You've heard about Clarence Thomas, but not by name. He is one of the black people now on center stage in American politics: he is a Republican, a long-time supporter of Ronald Reagan, opposed to the minimum wage law, rent control, busing and affirmative action. How a black man can say no to those policies is a mystery to most black people.

But Clarence Thomas, 32, who paid his own way to fly here from his home in Bethesda for a weekend meeting of top black Republican policymakers, is convinced that the real mystery is how 90 percent of black Americans could support those policies and vote for Jimmy Carter.

"I marched. I protested. I asked the government to help black people," says Thomas. "I did all those things. But it hasn't worked. It isn't working.And someone needs to say that."

So when Thomas rose to speak here on the problems of black education before 100 fellow black conservatives, a broad smile crossed his face. The first words he said were in praise of his fellow black conservatives for having the courage to come together publicly and show their strength. The conservative blacks, like Thomas, who have thought of themselves as the outcasts or the minority within a minority, had finally found a home.

To talk with Thomas is to realize that his conservatism is born of the same personal anger at racism that fired the militants of the 1960s. The worst experience of his life, says Thomas, a lawyer who is an assistant to Sen. John Danforth (R-Mo.), was attending college and law school with whites who believed he was there only because of racial quotas for the admission of blacks.

"You had to prove yourself every day because the presumption was that you were dumb and didn't deserve to be there on merit," Thomas says. "Every time you walked into a law class at Yale it was like having a monkey jump down on your back from the Gothic arches. . . . The professors and the students resented your very presence."

The same racism, the assumption that he got his job because he is black, trails Thomas to this day. He refuses to work on any issue directly related to black people because, he says, his colleagues again would assume that he has the job only because he is black. Thomas works only on energy, environment and public works policy for Sen. Danforth, staying away from black policy issues until last weekend.

"If I ever went to work for the EEOC or did anything directly connected with blacks, my career would be irreparably ruined," he says. "The monkey would be on my back again to prove that I didn't have the job because I'm black. People meeting me for the first time would automatically dismiss my thinking as second-rate."

Again and again last weekend that message was repeated here: blacks need to get out of the black-only issues and begin to show their competence in every field, in every political movement, if they want to be thought of as more than black free-loaders. That attitude has apparently impressed President-elect Reagan. Edwin Meese, who is heading Reagan's transition team, said that blacks will be assigned to the White House to deal with issues they know about instead of to be the black contact with the president. Meese said blacks will have the same contact as other groups seeking favors, and that the contact may not be through a black person.

"I'm tired of blacks being thought of only as poor people, people on welfare, people who are unemployed," says Thomas. "That's the only way the Jesse Jacksons and the other black leaders talk about black people. To them, we're all a monolith. Well, they are not talking for the 80 to 90 percent of black people in this country who have never been on welfare or in jail."

The reasons for Clarence Thomas' conservatism come out in other areas of his life. He pays $1,400 per semester to send his only son to a private school because, he says, the public schools don't educate people -- they teach them they can get by without working. He is a supporter of the voucher system for education that would allow parents to send their children to whatever school, public or private, they please.

Thomas is also a man who has a sister on welfare back in his home state of Georgia, but he feels that he must be opposed to welfare because of the dependency it can breed in a person.

"She [his sister] gets mad when the mailman is late with her welfare check," he says. "That is how dependent she is. What's worse is that now her kids feel entitled to the check too. They have no motivation for doing better or getting out of that situation."

As a follower of Thomas Sowell, the conservative black economist who was the star attraction at the weekend conference set up by a conservative policy study group, Clarence Thomas also questions black support for the minimum wage and government jobs programs. "The proof that they do not work is in the high black teen-age unemployment rate," says Thomas.

Thomas' attitudes and thinking, long the distant cousins of popular black thought, now come to the forefront because of Ronald Reagan's election. But blacks did not elect Ronald Reagan, and they did not ask for prominence to be given to a black silent majority. While the black conservatives like Clarence Thomas point out that not all blacks are poor or in jail, their challenge will be to remember that a disproportionate number of blacks are poor and are in jail. This country is not yet so sophisticated that blacks, even black Republicans, can say it makes no difference what color an American is. But thanks to Clarence Thomas and other black Republicans like him, new approaches to stagnant problems are being discussed for the first time since Martin Luther King Jr.