In the 1970s, as a result of Vietnam, the idea spread that there was such a thing as liberal international opinion and that it could be rallied and brought to bear--on, invariably, the United States--by prestigious international commissions. So it was that on the eve of Ronald Reagan's election, a call went out to form such a commission on security and disarmament. Its purpose was to mobilize opinion against, no, not the Soviet invasion of Afghanistan but the hard-line currents rising in the United States.

This was the genesis of the commission, named for its chairman, former Swedish prime minister Olof Palme, whose report has just come in. It included out-of-power Western liberals like Cyrus Vance and former British foreign secretary David Owen, neutralists like Palme, leftists like West Germany's Egon Bahr, communists like Kremlin "Americanologist" Georgi Arbatov and former Polish prime minister Jozef Cyrankiewicz, and a complement of Third Worlders.

How could anyone think, you might ask, that the recommendations of a 1970s group like this would carry much weight in a political environment dominated by a 1980s conservative like Ronald Reagan?

Don't laugh. We live in a mixed-up world, and a group rather like this one already exists. It is called the European peace movement, and it has already had measurable impact on Reagan, leading him to soften his statements on nuclear war and his policies on arms control. The new report, adorned by a photo of anti-nuclear demonstrators, invokes this constituency in the United States as well as Europe.

Why, you ask further, is a former American secretary of state taking part in what is so transparently, from a Soviet point of view, a propaganda exercise?

After talking with Vance this week, I thought the answer was obvious. Out of office he's working for the same things he worked for in office. He shows great regret that the proposal for deep cuts in strategic arms that he brought to Moscow early in the Carter administration overloaded the Soviet circuit. He is determined to redeem the error--by supporting a form of the Reagan deep-cut proposal (separation of its first and second phases) and by joining the Palme commission's work.

I suspect something else may be working, too. Vance believes, as did his erstwhile chief, that what unites men of different countries and ideologies--be those men Republicans or Russians--is more important than what divides them. A striving for peace and a fear of war unite them: Vance, ever the earnest plugger, wants to validate this core belief of 1970s liberalism. Then too, he obviously wants to show that his commission partners did not lead him down the garden path.

I think he came out pretty well. Look, for instance, at the pride of the commission's litter of 30 or 40 recommendations, its proposal to move small battlefield nuclear weapons away from the immediate East-West border area so that, in an invasion, these weapons would not be lost or fired in haste.

My first reaction was that here was a typically fraudulent "peace" proposal meant to unstring the nuclear tripwire that is central to Western deterrence. Since it is only the Soviets who conceivably would cross the line, this proposal would seemingly assure them of a nuclear- free probe or grab of the border zone. It would increase instability and the threat of war.

The Palme commission's thinking, however, reflects the longtime apprehensions of conservative American planners. They have feared that in a crisis those up-close nuclear weapons could force a president to go nuclear, or to devolve firing authority to a lower level, before he really wanted to. Better, by this logic, to hold outside the border zone the sorts of nuclear weapons that afford a president the time and control to respond to a Soviet attack on his own terms.

This proposal for a "battlefield nuclear- free zone" is no big deal. But in the Palme commission's context--which is also the Reagan administration's context--of the West's first use of nuclear weapons and a negotiated agreement for parity of conventional forces, it has a practical value.

In any event, it is therapeutic to see that Western liberals such as Vance and Owen could spend a year and a half working with neutrals, leftists and communists and come out promoting some ideas that Ronald Reagan might yet take as his own.