THE Baby Boomers saw their political leaders murdered, first President Kennedy, then Dr. King and then Bobby Kennedy. In a sense, an entire generation of political leaders was gunned down.

But if their heroes were murdered, the Baby Boomers themselves seem bent on commiting political suicide, and Sen. J. Danforth Quayle, Vice President George Bush's running mate in the run for the White House, is but the latest casualty.

The 1988 election was meant to mark the coming of age of the Baby Boomers. On the Democratic side, Senators Jospeh Biden and Gary Hart both ran as candidates who could relate to the post-World War II generation, and just as JFK noted that a torch had been passed to a new generation, Hart and Biden maintained that they were now carrying a new torch.

Political analysts noted that hardly a stump speech was offered by the Baby Boomers without an allusion to the Kennedys. But simultaneously, they questioned whether there was anything at the core of the Baby Boomers beyond some faint hope of tapping into the legacy of their fallen heroes.

But doubts about experience and substance which plague any newcomer to national politics soon became serious questions of character. It's one thing to be young; it's quite another to be young and foolish and running for the presidency.

GARY Hart became the first victim. The revelation that he had spent the night with a Florida model, Donna Rice, proved so damaging as to end Hart's campaign even though he was the clear front-runner at the time.

The historian Alan Brinkley noted in The New York Times that Hart's down fall stemmed from the simple fact that he had no following, no deep-rooted constituency, in short, no claim to be running for the White House other than his own ambition.

In the end, Gary Hart became a political ghost at a tender age. He tried to make a comeback and instead became a laughingstock and an embarrassment to his party.

Biden was the next of the Baby Boomers to go. An "attack video" was released which indicated that Biden was not altogether clear what were the words and ideas of his predecessors and what were his own. The problem became fatal when it was revealed that the Delaware senator had cheated as a student at Syracuse Law School.

Douglas Ginsburg was a Baby Boomer of sorts himself, and though not a political candidate, he would have been the first of his generation to have become a Supreme Court justice. But he too fell victim to the same pattern. It began with questions about his competence: What scholarship had he really done? How many cases had he ever argued? Had he proved himself as a legal mind worthy of the Court? Soon it mushroomed into questions about his character, with the final blow being the revelation that he smoked marijuana while a Harvard law professor.

Dan Quayle, then, is merely the latest of the Baby Boomers who has fallen victim to the age factor. From the moment of his selection, the two reactions to youth which are inevitable came forth. He is young and exciting--it was said--vigorous and attractive, a great campaigner with amazing energy. He is a bright young star, who is charismatic and represents the future. And then there were the doubts. His name became an interrogative. Dan Quayle? Who is Dan Quayle?

He had a limited record in Congress and when pressed to prove his credentials he was forced to list summer internships he held while still a student. On his first day on the stump as a vice presidential candidate. Quayle seemed overwhelmed, jumpy, amateurish.

YOUTH is by definition a Janus-faced attribute, and he would likely have not suffered greatly had it been that he was only young. But in no time at all, questions about his substance as a political figure turned into questions about his personal character, and the combination is politically life-threatening.

First there is the matter of his weekend in Florida with lobbyist Paula Parkinson, who claims to have had affairs with several Republican lawmarkers. All evidence indicates that Quayle did nothing improper. The same is not clear in regard to his military record. Rather than going to Vietnam in 1969, Quayle signed up with the Indiana National Guard. Recent reports suggest that he used his family's influence to have his name bumped up on the list so that the Guard would take him and he would not have to see combat duty.

What is troubling is that for men of such young ages, who have had so little time to accomplish much of anything, they all seem to have found plenty of time to become entangled in personally embarrassing episodes. It is not fair to expect that someone who is not yet a half-century old will have a long and distinguished record of public service. And by and large the public is charitable on that score.

INEXPERIENCE in the young is forgiven in much the same way that past transgressions are often overlooked in the old. In a long life, the likelihood of making a misstatement, having a bad idea or suffering a lapse of judgement is high. If blemishes are discovered, we check to see if they have been corrected and, so long as there is a long list of counter-balancing accomplishments, we forgive.

The recent challenges to George Bush's war record are perhaps the best example of this phenomenon. It was suggested that Bush had exaggerated his heroic exploits in World War II, but it was forgiven in part because the event in question occurred more than 40 years ago, and in part because Bush was in the navy, did fly several combat missions and has over his long tenure of public service proved himself to be, if nothing else, honest.

A younger candidate does not have such benefits.

But so far the Baby Boom generation's leading lights have not been able to understand the bargain the public makes with age. They exaggerate their own accompishments, as Quayle has done in suggessting that he is unrivalled in his knowledge of national defense policy or Hart did in proclaiming himself a candidate with ideas. And they are vindictive and defensive when questioned about past improprieties, not understanding that a short resume requires a clean character.