Descartes's epistemology is a special case of Aristotle's virtue ethics.

Knowledge in my view is a form of action. It involves endeavors to get it right, and more broadly it concerns aimings, which can be functional rather than intentional.

Animal knowledge is metaphysically constituted by apt belief, by belief whose correctness manifests the believer's epistemic competence, a relevant disposition to get it right on the matter at hand when one tries to do so.

Any defense of common sense must allow that it is revisable.

When we speak of ordinary unqualified knowledge, my thought is that we are implicitly relativizing to the standards imposed by our evolution-derived humanity. These are standards that determine when we consider it appropriate to store beliefs just as a human being, rather than in one's capacity as an expert of one or another sort. Such stored beliefs are to be available for later use in one's own thought or in testimony to others.

When there are conflicts of observation, when experiments cannot be replicated, scientists may then retreat to a study of the various specific observations so as to explain the conflict, in the course of which they would make use of the concept of observation, or of some specification of that concept.

You attain aptness by judging while in good shape and in a good situation (good light, good distance, etc.), through the exercise of good barn-sorting epistemic competence.