One way to define the '70s is to ask the famous question: whatever became of the '60s? For the first part of the decade now ending brought to power in Washington those who had earlier raised the banner of revolt against post-war consenses. In office they brought this country, during the last part of the decade, to the condition announced by such cliches as the "energy crisis" and "persistent inflation" and "the decline of American power."

The post-war consensus, hindsight to the contrary, was not all sweetness and light. Business and labor, city and country, North and South all staked rival claims. But the United States expanded steadily both in economic output and international reach. Growth provided an atmosphere for resolution of conflict, and the believers in growth-those whom I have called Big America-ruled the roost.

The revolt of the '60s came on as pure social tumult. Women, entering the work force at all levels, challenged ethics that revolved around the single breadwinner. Blacks and browns demanded not only equality but affirmative action to wipe out past unfairness. A new elite composed primarliy of intellectuals, using television and the press as its battering ram, asserted that growth in America menaced peace and the environment in ways that made life itself an endangered species.

In retrospect, a common feature characterized the revolt. The rebels asserted over the god of growth the god of life style. They argued that small is better, and taken en bloc they constituted a group that can fairly be called Little America.

Vietnam and Watergate, the convulsive events of the late '60s and early '70s, constituted a kind of national battle ground. Big America showed that it could neither fight a war nor run a decent government. It lost confidence, and came close to collapse.

Little America, its doubts vindicated, rushed in to fill the void. In 1972, with the nomination of George McGovern, it conquered the Democratic Party. In 1974, it took over the Congress. In 1976, with the election of Jimmy Carter, it won control of the White House.

Many healthy changes accompanied the change at the top. A multitude of new jobs were opened in the work force. Women did much better, as did minorities. Care for the aged and the mentally ill improved. Organized sports boomed, as did the great outdoors. People came off television in favor of art galleries, concerts, museums, discos, theater and the movies.

But Little America proved unequal to the task of running Big America. The confidence of the haves waned and investment and innovation fell off. Growth slipped and output-per-worker, or productivity, fell disastrously. Leading industries became less competitive with foreign rivals, and major companies turned into basket cases. Inflation rose and kept rising.

A central element in slow growth and high inflation was overdependence on foreign sources of oil. The president and his associates sensed the difficulty, but could not muster out of the Little American constituency a majority for action and sacrifice. Frustrated, the administration then sharpened its teeth on the oil companies, thus deepening the suspicion that inhibited sacrifice in the first place.

Nor could the administration face up to the foreign-policy implications of dependency. Its constituents demanded, and got, an emphasis on human rights in the Third World.

So committed, Washington proved impotent to stay advances by the Soviet Union and its friends in Iran and the zone of insecurity around that vortex of world politics. Insofar as it existed, public apprehension surfaced in opposition to the armscontrol treaty with Russia-thus paradoxically worsening chances for an easing of tension with Moscow while impairing ties with Japan and the European allies.

The failure of Little America to govern is so far without political consequence. Though fundamental problems assert themselves at every turn, the country prefers to indulge itself in lighting candles for hostages. Political conditions favor candidates who gloss over difficulties with appeals to morality or good nature.

At the turn of the decade, if this diagnosis is correct, the country finds itself in a deep hole. The prospect of early extrication seems dim, for it depends on something of which there is still no sign-a fundamental change of outlook, a switch from Little to Big America, and years of concentrated effort.