In arriving at the relevant theory about the specifics of our faculty of vision we will presumably use our eyes to gather relevant data. Based on such data we come to know about the optic nerve, the structure of our eyes, the rods and cones, etc., so as to explain how it is that vision gives us reliable access to the shapes and colors of objects around us. In reliably arriving at that theory we thus exercise the very faculty whose reliability is explained by the theory. There is no vice in this sort of circularity.
Ernest SosaIn my view (animal) knowledge is apt belief, where not only the belief (its existence and content) but also its correctness is creditable to the subject's competence.
Ernest SosaWe need some standard that will determine how likely a belief is to be true given just that it is stored in one of us, including strangers that one can ask for directions, and with whom one might collaborate.
Ernest SosaSuppose we wonder whether we should trust the deliverances of our basic epistemic competences. If those are indeed our basic competences, then in order properly to satisfy our curiosity we will inevitably rely on one or more of them. So, either we squelch our curiosity or we will have to fall into the circularity or regress to which the skeptic objects.
Ernest SosaA hunter archer can also be out to shock by taking crazy shots. What makes his shots "crazy" is set by excessive risk, judged by hunting-archery standards, which would tend to draw agreement from knowledgeable observers.
Ernest Sosa