Washington — With ideological zest and political determination, Ronald Reagan set three major goals when he stepped into the Oval Office: to fire up the American economy, to shrink the size of government, and to build up the nation's defenses.
Although he received only 51 percent of the popular vote in 1980, Mr. Reagan interpreted his victory as a popular mandate to carry out an agenda based on long-held conservative principles. His partisans said it would be a ''revolution.''
As he nears the end of a term in office, the President can point to a change on all three fronts. But his accomplishments fall more in the category of evolutionary change than a revolutionary break with the past, and his presidency has had mixed results:
* The US economy has registered a healthy recovery, with inflation declining dramatically and unemployment down appreciably. Yet Reagan not only has failed to bring the budget into balance, he has presided over the largest budget deficits in history.
* The growth of government has been slowed through sharp cuts in social spending and modest regulatory reform. But, largely because of the sharp rise in military spending, the government sector is now larger than it was when Reagan took office.
* America's military posture has been stiffened and there seems to be a general perception in the world that the US, following the Vietnam era, once again has confidence in itself and is prepared to be more assertive in defending its national interests. But there have been no major achievements in diplomacy.
What has surprised many people (especially those unfamiliar with his record in California) about Reagan is his capacity for flexibility. In four years he has proven to be more a pragmatic politician than an unyielding ideologue. He believes in cutting taxes but agreed to raise them. He put troops in Lebanon but withdrew them. He inveighed against the Soviet Union as an ''evil empire'' but now seeks to negotiate with it. He tilted toward Taiwan but journeyed to Peking.
The President does not change his conservative beliefs, but in policy terms he bends when he has to.
Reagan's principal achievement came during the early honeymoon period of his presidency when he skillfully won adoption of an economic package designed to halt trends set in motion by the New Deal and Great Society and to energize a weakened economy. Most analysts agree that the President's goal had the support of the bulk of the American people. Though Americans did not want to abandon federal help for the needy, they felt that government had in fact grown too big and complex and could no longer be looked on as the main solution to social problems. They wanted government to be more effective.
The net result was less than Reagan wanted, but it represented a shift from the past. Though Congress forced him to leave intact the basic welfare ''safety net,'' the President did manage to slow the rate of increase in social spending and reorder government's priorities.
''He didn't roll back the New Deal,'' commments University of Maryland budget expert Allen Schick, ''but he did change the conception from the expansion of government to the maintenance of government.''
Roosevelt and Reagan are bookend presidents,'' says Charles Jones, a scholar at the University of Virginia. ''Both are radical in their own way. We have moved from the FDR expansion to Reagan's period of consolidation.''
Ironically, it was President Jimmy Carter who started out to cut the growth in social spending and boost defense expenditures. But he was inept at working with Congress. Reagan, on the other hand, took the same issues, crystallized them, and with political finesse got his program through.
''Reagan brought together policies that changed realities,'' comments Norman Ornstein, political scientist at the American Enterprise Institute. ''The old-style liberalism will not be back.''
How the Reagan economic policies are assessed depends on one's political outlook. Broadly speaking, conservatives credit the President with the economic recovery - although even conservative economists fault administration policies for contributing to the deepest recession since the 1930s. Moderates and liberals decry the huge deficits, the mounting trade imbalance, and growing protectionism as threatening clouds over the future.
''It remains to be seen whether he can be evaluated positively,'' says Dr. Ornstein. ''Reagan has been irresponsible when it comes to the deficits - talking about the non-panacea of a line-item veto or balanced budget amendment instead of presenting balanced budgets. But if he gets another four years, he may contribute to the resolution of these problems. We don't know yet.''
''The massive deficits haven't sunk in with the public yet,'' comments Lester Salamon of the Urban Institute. ''Over time there will be a sense of disillusionment as great as that after the Great Society.''
Politically, perhaps the most damaging charge against the President is that he has shown favoritism to the rich, achieving recovery at the expense of the poor.
The Urban Institute, a respected nonpartisan think tank, concludes in its study titled ''The Reagan Record'' that the costs of the recession were higher than they needed to be, that the costs were unequally shared, and that the gap between the rich and poor widened in the period 1980-84 - partly as a result of Reagan's tax and benefit reductions.
''The typical middle-class family experienced a negligible increase in after-tax income between 1980 and 1984 and has at best only a modest increase to look forward to over the rest of the decade,'' says the study. ''Lower-income families have lost substantial ground and are unlikely to regain it in the remainder of the decade. Only the most affluent families are likely to realize major income gains.''
Adding to the impression of unfairness are the findings of the US Census Bureau, which reports that poverty has grown under the Reagan presidency. The number of poor reached 35 million in 1983, up from 34 million in 1982 and the highest level in 18 years.
Although Reagan failed to realize the fiscal discipline he promised, the Urban Institute economists credit him with achieving much of his program: reducing tax burdens; curtailing the dependence of the states on the national government and engaging them in the effort to control the cost of government; and reducing inflation to its lowest level in more than a decade.
''All in all, it is a record of substantial, if not revolutionary, change,'' says the study.
Actually, the staggering deficits could become the instrument for advancing the Reagan approach. Whoever is elected in November will have to tackle the deficits in part by curbing domestic spending - going after not only defense spending, but also business subsidies and certain entitlement programs (like social security) Reagan has carefully avoided touching. With the economy on the upswing, however, it is as much the foreign scene as the domestic which exposes the President's vulnerabilities. He was well into his second year before he gave much attention to diplomacy, which preoccupies most American presidents.
