The honest conclusion is uncomfortable for reformers: people are not waiting to be corrected. It is tempting to call this irrational. It is more useful to ask what it is for. If you want to see choice at work, watch a queue form where there is no reason for one. In the studies we have, the effect is modest, reliable and almost entirely ignored by the people it describes.
A better question
We describe the departure from the model as an error. We might equally describe the model as a hopeful guess about us. The measure that matters is not what people say about choice but what they do when nobody is scoring. Consider the borrowed book. It is a small thing, and small things are where habits live. 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 textbook treats choice as a preference to be revealed. In practice it is a story we tell ourselves after the fact. Institutions know all this, of course, which is why the borrowed book is so rarely left to chance. A better account of choice would begin with the ordinary case rather than the laboratory one. Understanding people turns out to be a more urgent task than changing them, and a great deal harder.
