THERE IS A great deal of talk these days about the Supreme Court, especially because the next president may well have the power to shape the court for years to come. Justice William Brennan seems likely to retire soon, and Justice Thurgood Marshall, who has been ill, may not be far behind. Moreover, Chief Justice Warren Burger and Justices Harry Blackmun and Lewis Powell are all over 70 years old.

Unfortunately, however, much of the chatter about future High Court nominees has been short-sighted, limiated to which presidential candidate would pick which kind of man, woman, black or other attorney . Why does everybody assume that a Supreme Court justice must be a lawyer? There is in fact no good reason, much less any requirement, for lawyers to be named, and it will be a serious loss for the country if we persist in this mistaken notion merely because "that is the way it has been."

Attorneys, after all, are generally legal mechanics, urbane technicians for hire by official agencies, individuals, corporations and other institutions. As a rule they have little grasp of the large issues of public policy, which is precisely what the High Court deals with in constitutional cases.

The U.S. Supreme Court in these matters is not like, say, the Supreme Court of Alabama or of Oregon. It resolvs questions of political theory and social ethics, and it rules not merely for the parties before it but for the entire nation and for generations yet unborn. Justice Benjamin Cardozo, for one, recognized the difference when he ended his years as chief judge of New York's highest court to join the U.S. Supreme Court: His previous experience, he said, was of no help to him.

If being a judge or lawyer does not prepare one for a High Court seat, why name one? The intricacies of legal procedure are not so difficult that anyone with average intelligence cannot master them. Besides, law clerks would always be available to help.

Does Education Secretary Shirley Hufstedler, a former federal judge who is amoung the many High Court contenders, have any particular expertise in education? At best, not much.

She has to rely on aids with special knowledge of the filed. So much former HUD -secretary -turned -HEW -secretary -turned -HHS-secretary Patricia Roberts Harris, another lawyer and potential Supreme Court nominee. Obviously, somebody outside the legal profession could do the same thing if named to the Supreme Court, and nother would be lost.

But a great deal will be lost -- and, judging by the current Supreme Court, already has been lsot -- if we restrict our choice of justices to lawyers. Attorneys are generally too narrow-minded, too client-oriented, too scarred by education and practice to have a monopoly on Supreme Court seats.

Some law schools themselves have begun recognizing the shortcomings of their graduates. "If law schools are seriously concerned about 'educating,'" says Georgetown University president Timothy S. Healy, S.J., "they have to spend time outside the 'training' ambit -- with sociology, political science, economics, history, philosophy, theology."

If that is the need of ordinary attorneys, it is certainly a requirement of judges, especially Supreme Court justices. Judge Leared Hand said it well many years ago:

"I venture to believe that it is as important to a judge called upon to pass on a question of constitutional law, to have at least a bowing acquaintance with Acton and Maitland, with Thucydides, Gibbon and Carlyle, with Homer, Dante, Shakespeare and Milton, with Machiavelli, Montaigne and Rabelais, with Plato, Bacon, Hume and Kant, as with the books which have been specifically written upon the subject. For in such matters everything turns upon the spirit in which he approaches the questions before him. The words he must construe are empty vessels into which he can pour nearly anything he will."

While there doubtless are persons of such reach within the legal profession, can anybody seriously think that only lawyers can fulfill that prescription? Why, then, have lawyers been allowed to monopolize our courts in general and our highest court in particular?

Historical accident. The excessive legalism of Americans. The American Bar Association. A shortage of debate and organized pressure on the issue. Those are the main reasons.

The Constitution says nothing about the type person to be named to the High Court. A president can choose anyone he wishes, limited only by the constraints of politics. The members of Congress who write our laws need not be attorneys. The president who proposes and administers our laws need not have legal training. It is no different for Supreme Court justices.

The habit of picking attorneys simply began with George Washington and has continued every since. That did not mean, however, that they had to be schooled in the law.

In fact, it was not until 1957 that the Supreme Court was composed for the first time of law school graduates. Justice Stanley Reed, appointed By Franklin Delano Roosevelt, did not have a law degree and Justice James Byrnes, another FDR appointee, was the last one never to have attended law school.

If anyone who hadn't graduated from law school were named to the High Court today, the ABA would likely howl. But popular political sentiment could outweigh a special interest like the ABA in this matter as in others.

The public's reaction, of course, would depend largely on the person nominated. But it is difficult to believe that a nation of 220 million persons could not find someone of stature and integrity and wide knowledge beyond the small group of a few thousand lawyers who inhabit the land.

There is, for example, Walter F. Murphy of the Princeton political science faculty, a longtime student of the court with a deservedly high reputation. There is philosopher John Rawls of Harvard University, whose book "A Theory of Justice" has had enormous success. There is Robert Nozick, another Harvard philosopher of more conservative bent and also of great stature.

One could name, offhand, many other potential canadates. To cite just a handful: Tufts University president Jean Mayer, physicist John Platt, economists Marina Whitman or Juanita Kreps, diplomat and historian George Kenna, New York Rep. Shirley Chisholm, political scientists John Schmidhauser and Henry Abrahm. You might dismiss some of these and add others from many different backgrounds. Fine. The point is just that: There are many non-attorneys out there who are first-rate thinkers and doers, and we should demand no less of those chosen to sit on the court that is the keeper of the American conscience.

"By the very nature of the functions of the Supreme Court," Juistice Felix Frankfurter once wrote, "each member of it is subject only to his own sense of trusteeship of what are perhaps the most revered traditions in our national system." Or as Chief Justice Earl Warren said in his candid valedictory, the justices have the last word in "great governmental affairs" and are guided only by the Constitution and "our own consciences."

No one can validly say that lawyers have better consciences or better insight into America's "revered traditions" than do others.