PRESIDENT REAGAN FOUND himself in a bind recently when his Cabinet was discussing the extension of the Voting Rights Act of 1965. On one side were presidential counselor Edwin Meese III, White House chief of staff James A. Baker III and Melvin Bradley, the domestic policy adviser who is black, and others. They supported a House-passed version that Reagan had earlier called "pretty extreme" but which civil rights leaders unanimously supported. On the other side, Attorney General William French Smith urged amendments that effectively would cripple the measure.

Enter Samuel R. Pierce Jr., secretary of Housing and Urban Development and the only black in the Cabinet. "I presented three alternatives to the president," Pierce recalled the other day. " . . . Maybe civil rights leaders have been against a bailout provision, but my job is to give alternatives to the president. Trying to be objective as possible, that provision could cause a lot of litigation."

Reagan emerged from the meeting saying he would support an extension of the measure. But he also said he would support two weakening provisions favored by Smith and conservatives and feared by many blacks as devices that would leave the act impossible to enforce. That leaves the president in somewhat of a no-lose situation, depending on what happens to the bill in the Senate. The same cannot be said, however, for Pierce.

The secretary insisted the other day that his actions in the meeting "did not hurt the black people at all, in my opinion." That opinion was not shared by the host of civil rights and political leaders who denounced Reagan's stance once it was announced.

The important point here is that extension of the Voting Rights Act in a strong and workable form has been one issue that blacks have considered sacred and fundamental. Black dissenters have been difficult to find. By taking a more flexible view than Bradley (and former senator Edward Brooke, who had lobbied the White House earlier), Pierce, in the code language of politics, signaled a weakness in the united civil rights and liberal opposition to diluting the bill. And like any old football player who sees an opening in the line, the Gipper took the ball and ran for daylight. Nice work, Sam.

"Why can't I be objective?" Pierce asked the other day. "I like a black guy to be objective just like I would like a white guy to be objective. I'm trying to be as objective and honest as I possibly can. I think I owe that to the president."

But what does he owe black people? That's the deeper issue with blacks who occupy important positions -- accountability. What is their obligation to other blacks? Where do they draw the line? To whom are they accountable, and must some individuality be given up for the greater good?

Those are timely questions these days, when black conservatives seemingly at odds with everything black people have stood for are popping up all over the place: economists Thomas Sowell and Walter Williams and J.A. Parker.

Now I certainly would not put Pierce into the same category as these darlings of the New Right. But all share one thing in common: They are more valuable in the positions they hold and the things they say because they are black. This may be lost on them, but it is not lost on the whites who put them in their positions.

Pierce is an outstanding constitutional lawyer, a former partner with a Park Avenue law firm and member of several Fortune 500 company boards. But as hard-working and as capable as he is, certainly, Pierce's candidacy was helped along by the pressure and demands of black people. When Pierce spoke at the Cabinet meeting, his words came as much -- or more so -- from someone black as from any expert on constitutional law.

Any black who reaches a certain station in life is there partly because a lot of unlettered men and women who cared about justice were willing to march and picket and put their lives on the line in order to bring about change in this country. And when Pierce took office, the country effectively reaffirmed its commitment that blacks would have a voice at the highest levels of the land.

In a perfect world, any individual should have the freedom to take independent actions and to be an "objective" human being. But given the racial realities in this country -- and today's atmosphere in particular -- such colorblind "objectivity" is a luxury that blacks in positions of power and influence cannot afford -- especially on issues as fundamental as the Voting Rights Act.