WHAT DOES the leadership transition in Moscow mean to the United States? Is there something this country should do to reduce whatever dangers the transition might hold and to lengthen the odds on a favorable change? Actually, the idea that it might hold dangers -- early dangers, anyway -- appears to have been pretty widely written off, if only because Leonid Brezhnev's immediate heirs are familiar members of the cautious, collective-minded consensus that he guided. But are there opportunities? Already, the lines of an interesting argument are forming.

The administration's view is that this is not the pivotal moment the transition was when Lenin, Stalin and Khrushchev left power. Even if the tight pinch on Soviet resources makes it a potentially pivotal moment, this view goes, the United States had best stick with its chosen policy and let the resources pinch get tighter. Certainly this is no moment to relieve the Kremlin of the crisis to which it has been brought by its own adventurism and narrowness of view. The assumption is that the new group, which is really the old group minus one, is cautious and collegial and without a taste for new departures. As the saying goes: stay the course.

From some students of international affairs, however, comes a different approach, one more congenial to those who feel Ronald Reagan has been pushing the Soviets too hard. In their opinion, a concealed and partial but nonetheless real pluralism operates in Moscow and this gives Washington the chance, at a rare moment of the rearrangement of Kremlin power, to play to the "doves" or "liberals" or "reformers," as they are variously called. The new general secretary of the ruling Communist Party, Yuri Andropov, 68, is widely identified as someone who, precisely by virtue of his particular secret-police background, is qualified to maneuver on that terrain. The systemic difficulties cited by the administration to justify keeping the pressure on are invoked in this second approach as an argument for letting some of the pressure off, or at least for contriving situations to reward the Kremlin for a good policy choice.

There is much wrong -- fundamentally -- with this second approach. It is silly to think of "good guys" fighting "bad guys" in the Kremlin, of closet liberals, of Politburo members aching for an American bailout, of people "just like us" except that they happen to be Russian or Communist or something supposedly minor like that. To play simplistically to the "reformers," moreover, can strengthen the hardliners' contention, in whatever debate goes on in the Kremlin, that the United States will yield goodies cheaply. It is not a mere misunderstanding that gives trouble between the two countries, though there is misunderstanding. What makes them a danger, to each other, is neither caused by gestures nor susceptible to cure by gesture. Given the record of the past year and a half, or 10 years, or 65 years, it is idle to imagine that much more than modest improvements can easily be made.

But it is no less foolish to dismiss whatever prospects there may be for even those modest improvements -- improvements measured, however subjectively, in a lowering of the fear of war and in a widening of the area in which great-power agreement, or at least consensus, holds. No reasonable person can expect President Reagan to alter the course of his foreign policy simply because of the transition in the Kremlin. But he has an obligation to show he is not missing any new possibility that is consistent with a broad view of the American interest.

There is a virtue in steadiness; it keeps policy off the perilous roller coaster of unwarranted expectations and crushing frustrations. There is also a virtue in openness to changing circumstances. Something has just changed in the Kremlin, and the Reagan administration will make a terrible mistake to proceed as if it has not.