I don't remember the exact quote or source, but I once read something along the lines of "humans don't prove anything, we just decide which side of the argument we will hold to a higher standard of proof."
Motivated Continuing and Motivated Stopping? But accusing someone of that would be incurring in the Genetic Fallacy...
I'm mostly asking this open question to those among us who are well-versed in developmental psychology (I'm mostly thinking of children) . Although, failing the actual scientific research on the topic, I guess some testable hypotheses would be great too.