SOMETHING of a pattern is being established as the Reagan-Gorbachev summit approaches.

The Russians moan that the American position is unthinkable. Many Americans, and Europeans, nod in agreement. The administration frets that the wily Gorbachev is making public-relations hay. But then the Russians shuffle forward all the same. This is the way it was when the Kremlin came back to the table after having walked out, when it eased off its hard-to-get pose and agreed to a summit, when it dropped its insistence on outlawing self-evidently un-outlawable research on defensive strategic weapons, and when it went beyond slogans and said it would be offering a new proposal at Geneva to reduce offensive arms.

From this account, we do not draw any hard conclusions. Things are moving, but one reason is that the Russians are retreating from unserious positions. Their strategy of playing to American public opinion eats at some Americans, but it is forcing the Russians to moderate their position in order to appear presentable in foreign eyes. The more the Russians seek to gain propaganda advantage, and to position themselves to put the blame on the Americans if the summit fails, the more moderate they have to become. This is the other side of the propaganda coin.

Still, it troubles the United States to see the Soviets trying to manipulate American opinion. Hence, Secretary of State George Shultz's insistence Friday that the private talks at Geneva are the proper forum for the exploration of the new Soviet position. They are. It is the annual visit of the Soviet foreign minister to the United Nations that has prompted this latest surge of public diplomacy. There may not be a comparable surge until the summit in November.

Careless optimism remains unwarranted. If the two sides stopped right now, they would be far apart on the big arms control issues, not to speak of the other issues of regional disputes, human rights and ideology that Mr. Reagan also hopes to discuss. Nor does either side appear to have calculated the final price it is willing to pay for an arms agreement. The Russians have made some relatively easy choices. Neither the Russians nor the Americans have yet addressed the hard ones.

The notion is current in Washington that Mr. Gorbachev, having consolidated power, can do pretty much what he wants. It's almost certainly not so: Mr. Gorbachev has removed only one man from the place where it counts -- the Politburo. It takes a large faith in President Reagan's bargaining talents, moreover, to believe that the Kremlin will reverse course and end up accepting the Reagan Strategic Defense Initiative in the form in which the president continues to press it. The tough part hasn't even begun.