Is it my imagination or are the usual prognosticators biting their tongues these days? Those cursed What's In, What's Out lists that come out this time of year should definitely include economic forecasts as being on the outs. The great lesson of 2008, writes Wash Post columnist Robert Samuelson, "is how little we understand and can control the economy. This ignorance has bred today's insecurity, which in turn is now a governing reality of the crisis." In other words, the market for conventional wisdom has cratered.

It was once believed that the crisis of "subprime" mortgages -- loans to weaker borrowers -- would be limited, because these loans represent only 12 percent of all home mortgages. Even better, they were widely held, diluting losses to individual banks and investors. Wrong. Subprime mortgage losses (20 percent are delinquent) triggered a full-blown financial crisis. Confidence evaporated, because subprime loans were embedded in complex securities whose values and ownership were hard to determine. Similar doubts afflicted other bonds. Demand for all these securities shriveled. Lenders hoarded cash and favored safe U.S. Treasuries. Because investment banks and others relied on short-term debt (a.k.a. "leverage"), a loss of confidence and credit threatened failure. Lehman Brothers failed. The financial system had overborrowed and underestimated risk.

[CUT]

All the bad habits of recent years -- excessive borrowing by consumers and money managers, careless and reckless lending -- grew in a climate when gains seemed ordained. Even after the "tech bubble" burst in 2000, stock prices at year-end 2002 were seven times their year-end 1981 level. Home prices increased steadily; in the 1990s, they rose 45 percent. Prosperity, apparently forgiving of mistakes, bred the complacency that undid prosperity. On bad mortgages, losses could be recovered by selling the homes at higher values. Thus rationalized, bad loans were made. Some stocks might decline, but over time, most would rise. Risk seemed to recede, so investors and money managers undertook riskier strategies.