John W. Hinckley Jr.'s first answer was ambivalent. "I have no intention now of taking the stand," he told Judge Barrington D. Parker last week. Confused, the judge asked what he meant by "now." "Well," Hinckley said, "I have just been advised by counsel that I have no intention of taking the stand."

It's bothersome to know that we won't hear directly from this quirky young man with the dead eyes. John Hinckley Jr. is only 26, yet during his lifetime a number of other weird loners who seemed to come from out of nowhere, have taken shots at our leaders and twisted the course of America on to unexpected paths. And he is one of the few would-be assassins who has been around to come up for some kind of trial with a chance to testify extensively and give us insight into his actions and, perhaps, those of the others.

Of course, it is Hinckley's right not to take the stand, and his lawyers' advice presumably was in Hinckley's best interest. But I suspect we could gain some deeper insight into ourselves if we could hear Hinckley tell his own story.

What we're getting now is frustrating and inconclusive. We're left with many unanswered questions.

Everything we're hearing is filtered through the screen of competing psychiatrists. We're hearing quotes of what Hinckley supposedly said, interpreted one way by psychiatrists for the defense and another way by those for the prosecution. There is enough in the testimony of others to suggest that Hinckley is quite lucid, enough in this expensive courtroom spectacle to make you wonder if his lucidity is one reason his lawyers don't want him to take the stand.

Except for the emotionally wrenching testimony of JoAnn and John Hinckley Sr., this trial has been as antiseptic as a mouthful of Listerine. The point-counterpoint of expert witnesses is beginning to resemble a television talk show. A matter as deep and serious as this deserves better. We need to hear Hinckley's voice telling us what was on his mind when he shot President Reagan and three others and touched the emotions of us all.

We did not hear from John Kennedy's killer, Lee Harvey Oswald. After being arraigned, he was gunned the next day during an almost routine prisoner transfer. Oswald's killer, Jack Ruby, was convicted and sentenced to death, but never testified at his trial. He went to jail, and died there of cancer. James Earl Ray was accused of killing Martin Luther King. At first, he pleaded not guilty, then switched his plea to guilty. That same day, he was sentenced to 99 years in prison--no testimony from him.

The one exception was Sirhan Sirhan, who testified for four days in the murder trial of Robert F. Kennedy. He admitted that he had shot and killed Kennedy. But he said he could not remember writing death threats in his notebooks. He decided to kill Kennedy after seeing him on TV, Sirhan said.

None of this silence or amnesia would matter if there weren't still such lingering questions about these large and terrible public crimes. The suspicions are not about the men who did the deeds, but about the circumstances and motivations of the misdeeds, and they haunt us and stir us to debate and suspicion years and decades later. The assassination of John F. Kennedy in 1963 was the subject of a television documentary spotlighting the life of J. Edgar Hoover. It provided new and shocking details 19 years later, and made even the few purists among the public question the wisdom of what they're told.

We need as much illumination as we can get, on the motivation of all these men, on the motivation of John Hinckley Jr. Too bad we'll just have to wait for the book. Then the words will not be under oath.