs. If testimony is the only evidence we have to justify philosophical beliefs, this entails skepticism about philosophy. Call this the testimony challenge. First, the paper argues that philosophical testimony does not meet the conditions under which evidence can justify our beliefs. Second, it shows that philosophical testimony cannot provide preemptive epistemic reasons as science and mathematics do. Finally, it answers the self-defeat objection and a set of objections aiming to block the thesis that philosophical testimony does not justify philosophical beliefs. The paper aims to rethink the role of philosophical testimony in philosophy and reinforce the skeptical worries raised by methodological and disagreement challenges.