WASHINGTON — FOR SOME unaccountable reason, the past decade has seen the rise of what some call newstalk and I call rubber-duck television -- shows in which normally sane and civil journalists interrupt and insult each other, and barely get off the air before they start whapping each other over the head with rubber ducks.
At the same time, the network news programs have surrendered to show business in the morning and star worship in the evening; no major story is official unless the anchor and his trenchcoat have been flown to the scene for a standupper.
While this screaming and shouting, this frantic competition for rating points has gone on, three other developments in TV news have quietly become more important to educated Americans than anything the newstalk and broadcast network producers do.
One is Ted Turner's Cable News Network and its sister Headline News, offering news around the clock. CNN carries major stories live, beginning to end, without interruption for soap operas or golf matches. Cable technology makes it the worldwide real-time news medium, watched simultaneously in Washington, Berlin and Baghdad.
Another is C-SPAN, the Cable-Satellite Public Affairs Network, which carries congressional hearings and proceedings live and often offers debate from the House of Commons. It fills in with speeches and interview programs that provoke audience calls from all over the country -- pulse-taking without the crowd-baiting hype that characterizes so many radio call-in shows.
The third development is not a phenomenon of the cable revolution, but the premier example of non-commercial broadcast television, television for grown-ups. It is simply the best regular public-affairs program in TV history, surpassed only rarely by the CBS Reports documentaries of yesteryear.
It is the MacNeil-Lehrer Newshour, which happens not occasionally but every workday, 260 days a year. While it originated 15 years ago when its key men both had sideburns, it has gained stature year by year, especially since it became the only national daily news program that runs for a full hour.
Robert MacNeil and Jim Lehrer have prospered in prestige, if not in the seven-figure terms of commercial TV, by defying the cliches of the television age. No rule of the living-room screen has been repeated more often than the one against ''talking heads,'' which insists that people merely talking, without action film or distracting decolletage or the threat of rubber ducks, drives viewers away.
Talking heads are in fact the central attraction of the Newshour -- people being interviewed, debating, being allowed to finish sentences! whole paragraphs! full minutes! without interruption.
The other evening, the anniversary of their show, the two anchors and their supporting cast began with the usual brief summary of the day's events. Then they spent five minutes with Sheldon Segal, inventor of the newly approved Norplant birth-control method; 15 minutes with former President Carter on worldwide human rights and the Middle East; 18 minutes with various Poles on the government shakeup there, and finally offered an essay on airport safety. There were film clips that supplemented the words, not the other way around.
That doesn't add up to an hour because public TV used that anniversary occasion to make an extended pitch for viewer support, something regular fans have to put up with only a few times a year. The Newshour is a valuable vehicle for those solicitations, because its audience is both blue-chip and loyal.
After that evening's program, Messrs. MacNeil and Lehrer sat still for an unprecedented promotion exercise, another hour in which they talked about themselves and others said admiring things about them and their program.
The defiantly untrendy tone of the occasion was set by Mark Shields and Dave Gergen, the interviewers who interviewed the interviewers. They are the Mutt and Jeff of political commentators, whose Newshour dialogues are sharp and fair but who need help from the studio cosmetologist to compete with the talking hair-dos now featured on the morning ''news.''
Walter Cronkite, Jane Pauley, Barbara Walters and Peter Jennings, all of commercial TV fame, all said nice things. The dominant theme was envy; Mr. Jennings said ''agony'' was what he felt when MacNeil-Lehrer went to a full hour.
Despite their careers with networks that chop the news into ever-smaller giblets, those four are intelligent people. Because of those careers, I suspect they feel as much guilt as envy when they see Robert MacNeil and Jim Lehrer appear each evening, speaking to Americans as grown-ups to grown-ups.