It would be straining credulity to believe that the Soviet Union is considering taking out observer status in GATT - the 88-member General Agreement on Tariffs and Trade - for purely idealistic reasons. (GATT is the international , though essentially Western-led, organization that sets global trade and tariff policies.) Moscow has not indicated a willingness eventually to join GATT, or follow its rules. It would undoubtedly use observer status in GATT, where it could speak out on trade issues though not participate in the policymaking process, to press its own objectives on such matters as trade boycotts.
However, that is exactly what allm the members of GATT, including the United States, do anyway. So the US and Europe need not be unduly wary of granting Moscow observer status or, as they are doing, try to keep the Soviet Union from winning such status. As President Reagan noted in his State of the Union address, keeping the channels of international trade open and avoiding protectionism is now one of the most urgent demands facing all governments. In this connection a case can be made that it is better to have the Soviets operating within the GATT system, even as observers, than outside it, as is currently the situation. China, it might be noted, now has observer status, and its presence has not injured GATT deliberations. The goal, eventually, is to have all trading nations responsive to and governed by an international code of behavior.
Although it is likely that the Soviets would use their association to engage in ''mischief,'' as one US official notes, the major points of controversy among GATT members will remain as pressing as ever. These involve agricultural subsidies, finding ways of furthering trade in high technology and services, and the use of quotas in general. The din of robust debate has been no stranger to GATT deliberations over the years. The world can only profit by Soviet exposure to such democratic give-and-take.