THE U.S. SENATE will vote today whether to confirm Clarence Thomas as a justice of the Supreme Court. There are many independent reasons why the Senate should vote against Thomas. The sexual harassment issue that has arisen of late is yet another one.

It is unfortunate, both for Thomas and for Oklahoma law professor Anita F. Hill, that this case has become the nation's latest daytime (and nighttime) soap opera. Certainly, the Senate Judiciary Committee should have recognized the seriousness and validity of these charges long before it forwarded Thomas to the Senate floor early last week.

It is too late for that now. But perhaps this debate, on a subject too long ignored, has helped people to realize that sexual harassment is not the practice of only a select few; it exists on many levels, behind many office doors. We hope this case may move more employers and institutions to establish proper and responsible procedures for handling sexual harassment cases in the future.

Not every man or woman who talks about sex is guilty of sexual harassment. Most, we would argue, are not. It is not so much what is said, but how it is said, when it is said, and to whom. Sen. Orrin G. Hatch (R-Utah) said Friday night that only a truly perverted and sick individual would talk about his penis or discuss pornographic films, as Thomas is said to have done. Thomas is probably neither perverted nor sick, but he may have talked about sex at the wrong time, to an unwilling listener, in an inappropriate manner.

PERHAPS ANITA HILL is a brilliant, psychotic, pathological liar with a grudge. Perhaps she made up her entire story out of thin air--public hair, "Long Dong Silver" and all.

But it is extremely unlikely. Anita Hill had everything to lose by coming forward with her story and not much (if anything) to gain. On the contrary, the entire process has been intensely traumatic. It hasn't helped her career one bit.

Anita Hill does not come off as a sociopath. She comes off as a brave, suffering and credible witness. She passed a lie detector test. She is a well-respected law professor. She has four credible witnesses testifying that she had told them about her difficulties with Clarence Thomas when they began.

Hill's story is convincing, and the scenario she poses is entirely plausible. In 1983, Stanford University professor Terry Karl left her post at Harvard even after she won a sexual harassment case against a senior professor here. In this Saturday's Boston Globe, speaking on the record for the first time, Karl wrote, it is "strange to insist that Hill or any other woman must quit her job, not take advantage of job opportunities, or file a complaint in order to demonstrate her credibility in a sexual-harassment case." We agree.

On the other hand, we have every reason not to believe Clarence Thomas. Unlike Hill, he has every reason to lie--his confirmation is on the line.

Thomas may exude moral authority while categorically denying ever asking Hill out or ever talking about sex with Hill, but he exuded that same moral authority while insisting that he has no opintion on Roe v. Wade, or that his heartfelt defense of natural law was nothing but philosophical musings. We didn't believe him then, and we don't believe him now.

THOMAS IS NOT JUST ANYONE, seeking just any position. He is seeking appointment to the highest court in the land, where sexual harassment cases would reach their final ruling, where attitudes toward women affect more people than they do from anywhere but the Oval Office.

Given what we have seen of Clarence Thomas over the past two weeks, we don't see how anyone can consider him the most qualified justice for the job.

If confirmed, Clarence Thomas could shape this nation's direction for the next 40 years. It's not worth the risk.