A plus for voters

The US election process was well served by the presidential debate in Louisville, Kentucky, Sunday night, quite apart from how it might have affected the prospects of either candidate. If anything, this debate on domestic affairs should have come sooner; the other scheduled debate, on foreign affairs, is two weeks off. There should be more such direct confrontations - at least, this year , a third, on the candidates' visions, plans, and programs for America's future.

An election comes down, in the end, to a choice between two individuals. A voter must simplify a remarkably complex set of reactions - emotional, personal, financial, social, political - into a single act of pulling one lever. The voter needs all the help he can get in making that decision. The modern presidential campaign has become so media dominated that it often appears the voter must choose between two campaigns, not between two individuals.

Keeping that distinction, it can be said that the Mondale campaign was helped by the Democratic challenger's performance. Mr. Mondale was the more relaxed, the more in command of his game plan, the more aggressive. A quick post-debate Gallup survey for Newsweek showed the public rated Mondale the winner of the debate by 54 to 35 percent; this reflected the judgment of most political analysts. The debate gives the Mondale camp a much needed boost in morale. It could encourage many Democratic contenders to want to associate more closely with the national ticket.

Mr. Reagan, in the early consensus, was off his anticipated form in the debate. He delivered an occasional vintage political jab: ''I don't believe that Mr. Mondale has a plan for balancing the budget; he has a plan for raising taxes.'' But he appeared hesitant; he often labored to recite facts, as if to defend against a charge of insufficient command of detail. For the Reagan team to claim that the President ''won'' the debate because he was not knocked out by his opponent is to seek comfort in the larger political context.

That context does afford Mr. Reagan a lot of security. His margin over Mondale nationwide going into the debate was 55 percent to 37 percent (a quite neat inversion of the Mondale debate edge) in an unusually extensive ABC/Washington Post survey of 12,000 voters. This translates into an even sharper electoral college advantage. Events will tell whether any erosion follows the debate. There is no reason to assume the impact will be anything but modest. At the most, if Mondale turns his campaign around, it might be said his recovery began with the debate.

As leader of one of America's two major parties, Mondale has needed to be a better candidate than he has been. He made a start on that Sunday night. But Mr. Reagan will have to do better too, as was shown on the central issue of the first debate. We don't agree with Mondale's assertion that Americans have no idea how Mr. Reagan would approach the deficit-taxes issue. If the President follows past form, he would resist raising taxes. But Washington as a whole will decide the issue: Congress and leaders in the President's own party would make the pragmatic case in 1985 about what must be done, and a solution would be negotiated. Still, Mr. Reagan could do better in discussing the options.

Americans don't pick leaders by forensic tally.

This first debate served a different purpose. It helped clear deadwood from the presidential campaign forest. Both candidates were driven more to the political center on key issues like church-state relations, social security, the environment.

Mr. Mondale has been offering the Democratic past, Mr. Reagan the Republican present. We have yet to hear enough about the American future.