Understanding people turns out to be a more urgent task than changing them, and a great deal harder. None of this is new. Adam Smith noticed most of it, and then the profession spent two centuries forgetting. There is a version of this essay that ends with a policy prescription. This is not that version; the mechanism is interesting enough on its own. The measure that matters is not what people say about trust but what they do when nobody is scoring.
The ordinary case
The point is not that people are foolish. The point is that trust is expensive, and we economise on it like everything else. Consider the shortcut. It is a small thing, and small things are where habits live. Economists have spent decades modelling trust as a quantity. It behaves more like a weather system. Notice how rarely anyone is argued out of the shortcut, and how often they are simply moved past it by a change in circumstance.
