A little knowledge is a dangerous thing, but a little want of knowledge is also a dangerous thing.

Knowing a little makes you confident enough to act and blind to what you are missing. Knowing nothing at all leaves you unable to tell an expert from a salesman. The real risk is the mismatch between how sure you feel and how much you understand, and both kinds of danger feel identical from inside. Confidence should move with evidence, not with the first satisfying explanation.

A useful habit is to say out loud how sure you are, and why, before acting. If you cannot state the strongest objection to your own position, you are probably in the first kind of danger.