Psychological observations are by now well integrated into economics, especially in the theory of finance, as can also be seen in the Nobel Prize awarded to Thaler. On the contrary, Simon’s attempt to reforge economic theory on the paradigm of bounded rationality failed. Starting from the birth of the neoclassical paradigm, we’ll describe the attempt to give it psychological foundations with a direct measurement of utility, then the axiomatic turn of the paradigm and its first anomalies. We’ll then sum up (...) the debate on rationality, taking place in the group of economists led by Simon, which brought to the rational expectations hypothesis. Finally, we’ll discuss the development of behavioral economics and its progressive acceptance in economic theory. This historical reconstruction allows us to understand the actual hard core of the neoclassical paradigm and the growing need of the paradigm for practical flexibility that determines how to choose arguments, methods and evidence that can be useful to its development, including psychological ones. (shrink)

Heterogeneous beliefs and decision processes generate positive externalities for social and economic systems, analogous to biodiversity in biological systems. Although some aspects of biodiversity (e.g., pests, parasites and bacteria) can lead to ecological and economic problems, biodiversity provides flows of beneficial ecological services and is widely regarded as a valuable natural resource and informational asset, whose value increases as we learn more and science progresses (Wilson in Bioscience 35(11):700–706, 1985). Heterogeneous beliefs and decision processes (and heterogeneous behaviors they generate) similarly (...) provide flows of beneficial economic services. Behavioral diversity should therefore be seen as a natural resource and informational asset likely to improve human wellbeing in surprising ways in the future. Paternalistic policies motivated by the goal of “correcting” allegedly suboptimal beliefs and behavior that diverge from expert recommendations jeopardize behavioral diversity at a substantial cost to social welfare. The risk of encroaching on this beneficial behavioral heterogeneity with policies that aim to induce behavioral and belief monocultures should be included explicitly as costs when evaluating nudges and other paternalistic policies. (shrink)