RONALD REAGAN'S appearance on Soviet television while we were listening to Mikhail Gorbachev here was a triumph for the president -- empty, but what he wanted most.

There was the president talking about technology to the Soviets and Gorbachev talking about trust to the American people -- a switch, considering that one is the chief of a democracy and the other of a police state.

Both referred to the summit as a wonderful thing, Reagan because it really was wonderful for him and Gorbachev because he can hardly do otherwise. What the summit produced, beyond the exchange of the Bolshoi and the Beach Boys, was the chance for Reagan to play Moscow on New Year's Day. He asked no more of Geneva.

He successfully upstaged the Soviets' new international media star. By swamping him in firelight and affability, he diminished Gorbachev as a threat and a challenge. There was no serious talk about arms control. The world had to settle for smiles.

If Reagan learned anything about the Soviet system and its new leader in Geneva, he did not divulge it in his New Year's Day message. He just repeated a bromide he was uttering before he met Gorbachev: "The American people do not wish the Soviet people any harm."

Gorbachev, who for the benefit of the Politburo and the Europeans must appear to be pleased with the outcome, also spoke of bridging the gap in mutual understanding between Soviets and Americans. He is, for the moment, dancing to Reagan's tune.

Arms controllers have been consoling themselves with the thought that the next summit will have to produce something of substance, that Reagan cannot come away empty-handed a second time. It could be that as the 1986 elections draw near, Republican senators up for re-election will begin to pressure Reagan for results. But they are not presently feeling any heat from their constituents, and the Democrats have no coherent position on arms control.

Only the military, which may balk at seeing billions going up in space, or the budget makers, caught in the vise of the Gramm-Rudman-Hollings amendment can stop the quickening pace of Star Wars.

In the meantime, the Soviets seem to be joining in what paranoids of the left regard as a world-wide plot to make Reagan look good. Suddenly, mysteriously, they have pushed the date of Gorbachev's American visit back from June to September. It's Reagan's luck again. Gorbachev, for all his savvy, may be falling back into the Soviet trap of focusing implacable opposition on one weapons system -- and losing the public relations game in the process.

Andropov so opposed European missiles that when they were accepted, he yanked his negotiators home to Moscow. Reagan for a year was able to throw up his hands and say, "What can I do? -- they walked out." Arms control was not an issue in the 1984 campaign.

If Gorbachev wishes to underline his hostility to Star Wars by putting off the summit, he plays Reagan's game.

Reagan is one of those rare politicians who live a day at a time. He knows by now that, for him, something will always turn up. He pushes ahead with his own agenda, trampling on Washington's conventional wisdom about what he must do with every day that passes.

What other president, for instance, could walk away from the mess that was created over a secret order issued in November which would require thousands of government workers to take routine polygraph examinations?

Secretary of State George Shultz announced that he would not submit to such an indignity. He and the president later met and he was excused from being hooked up to the truth machine.

"Neither one of us are going to," Reagan said airily and ungrammatically. The president's people reflexively put out the word that Reagan didn't know what he was doing when he signed the order. The next day, however, his spokesman Larry Speakes said the president was, too, "fully aware" of what he had signed.

Any other president would have been in a lather about the whole thing. But Reagan brushed it all aside. He got credit instead for making an exception to an odious rule out of personal regard, for derelection of duty and for deliberately issuing an order that reflects on the integrity of the people serving him. Only Reagan could get away with it.

But such is the perspective in the Reagan years that it was Shultz who got all the ink, hailed as a hero ready to resign on a point of honor. The perpetrator, the president, got off scot-free.

Reagan hears the talk that he is a "lame duck." He will ignore it. He will be in the Oval Office for the next three years, and his history is of somebody who more often than not gets his own way. His appearance on Moscow television is just more proof.