A rare insight into the true business of the Supreme Court was provided by Potter Stewart when he announced his resignation last week. Among other things, Justice Stewart said: "It seems to me that there's nothing more antithetical to the idea of what a good judge should be than to think it has something to do with representative democracy."

That comment describes the morass in which the court now flounders. It delineates the kind of person who ought to be appointed to lead the court back to sure ground.

The plurality decision, or ruling that commands no majority of the justices, is the hallmark of the court at present. Between 1969, when Chief Justice Warren Burger took over, and the end of the 1979-1980 term, 88 plurality decisions were handed down.

Only 87 plurality decisions were handed down by the Supreme Court in the 180 years prior to the advent of Chief Justice Burger. More than 40 of those were made by the court under the last chief justice, Earl Warren.

The frequency of plurality decisions announces that more and more there are coming up for judgement hard cases where the judicial mind is at the end of its tether. But it is not just any old issue that proves so baffling. On the contrary, rulings in which no majority prevails are concentrated around very few issues. Plurality decisions are particularly common in such matters as civil rights, including school desegregation, busing and affirmative action; criminal justice, including the right to a lawyer and trial by jury; the death penalty; private aid to public schools; abortion and voters' rights.

What all those issues have in common is that they have traditionally been settled by the processes of representative democracy -- by the states, or Congress, or the president. They became judicial business thanks to the activist impulses, the will to break social deadlocks, that have characterized the Supreme Court under the last two chief justices.

Chief Justice Warren led a court famous for judicial activism. The Warren court broke new ground in sweeping decisions regarding school desegregation, voting rights and the right to counsel.

Chief Justice Burger, though the fact has been largely obscured, has presided over the same kind of tribunal. The Burger court has reached out for a wide variety of issues traditionally left to the states or other branches of federal government. Busing, for example, and affirmative action; the death penalty and state aid to private schools.

The result has been the same for both the Warren court and the Burger court. In trying to settle matters normally handled by other parts of government, the court has outsmarted itself, gone beyond its range. It has invited questions it can't answer, and cases it can't settle. The consequence is not only a surge in plurality decisions. As a further result, the rulings of the court tend to resemble tea leaves as a guide to the future. Government itself becomes less certain, and more an object of obloquy.

The Burger court, in these conditions, has begun to grope its way out of the morass. A notable feature of the term now winding to a close is the number of cases in which the court declined to go beyond the strict terms of applicable statue. Bruce Fein, a legal scholar who surveys the work of the court for the American Enterprise Institute, began his account of this year by listing six cases in which he sees the court "frowning on judicial embellishment of federal statues. . . ." Since then, and in the same spirit, the court has upheld the right of the New York state liquor licensing authority to bar topless dancing. It has also endorsed the power of the Minnesota state fair to limit religious fund raising.

What the court now requires is a theory that explictly enunciates the self limits it is imposing in hit-or-miss fashion. The need is for a judge who can preach the self-restraint the court has begun to practice.

That suggests the next justice should not be a person distinguished by the parochial experience that goes with membership in a particular group, or expertise in a special branch of the law. On the contrary, the requirement is for somebody with a feel for the just preserves of the other branches of government, and a belief in the limitations that necessairly hedge the capacity of the court to enact its own views on the best organization of society. What is wanted is a broad, institutional vision, a conviction that the court, like Congress and the presidency, has a duty to make government work.