A comment on Twitter this morning reminded me of a few points from Philip Tetlock’s book Expert Political Judgment.
- Experts are under pressure to form opinions quickly so they can respond to interviewers.
- You don’t get invited to appear on talk shows for having conventional opinions. An expert who, after long deliberation, decides things are going to continue the way they’ve been going is not likely to appear in the press. This causes a selection bias in the predictions that receive publicity. It also creates incentives for experts to make sensational predictions.
- Experts have many facts to draw on, and so can be uncommonly good at confirming incorrect beliefs. Someone less knowledgeable might be forced to do some research.
Tetlock’s book focuses on political experts, though the same principles apply to other areas.