We must distinguish judging from guessing.

In 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.

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.

The correctness of much testimonially based belief is no more than minimally creditable to the believer.

If we have a better understanding of knowledge than we do of such justification or competence, then we can explain the latter through the former.

Epistemology now flourishes with various complementary approaches. This includes formal epistemology, experimental philosophy, cognitive science and psychology, including relevant brain science, and other philosophical subfields, such as metaphysics, action theory, language, and mind. It is not as though all questions of armchair, traditional epistemology are already settled conclusively, with unanimity or even consensus. We still need to reason our way together to a better view of those issues.

The concept of intuition is more often used in philosophical theorizing than is the concept of observation in scientific theorizing (proportionately). One reason is that there is (proportionately) more ostensible conflict of philosophical intuitions than there is ostensible conflict of scientific observations. So much for the use of a concept of intuition in philosophical theorizing.