From an evolutionary standpoint what would be the benefit of the brain looking inwards and constantly questioning itself? Certainly lower animals mostly just go with what instinct tells them, maybe with memory of prior experience in the larger-brained ones. Most people also seem to operate on their feeling of "common sense" without much reflection, at least in my observation.

> what would be the benefit of the brain looking inwards and constantly questioning itself?

When what you think matters. An animal that questions its belief "there is no tiger behind that bush" and finds a tiger lives longer than one that doesn't.