Ninety-five percent sure, on almost nothing

A friend is certain about the effects of a proposed economic policy. Push gently and it turns out her position rests on one article she read, one conversation with a colleague, and a general sense of how the world works. She is not lying and she is not foolish. Her confidence simply grew independently of her evidence.

How confidence detaches from evidence

1. 1You form a tentative view from limited information.
2. 2You state it out loud a few times. Stating it makes it feel more solid.
3. 3People who agree respond warmly, and the view becomes part of belonging.
4. 4Someone attacks it, and you defend it — which strengthens it further.
5. 5The original thin evidence is now years behind you and never gets revisited.

This is not a story about her. Every person reading this has several beliefs at that exact stage right now, and cannot easily tell which.