In a conferencee hall in Madrid this week, delegations from the United States, the Soviet Union, Canada and 32 European nations are meeting under the aegis of the 1975 Helsinki Accords. The meeting promises to be full of rich, rancorous -- and inconclusive -- debate over martial law in Poland, Afghanistan and assorted other Soviet iniquities in violation of Helsinke's terms.

You yawn? Understandably; to many critics, Helsinki is an empty exercise. The original idea was to promote and protect human rights within the member states while easing tensions between them. But the record of an earlier follow-up meeting in Belgrade and the second so-called Conference on Security and Cooperation in Europe now reconvening in Madrid reveal little more than procedural point- scoring--and substantive impasse.

So why, having adjourned fortuitously for Christmas just after the Polish crackdown, didn't the CSCE stay shut down in protest? And, more to the point, why didn't the Reagan administration, with its no-more-business-as- usual line, insist on it?

Those questions were put to the head of the American delegation, Ambassador Max Kampelman, just before his departure for Madrid. A Democrat who got his job originally from Jimmy Carter and was retained by the Reagan crowd, Kampelman brings to the execution of this part of the administration's foreign policy a rare degree of bipartisanship. He brings, as well, a hard-earned understanding of how the CSCE works. He's convinced it can be made to work to the interests of the West and the discomfort of the Soviets.

Some sense of this may already be apparent. By careful prearrangement, not only Secretary of State Alexander Haig but the foreign ministers of all 17 members of the "Western Group" (NATO plus Spain and Ireland) in CSCE will be on hand for some part of the current proceedings. With predictable variations, all 15 will concentrate on the Polish question.

"We intend to use Madrid as a forum on Poland," Kampelman said before he left. "The more furor, the better."

And then? It is the firm intention of the United States to quietly engineer an adjournment until the fall, says Kampelman. How long this session may drag on is not yet clear--conceivably two or three weeks. But barring an unlikely break in Western ranks, no other new business will be taken up. The focus will be exclusively on Soviet transgressions under the Helsinki accords.

More than a propaganda score is involved here. Perhaps because of Helsinki's distinctively European context and its preoccupation with human rights and security in a general sense, the "Western Group" has found it possible to work within the CSCE framework far more harmoniously than in, say, NATO, where specific military matters, including nuclear deployments, raise deep divisions.

Thus, at Madrid, the Soviets will be confronted by a measure of Western unanimity far more impressive than any that can be achieved within Western councils where the nuts and bolts of economic sanctions, for one example, is on the agenda.

"Madrid has been our ball game," says Kampelman, "so why walk away from it?" If that's so, why don't the Soviets walk away? They may, but one reason they haven't so far is that they have been battling to turn the conference to their own propaganda advantage, pushing for disarmament proposals and/or "confidence building" measures that might lull Western Europeans into resisting defense buildups. So far the United States has carried the Western members along with the argument that new agreements under Helsinki are useless while the accords are being systematically violated by the Soviets. That same argument is counted on to carry the day on limiting this session to the question of Poland.

A second reason, Kampelman believes, is that the Soviets don't want "the onus" of breaking up a "peace process" that is popular in Western Europe -- even if they find themselves regularly on the defensive. It comes down, then, to procedural maneuver--and propaganda points.

But it is other, useful things. It is a showcase of the art of the possible in constructive Western diplomacy, and of the value of not shutting down all business with the Soviets--when there are useful propaganda gains to be achieved. It is also a laboratory of sorts for the study of the virtues of patient, quiet, conventional diplomacy.