Confident and Clueless

In 1999, psychologists David Dunning and Justin Kruger tested students on logic, grammar, and humor. The students who scored in the bottom 25% estimated their performance as above average. Meanwhile, the top performers slightly underestimated themselves.

This is the Dunning-Kruger effect: incompetence robs you of the ability to recognize your own incompetence. The skills you need to produce correct answers are the same skills you need to spot correct answers. If you lack them, you lack both.