EDITH BUNKER Is A national treasure. She is the crowning achievement of a 30-year evolution - the lineal descendant of all the sit-com housewives who have gone before her, yet more real and more universally cherished than any of them. Edith Bunker is the TV mother of us all. How heartbreaking to watch as a man tries to rape her on television tonight.

The Bunkers have gone through many true-to-life traumas in their seven years on CBS, but tonight's special one-hour episode (actually two half-hour shows back-to-back). at 9 o'clock on Channel 9, is the most nerve-shattering and one of the most brilliant of all. To some, subjecting an icon as beloved as Edith to this sort of indignity may seem too cruel, but that is the point of the program - that rape is not only a crime, but a desecration, and that its victims may remain victims long after the crime itself has been committed.

How many times Edith has lumbered cheerfully across that living room floor to answer the Bunker doorbell. This time, her friend Sybil Gooley is waiting, angered that she wasn't invited to Edith's surprise 50th birthday party. Sybil leaves and a handsome stranger approaches. Edith closes the door and fastens the chain bolt before she'll talk him; "You can't too cautious," she says.

The ordeal that follows may be all the more shocking not only because it is happening to Edith, whom we revere outlllandishly as a symbol and a person, but because the sorrow and the terror of the situation are punctuated with comedy. The rapist has removed his shirt and forced Edith onttto the couch when he tells her. "You know you smell wonderful."

"That's Lemon Pledge," says Edith and the studio audience roars nervously.

Certainly producer Norman Lear and the writers of this episode, Bob Weiskopf and Bob Schiller will be criticized for sweetening the subject with laugh lines. But without the laughs, the program might in fact seem too polemical - just another of TV's social problem shows - and have less impact. Edith's indefatigable daffiness validates her, in a way, as a believable character, like Archie, that magnificient, pathetic speimen to whom she is married and devoted, she reminds almost everybody of someone they know. Most TV series characters only remind you of other TV series characters.

And to keep an audience simultaneously on the brinks of laughte and tears is one of the most difficult feats a writer can accomplish. Schiller and Weiskopf, along with impeccable director Paul Bogart, bring this off beauutifully. Ironically or not, both writers worked previously together on another television milestone, "I Love Lucy." It is true Lucy was never in straits to equal Edith's plight tonight, and yet the kinship between the two is undoubtedly there. The attempted rape of Edith Bunker is in effect the attempted rape of Lucy Ricardo, and of all the TV surrogate mothers created in their images.

When Archie and son-in-law Mike learn of the attack on Edith, they return to the Bunker house to search for the rapist. Sudddenly they are bopping into each other in a slapstick panic that recalls such moments of "Lucy" lunacy as when Ricky, Fred and Ethel tumbled around hysterically when Lucy announced it was time to go to the hospital and give birth (to "Little Ricky").

Television has given us new ways to measure the passage of moments, years and our lives.

You could watch a hundred poshly produced Shakespearean plays on public TV and never feel as devastated as you do watching the assault on Edith Bunker. Television is at its best wehn it sidesteps esthetic considerations and connects on an intimate, personal, emotional level no other medium can duplicate.

Theer are flaws in the show. When Archie first learns of the incident from a distraught Edith, everything we know about him tells us he would be enraged and ready to wreak vengeance. Instead, the writers make him appear something of a coward, and this weakens the program considerably. They also underestimate our concern over Edith and the other characters by going too far with the comic relief, especially at crucial junctures of peril.

Lear will probably get some flack for treating rape at all in a comedy show (though, as mentioned on tonight's program, daughter Gloria suffered a similar ordeal in a previous season). From Hollywood, Lear is naturally indignant at the thought of such criticism, and at the notion that he is topic-dropping again by doning a rape show now that the subject is so popular.

"How could we be reaching for sensationalism when we're taking something right out of our national life and dealing with it?" he says.

Rape is the fastest growing crime in America. We worked on this script for over a year to get it right."

The program was being taken seriously by some viewers days before its scheduled telecast. On Wednesday, Reps. Herbert Harris (D-Va.) and Peter Rodino (D-N.J.), co-sponsors of legislation to protect the privacy of rape victims, held an advance screening of the program for 175 people on Capitol Hill. Among the guests were women who work as volunteers at rape crisis centers in the Washington area. Some of them have been through expreiences similar to Edith Bunker's. And some of them wept as they watched her struggling to escape and, later, reacting with horror to the sound of the doorbell ringing again.

The weekly performances of Caroll O'Connor and Jean Stapleton as Archie and Edith Bunker are the best acting regularly on television. They continue to expand on characters who might have become caricatures in other hands. But tonight's program, as one might expect, is Stapleton's particular triumph, an eloquent portrait of fear, vulnerability, dignity and, finally, victorious resolve.

There is talk in Learwood that this season will be the last for the Bunkers on the air. Perhaps a presidential intervention could prevent his; it might be considered. When 1980 rolls around and we indulge ourselves in backward glances, "All in the Family" and "Roots" will be remembered as the decade's great television and television's great vindication. Life without The Bunkers would have irrefutably been worse.