When you dream, your perceptual (and other) competence is affected. You are then unable to get it right competently with the beliefs in your dream.

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.

One does not avoid incompetence if one makes an attempt whose likelihood of success is too low. This seems little more than analytic: when the performance is in a domain that imposes standards of risk, attempts may or may not meet such standards. And the relevant competence of agents then includes reliably enough meeting those standards.

There's not much to be done about the impossibility. One must instead get rid of the desire.

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.

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

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.