The American debate over the Gorbachev reforms is coming to a new place. No longer is the focus on whether the reforms will deepen and stick. There is still much doubt on that question, but the working assumption now is that the reforms have a good chance of succeeding and that their success would be a surpassing geopolitical event. All this sharpens the question of whether reform would make the Kremlin more mellow or more menacing and -- here is the cutting edge -- of whether the United States can do anything to make it come out the right way.

One answer was offered this week by the State Department's ranking Soviet-affairs hand, Thomas Simons Jr. Speaking for the administration's cautious optimists (who on a day-to-day basis are not necessarily its dominant school), he said the United States should hold to its present policy course, which he described as being ready to test Mikhail Gorbachev's promise across the board. Of ''well-intentioned but illusory'' efforts to '' 'help Gorbachev reform,' '' he said: ''there is nothing to be gained by offering preemptive concessions in the hope they will promote positive change.''

Meanwhile, a very different appeal was coming from a bipartisan study group of the Institute for East-West Security Studies. Decrying a ''purely reactive Western approach,'' the group suggested the West should ''welcome and encourage the reformist inclinations that Gorbachev has set in motion.'' Two members of the group, Cargill CEO Whitney MacMillan and Princeton professor Richard H. Ullman, went on to sum up the institute's findings in an article in The New York Times titled ''America's Self-Interest in Helping Gorbachev.''

In sorting all this out it helps to recall how the Reagan administration's own thinking has come along. It started out inclined to believe that the Kremlin was hostile and probably irreversibly so because of its basic nature and that while Soviet policy might be blunted by American pressure there was only slight hope -- though there was some -- that steady pressure would soften the system itself. The Reagan team doubted that the Gorbachev reform program could amount to much, and suspected it might be designed, or in any event used, to give the regime a ''breathing spell'' for economic catchup.

From this base line of skepticism the administration has come to terms in its fashion with Gorbachev's progress. It isn't that Ronald Reagan's own ambitions for his presidency had nothing to do with it, but, playing political catchup, he has moved to engage Gorbachev -- most conspicuously in arms control but in human rights, regional disputes and direct relations too.

Reaganites are sensitive to any suggestion that their man has tiptoed away from his old ideological convictions about the Kremlin. Quietly but with some justice they contend that his earlier analysis of a Soviet Union under great economic and technological stress was precisely the analysis that Gorbachev made in turning to reform, and that American pressure -- arms competition, the technology and credit squeeze, the contest of ideas and development models -- helped aggravate the huge systemic difficulties driving the Soviet leader. It follows that the United States, far from determining to do Gorbachev a favor, should act in its own interest and sustain a certain level of pressure even in these more civil times.

This strikes me not only as consistent with conservative precept and with Reagan's obligations to his political base but as sensible and prudent, even assuming, as we have no right to assume, that the United States could actually ''help'' Gorbachev if it chose to do so. Not to play with words, but making ''preemptive'' concessions, as distinguished from reciprocal ones, could simply invite the Kremlin to pocket unearned gains. I am leery of what might be the substance of the East-West Institute's preferred ''creative'' response, especially when it is comes from people unable to acknowledge that in criticizing Reagan earlier for pushing Moscow too hard, they went too far.

Still, if the ''creativity'' crowd is on the mushy side, it is on target in recognizing the special quality and opportunity of this East-West moment. When to apply the stick and when the carrot and in what combination and with what intensity: these are the tactical questions that must be tended diligently to make any broad strategy work. "Making 'preemptive' concessions, as distinguished from reciprocal ones, could simply invite the Kremlin to pocket unearned gains."