Let us suspend cynicism for a moment and acknowledge that what Ronald and Nancy Reagan did on Monday was a very good thing: correct, well motivated and potentially beneficial for the whole country.

What they did was to drop in on a black family in suburban Prince George's County whose home had been the scene of a cross- burning. They had read about the incident in the papers, the president told Phillip and Barbara Butler, and he wanted them to know that it "is not something that should have happened in America." The two couples chatted for a few minutes in the Butler's living room; the president gave 4-year-old Natasha Butler a jar of jellybeans, and that was it. The Reagans helicoptered back to the White House.

Politics? Of course. But politics that beg for context. In late October 1960, when Martin Luther King Jr. was in a Georgia jail as a result of a civil rights demonstration, John F. Kennedy made a call to Mrs. King, offering to do what he could to help her husband. That call, together with Kennedy's success in the televised debates with Richard Nixon, is credited with swinging the black vote to the Massachusetts senator and catapulting him into the White House.

Blacks who will dismiss the Reagan gesture as political cynicism remember the Kennedy phone call as a statesmanlike gesture. They ought to remember, though, that Kennedy was in a close political struggle, only days away from the election. It was known, too, that President Eisenhower was contemplating making a statement that the jailing of King was "fundamentally unjust." (King was in jail because a Georgia judge ruled that his arrest for demonstrating at Rich's department store in Atlanta violated the terms of his probation on an earlier traffic offense.)

If we can give credit to Kennedy for a gesture calculated to help him win an election, can't we give credit to Reagan for a gesture that won't win him a single vote? Kennedy had to make the phone call. He needed the electoral boost, and blacks and liberals across the country were urging him to do something. Reagan was under no such pressure with regard to the Butlers. And yet the very day he learned of the cross-burning (which took place five years ago) he was at the Butler home.

No doubt there were political considerations involved in the Reagan visit. He has lately been at great pains to rid himself of the "racist" label. He has been trying to make the point that his conservative approach to government is not anti-black. He has been concerned to rehabilitate his image, both because he really does consider himself a decent man and because he understands that it is hard to govern when a substantial minority views him as indifferent to their interests.

The brief visit to the mostly white 500-home subdivision of College Park Woods may have helped. It may have prodded the Butlers' neighbors into a more overt display of neighborliness. And it may also have served the more useful purpose of announcing to America that Klan-type racism is not acceptable. It is as though President Eisenhower had not merely pledged to uphold the law at Central High School but had put his arm around one of the Little Rock Nine and said "I'm on your side."

What Reagan did on Monday does not soften the impact of his economic program on black America. He clearly believes that his troubled program is the correct approach to restoring the American economy.

But it did show that he believes some other things as well. And for that, he deserves some credit.