The fact that in extreme circumstances we pull explanations out of our asses (or even that we do so in non-extreme circumstances) doesn't mean we are incapable

The fact that in extreme circumstances we pull explanations out of our asses (or even that we do so in non-extreme circumstances) doesn't mean we are incapable of genuine meta-cognition. No one is rational most of the times, but mathematicians can be rational for brief periods on limited subjects.