THE DEMOCRATS are asking about the next presidential election, as politicians do, but they have got the question wrong. Democratic National Chairman Paul Kirk said last month that Democrats should nominate a southerner for president or vice president next time. New York's Gov. Mario Cuomo, speaking in San Antonio last week, said that he might decide to run himself if "slurs" against his Italian origin continue. He cited one newspaper column that quoted an unnamed southern Democrat saying "there aren't many Marios in the South," and another column that said he looked like a character from "The Godfather."

Surely neither Mr. Kirk's statement nor Mr. Cuomo's is to be taken literally. Mr. Kirk must know that voters don't decide to vote for a candidate simply because his or his running mate's voting residence is in one state rather than another. Mr. Cuomo surely will have weightier reasons for seeking the presidency, if he does, than irritation with two newspaper columns. What is wrong here is that the argument is over the candidates' r,esum,es: what regions they're from, what churches or ethnic groups they belong to. But on Election Day in 1988 people will be deciding on human beings, not on lists. We don't decide who should be president by selecting one characteristic from Column A and one from Column B.

So let us offer Mr. Kirk the chance to change his statement and say, unexceptionably, that he wants a ticket that can carry the South -- since it's highly unlikely that a ticket that can't can win. And let us second Gov. Cuomo if he is asserting that Americans in all regions should and will give serious consideration to candidates of every ethnic background. Some columnists' sources may think voters believe that most Italian-Americans are involved in organized crime. Voters and most politicians, we believe, have more sense. This is a nation whose great political scandal was unraveled by, among others, a Judge Sirica and a Chairman Rodino.

In 1988, the public will decide a contest between live human beings. Before making any decision, it will watch how each responds to the difficult choices and genuine stress of public life. A candidate's personal characteristics can be an asset: voters may believe they help him or her better understand the nation's or the voters' own problems. But the advantage is only marginal. The liability in most cases is even more limited. Human beings vote for human beings. The Democrats, and the Republicans as well, should weigh all the qualities of their potential candidates. Mr. Kirk and Mr. Cuomo are on their way to the right answers if they can just ask the right question.