ON OCTOBER 3 of this year the most important strategic arms agreement of the decade will expire, leaving the world's two superpowers faced with the prospect of preventing nuclear war without the help of a Strategic Arms Limitation Talks (SALT) accord. Even Big Bert Lance and his big problems look almost petty when lined up against the largest question of them all, the ultimate question of peace. Indeed, so do all the other domestic concerns that have overshadowed the complicated SALT issue since President Carter's ill-fated Moscow initiative last spring.

As negotiations continued over the summer, the situation reached a critical stage. Even if greatly modified, those "comprehensive proposals"--as the Carter package is called--have no more chance of succeeding in the Kremlin now than when they were first proposed. The Russians justifiably condemned Carter's initiative then as one-sided. In seeking to curb the Soviets' efforts to turn their stable of intercontinental ballistic missiles into MIRV's (multiple independently-targeted re-entry vehicles), the President proposed the restriction of a system that the Russians depend on heavily, and the U.S. does not. Our ace in the whole, after all, would appear to be the new cruise missile.

The New York Times can pound it into the public consciousness, as it did last Sunday, that "cruise missiles are not really comparable to MIRV s," but they don't care much for the Times in Moscow--and that's what counts. Unfortunately, approaches along the lines of the Carter proposal, which the Soviets have already rejected, make up about the only arguments that both hawks and doves in the U.S. can agree upon. Or so says Earl C. Ravenal, a former Defense Department policy-maker, in the September issue of The Atlantic Montly. The 1974 Vladivostock accord, he argues, pleased no one in this country: hawks were convinced the negotiated arms ceilings froze Soviet superiority in place, while doves saw the numbers game the negotiators played as just another example of "overkill." Either way, someone lost.

Yet despite the avowed willingness of the U.S. negotiators to do so, Ravenal does not see much room for compromise between the Vladivostock agreement and the Carter plan. More important, he says that even if the talks are "successful" in the traditional, treaty-signing sense, they will still not amount to much. In that, he may be right: the number of arms each side possesses has in many ways become irrelevant. That irrelevance, however, stems not from the fact that each side can already blow up the world dozens of times over, but from the fact that instability (what Ravenal says we should fear most) still exists, independent of mere numbers.

The author is not alone in his contention that even the most optimistic SALT agreement would not "eradicate the threat to our land-based missiles and thus cure the instability of the strategic balance." In explaining why true stabilization will not emerge from SALT, Ravenal deftly separates "arms control" from the control of "arms," in the generic sense. Because the former term implies the existence of a forum, agreements, inspection, and reciprocity, it cannot accommodate any effort at stabilization that may exist outside such a framework. Nor, he says, do the "posturing, stonewalling, constructing bargaining chips and .. games of chicken" that accompany formal negotiations help matters much.

RAVENAL IS certainly correct in assuming that the objective of arms control is stabilization, rather than a formal treaty, and in arguing that if the former can only be accomplished without the latter, then so be it. He neglects to mention, however, what cutting off the lines of communication in Geneva would mean to U.S.-Soviet relations. The diplomatic tremors from such a shock could easily affect the international balance of power adversely.

Still, the idea of taking unilateral action is a good one. And Ravenal's explanation of the form such efforts might take--a task directly related to his well-outlined definition of strategic "stability"--is particularly interesting.

He bases that concept on a series of well-founded assumptions. Ravenal claims there is no "magic number" of missiles at which the Soviets will decide they have the necessary superiority to attack the U.S. Instead the crucial question, he says, is where they might attack. And he is convincing in his explanation that it is not our cities, but our weapons, that would be their first target--in an attempt to limit the damage the aggressor would incur in a retaliatory strike.

In thinking the unthinkable, he argues that the well-known "counter-force" approach--a balancing act between "their" capability and "our" vulnerability--is the only sensible perspective. "If they can't disarm us, they aren't going to hit us," Ravenal concludes.

Accordingly, he says, we should not expand our forces, but retrench them. Ravenal would accomplish this by moving from the United States' present "triad" of nuclear forces to a "dyad." The U.S. should keep its bombers and submarines, he insists, but remove all its land-based missiles (veritable "sitting ducks," as he calls them) as they become more vulnerable to attack.

These, however, would not be replaced by a mobile land-based missile--namely the proposed MX missile that hawks are now pushing on Carter. By Ravenal's well-thought-out standards, that new kind of technology, which represents the direction in which the Pentagon is currently moving, would be disastrously destabilizing.

Ravenal's "modest proposal for ending Armageddon" also includes firm U.S. commitments not to bomb civilian targets and to foreswear the first-strike use of nuclear weapons. The result, he argues would be a lessening of the probability of an American first strike, accompanied by our own diminished vulnerability.

An added element of stability resulting from the "no first-use" doctrine would be the protection we would afford ourselves from ourselves, a la "Dr. Strangelove." The Pentagon mentality being what it is, this is of no small importance; anyone who understands the dangers of the neutron bomb, for instance, would quickly point out the benefits of such a plan.

Ravenal's major weakness, though, is that in arguing that the present stalemate can only be broken unilaterally, outside of formal negotiations, he makes the same mistake as those who rely too heavily on SALT alone, at the expense of unilateral efforts. In short, he lacks the flexibility that comes from using both approaches to the proper advantage.

The focus of arms limitation in the future must center on qualitative, more than quantitative, controls. Still, both sides must also seek to regulate the accuracy of their weapons--and that can only come from serious bargaining by both sides. Getting a handle on this issue will in the long run prove as important to "stability" and minimizing vulnerability as any unilateral moves.

In referring to the "swaying scaffold of detente," Ravenal displays excessive pessimism about the eventual possibility of breaking the current deadlock. While he is correct in his assumption that the unilateral efforts must come first, simultaneous advances should be sought at the bargaining table. And although he almost admits this early on, he never stresses the importance of negotiation as a complement to unilateral initiatives.

In the final analysis, the U.S. must be willing to disarm both by itself, and in cooperation with the Soviet Union. It is to these twin tasks that Americans should now turn their full attention.