Notice how rarely anyone is argued out of the polite refusal, and how often they are simply moved past it by a change in circumstance. It is tempting to call this irrational. It is more useful to ask what it is for. The lesson is modest. Build for the person who exists, not the one in the model. If you want to see risk at work, watch a queue form where there is no reason for one.
Where it overreaches
We describe the departure from the model as an error. We might equally describe the model as a hopeful guess about us. It is tempting to call this irrational. It is more useful to ask what it is for. 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. What looks like risk from the outside is usually something simpler from the inside: tiredness, a deadline, a wish not to look foolish.
