I'm walking our sushi order back to the cafe table at the Reading Terminal Market in Philadelphia when I notice that Adam Wildavsky is talking to a fan. His name is Kumar, a retired pharmaceutical rep from India by way of Ohio. He's a bridge player like Wildavsky, here for the Spring Nationals, and he's sitting in my seat.

Wildavsky, tall and gaunt with a trim brown beard, is listening to Kumar's questions, nodding placidly in a birdlike dip. He has attached his portable back-support pillow to his chair, as he does to every chair, because he spends most of his life sitting down. He is a computer programmer -- specifically, an adherent to a hyperefficient system called ''Extreme Programming'' -- and he is also one of the best bridge players in the United

IN 1996, he questioned the 'irrational exuberance' of the American investor. Last Tuesday, Alan Greenspan, chairman of the Federal Reserve, brought that era to a definitive end with his diagnosis that 'an infectious greed seemed to grip much of our business community.' Acknowledging he was wrong in his long-held belief that the government should not regulate the accounting industry, Mr. Greenspan also said: 'It is not that humans have become any more greedy than in generations past. It is that the avenues to express greed had grown so enormously.'

Mr. Greenspan's embrace of greater regulation is a remarkable turnaround for an economist who for many years was a close friend and colleague