IT'S USEFUL that the Joint Chiefs of Staff have publicly disparaged Air Force Maj. Gen. George J. Keegan Jr.'s claim, made as he retired, that the Soviet Union has achieved military superiority over teh United States. This doesn't prove absolutely that Gen. Keegan was wrong. But his erstwhile peers are surely familiar with his information; and, as professional military men, they presumbly share his feeling that the U.S. military must, if it is to be responsible, anticipate such stark contingencies. So if he is unable to persuade them of the perils he professes to see, the rest of us are entitled to breathe a bit more easily.

But, of course, that is saying very little. A close reading of the Joint Chiefs' views, presented by Chairman George S. Brown in response to a query from Sen. William Proxmire, reveals that the Chiefs are not providing any basis - beyond their own flat assertion - to ease a bewildered citizen's anxieties. As it happens, the Chiefs do not accept Gen. Keegan's proposition that the Russians are here - that is, ahead. They believe the Russians are coming - that is, trying to achieve superiority.But no more than he do they provide the materials on which their judgment is based.

In fact, there is an element of unreality threaded through almost all discussions of the Soviet-American strategic equation. Only the smaller part of it arises from the simple fact that some of the relevant information is secret. By far the larger part arises from the more complicated fact that there is no agreed measuring rod among professionals (as we learned from the recent Team A/Team B controversy). Some analysts count missile warheads; others count missile throw-weight. Some analysts stress hardware and technology in hand; others stress what's in the pipeline. Some analysts subtract from Soviet power those of its military forces trained on China and East Europe. Others lump everything the Russians have in the total available to hit the United States. Factors of each nation's putative will and its capacity to inflict or suffer attack are weighed in very different ways. So the argument goes.

It should be obvious from the debates of the past few months, not to speak of teh past few decades, that in the absence of a minimal and explicit consensus on standards, either confusion will reign or arbitrary judgements will be made. The Carter administration, if it is to satisfy the public's legitimate concerns to be secure and to be consulted about its own security, must try to recast the framework of decision-making and discussion. It must expose not only its conclusions but its premises. It must provide more facts about defense, and more insight into the methods by which it fits facts into strategic judgments.