The expert and the beginner both say “I don’t know.” Only the middle guy is sure.

Confidence follows a curve that is highest in the middle. At the start you know you know nothing, and far along you have met enough exceptions to be careful about general claims. The middle is where you have learned enough to have a system and not enough to have seen it fail. That stage feels like mastery and behaves like risk.

When you notice yourself being very certain about something you learned recently, treat it as a stage rather than an arrival. Go and find the case that does not fit your rule. Being in the middle is fine, and it is useful to know you are there.