THE REAGAN administration has now announced its basic policy in respect to East-West trade. Actually, it's announced two basic policies. One is to limit trade with the Soviet bloc so as not to build up its military and adventurist potential. The other is to widen trade for economic reasons and to accommodate the United States' more trade- and detente-minded allies. Sound like the familiar old contradiction of administrations past? You bet it does. It's just as well, too. Only ideologues and the naive dream of building policy on just one of those strains. Accepting that they both must be juggled is the beginning of wisdom. It leads you to the hard cases.

The hardest currently going is the 3,500-mile pipeline the Soviets want the West to build to carry Siberian natural gas to Europe. To Moscow, this multi-billion-dollar project, the biggest East-West deal ever considered, is the key to development of a huge energy and hard-currency asset. To Washington, it would make Europe dependent on the Soviets. Uncomfortable, Western Europe, especially West Germany, seeks to put on the United States the burden of locating alternate supplies. But there are no energy rabbits to be pulled quickly out of reliable, non-communist, non-Middle Eastern hats. As the grain embargo shows, moreover, Washington is no stranger to the domestic pressures pushing Bonn toward Siberian gas. The more time Moscow gives Poland, the more the case against the pipeline deal weakens.

Sparing the West vulnerability to Soviet whim is a worthy objective, taken by itself. But in the trade field nothing can be taken by itself. One does not have to accept the silly argument that trade melts political tensions in order to grasp the strategic and economic imperatives for doing everything possible to expand the world's energy supplies. That means helping bring Siberian gas to Western terminals. It also means selling the Kremlin technology to expand its own energy production -- the better to reduce its appetite for foreign oil. i

The argument for letting the Soviets stew in their own backwardness is much stronger in respect to non-energy technology. Technological innovation is an ever tighter bottleneck of the Soviet economy, a systemic problem. It is not possible to conceive of Polish-type ferment or, for that matter, real destabilization coming out of it. But the industrial democracies should not go out of their way to rescue the Soviet system from its own failings, unless there are real gains for the West. Energy is one area in which this principle can be applied.