IT IS FASHIONABLE now to wring hands over the state of Soviet-American relations, to declare them worse than at any time since the Cuban missile crisis and the cold war, to speak ominously of "a march toward war," as George F. Kennan put it recently.

Yes, formal relations between the two superpowers today are terrible. As a wise Soviet observer put it recently, no one in Washington believes anything that is said in Moscow, and no one in Moscow believes anything that is said in Washington. There is very little constructive communication between the two capitals, and each seems baffled about how to deal with the other.

But this lousy situation does not compare with the depths of the cold war. Things are really much better now than then. Unfortunately, though, we are on the verge of a situation that is much worse than any earlier phase of the Soviet-American relationship. The prophets of doom may be prophets indeed before long.

The cold war parallel doesn't stand up because Soviet-American relations were transformed during the 1970s -- transformed fundamentally, in ways that cannot be easily erased.

There was a reminder of that in Minneapolis the week before last.

Two dozen Soviet citizens, including some important officials and academics, came to Minneapolis to meet with a delegation of Americans put together by Washington's Institute for Policy Studies (IPS), a liberal think tank that passes for a left-wing bastion in a society lacking a real left wing. It was a curious meeting -- earnest, occasionally flakey American dissidents meeting for five days with mostly solemn members of the Soviet establishment. But there was a lot of genuine exchange of views.

Such exchanges are now quite common. Hundreds of Russians and hundreds of Americans now know each other reasonably well. Most of them are specialists, but we also have political leaders on both sides who -- in a crisis -- could draw on past associations and shared experiences to ease communication between Moscow and Washington.

In fact the United States and the Soviet Union now have a real relationship -- something that was simply absent from 1945 to 1969. We have extensive dealings with the Russians, even now when most of the formal exchange programs instituted in the palmy days of detente have been suspended. The State Department's cultural exchanges are in hibernation, but just last weekend audiences in California and Moscow shared a live, televised rock concert with one another -- a private undertaking financed by one of the inventors of the Apple computer. (Of course, on the Soviet side the audience was carefully selected by the "relevant authorities" -- the relationship we have has not transformed traditional Soviet behavior.)

We forget too easily how isolated the two countries were before detente. Before 1972 a Soviet citizen visiting the United States was a rarity. Most of our dealings with each other were conducted at arm's length. Both sides held utterly caricatured images of the other.

Mutual understanding has increased substantially. Even at the top of the Reagan administration, whose florid anti-Soviet rhetoric has done much to aggravate formal relations, important officials have caught on that the Soviets are not so ominous as they once feared. In recent times the rhetoric on both sides has been hair-raising, but as Robert Legvold, a Kremlinologist at the Council on Foreign Relations, observed last week, we are not headed for imminent confrontation or crisis -- not yet, anyway.

The biggest change in Soviet-American relations in the '70s involved the redefinition of the arms race -- a change of enormous significance, though we seem to slight it constantly. Before 1972 -- and apart from atmospheric nuclear tests, which had been banned by treaty in 1963 -- the competition in nuclear weapons was a wild and woolly affair, unregulated in any significant way. In 1967, when Lyndon B. Johnson proposed to Alexei Kosygin at Glassboro, N.J., that the two superpowers agree to ban anti-missile missiles (ABMs), the Russian haughtily dismissed the idea as ridiculous.

Five years later, Kosygin watched Leonid Brezhnev and Richard M. Nixon sign a treaty strictly limiting ABMs, and another agreement limiting both countries' offensive arsenals. Those first SALT agreements made the arms race a contractual affair.

Now both superpowers routinely eavesdrop on each other's weapon's tests, count each other's missiles and planes one by one, even watch them being built from satellite eyes in space. Both countries have agreed not to hide their weapons. Both accept "counting rules" that say, for instance, that every Soviet SS-18 rocket is considered to carry 10 nuclear warheads, though in fact some of them carry only one and some carry eight.

The Russians agreed in the SALT II negotiations that to maintain an orderly accounting system, every rocket of a certain type has to be considered as carrying the largest number of warheads carried by any rocket of that type. (It's relatively easy to identify different types of rockets from spy satellites, but it is impossible to count warheads visually, since they're hidden inside the tip of the rocket. But you can count the number of warheads fired by a particular type of rocket in tests; so, for example, we have seen SS-18s fire one, eight and ten warheads.)

Because effective defensive missiles are essentially precluded by treaty and both sides know how many weapons the other side has, and where most of them are, the nuclear balance of terror is vastly safer than it might be otherwise. Both sides are reassured by the knowledge that under the existing rules, neither can get an advantage that would be significant enough to justify a decision to initiate a nuclear war with theeexpectation of winning or even surviving it. After all the strategists' mumbo jumbo, that is the bottom line; a Soviet politburo or an American president would have to be crazy to initiate nuclear war out of any calculation or emotion short of sheer desperation.

Crazy as the arms race is, then, it's a lot less crazy than it easily might have been -- and might yet be. The real measure of the danger of Soviet-American relations is not the temperature of public rhetoric, but the state of that contract. As long as it holds, we are not reverting to the bad old days, no matter what the atmospherics are like.

