Signs of big-power fence mending

Very tentatively, very suspiciously, the superpowers may now be trying to inch their way out of the trough in their relations - a nadir some observers view as the lowest point since the Cuban missile crisis 20 years ago.

This is the implication left by remarks of senior American officials after the first high-level Soviet-American contact in four months - and the first civil high-level contact in 16 months.

The Jan. 18 meeting in Stockholm between US Secretary of State George Shultz and Soviet Foreign Minister Andrei Gromyko lasted, significantly, five hours and 10 minutes, or much longer than the three hours expected by the Americans.

Efforts at reconciliation go against the grain for both sides. The natural instinct of the Reagan administration is to regard the Soviet Union as an ''evil empire'' (in President Reagan's earlier phraseology), whose leaders ''reserve unto themselves the right to commit any crime, to lie, to cheat.'' Similarly, the natural instinct of Moscow is to regard the United States as the No. 1 capitalist enemy and the Reagan administration as representative of the most hostile ruling circles in America.

Survival in this age of vast nuclear overkill, however, depends on some degree of mutual tolerance, and both superpowers seem to be newly aware of this. On the American side the signals are public, both in President Reagan's overture to Moscow in his Jan. 16 speech and in Secretary Shultz's turning of the other cheek in Stockholm to Gromyko's stinging public denunciation of the US.

On the Soviet side there are no public signals (other than the length of the Gromyko-Shultz meeting), and the only evidence to go on is the American stress on the need for confidentiality following that meeting.

Even that much of a clue is a significant counter, however, to Gromyko's excoriation of American ''militarism and aggression'' in his opening address to the Stockholm conference on confidence-building measures in Europe. Mr. Shultz - unlike four months ago, when the two men last encountered each other just after the Soviet shooting down of Korean Air Lines Flight 7 - issued no rebuttal to the Soviet statement.

And in explaining Shultz's lack of response, a senior American official noted laconically that Shultz took the Gromyko speech ''as a speech.'' The implication was that this was a declaration for public consumption and should not be overreacted to.

The current Soviet-American probes of their mutual readiness to hold their noses and do business with each other are at an extremely sensitive stage, especially for the Soviets. Reagan, elected as the candidate of the right in 1980, can presumably protect his right flank domestically and continue the overture to Moscow if he so chooses. The Soviet leadership, however, is still in an unsettled succession period - a phase in which orthodoxy traditionally prevails over experimentation.

Typically, orthodoxy during a Kremlin succession has meant no new military ''adventures'' abroad - a positive prospect from the West's point of view. But it has also meant reluctance to take risks in getting too chummy with the international class enemy - a negative prospect from the West's point of view.

In this context many Soviet leaders who might now like to explore some reconciliation with the US - even on such urgent grounds as mutual survival - are extremely vulnerable to rivals' accusations of being too ''soft'': competitors can argue that there is no guarantee Reagan won't change course again and veer back to an ''evil empire'' dismissal of the Soviet Union - and that Moscow would anyway lose face in a reconciliation so soon after it has conspicuously failed in its strenuous attempts to block NATO Euromissile deployments.

Nonetheless, it is now or never for Moscow in East-West relations. Reagan has in fact just made his first overture to the Soviet Union, and he looks like being reelected next November.

If Moscow is going to have to deal with him for the next four years anyway, it has a strong incentive to set agreed limits to superpower confrontation now rather than wait until Reagan's negotiating hand is strengthened by a new electoral mandate.

Foreign-policy rationality thus clashes now with domestic political necessity - in a closed system in which no member of the untested new Politburo except Gromyko (and to some extent Andropov) has any firsthand knowledge of the outside world.

Under these circumstances Soviet feelers about a possible new beginning in superpower relations are still tentative, ambiguous, withdrawable, and deniable.