The Death of 'Rational Man'

By David Ignatius
WashPost
Sunday, February 8, 2009

What allowed some people to see the financial crash coming while so many others missed its gathering force? I put that question recently to Nouriel Roubini, who has come to be known as "Dr. Doom" because of his insistent warnings starting in 2006 that we were heading into a global firestorm.

Roubini gave two kinds of answers. The first involves standard number-crunching of the sort that economists routinely do -- and that Roubini just did better and sooner. It's his second answer that's more interesting, because it goes to the heart of what we should take away from this crisis: Roubini decided to discard the assumption of market rationality that underlies most economics and to embrace the psychological insights of what's known as "behavioral economics."

First, the standard analytical explanation: Roubini said that he studied a chart in economist Robert J. Shiller's book "Irrational Exuberance." It showed that U.S. housing prices, adjusted for inflation, had remained essentially flat for a century, until the mid-1990s, when they began to shoot up. What's more, Roubini saw that the most recent housing correction in the late 1980s had a severe effect on the financial system -- leading ultimately to the collapse of the savings and loan industry.

So Roubini knew two things: Housing prices wouldn't keep going up forever, and when they went down, they would take a big piece of the financial system with them. From then on, it was a matter of watching the data.

(More here.)