President Reagan and his colleagues seemed to understand this, despite all their bluster. Reagan has taken only one transcendingly important decision on nuclear weapons since becoming president -- the decision to respect the SALT II treaty that he had campaigned against as "fatally flawed." Apparently Reagan got the message that to ditch SALT II would mean ripping up the contract. He didn't want to go that far.

Nor have the Russians. They are furious with the United States for failing to ratify SALT II, and they seem to be showing their anger by stretching the treaty to its limit, but they are respecting it.

Now the president is busily trying to convince the House and Senate (not the Russians yet, just Congress) that he seriously wants to renew and broaden the contract with new arms deals. The Russians, however, don't believe he is really serious yet. That was the message they delivered in Minneapolis, and their reasoning was difficult to fault. From a Soviet point of view, all Reagan's arms control proposals up to now look like propoganda ploys, not serious bargaining positions. (From an American point of view, Soviet proposals have been similarly unappealing.)

The lack of seriousness in formal American and Soviet proposals to date is not an accusation, but a fact, confirmed last year by the administration's own negotiator at the Geneva talks on European weapons, Paul Nitze. Nitze and his Soviet counterpart, Yuli Kvitsinky, apparently took it upon themselves to find a framework for a deal that really might interest both sides.

To do this they had to ignore the formal positions they had put on the table, which they did. And they found a new framework, too. At first it attracted a lot of interest in Washington, but then the Pentagon intervened and quashed it. The Soviets in Moscow also rejected the Nitze-Kvitsinksy scheme. But its contents were leaked, and now most of Western Europe looks to that rejected formula as the way out of the current impasse over Soviet SS-20s and American Pershing II ballistic missiles and land-based cruise missiles that we are supposed to begin installing in Europe at the end of this year.

Conceivably, the Nitze-Kvitsinsky formula will be revived in the months ahead. It calls for the dismantling of some Soviet rockets aimed at Europe and the installation of some American cruise missiles (relatively slow, unpiloted drones that can carry nuclear bombs into East Europe and parts of the Soviet Union) but no Pershing II ballistic missiles, which seem to worry the Russians most.

Reviving this idea is conceivable, but not probable, because the two sides are now very far apart indeed. The Soviets have invested heavily -- indeed, extravagantly, and probably foolishly -- in a propoganda campaign intended to prevent the installation of any new American missiles in Europe. This investment has backfired, and there now appears to be strong enough support for new missile deployments in Europe to insure that they will begin as scheduled. President Reagan hopes that the Soviets will now realize this, and respond by negotiating a deal before December or soon afterward.

But this is unlikely, because a flip-flop now would be extremely embarrassing for the Soviets, and would gain them little. The first phase of U.S. deployments next year will result in the installation of just nine Pershing II's and 32 cruise missiles -- a militarily insignificant number for the Soviets. It's easy to imagine Soviet officials deciding they would prefer the spectacle of angry protests in the streets and general turmoil in Europe -- both likely if deployment goes forward -- than face the humiliation of caving in to Reagan's strong-arm diplomatic tactics.

Soviet sensitivity to the appearance of caving in will be particularly acute this year, while Yuri Andropov is still trying to consolidate his position as a strong new leader. He is unlikely to risk looking soft at this crucial time in his own career.

If the Soviets don't cave in, they will have to respond to the beginning of new American deployments. They will likely do this by building additional SS-20 rocket batteries in European Russia. They will also have to make good on their promise to match a new threat to the Soviet homeland -- new U.S. missiles in Europe -- by creating "an analagous threat" to the United States.

So we face the prospect of an intensified arms race of European-based missile systems on both sides, and it may spread beyond Europe. An untrammeled European missile race could so undermine the previously-negotiated nuclear balance that either side could decide it had to abandon the SALT contract.

That is the true danger before us, and it is a great danger. For if the fashionable proposition about the state of today's Soviet-American relations is wrong, tomorrow's relationship can be truly horrendous. A world in which the contract achieved with such difficulty has been torn up will be much more dangerous than the world that predated the existence of the contract. Mistrust will be greater than ever, and the arsenals on both sides are vastly more dangerous now than they were in 1972.

This unhappy ending is still avoidable. Avoiding it will require restraint on both sides, though, which may be too much to hope for.

In fairness, the Reagan administration has shown restraint despite its anti-Soviet crusade. Think of the temptation President Reagan has resisted to blame the Soviets openly for trying to kill the pope, for example. And for all the ballyhoo surrounding it, the great Reagan defendeal thse buildup has stayed inside the paramaters of the old superpower contract. There is still room for maneuver.

Moreover, America's hand appears stronger today than it has in many years. The Soviets have pulled back from their adventurous ways of 1975-79 (Angola to Afghanistan). They have shown restraint in Poland. They are having grave economic problems and are obviously eager to maintain their access to the world capitalist economy, on which they now depend for food, technology and investment capital.

To salvage the necessary degree of sanity in the Soviet-American relationship, the Reagan administration has to have a policy toward Moscow. Now it has a posture -- hostility. A real policy would give the Russians a sense of what the United States is prepared to give them as well as deny them. It would include some place in world affairs for the U.S.S.R., and also some prospect of rewards for better Soviet behavior. Without a coherent policy, the contract will not survive.