Millions of politically disaffected citizens, the polls report, are disposed to boycott the presidential election this year because, in their scorn for both the major candidates, they feel the outcome won't matter much, one way or the other.

It's a shortsighted view, if for no reason other than that the future shape of the Supreme Court is at stake. Jimmy Carter and Ronald Reagan may, in some respects, be little better than Tweedledee and Tweedledum, but few doubt that their appointments to the high court would be profoundly different. The same could be said of John Anderson. On that score, at least, there is a choice.

Just how significant the change of merely one justice on the court could be, how it could drastically alter the lives of many American families, was dramatically illustrated a few days ago when, in another 5-to-4 split, the court upheld a ban on the public funding of abortions for women too poor to pay for their own.

What makes the decision painful for many to accept is that it might well have gone the other way if Carter had been able to appoint just one new member to the court. It is no secret that his choice would almost certainly have been a woman -- obviously one acceptable to the equal rights movement, which the president, unlike Reagan, fully supports.

Reagan, not only opposes the Equal Rights Amendment to the Constitution, but firmly backs the proposed amendment to outlaw abortions altogether. Women voters can judge for themselves how, if elected, he would fill vacancies on the court. As for Anderson, he is the most ardent feminist of all the candidates.

But abortion is only one of numerous vital issues that in recent years have been decided by one vote in the Supreme Court and that, as in the past, could be reversed, modified or reaffirmed by the next president's appointments to the highest tribunal.

There has seldom been a time when so many changes on the court appeared to be so imminent. Five of the nine justices are now over 70, and some are in failing health. The next president could determine the character of the court for years to come.

Richard Nixon was driven from the presidency by disgrace and the threat of impeachment, yet through his four appointments to the court his influence on our society lingers on. Nixon was well aware of this. When he named Lewis Powell and William Rehnquist to the court in 1971, he said: "Except for the contribution he may be able to make to the cause of world peace, there is probably no more important legacy that a president of the United States can leave in these times than his appointments to the Supreme Court."

the court's power over the American way of life sometimes surpasses that of Congress or the president. The historic 1954 desegration decision transformed U.S. society; the later one-man, one-vote reapportionment ruling transformed our politics.

For almost three decades, the court has had either a Republican-appointed majority or a Republican chief justice, or both, but until recent years the court has generally been closely balanced in a partisan sense. Today, however, seven of the nine justices are Republican appointees. That 7-2 imbalance could become 8-1, or even 9-0, if the next occupant of the White House is a Republican.

Dwight Eisenhower named five to the court, Nixon four. Nevertheless, the court has remained fairly evenly balanced ideologically, which accounts for so many close and often surprising decisions. The coming election, however, is likely to change that.

A few appointments by a new president with Regan's outlook would virtually gurantee a much more conservative court, perhaps the most conservative court, perhaps the most conservative since pre-new Deal days. Conversely, with either Carter or Anderson in the White House, the court would probably regain much of its old Earl Warren look.

The court's most indefensible imbalance is the absence of a woman on it. It remains one of the country's last great all-male strongholds, even though women now make up a majority of the electorate and are intimately involved in most of the key issues that come before the court. And the woods are full of able women lawyers; many have served on district and appeals courts with distinction. For true balance there ought to be not one but several women on the court. Logically, why not female majority?

Also, up until the Nixon-Ford administrations, there had always been at least one Jewish justice on the court for the previous 50 years. Time and experience proved it a good tradition.