'The Rationality Debate, Simmering in Stockholm'

Robert Shiller:

The Rationality Debate, Simmering in Stockholm, by Robert Shiller, Commentary, NY Times: Are people really rational in their economic decision making? That question divides the economics profession today, and the divisions were evident at the Nobel Week events in Stockholm last month.

There were related questions, too: Does it make sense to suppose that economic decisions or market prices can be modeled in the precise way that mathematical economists have traditionally favored? Or is there some emotionality in all of us that defies such modeling?

This debate isn’t merely academic. It’s fundamental, and the answers affect nearly everyone. Are speculative market booms and busts — like those that led to the recent financial crisis — examples of rational human reactions to new information, or of crazy fads and bubbles? Is it reasonable to base theories of economic behavior, which surely has a rational, calculating component, on the assumption that only that component matters?

The three of us who shared the Nobel in economic science — Eugene F. Fama, Lars Peter Hansen and I — gave very different answers in our Nobel lectures. ...