It is possible to produce something that is grammatical either by chance or under the supervision of another. To be proficient in grammar, then, one must both produce what is grammatical and produce it grammatically, that is, in accord with knowledge of grammar in oneself.

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

It is also certain that when we assent to some piece of reasoning when our perception of it is lacking, then either we go wrong, or, if we do stumble on the truth, it is by accident, so that we cannot be sure that we are not in error.

Judgment is affirmation with the intention to thereby affirm competently enough, and indeed aptly. That distinguishes judgments from mere guesses.

Through our perceptual systems, we represent our surroundings, aiming to do so accurately, where the aiming is functional or teleological, rather than intentional. And the same goes for our functional beliefs. Through our judgments, however, we do intentionally, even consciously, attempt to get it right.

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.

Suppose 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.