For Reagan, the major priorities were to spur the US economy and to bolster America's national security in the face of what was viewed as a dangerous Soviet military buildup. Some diplomatic experts consider that a foreign-policy contribution in itself. After the vacillation of the Carter period, they say, the challenge was to restore a sense of consistency to US policy and convey America's determination to remain strong and to project its power, though prudently. Under Reagan, the toughened stance vis-a-vis the Soviet Union, the successful deployment of nuclear missiles in Europe, and the invasion of Grenada are cited as gains for US policy which have sent an important message diplomatically.
''The strengthening of our military forces was necessary in certain areas where the Soviets appeared to be getting the upper hand,'' says Theodore Eliot, dean of Tufts University's Fletcher School of Law and Diplomacy. ''The way the Euromissile problem was worked out is generally regarded as a real plus. The situation in the Persian Gulf and, more recently, the Red Sea was handled with finesse but also required a military capability that the US might not have had five years ago.''
But some analysts disagree. Says Malcolm Toon, a former US ambassador to Moscow, ''The alliance has weakened today and European opinion is much more anti-American. It's not a very good record.''
And David Newsome, director of Georgetown University's Institute for the Study of Diplomacy, comments: ''In the short term, those around Reagan ... can make a good case that the world was waiting for an America that would stand up to the Russians and the 'forces of evil,' and (that) the lack of reaction abroad means that's what was wanted. But it's dangerous because the unresolved problems that are being swept under the rug - the Arab-Israeli conflict and the situation in southern Africa - will not go away.''
Reagan's critics see the worsening of relations with the Soviet Union and the collapse of all major arms negotiations with Moscow as his most glaring failures. Some of the blame for the strain in relations lies at the door of the Soviets, who among other things targeted new nuclear missiles on Europe and then tried to drive a wedge between the US and its European allies when they moved to counter the Soviet buildup. Two leadership changes in the Kremlin during the Reagan presidency also have made it difficult to get relations back on track.
Reagan was not early disposed to try to find an accommodation with the Russians. His anti-Soviet rhetoric was sharp. He brought with him into office an ideological view that tended to see the world in black and white and the Soviet Union capable only of aggression. He presented proposals at the nuclear arms talks which his first secretary of state, Alexander M. Haig Jr., later admitted held out nothing that could seriously interest Moscow.
As European and American public criticism of Reagan's stance grew, however, the President began shifting toward the center.
Since the beginning of the year he has backed away from his ''evil empire'' talk and adopted a more conciliatory stance. He eased his terms for a summit meeting and responded favorably to a Soviet proposal for talks on antisatellite and space weapons.
Now he has finally met face to face with a Soviet leader, Foreign Minster Andrei A. Gromyko. The recent rigorous talks appeared to lay the groundwork for some movement toward an improvment of relations, including resumption of arms negoitiations. But doubts about Reagan's true posture persist among professionals and public alike.
''Failure to stabilize the arms race is the most serious thing,'' comments Betty Glad, a presidential scholar at the University of Illinois. ''We're moving into an area of unceasing competition and now even opening up a new 'star wars' defense.
''Reagan has an ideology and can compromise when he does not get what he wants. But in the foreign policy arena there is less check in the bureaucracy on what he wants to do, and this is dangerous, especially when he's a hawk and can call on nationalistic pride. Militarization of our foreign policy is not to our advantage in the long term.''
Setbacks in the Middle East also mark the Reagan record. In the wake of the Israeli invasion of Lebanon, which the US did nothing to forestall, Reagan committed American marines to the defense of a pro-Western government only to see more than 250 American lives lost to terrorist attacks.
A peace initiative for the West Bank which the President launched in September 1982 has never gotten off the ground, and Israeli settlement of the occupied region has continued with virtually no American opposition. The Russians, in the meantime, have expanded their presence in the Middle East.
In Central America, the elections in El Salvador and installation of the moderate Duarte government enabled the President to win congressional approval for more military aid. But Congress repudiated CIA mining of Nicaraguan harbors and is resisting his efforts to secure more assistance for the rebels fighting the Sandinista government in Nicaragua. But as diplomatic efforts by the US and others have increased in the region in recent weeks, Central America seems to have receded as an election issue.
In sum, Reagan's domestic and foreign record is a blend of accomplishment and stalemate, of ideological rhetoric and pragmatic accommodation. After his triumphant early victory on the tax-cut issue, the President could not go on to capitalize on his gain. In 1982 he was forced to accept a tax increase, and for the past two years he has in effect been marking time, presumably waiting for a popular mandate to carry out more of his agenda.
Viewing the Reagan presidency from the narrow perspective of a not-quite-completed first term, political experts are ambivalent.
''Reagan has made the presidency work and shown how in a highly pluralistic system it is possible to achieve direction in government,'' says Stephen Wayne, a presidential scholar at George Washington University. ''But the record is open on how successful his policies are. We don't know if the relative peace and prosperity are a consequence of what he has done.''
Others suggest that, if the history of his presidency were written today, Reagan would be evaluated positively on the intangible rather than tangible results of leadership.
John Sears, a former Reagan political strategist, says: ''He has not come forward with a new vision of the future. He speaks optimistically of the future and that has benefit, but he has no idea of how to get from here to there. ... His greatest contribution has been to reinstill confidence again, and with confidence you can discuss the questions that need addressing. That is a big thing.''
Thomas E. Cronin, author of ''The State of the Presidency,'' says that, by his own yardstick, Reagan has ''made the presidency come alive.'' But in terms of such goals as turning away nuclear war, addressing the rights of women and others, and curbing waste in the military - which might be considered yardsticks for the 1980s - ''Reagan comes out average.''
But, Mr. Cronin adds, ''This could change in a second term.''