This time, it was Joe Biden's turn. In barely more time than had elapsed between the first press reports of Gary Hart's indiscretions and his forced withdrawal from the Democratic presidential race, the senator from Delaware has gone from serious contender to shocked victim -- done in by news reports and television pictures of his plagiarizing speeches and his hyping his rather flawed academic record.

What gives? Is the press out to prove its power -- and disprove the charges of left-wing bias -- by sabotaging one liberal Democrat after another? No. We are taking seriously our responsibility to deal with potential presidents' character and competence. But we are doing it in our usual imperfect way.

In neither case are we dealing with trivia. Hart's behavior was not simply a matter of gossip. His inability to maintain a minimum degree of self-discipline or discretion raised serious questions. So did the difficulty he displayed in facing the truth and reality of his situation.

Doris Kearns Goodwin, the biographer of Lyndon Johnson and the Kennedys and scholar of the presidency, recently made the point that political journalists ought to pay close attention to how truthful presidential candidates are in their reflections of reality. The reason, she said, is that once behind the fence at 1600 Pennsylvania Ave., there is inevitably a strong temptation to reconstruct the world as you wish it to be.

The same LBJ who invented a grandfather who died heroically at the Alamo, she pointed out, had no problems converting what was at best an ambiguous naval incident in the Gulf of Tonkin into the excuse for a massive escalation of the U.S. involvement in Vietnam. The fake grandfather seemed mere hyperbole, perhaps worth only a laugh. But the Gulf of Tonkin incident led to tragedy.

That was the serious warning sign that made reporters highlight Biden's appropriation of others' words and sentiments and -- in the case of British Laborite Neil Kinnock -- even their life experiences. And it is why we twitched when we learned he had invented an academic renown for himself far greater than his record.

A second element in his behavior was also worrisome. In many of the troubling campaign incidents, Biden was simply acting on instinct. The Kinnock plagiarism, probably the most damaging, occurred to him in a van on the way to an Iowa debate. The videotaped exchange with a New Hampshire voter, in which he misrepresented his own academic record, was a spontaneous question-answer session.

The concern about Biden among many who have known and worked with him is that his impulses are unchecked by judgment or reflection. Two longtime personal and political associates of campaign consultant Patrick Caddell, Biden's close friend and mentor, told me in separate conversations last year that they had declined to join Caddell in helping Biden because -- as one put it -- "there is no filter" that Biden applies to Caddell's input.

In Senate hearings, Biden often appeared so caught up in his own thoughts that he could barely define a question to the witness. In his celebrated exchange with Secretary of State George Shultz on South Africa policy last year, the senator appeared almost out of control. A liberal lobbyist who worked with him trying to derail Reagan administration judicial nominations commented on his habit of showing up late for strategy meetings and often straying from the agenda: "When you're elected to the Senate at age 29, it's easy to think the meeting begins when you walk through the door and the subject is whatever you've got on your mind."

All those things provided the context in which reporters viewed these recent, self-destructive incidents. I do not think we exaggerated their import -- any more than we did in the very different incidents involving Gary Hart.

But there is still a distortion, because no human being can be reduced to one or two traits without serious risk of caricature. In Hart's case, the picture we drew at the end omitted many of his redeeming qualities: his intelligence, his willingness to do the hard work of policy analysis on critical questions, even the steadfastness of his political course, in sharp contrast to his out-of-control personal behavior.

Similarly with Biden, the focus has been too narrow to do justice to the man. He is impulsive, but not all his instincts are self-serving or self-aggrandizing. His sister Valerie tells touching and convincing stories of his generosity and protectiveness as an older brother. And last summer, I saw him walk away from a large number of clamoring fans at a Chicago meeting (many were political activists any presidential candidate would love to recruit) and closet himself for close to an hour with a stranger in pain.

The man had almost broken down while telling Biden he had just learned he had a fatal disease -- AIDS. He could deal with the threat to his life, but not with the prospect that his treatment might leave his family financially bankrupt. "What kind of a society is this?" he asked in his pain.

That much I overheard. The rest was between Biden and this man, but when I saw the man later in the meeting, he seemed calmer. Biden had found a way to help him, if only by listening. And he did it out of a generous impulse. That compassion, too, deserves to be noted about the latest departed candidate.