Knowledge becomes dangerous when confidence grows faster than competence.

Trouble arrives when confidence outpaces ability, because confidence determines what you attempt and ability determines how it goes. A little knowledge is especially prone to this: you know enough to have opinions and not enough to know what you are missing, and nothing in the experience signals the gap.

When you feel confident about something you have recently learned, ask what you would have to know to be sure and whether you know it. Talking to someone genuinely expert is the fastest correction available, and it usually restores the right amount of caution within an hour.