Keep a list of things you used to be sure about. It keeps you humble and curious.

Certainty feels exactly the same whether you happen to be right or wrong, which makes it an unreliable guide on its own. The only real check is history, and memory will not supply it, because you quietly update the past to match what you believe now. A written record is the one thing that refuses to cooperate with that.

Start with three things you were completely sure about five years ago and are not sure about now. Add to it whenever you catch another. Reading that list before a strong opinion goes public takes about ten percent off the confidence, which is usually the right amount.