He smiled at the wrong times, he evaded questions and he looked into the camera instead of at the reporters to whom he was speaking, but Walter Mondale gave his best campaign performance of the election year so far last night in the first of two scheduled televised presidential debates, this one live from Louisville's Kentucky Center for the Arts.

The performing arts were well represented by both men, Reagan with his battery of anecdotes and a jumble of statistics, many of them seemingly meaningless, and Mondale with a newly discovered resolve that turned him into a Louisville slugger even while he was careful to tell the viewing audience, "I respect the president. I respect the presidency" and "I like President Reagan. This is not personal."

Heck, everybody likes President Reagan, but they may have had a little less respect for him after the debate, during which Reagan seemed clearly on the defensive, occasionally lost track of his own remarks and at one point did a slight Porky Pig stutter on the word "deductions."

Reagan's closing statement was much less cohesive and pointed than Mondale's was, and Reagan's performance was generally so far below his usual standard that even Reagan loyalist George Will said of the president during ABC News' post-debate analysis that "His opponent looks somewhat more formidable" than was previously imagined. Will said Mondale looked "effective, poised and in command."

And Will also said, "I was astonished, frankly, at the president's closing statement with which, I thought, he was profoundly uneasy." Obviously it's back to the old briefing book for the Reagan team.

In practical terms, Mondale's good showing last night may amount to nothing more encouraging for Mondale forces than a tiny erosion of Reagan's enormous lead in public opinion polls. But word of mouth and word of print over the next few days asserting that Mondale, so frequently characterized as weak, looks pretty good after all may force Reagan to be even more defensive when the second debate is staged on Oct. 21.

In a way, the debate was a case of role reversal. Reagan, normally the programmed man who sticks to pre-arranged scripts, seemed determined to be spontaneous and thus talked himself into a corner or two. Mondale was the programmed one last night, evading questions so bluntly that he answered one or two by admitting first that he wouldn't address the question directly. Surprisingly perhaps, it was Mondale, not Reagan, who at least twice made reference to last summer's Olympic Games. And he managed to interject the subject of Lebanon even though the debate was supposed to concentrate on domestic issues. Mondale's cheek naturally provoked a stern rejoinder from moderator Barbara Walters. "Foreign policy will be the subject of the next debate," she said, smiling but stern. "Stop dragging it by its ear into this one." On ABC afterward, Walters also awarded the debate laurels to Mondale for being "more in command" than the sometimes flustered president.

In television, how one looks is as important as what one says, and Reagan, despite his fits of befuddlement, looked handsomely presidential, his eyes glistening. When he answered questions, he looked to his left and spoke to the reporter who had asked them. Mondale's fried-egg eyes didn't look so sunken as usual, but they didn't particularly glisten, either, and he chose to address most of his answers directly into the camera. That's fine for making contact with the estimated 100 million viewers who were watching, but why then did Mondale continually refer to "the American people" and call them "they" when he was speaking directly to them? The American people don't like being referred to in the third person when someone is staring them right in the kisser. It makes them feel like maybe they're not the American people.

This was one of the few times in the campaign that Mondale made a public appearance in which he did not seem to be shouting. Media specialist Tony Schwartz recently observed that in Reagan's appearances he has been miked in such a way that he could speak in his normal tone of voice and not have to shout, even when addressing large groups. This makes him a good living-room guest. Mondale always sounds like he's straining to be heard. Schwartz gives the Republicans credit for brilliant audio. It is often said of Reagan that the camera loves him but the microphone loves him, too.

In terms of demonstrating leadership capabilities, moderator Barbara Walters won those honors hands down. She shushed the audience when it broke into applause, she shushed the candidates, including the president, when they talked too long, and she even gave them a royal tsk-tsk at the beginning of the broadcast, complaining that between the two of them the Reagan and Mondale camps had rejected all but four of the more than 100 reporters suggested as questioners (the fourth reporter agreed upon withdrew, making not-so-vague allusions to sham). "As the moderator and on behalf of my fellow journalists, I very much regret, as does the League of Women Voters, that this situation exists," Walters said.

She's tough. She's a toughie. She laid it on the line. And she all but apologized for the overly rigid format imposed by the League at the end of the broadcast by saying, "No matter what the format is, these debates are very important."

Essentially the format is to drown all participants in rules and regulations so as to make electric and unexpected moments unlikely; the Reagan camp insisted on these terms. It made it almost impossible for the candidates to speak directly to each other. But questioner Diane Sawyer, of CBS News, deftly surmounted that obstacle when she asked each candidate, "What do you think is the most outrageous thing your opponent has said in the debate tonight?" and "What remaining question would you most like to see your opponent forced to answer?" Mondale ducked this chance to be direct, however, and in the course of his tap dance declared that the deficit (and not nuclear proliferation?) is "the most important single issue of our time."

The other two reporters were James G. Wieghart of Scripps-Howard newspapers and Fred Barnes of the Baltimore Sun. On yesterday's edition of "This Week With David Brinkley," it was stated that both sides had rejected Sam Donaldson as a questioner out of hand. Sam beamed a proud smile when that came up.

Despite the rigidity of the rules, the debate was in fact not dull but consistently engrossing, and once Mondale did manage to engage the president in a tiny to-and-fro. Reagan had reprised his 1980 "There you go again" shtick, and Mondale turned toward him and asked, "Remember the last time you said that?" To which Reagan replied, "Mm-hmm." Mondale said the last time he said it was when he denied he would cut Medicare benefits and that then he proposed such cuts once in office.

Earlier, however, Mondale seemed almost to be conceding defeat when he said, "After the election, Ronald Reagan will propose a tax increase." Presumably he didn't mean Reagan would propose it from a cozy retirement rocking chair at his Santa Barbara hacienda. To Mondale's benefit, Reagan, even when pressed, never did spell out a plan for continued economic recovery and reduction of the deficit.

The questioners were fairly rugged, perhaps most so when Reagan was asked why despite his protestations of religious faith he never goes to church or brings ministers into the White House for services. Reagan said to go to church would be to subject other churchgoers to a possible terrorist attack, but didn't really address the second part of the question.

Dan Rather of CBS News grumped to viewers before the debate began that "This will not be an actual debate" but more of a televised joint press conference, and Tom Brokaw of NBC News also advised viewers that what they would see is "actually . . . not quite a debate."

But for all the qualifiers and the dire predictions of pundits on TV yesterday that this would be a pointless exercise, the 90-minute debate (which ran overtime by about 10 minutes) was compelling viewing and not without value as a discussion of issues. It also helps make the election look like more of a real contest, and that should lead to a bit more concern and interest on the part of the electorate. Without question, a debate like this is better than no debate at all.

What one may most remember about it, though, is the whip wielded by Walters, who at one point congratulated the candidates for obeying her commands by saying, "You're both very obedient. I have to give you credit for that."