THE SENATE'S SALT ratification debate, which opened yesterday, seems almost anticlimactic. Has not SALT already been under the most intense, detailed and, yes, tendentious scrutiny, in the Senate as in the country, for months, for years? Can the secretaries of state and defense, the administration's lead witnesses, or the others who will come before the Senate by the time of its decision in the fall, really be expected to provide anything new? There is a sense in which even the most conscientious citizens must look with regret and incipient fatigue on the unfolding of this long-awaited exercise.

Yet there is an undeniable logic to taking this unruly, hydra-headed monster of a subject and attempting to squeeze it into the relatively square, hard-edged confines of a formal Senate proceeding. It is the logic of the democratic process in which no executive branch can be "answered" until it has worked its way to the end where the representatives of the people sit. Just as the process forces the discipline of negotiation upon the president, so it forces the discipline of ratification upon the Senate. Its members in the coming months will be pushed away from the safe shore of questioning, of ambivalence, of posing and easy stance-taking. They, or many of them, will have to work their way to positions that, in the eyes of their constituents and their fellow senators and themselves, look to be substantial and to have been arrived at on serious grounds.

For that is ultimately what this debate is about. There is a particular set of mutual undertakings on the table, and a decision must be made on whether the nation is better off with it or without it. But the decision should not be made until the Senate is satisfied that the debate has given full expression to the anxieties and aspirations underlying people's diverse feelings about the country's security. There can be no resolution of issues. But there is within reach a consensus, pegged to the voting requirements stipulated in the Constitution, on how Americans wish to deal with the nuclear uncertainties of the age.

So it's not that the debate will produce new facts about missiles, new strategic insights: All of that is written down somewhere already. But the debate almost certainly will produce new patterns of understanding. On the eve of the debate, for instance, the Senate majority leader, Robert Byrd, deftly positioned himself opposite the minority leader, Howard Baker, on the advisability of amendments. In the opening round yesterday, Mr. Baker, whose strength is not technical expertise, found himself up against the secretary of defense. The treaty looks different if you think that amending it, rather than winning more concessions from the Russians, will simply lead them to demand more concessions from the United States. It looks different if one of its important opponents seems to be making less than an overwhelming case.

The debate will ebb and flow, depending on your point of view. Whatever the outcome, what the Senate's final vote will announce is not simply a decision on the treaty, as important as that will be, but a collected judgment on how the nation wishes to face its future in a harsh yet improvable world. It is the Senate's responsibility to make the debate worthy of the burden it inescapably carries.