Had Bob Haldeman chosen to write a serious book about Richard Nixon he could have made a contribution to history. Instead he decided to go for a socko revelation.

He then apparently drew back before the legal implications. The upshot is a tawdry business for everybody involved.

Despite the niagara of material written and spoken by and about Nixon, large historic questions remain. How was it possible for someone so ill at ease with people to rise so far in American politics, and to serve as president?

What is the connection between Nixon's often foolish comments and his capacity to make some considerable decisions in both domestic politics and foreign affairs? How did it happen that the man who came on to Arthur Burns and Henry Kessinger as hightly analytical, could be a blasphemous crook in his dealings with many other people?

Haldeman was in good position to answer at least some of those questions. He saw Nixon plain. He reinforces with new material the now widespread impression that Nixon tired easity, had a foul temper and often concentrated on details while ignoring major matters.

But no picture of the whole man is painted. Instead, haldeman falls back on the wholly inadequate views, previously advanced in other books, about the good Nixon and the bad Nixon, the light side and the dark side.

Failing deep psychological insight, Haldeman could fall back on a store of detailed information, important because it came from him. In one episode that I know particularly well, the bugging of my home in Georgetown and my hotel in Paris, Haldeman confirms some suspicions that were never proved.

He says that Nixon personally ordered the bugging in each case. He says that those buggings were the first criminal actions undertaken by Nixon as president. He intimates that the purpose of the bugging was to get information on what Henry Kissinger was saying about Nixon to outsiders. Indirectly, in other words, he places at the root of all the White House horrors Nixon's neurotic suspicions.

But Haldeman affects to go way beyond all allegation and intimation. A good example is what has been billed as the "true story" of the missing 18 1/2 minutes on the tape of Haldeman's meeting with Nixon on the first White House work day after the Watergate burglary. In discussing the 18 1/2 minutes Haldeman purports to have Nixon confessing that he had another White House aide, Charles Colson, arrange the burglary through the former CIA employee, Howard Hunt, in order to get some dirt on the Democratic national chairman, Lawrence O'Brien, and the late industrialist Howard Hughes.

The book attributes to Nixon the following comment: "I was on Colson's tail for months to nail Larry O'Brien on the hughes deal. Colson told me he was going to get the information I wanted one way or the other. And that was O'Brien's office they were bugging, wasn't it? And who's behind it? Colson's boy, Hunt? Christ."

But Haldeman had previously testified under the oath that he had no knowledge of what was on the missing section of tape. He could not make the above accusation directly without facing a perjury rap. Instead he says that the comment attributed to Nixon during the 18 1/2 minutes was "reconstruction" - "the way the conversation might have gone.

Similar evasions characterize his accounts of a great many other matters. So the Haldeman book brings no conclusive evidence to bear on such questions as whether Nixon knew of the burglary in advance, or approved the coverup.

In advance briefings for publicity purposes, however, Haldeman's publishers claimed that the book answered those questions decisively and also threw new material on such matters as the role of the Central Intelligence Agency and the identity of the White House leak known as "Deep Throat." In fact, the book did not give useful information on those matters. But from the bogus claim it was only one step to the corridors of gossip and then a jump to a break of the Republican date.

In restropect, everybody involved ought to have at least a red face. Also a strong sense that those of us in the press and television are all going to have to be more responsible if we expect to earn public respect and continue to enjoy the special privileges of the First Amendment.