UNQUESTIONABLY the Kremlin faced a dilemma at the Madrid conference, where the Europeans plus the United States and Canada have been consulting for 10 turgid months. To stay at the table was to give the West a continuing forum in which to reproach the Soviet Union for violation of the human rights vows it took at Madrid's parent enterprise in Helsinki in 1975. Yet to leave the table was to throw away the forum that Moscow has hoped to use, in eventual "disarmament" talks, to play on Western Europe's anxieties about the fading of detente.

Moscow's decision, as it evolved through the summer, represented a fine calculation. On human rights it stonewalled, rejecting both the West's critiques and its efforts to tighten the Helsinki human rights language. But to keep up the movement toward "disarmament" talks, it appeared to accept a Western proposal requiring countries to give notice of military manueuvers. We say "appeared" because Moscow's fine print would also require notice of maneuvers in the Atlantic remote from Europe, and elsewhere. To see how phony this requirement is, recall that this is a European security conference and that Moscow is the only Madrid party to have used troops in anger in Europe since World War II.

So now the Madrid conference is in recess until October and necessarily the quetion is not simply whether the Kremlin will let the Helsinki process fade out then -- on that, estimates differ -- but whether Washington has an interest in keeping the process alive.

Out own answer is yes. The Societs do cheat on many (not all) of their Helsinki human rights pledges, most egregiously by incarcerating the few brave souls who organize to ensure those pledges are kept. The Helsinki Final Act remains, however, the freshest, most relevant instrument legitimizing Western concern for human beings under state assault in Communist countries. The Soviets cannot easily repudiate it, since Helsinki also includes the West's affirmation of the Soviet Union's post-1945 borders.

The value of Helsinki surpasses the propaganda use to which American diplomacy, through several administrations, has put it. To let go would be to break faith with the embattled individuals behind the Iron Curtain who cling to it. In parts of Eastern Europe, futhermore, and perhaps sometimes even in the Soviet Union, the process actually helps people. That's what counts.