Abstract
Mainstream economics is based on the rationality assumption: that people act as best they can to promote their interests. In contrast, Behavioral economics holds that people act by behavioral rules of thumb - "heuristics and biases" - often with poor results. We propose a synthesis according to which people indeed act by rules, which usually work well, but may work poorly in exceptional or contrived scenarios. The reason is that like physical features, behavioral rules are the product of evolutionary processes, both biological and cultural; and evolution works on the usual, the common - not the exception, not the contrived scenario. Examples are given.
Recommended Reading:
R. J. Aumann (2019), "A synthesis of behavioral and mainstream economics," Nature Human Behavior 3, 666-670.
http://www.math.huji.ac.il/~raumann/documents/NatureHumanBehavior.pdf