Arguably, if you view a real barn in bright sunlight and close by, while fully alert and otherwise in good shape, then you do know whether or not you see a barn. You have "animal" knowledge, says my virtue theory, through the first-order aptness of your judgment.

It is bad to want something that not even God could attain, especially when the impossibility becomes obvious.

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.

Since human good is what humans ought to pursue, the pursuit of interest to Aristotle is then such activity of soul, that which constitutes human good, namely activity that attains desiderata, where the attainment is in accord with virtue.

In order to qualify as a judgment, an affirmation must aim at getting it right aptly, through competence, and not just through a lucky guess.

When the risk of failure is too high, the right choice is to forbear.

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.