Notice how rarely anyone is argued out of the borrowed book, and how often they are simply moved past it by a change in circumstance. The mind that evolved for small groups and immediate dangers is now asked to manage a pension. It does its best. Consider the borrowed book. It is a small thing, and small things are where habits live. Nobody sets out to be governed by the borrowed book, yet it shapes an astonishing share of the ordinary day.
A better question
Institutions know all this, of course, which is why the borrowed book is so rarely left to chance. The honest conclusion is uncomfortable for reformers: people are not waiting to be corrected. 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 remedy is rarely exhortation. It is a change to the situation so that the easier choice is also the better one.
The point is not that people are foolish. The point is that patience is expensive, and we economise on it like everything else. 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 patience from the outside is usually something simpler from the inside: tiredness, a deadline, a wish not to look foolish. The textbook treats patience as a preference to be revealed. In practice it is a story we tell ourselves after the fact.
