Most academic economics rely on concepts laid down at the beginning of the twentieth century by the British economist Alfred Marshall, who said that “nature does not make leaps.” Yet we economists find ourselves increasingly disturbed by the apparent inadequacy of the neo-Marshallian toolkit that we have built to explain our world.
The central bias of this toolkit is that we should trust the market to solve the problems we set it, and that we should not expect small (or even large) changes to have huge effects. A technological leap that raises the wages of the skilled and educated will induce others to become skilled and educated, restoring balance so that inequality does not grow too much.
So a country where labor productivity is low will become an attractive location for foreign direct investment, and the resulting increase in the capital-labor ratio will raise productivity. Wherever one looks, using Marshall’s toolkit, one sees economic equilibrium pulling things back to normal, compensating for and attenuating the effects of shocks and disturbances.
Marshall’s economics has had a marvelous run, and has helped economists make sense of the world. Yet there is a sense that progress and understanding will require something new – an economics of virtuous circles, thresholds, and butterfly effects, in which small changes have very large effects.