Beliefs should be like fluid entities within the mind, some malleable and doubtful, others more viscous and certain. But feeling certain should never be confused with being incontestable. Once a belief is allowed to solidify, it becomes like a shackle on the mind, inhibiting exploration, learning and growth. A fluid mind should never allow a belief to be so hardened that it is beyond rational scrutiny. A fluid mind always invites rational examination upon even its most cherished convictions.
“We should never forget that our reasoning process can go wrong. This is why you always want to check your careful reasoning for flaws. Make sure that no fallacious, instinctive reasoning slipped in. Try to find errors, even look for evidence that you're wrong. After all, how hard is it to confirm your beliefs if that's all you're trying to do? Anyone can find some evidence for anything! If you want to prove yourself right—try to prove yourself wrong. Because if you try to prove yourself wrong—and can't? Then it's a really good indication that you're right. Want to be even more assured? Invite others to prove you wrong. And remember—admit it when you are wrong.”
—David K. Johnson