“If you looked at a transcript afterward, it might seem clear that you had won the debate on points,” he said. “But somehow, with members of the audience, you always seemed to come off as elite, and Milton seemed to have won the day.”

Mr. Samuelson said he had never regarded Keynesianism as a religion, and he criticized some of his liberal colleagues for seeming to do so, earning himself, late in life, the label “l’enfant terrible emeritus.” The experience of nations in the second half of the century, he said, had diminished his optimism about the ability of government to perform miracles.

If government gets too big, and too great a portion of the nation’s income passes through it, he said, government becomes inefficient and unresponsive to the human needs “we do-gooders extol,” and thus risks infringing on freedoms.

But, he said, no serious political or economic thinker would reject the fundamental Keynesian idea that a benevolent democratic government must do what it can to avert economic trouble in areas the free markets cannot. Neither government alone nor the markets alone, he said, could serve the public welfare without help from the other.

As nations became locked in global competition, and as the computerization of the workplace created daunting employment problems, he agreed with the economic conservatives in advocating that American corporations must stay lean and efficient and follow the general dictates of the free market.

But he warned that the harshness of the marketplace had to be tempered and that corporate downsizing and the reduction of government programs “must be done with a heart.”

Despite his celebrated accomplishments, Mr. Samuelson preached and practiced humility. The M.I.T. economics department became famous for collegiality, in no small part because no one else could play prima donna if Mr. Samuelson refused the role, and, of course, he did. Economists, he told his students, as Churchill said of political colleagues, “have much to be humble about.”