Consensus grows that Gorbachev's overtures should be explored. NATO EYES SOVIET LEADER

The NATO allies are lurching toward a ragged consensus that there is more to Soviet leader Mikhail Gorbachev than just good public relations - and that the West should test his openness to new ideas in arms control. But the consensus is blurred. It is blurred partly because of domestic controversy over Soviet policy in various NATO countries. Too, it is blurred because of different national mixes of toughness and accommodation on various aspects of East-West relations. And, consensus is blurred because of second thoughts and cold feet on the part of conservatives such as British Prime Minister Margaret Thatcher, who pioneered the idea of ``doing business'' with Gorbachev.

A measure of the growing consensus is the emphasis at the NATO summit in Brussels yesterday and today on negotiating conventional arms reductions.

As NATO Secretary-General Peter Carrington said Wednesday, ``We all look forward to a more serious engagement with the Warsaw Pact on the central problems of European security arising from the imbalances we face in the field of conventional forces and chemical weapons.''

Reflecting the West's mixed hope and doubts, Mrs. Thatcher told the summit, according to British briefers, that Gorbachev genuinely seeks reform and should be supported in his courageous quest, but that he still has a long way to go before fundamental change is achieved.

NATO's efforts this week at ``serious engagement'' in conventional arms control contrasts sharply with NATO's reaction when Gorbachev first proposed new conventional talks in 1986. Then, the West viewed the Soviet offer as just propaganda. Now, everyone from the front-line West Germans to NATO Commander John Galvin draws encouragement from Gorbachev's hints he might agree to asymmetrical reductions in conventional and nuclear arms. They hope that by negotiating larger Soviet cuts in heavy weapons they might finally be able to redress the perennial Soviet conventional superiority in Europe.

The French are endorsing NATO's ``serious engagement'' in conventional arms control. Both the French President and prime minister are attending the summit - for the first time since Charles de Gaulle pulled France out of NATO's integrated military command more than two decades ago.

The French participation is motivated less by confidence in Gorbachev's ``new thinking'' than by fears that the West Germans might succumb to Soviet sweet talk, and be tempted into neutrality if the NATO allies do not back Bonn in entering conventional negotiations. Paris finally agreed last year to alliance-to-alliance talks (under the roof of East-West-neutral talks) and this week is signing on to a serious Western negotiating position.

The shift in the West's evaluation of Gorbachev can be seen in the unanimity between United States Secretary of State George Shultz and West German Foreign Minister Hans-Dietrich Genscher. No difference is discernible between Mr. Shultz's major speech on policy toward the Soviet Union of three weeks ago and Mr. Genscher's speech a year earlier urging the West to test Gorbachev's sincerity by forthcoming offers in negotiations. The US, judging from interviews with American diplomats over the past year, came around to the view that Gorbachev's words really did hold policy implications after the Communist Party Central Committee meeting last June.

But the current US position on Moscow has been obscured by the need to reconcile the new openness with President Reagan's traditional hard line toward the Soviet Union. By and large, the reconciliation has been accomplished by saying as little as possible and letting the superpower Intermediate-Range Nuclear Forces Treaty and strategic nuclear negotiations in particular speak for themselves.

Further muddiness in expression of the West's attitude toward the Soviet Union has been added by Thatcher's recent concern that the West may be going overboard in welcoming Gorbachev - and fears that in his lame-duck months Reagan cannot offer the West the necessary leadership and resolve. She lectured NATO two weeks ago that it must remain tough, and she has urged Bonn to modernize its short-range nuclear weapons.

One more factor in the murkiness of the West's current position toward the Soviet Union is the different emphases on firmness and flexibility in different areas of East-West relations.

This is most evident in the question of how hard to press Moscow on human rights before opening the conventional arms-control talks in Vienna. The US wants to extract more concessions from the Soviet Union. The West Germans contend that the West should respond positively to what Moscow has already done in releasing several hundred dissidents from prison over the past 14 months and octupling the number of Jewish emigrants in 1987.

Thatcher argues that the West cannot in any case expect to transform Soviet domestic society by international negotiations, and that the conventional arms-control talks should not be held hostage to a moral victory in human rights.