Jumping to conclusions is a safer sport in the world of our imagination than it is in reality. - Daniel Kahneman

The confidence we experience as we make a judgment is not a reasoned evaluation of the probability that it is right. Confidence is a feeling, one determined mostly by the coherence of the story and by the ease with which it comes to mind, even when the evidence for the story is sparse and unreliable. The bias toward coherence favors overconfidence. An individual who expresses high confidence probably has a good story, which may or may not be true.

To understand error in judgment, we must understand both bias and noise.

We often interact with professionals who exercise their judgment with evident confidence, sometimes priding themselves on the power of their intuition. In a world rife with illusions of validity and skill, can we trust them? How do we distinguish the justified confidence of experts from the sincere overconfidence of professionals who do not know they are out of their depth? We can believe an expert who admits uncertainty but cannot take expressions of high confidence at face value. As I first learned on the obstacle field, people come up with coherent stories and confident predictions even when they know little or nothing. Overconfidence arises because people are often blind to their own blindness.