The Reagan administration, in dozens of decisions over the past four months, has moved more quickly than commonly understood to lay down the outlines of a new foreign policy for the United States.

The patterns are becoming increasingly visible. But until now they had been overshadowed by the backbiting and disarray of internecine struggle, and made harder to grasp by the lack of an effecitve articulator. Nevertheless, a process and a policy are in motion, producing shifts in the American posture in almost every sector of the world.

The Reagan policy, at this early stage, is characterized by an unusually sharp contrast between sweeping, almost radical shifts in objectives and priorities and much more cautious, gradual shifts in international implementation.

"We are tilting the axis of the foreign policy globe," said a senior administration policymaker several weeks ago. The central alignment of this world is the East-West axis, and the basic Reagan administration view is that the most immediate problems of the world radiate from Moscow. A massive buildup of American military power and security alliances is seen as an urgent requirement.

This mindset and strategy is sharply different from that which was predominant in the Carter administration and most of its predecessors in the 1960s and 1970s. And it is drastically different from the predominant view, even today, in the community of nations.

The Reagan administration, in seeking to put its ideas into praactice in dealings with other nations, faced a practical dilemma. A U-turn in policies would court clashes with allies and friends already committed to earlier agreements, undermining the very growth of confidence in American steadfastness and reliability the administration also seeks.

The result has been a variety of decisions to accept and amend earlier commitments rather than abandon them, even though many are unpalatable to Ronald Reagan, to redirect rather than reject existing agreements, to seek evolutionary change within an agreed framework rather than more dramatic but more difficult revolutionary shifts.

A notable case in point was the decision, after a National Security Council debate, to move promptly toward arms control discussions with the Soviet Union on medium-range nuclear missiles in Europe. U.S. allies in Western Europe were strongly urging such a move in compliance with a December, 1979, NATO agreement that missile deployment and arms control talks would proceed side by side.

At this time, nobody in the top rank of the Reagan administration has much zest for Soviet arms control talks, believing that a U.S. military buildup should come first. Nonetheless, Secretary of State Alexander M. Haig Jr. argued successfully that failure to move in this direction would damage or destroy the political basis in Eurpoe for deployment of the Euro-missiles, and that it might even be possible to redirect the policies of the allies somewhat in return for Washington's cooperation.

Secretary of Defense Casper W. Weinberger and his Pentagon associates were more reluctant than Haig to move toward Eurpoean arms control negotiations, and the debate was joined in policy papers from the two sides at the NSC, conversations and private negotiations among high officials, and finally a presentation of both positions among high officials, and finally a presentation of both positions to be president on April 30. Reagan endorsed the view of Haig, who took it to the North Atlantic Treaty Organization foreign ministers in Rome. As a result, the U.S. pledge to begin arms control discussions was balanced by a NATO statement linking the future of the East-West dialogue to Soviet behavior.

Regan administration policy toward Southern Africa, and especially the future of heavily contested Namibia, is another case in point. Scarcely anybody in the Reagan high command was happy with the existing western effort to create an independent Namibia through international negotiations and internationally supervised elections, because the result is likely to be the victory of a Marxist-oriented local group. Yet to abandon the joint effort unilaterally would be to court an immediate collision with black Africa and to ignore the advice and entreaties of western allies.

The administration's decision, unveiled in stages over recent weeks, was to accept the existing framework for a Namibian solution through joint negotiating efforts of the "western five," the United States, Britain, France, West Germany and Canada, but to add a requirement for constitutional guarantees which could change the parctical outcome. The allies have accepted the amended plan as a basis for proceeding.

"We have to change the impression that everything is changing," said a senior State Department official in explaining the emphasis on continuity which has marked many of the decisions of these early months. In this pursuit, the Reagan administration endorsed the Carter hostage settlement with Iran, continued unofficial relations with Taiwan in the previously established framework, continued the implementation of the Panama Canal treaties and agreed to participate in forthcoming North-South talks in Mexico City -- though in each case the opposite might have been expected on the basis of Reagan's prior political positions.

The two areas of most dramatic change in foreign policy to date are areas of relatively unencumbered U.S. prerogrative:

Bilateral relations with the Soviet Union, which were already poor in the last year of the Carter administration and which have become even chillier after harsh rhetoric and symbolic gesture from the Reagan team. Unlike every other president of recent years, Reagan's initial tone toward the other superpower has been entirely negative, with no balancing bow toward future accommodation.

The Europeans and others committed to detente were disturbed by the Washington shift, uncertain how far it might go and what dangers it would bring. Even such a deeply anti-Soviet leadership as Saudi Arabia's was initially concerned about a potential rush to confrontation which placed vulnerable allies, including the cautious Saudis, at risk. Haig has assured the Europeans and Saudis that the United States is not hellbent on conflict.

El Salvador and Central America, which have been considered a U.S. sphere of influence where other friendly powers defer to Washington. Growing evidence of Cuban-Nicaraguan involvement on top of longstanding and continuing social disintegration in El Salvador might well have forced President Carter to take a much stronger role there had he been reelected. The Reagan reaction was to "draw the line" against communism in Central America with a flourish and to threaten to "go to the source," meaning Cuba, if the outside involvement did not cease.

The Salvadoran drama, seen by many as a potential reenactment of the Vietnam tragedy, drew distinctly mixed reviews from the American public, judging from mail and other indicators of public sentiment. The White House and State Department toned down the rhetoric in an effort which proved successful, to move the issue of a Salvadoran Saigon off the television evening news and the front pages.

More than 40 interagency policy formulation groups, most of them chaired by the State Department, have been at work compiling foreign policy recommendations and options for consideration by Cabinet committees and ultimately by Reagan. This process has produced a large number of decisions and actions covering a wide variety of countries: Argentina, Guatemala, Jamaica, Poland, Turkey, Iran, Saudi Arabia, Lebanon, Israel, Egypt, Libya, Morocco, Angola, Zimbabwe, Pakistan, India, Japan and South Korea, to cite a very incomplete list.

Most of these decisions were forced by a dealdline of some sort, such as a requirement of Congress, a trip by a high official or an event that required a response. Some of the groups were assembled, did their work, and were adjourned until further notice.

For example, the Poland group which considered and approved contingency plans to meet a Soviet invasion and the rollover of Polish official debt has finished its job but can be recalled in case of developments. The group considering the U.S. attitude toward the Iran-Iraq war has been disbanded. The Pakistan group has completed formulating a new policy and aid program, which is on its way to approval in Islamabad.

In some cases the result of the policy discussions was a decision not to decide at the present time, as in the notable case of strategic arms talks with the Soviet Union. The Reagan administration would like to build strategic nuclear strength as its first priority, though the means of doing so may cast a long shadow over future SALT negotiations. For example, an impending set of decisions about the proposed MX missile could deeply affect the chances for verifiable future agreements with the Russians.

Another decision deliberately postponed is the sale of advanced aircraft to Taiwan, which could deeply affect Washington's relations with the People's Republic of China.

Most of the early choices were derived from existing situations and limited options rather than well-considered or coherent strategy. In part the limitation was due to the bureaucratic disarray arising from jockeying for power, but in part it arose from a view that quick decisions might be wrong decisions, especially with such basic changes of overall direction in prospect.

"The Carter administration started off with a lot of rhetoric but not much practical policy, and Reagan has begun with a lot of practical decisions but not much overall policy," said an official who watched them both. After a few months, though, an accretion of tactical decisions adds up to a policy, if not a grand strategy, for a troubled world.