Making enrolment in pension plans the default for new employees (ie, they must decide to opt out rather than opt in) dramatically increases the share of employees saving through such programmes, for example.
Mr Thaler, with Mr Kahneman and Jack Knetsch, also worked to understand the role of fairness in judging economic outcomes.
They conducted experiments in which a student chosen at ran dom was asked to divide $20 between himself and another subject.
Only rarely would the student keep most of the money, as pure rationality suggests he should.
Similarly, the authors used surveys to show that people find practices like price gouging in the wake of disasters unfair.
In some multi-round experiments players chose to punish participants who acted selfishly in early rounds, even if that meant accepting a lower payout themselves.
These insights—that people care about fairness, find self-control hard and hate losing what they already have—may seem trivial outside the strange world of economics.
In fact, the greatest contribution of behavioural economics may have been to nudge the field away from attempts to extrapolate grand theories from basic rules of individual behaviour.
Today ambitious economists are quite likely to immerse themselves in empirical work focused on specific policy questions.
That is a legacy worth treasuring, however you do the mental accounting.