Challenging Samuelson on Keynes, government intervention and market regulation. "It is not enough that I should succeed," Gore Vidal once remarked. "Others must fail." Economist Paul Samuelson evidently agrees. A big government man from way back--in an edition of his best-selling college textbook Economics, he argued that "the remarkable fact is not how much government does to control economic activity, but how much it does not do"-- Samuelson, now 93, gave an interview not long ago. The current crisis, he claimed, validates his own economic views--and invalidates those of his longtime rival, the late free-market economist Milton Friedman. "Today we...