It seems to me a civic-minded organization whose name is synonymous for most of us with dull parental duty has made an exciting accomplishment.

I refer to the diminishment of violence on television, an achievement entirely due to the work of the Parent-Teachers Association.

And a very tough-minded association it has turned out to be, though it overcame its contrary image. The PTA did not merely say to the broadcasters, "We'll give you six months and if you don't cut down on violence, we'll boycott the advertisers on the violent shows."

Network executives huddled briefly, murmured weakly about censorship and then proceeded to cut down on violence. There is less of it this year than last and there will be less of it next year than this.

A cheer should be raised. When did you last hear of the PTA doing anything except holding another meeting?

But I mean the cheer for the accomplishment as well as for the organization. Nobody can any longer doubt that violence on television is catching. In their book,"Remote Control," Frank Mankiewicz and Joel Swerdlow have listed violent crime after violent crime that police departments throughout the nation have reported as the direct result of some mentally unstable persons trying to copy the plot of a television show.

Take just one of their illustrations: On Dec. 13, 1966, NBC aired a film called "Doomsday Flight." It told the fictional story of an extortionist who placed a bomb aboard a commercial airliner within the United States. While the plane was in flight, he calmly notified authorities that a special pressure device would set off the bomb if the plane flew below a certain altitude. The Airline Pilots Association previewed the film and begged NBC not to show it.

The association knew what it was talking about. While the show was still onthe air, a U.S. airline received a threat clearly modeled on the unfolding story. Within 24 hours there were four more threats and eight more within next week. Seven years later when the film was shown again, an airliner about to take off from New York to Madrid had to be grounded while authorities investigated still another call.

Television executives have argued that they cannot be expected to worry about "nuts." But if they continue to show violence, the rest of us must worry. The National Institute of Mental Health estimates that at least 20 million Americans suffer from "some form of mental illness." If only a small percentage of those people are moved to violent crime by what they see on television, it is cause for us to worry.

Each day the average American watchers rape, murder, mugging, assault and other violent crimes on his favorite shows. If only one-tenth of 1 percent of the nightly television audience is moved to imitation, that means an additional 85,000 acts of violence.

But the PTA is primarily interested in what violence on television does to children; how it suggests to them that violence is normal, that it is to be tolerated, even expected; how it teaches them the clear lesson: Every problem from money worries to marital difficulties to the catching of bank robbers can be solved by a violent deed.

The country is approaching the time when most of its adult population will have been reared during the TV age. Translated in terms of crime, that means that most of the adult population will shortly have been constantly exposed to the violent solution of all problems.

I don't know what that will do to us, but it can hardly be good. So I say more power to the PTA. I hope the organization sticks with its cause.