Den beteendeekonomiska forskningen identifierar fall av individuell irrationalitet: ekonomiska aktörer präglas ofta av olika kognitiva imperfektioner i sitt beslutsfattande. Ekonomipristagaren Vernon Smith har emellertid påpekat att irrationalitet på individnivå inte behöver leda till ”irrationalitet” på makronivå:

Why is it that human subjects in the laboratory frequently violate the canons of rational choice when tested as isolated individuals but, in the social context of exchange, institutions serve up decisions that are consistent (as if by magic) with predictive models based on individual rationality?

Professor John List

Smiths resonemang får stöd i studien ”The Market: Catalyst for Rationality and Filter of Irrationality” av John List och Daniel Millimet, publicerad i B. E. Journal of Economic Analysis & Policy:

Using field experimental data gathered from more than 800 experimental subjects, we find evidence that the market is a catalyst for this type of rationality. The study then focuses on aggregate market outcomes by examining empirically whether individual rationality of this sort is a prerequisite for market efficiency. Using a complementary field experiment, we gathered data from more than 380 subjects of age 6-18 in multi-lateral bargaining markets at a shopping mall. We find that our chosen market institution is a filter of irrationality: even when markets are populated solely by irrational buyers, aggregate market outcomes converge to the intersection of the supply and demand functions.

Resultat som dessa antyder att man bör undvika att alltför snabbt dra slutsatsen att förekomst av individuell irrationalitet gör marknadsprocessen ”irrationell” och att den därför behöver styras, i alla möjliga sammanhang, av detaljerade statliga regleringar. Man bör inte stirra sig blind på mikroresultat i isolering, med andra ord, utan också se på hur individer i interaktion under vissa allmänna institutioner kan bete sig som om de vore rationella, med ”goda” makroutfall.

Tips: Café Hayek.