GEORGE BUSH'S loyalty to one who has done much for the world is commendable. It is also bad politics.Mikhail Gorbachev was crucial to the reform process in his country as long as politics was confined to reform within the system. He was one of the most progressive leaders in the Communist Party, and his outstanding accomplishment was to preside over that group's retreat from its monopoly on power. But even Mr. Gorbachev was not endlessly adaptable. As politics extended beyond the purview of communists and former communists, his role became more anomalous. The end of Gorbachev's positive contribution came in the aftermath of the August coup. During the first 24 hours following his return from detention in the Crimea, his public statements showed a nearly total failure to comprehend the political meaning of the coup's three days. Boris Yeltsin was criticized for rough handling of a leader who had been held hostage, prevented from receiving full information. Yet even after he examined material on the putsch, Gorbachev still wrote an "instant book" asserting the virtues of socialism and union. He has the courage of his convictions. But political survival requires more than courage. Gorbachev was the victim of his own success. He changed the political landscape so completely he made it impossible for a politician of his persuasion to play a major role. In about seven years, Gorbachev went from being the most reformist member of the top communist leadership to being one of the more conservative (but not reactionary) leaders in the post-communist Soviet Union. That his own basic political views did not change very much during this period is instructive. What changed was the political spectrum and the accompanying political "game" in the former USSR. Why did Gorbachev develop less than former communist colleagues like Mr. Yeltsin? While both learned a great deal, Yeltsin discovered how to cease being a socialist; Gorbachev can't make the same break. Perhaps it is the very sense of himself as an intellectual that holds Gorbachev back. How could an intelligent, informed political leader have been that wrong? Yeltsin, with much more modest intellectual pretensions, has had less difficulty shedding his communist baggage. Critics who call Yeltsin an old "apparatchik" are technically correct, but they should perhaps pay more attention to the people with whom he has surrounded himself. Unlike Gorbachev, Yeltsin has brought in a striking number of much younger individuals - to be sure, along with a sizeable group from the Sverdlovsk "mafia." How should the US and its allies react to creation of the new commonwealth? Some voices invoke the specter of uncontrolled ethnic rivalries leading to violence - a scenario of "Yugoslavia with nukes." The situation could come to that, but there is no reason why such an outcome is inevitable. Pessimists (they might call themselves "realists") suggest that while Yeltsin is in power now, there is no way of knowing who might be in the future. EVENTUALLY we must put our faith in democratic principles. Rather than being an effective barrier to a Soviet civil war, Gorbachev's desperate attempt to cling to power and preserve a tattered union could be the very thing that might provoke armed conflict. If the conditions in the Soviet successor states - ethnic tensions, economic crisis, and political confusion - seem to invite demagoguery, we might devote our attention, and our resources, to alleviating the causes of the danger, rather than advocatin g the preservation of an unelected imperial administration that has little chance of keeping the lid on.By opting to replace the union with a voluntary commonwealth, the leaders of the three Slavic republics changed the political game in an important way. Negotiations about "preserving the union" placed separatist-minded republic leaders in the driver's seat: They could make demands on the "center," exacting a price for their willingness to remain part of the union. Now there is no center. There is an assoc iation of republics agreeing to cooperate. The other republics are invited to join, but their participation will be negotiated on the basis of what they can bring to the commonwealth, rather than the price they exact for not leaving. It is a healthier negotiation. The coincidence of the commonwealth meeting taking place as the European Community leaders gathered in Maastricht underscored that the commonwealth embodies most of the goals the EC set for itself: a central bank, monetary union, customs union, a common currency, common foreign and security policy. Commonwealth members pledged to honor international agreements: economic, political, nuclear. What more could we want? The answer is a guarantee that words will be matched by deeds. The litany of reasons for preserving Gorbachev's union is growing: We do not know who will succeed Yeltsin. There might be another coup. A demagogue could take advantage of economic collapse and ethnic passion. Successor states could turn to war. Yet genuine solutions require faith in the elected leaderships forming the commonwealth and a constructive policy of assistance in weathering an economic crisis and building new institutions. Why is it so difficult for Western observers to accept the idea of a Russian or Slavic shift to a democratic system? There's certainly an element of cultural chauvinism, if not racism, in many analyses. There's also a disturbing lack of "new thinking" about the post-Soviet political system. The Serbs and Croats, with their long-standing animosity and recent history of violence, were also unfortunate enough to have unwise leadership at a critical time. Similar conditions do not necessarily pertain to the post-Soviet experience.