Philosophers, like scientists, make various claims. But, unlike many scientists, philosophers do not use test tubes, telescopes, cloud chambers,or similar equipment in their work. This raises the question: what kindsof evidence are there for philosophical claims? Philosophical claimsare characteristically speculative. Yet, if this means that such claims areunsupported, we might reasonably wonder why anyone should makesuch claims and why anyone should give them the slightest degree ofbelief.Citing the published work of others will not tell us what kinds ofsupport philosophical claims have because it only defers the question.We now need to know what kinds of support there are for those written claims. What reasons did the authors of the claims have for makingthem? There is a general point about the evidential value of testimonyhere. Even if testimony can provide us with reason to believe that someproposition P is true, the ultimate sources of the testimony—namely, thephilosophers who made those claims in the first place—will have to hadsome other kinds of reason for believing that P. We need to know whatthose kinds of reason are.Again, it may be an important general lesson in epistemology that itcan be reasonable for someone to make certain claims even if that persondoes not have evidence to support those claims.1 But presumably not allclaims (not even all philosophical claims) have that status. Furthermore,even if it is reasonable for various philosophers to make certain claimswithout providing supporting evidence, if some of their claims aremutually incompatible we then face the challenge of selecting betweenthose claims. It seems that meeting that challenge will require havingreasons for the claims we select.