Less than a decade ago, “rational choice theory” seemed oddly impervious to criticism. Hundreds of books, articles and studies were published every year, attacking the theory from every angle, yet it continued to attract new converts. How times have changed! The “anomalies” that Richard Thaler once blithely cataloged for the Journal of Economic Perspectives are now widely regarded, not as curious deviations from the norm, but as falsifying counterexamples to the entire project of neoclassical economics. The work of experimental game theorists has perhaps been the most influential in showing that people do not maximize expected utility, in any plausible sense of the terms “maximize,” “expected,” or “utility.” The evidence is so overwhelming and incontrovertible that, by the time one gets to the end of a book like Dan Ariely’s Predictably Irrational,1 it begins to feel like piling on. The suggestion is pretty clear: not only are people not as rational as decision and game theorists have traditionally taken them to be, they are not even as rational as they themselves take themselves to be. This conclusion, however, is not self-evident. The standard interpretation of these findings is that people are irrational: their estimation of probabilities is vulnerable to framing effects, their treatment of (equivalent) losses and gains is asymmetric, their choices violate the sure-thing principle, they discount the future hyperbolically, and so on. Indeed, after surveying the experimental findings, one begins to wonder how people manage to get on in their daily lives at all, given the seriousness and ubiquity of these deliberative pathologies. And yet, most people do manage to get on, in some form or another. This in itself suggests an alternative interpretation of the findings. What experimental game theorists may have demonstrated is not that people are systematically irrational, but that human rationality is heavily scaffolded. Remove the scaffolding, and they don’t do very well...