MUCH IS BEING said of the staggering scope of Ronald Reagan's electoral triumph, and little wonder. Dazed Democrats groping for ways to regroup, redefine and recover have this consolation: They may discover they are victims of a once-in-a-lifetime upheaval in the class of Franklin Delano Roosevelt's 1932 sweep, an election earthquake that transformed American politics for two generations.

While history cannot be anticipated, I believe that 1980 will be be one of the true watershed elections of this century, the end of one era and a decisive turn into another. What this new era demands, what the times dictate, is a fresh concentration on expanding the American economy as the basis for strength, peace, social unity and individual opportunity. It is a rejection of the zero-growth, withdraw-within-ourselves, a-perfect-world-or-nothing philosophy that evolved out of the old New Deal coalition when, after the Great Socity, government ran out of useful things to do.

Reagan's victory represents, I think, a reaffirmation of the American people's faith in themselves, a resounding recognition of the fact that when the federal government decides that it is responsible for defining and solving all of humanity's problems, we end up with just another enormous probelm -- the federal government itself.

This doesn't mean, as some have suggested, that the Reagan sweep is merely a mandate for nostalgia. Nor is it by any stretch of the imagination a popular demand for Reagan to forfeit his prize by staging a Nixon-Ford restoration and reinstating outmoded policies. Of course, we can expect a flurry of actions -- to regain control of the federal budget, reduce taxes strengthen our defenses, rein in the regulators, to cite some -- early in the Reagan administration to set the nation back on course. But beyond that we should also expect innovative, even radical actions to deal with our unprecedented problems of declining economic productivity and international competitiveness, which will not respond to conventional remedies.

The election was, to be sure, a referendum on the disastrous record of President Carter, especially on the economy. But this was no more a "negative landslide" than the 1932 election, when disheartened Rebert Hoover, and embraced FDR, whom they scarcely knew.

The voters 48 years ago had had enought of the sterile established political philosophy of that day, and the signaled their desire for a basic change. Last Tuesday the American electorate again signaled a sharp turn, this time rightward. They not only buried the remains of once-dominant and now largely irrelevant liberalism, wiping out a whole class of Senate liberals and giving the Republicans control of the upper chamber for the first time since 1954. To make the turn toward conservatism emphatic, they also seemed to apply a philosophical test in their ticket-splitting, supporting moderate and conservative Democrats and defeating liberals.

This creates a clear and immensely challenging mandate for the victorious Reagan: to demonstrate that conservatism -- often only a negative movement opposing change -- can now be translated into active and effective government for the 1980s and beyond.

I do not mean to suggest that the new era on which we are embarking will be happy days all the way. As much as the conservative euphoria today is justified, President-elect Ragan faces, for example, the terrible facts of accelerating inflation and persistent unemployment inherited from his predecssor. He confronts a flat economy, a busted housing market and a 15.5 percent prime lending rate that's headed even higher. The vast accumulated problems of the past will not be solved swiftly and painlessly. Reagan will have to be careful to stress the long-term nature of his promised solutions. And he will have little choice in the short run but to defer to the Federal Reserve's policy of monetary restraint, even though it delays recovery.

America's array of problems at home and abroad has, in fact, depressed public expectations for the Reagan presidency. In giving lasting meaning to his victory, Reagan's strongest asset, ironically, may be that millions of voters still know little about him. Many liberals and moderates are, quite simply, frightened by his right-wing image.

Reagan recognizes his chance to exploit these low expectations, allay fears and convert negative sentiment into enthusiastic support by doing a few important things early and well, thereby making favorable impressions at home and abroad. Moreover, because his opponent misrepresented him as a witless and reckless extremist, Reagan need only be himself -- inherently sensible, cautious and pragmatic -- to score impressively, lift public morale and enhance his authority as the nation's leader.

Many of Reagan's early policy decisions will be dictated by the country's plight. Based on what he has said privately as well as publicly, I believe he will move quickly to pursue these objectives:

1. Reagan control of the runaway federal budget.

Reagan realizes that Carter's downfall can be traced to his neglect of the economic crisis. The new president respects expert advice, and he will bring to bear all the experience that the Republican economic establishment can muster to resolve the crisis. He will lean heavily on George Shultzx and Alan Greenspan to devise strategies and assemble talent to achieve the urgently needed economic turn-around.

Reagan's advisers believe the economy is dangerously out of balance. The public sector has been growing far in excess of what the private sector can afford and finance without ever-spiralling inflation. Federal borrowing is crowding out productive private investment in the nation's capital markets. The Reagan strategy will be to contain and roll back the proportion of the gross national product claimed by the public sector.

Reagan is determined to change inflationary expectations by drastically revising President Carter's fiscal 1981 and 1982 budgets, aiming to trim deficits through reductions not only in wasteful social programs but in doubtful business, commercial and economic development subsidies as well. His declared goal of a 2 percent cut in Carter's fiscal 1981 budget translates into a $12 billion-plus spending reduction, and the target for fiscal 1982 could be as deep as $30 billion. These cutbacks, painful as they will be, are needed to relieve pressures on the credit markets and get the economy moving again.

2. Revive the stagnant economy through systematic tax cuts.

Renewed vitality and sustained growth in the private sector is the key to Reagan's success over the next four years. If the economy slumps, he risks failure. Economic growth and expanding private employment are essential to cushion the political impact of anti-inflationary spending cuts.

Despite continuing qualms among some of his establishment advisers, Reagan wisely remains committed to a 30 percent income-tax cut spread over three years, beginning with a 10 percent reduction in 1981. Here, again, Reagan will seek to change the expectations of consumers, savers, businessmen and investors. Reagan realizes that much of his support among blue-collar Democrats and independents rests on his promise to relieve the excrutiating tax pressures on their family budgets. He will act swiftly to redeem his promise.

Across-the-board tax cuts, though needed, are insufficient to stimulate economic recovery, especially in the high-technology, potentially high-growth sectors that are internationally competitive. Beyond depreciation changes that boost the cash flow of mature industries, the new administration will have to find ways to channel new investment into infant industries on the leading edge of change. One policy option: special capital gains tax treatment for profits earned in high-risk, high-potential industries.

3. Reassert presidential authority over the destructive growth of bureaucratic regulation.

Reagan will use the executive power of the presidency to halt and reverse the expansion of the regulatry bureaucracy that amounts to an autonomous subgovernment.