Early in their engaging book, Nudge, Richard Thaler and Cass Sunstein draw a distinction betweenHomo economicus, a species whose members they refer to as “econs”, and real people, whom they refer to as humans. “Homo economicus can think like Albert Einstein, store as much memory as IBM’s Big Blue, and exercise the willpower of Mahatma Gandhi. Really.” Real humans do indeed have cool, computationally gifted, far-sighted, and ethical minds, but these “econ” brains are constantly at war with their much older lizard brains, the “hot”, programmed-to-win, and action-oriented system that controls affect, that wants stuff, and wants it now.
Psychologists have known this for a long time, and economists used to know it too. Adam Smith, he of the invisible hand, and the hero of the econs and of laissez faire, wrote not only The Wealth of Nations, but also, 17 years earlier, The Theory of the Moral Sentiments, in which he analysed the difficulties of self-command over what he referred to as “the passions”. John Maynard Keynes built his analysis around simple psychological laws, backed by (mostly introspective) empirical evidence, and thought economic decisions were fundamentally influenced by confidence and emotions, what he referred to as “animal spirits”, a term that George Akerlof and Robert Shiller take as the title of their complementary book. Both Nudge and Animal Spirits argue that economists, despite the good examples set by Smith and Keynes, have subsequently paid too little attention to the passions, substituting econ for human behaviour. They argue that this mistake prevents us from understanding key issues in economics such as saving, credit markets, and the current financial crisis. Nudge also suggests a new approach to the regulation of markets, which Thaler and Sunstein call “libertarian paternalism”, exemplified by the helpful “nudge”. These approaches, and the broader endeavour called behavioural economics, promise to bring all of the social sciences closer together, and perhaps even to close the sometimes unbridgeable chasm between economists (who think people know what is good for them) and doctors (who know that they do not).