A marked change can be detected in the tone, style, and substance of United States foreign policy. It is a change for the better. When Ronald Reagan came into office, he brought with him a world outlook shaped more by ideological instinct than firsthand knowledge and experience. Certainly he has not altered his strong basic views about such matters as the Soviet threat and the need for a strong US defense. But, as a result of exposure to global realities, he is beginning to bring to international problems some of the flexibility and pragmatism he has displayed on occasion domestically.Such a capacity for change is reassuring in any presidential leader.
Considerable credit for the shift clearly belongs to the new US secretary of state, George Shultz. Not that Mr. Shultz's views differ all that much from those of Alexander Haig. But his low-key style, calm self-assurance, freedom from political ambition, and ability to work with others seem to be just what is needed in this administration. Little by little, Mr. Shultz appears to be pulling US foreign policy back toward the more moderate center and the bipartisan mainstream of past administrations. It is more focused on what is possible and practical.
To cite a few examples:
* Controversy with the People's Republic of China over the issue of Taiwan has been resolved for the short term. Despite Mr. Reagan's early uncompromising stand on US arms sales to Taiwan, he accepted an agreement gradually reducing such sales, thereby satisfying Peking's concerns and ending the tensions in Sino-American relations. He obviously was persuaded that the strategic relationship with Peking was too important to be held hostage to domestic politics.
* American sanctions against foreign companies providing US-licensed components for the Siberian pipeline - a policy which has created such strains within the Atlantic alliance - have not been abandoned. But the President has softened the sanctions, and efforts are being made to break the impasse. If allies can be persuaded to toughen credit and other restrictions on the Soviet bloc, a face-saving way may be found for the President to ease off his position and end the embarrassing quarrel in the alliance.
* There now appears to be a softer attitude toward the economic problems of the third world. Sobered by the threat of world financial crisis, the US moved quickly to provide relief for debt-ridden Mexico and has indicated a willingness to strengthen the International Monetary Fund and the World Bank with additional loan money for poor countries (though amounts have yet to be worked out). Mr. Reagan's reliance on a strong US economy and the ''marketplace'' to solve global ills thus seems to be giving way to more realistic approaches.
* Not least of all, the administration has finally ended its passive role in the Middle East by adopting a forthright position on the Palestinian issue and proposing a specific solution to the Arab-Israeli dispute. Mr. Rea-gan's policy is essentially that pursued by past US administrations - a policy that seeks Israeli withdrawal from seized Arab land and self-government for the Palestinian people. While the President has not retreated from his staunch support for Israel, it is clear that his perceptions of the Middle East have altered in the cold light of reality and that he now favors a policy sensitive to Arab as well as Israeli interests.
These are but the beginnings of what the American public must hope will be continued efforts to give consistency and steadiness to the conduct of US policy. It seems that every new president has a period of learning - and awakening. Mr. Reagan was highly critical of the Carter diplomacy and sought to depart from many of its essentials. Bureaucratic infighting added to the tension. The unhappy result was an even greater sense of confusion and inconsistency - alarming friends and foes alike. Something needed to be done.
There is no doubt American policy will continue to reflect Mr. Reagan's philosophical views. Mr. Shultz will not go against the President, even if and when he disagrees with him, and that is as it should be. But the secretary's professionalism and style should help ensure that US foreign policy is coherent, purposeful, and soundly grounded in international realities. His quiet influence on the President's thinking is already evident.