You're Alexander Haig, and you're in Peking to cut a deal whereby the United States agrees to sell weapons to China. Your problem is to maximize American leverage on the Russians and minimize negative fallout, expecially in Taiwan. So what do you do?

First you cut the deal on the quiet, hiding the facts behind a rhetorical screen of talk about "strategic coordination." Next, you tell the Russians privately, letting them know that the extent of arms sales will be influenced by the responsibility of their behavior, expecially in Poland. Then, when the Chinese do come to make purchases in August, you make public the arms sale agreement in the modest terms appropriate to what Peking can usefully buy.

Instead, Secretary Haig announced the deal in Peking with a theatrical flourish that enormously exaggerated its importance. Simultaneously, a series of Washington stories -- officially approved if not orchestrated -- divulged the previously secret arrangement for American monitoring of Soviet missile activities from bases on Chinese soil. A day later, at his press conference on June 16, President Reagan indicated communism as a whole and asserted that the troubles in Poland marked the beginning of its end.

The world, as a result, now believes that American policy toward Russia -- if so high-sounding a term much less pressure to behave responsibly; they have that much richer a chance to play, especially in Western Europe, upon fears of American recklessness. Moreover, the divulging of the secret listening agreement with China gives all countries reason to doubt the reliability of the United States as a partner in covert operations.

To enemies of Secretary Haig, what has happened merely confirms a stereotyped view of a power-mad general unconstrained by realistic considerations of the need for eventually negotiating with the Soviet Union. But those of us who have supported the Secretary of State, and admired his sense of global strategy, have to ask how he could have been a party to such a degradation of the diplomatic process.

Perhaps we have been simply wrong about Haig. It may be he is not a deep person, that his ideas are al onthe tip of his tongue, that what sounded like strategic thoughts were merely a parroting of notions picked up from Richard Nison and Henry Kissinger and others be served along the way.

Ascent to the heights of power would, in that case, work to expose the shallowness. In full public view, with a chance at eventually becoming president, Haig would play to the various lobbies -- going along, one day, with the Israelis, another day with the auto protectionists, a third with the Pentagon hawks. The resulting policy pattern is void of strategic coherence.

A second possible explanation centers on Haig's weak position inside the administration. He took some hard knocks early from the president's chief policy adviser, Edwin Meese, and from Secretary of Defense Caspar Weinberger. It signals a certain dispensability that last week, while Prime Minister Lee Kuan Yew of Singapore was in Washington meeting and lunching with the president, Haig was in Manila with the foreign ministers of Singapore and some other Asian states.

In those conditions, as a skilled bureaucrat, Haig might feel that he had to work his passage back. He would go along with the flow, being point man for policies he did not at heart embrace, the better to have the confidence of the president in larger enterprises later on.

My own sense is that Haig remains the only highly placed person in the Reagan adminstration with a feel for global strategy. He knows the world is round and interconnected, not flat and compartmentalized. He realizes American security includes arms controla rrangements with Russia. He did a brilliant job in setting up talks with the Russians on nuclear weapons in Europe. In the latest instance, he seems mainly to be courting a visible success, the better to cater to the whims of his boss.

But even if that view is right, even if Haig's recent performance is largely tactical, there is all the more reason for him to assert his true beliefs at this time. For the United States is now heading, almost blind, into what could be a very dangerous storm with the Soviet Union.