US political system: Does it work?

The final primaries are over and we have a minute to sit back and consider what we are doing. We are going through the unique American process of nominating a presidential candidate from the ranks. We are the only democracy that does it quite this way. In parliamentary democracies like England, Canada, or Sweden there is an intervening process: the potential chief executive is generally the party leader of the majority party in the parliament. There is, in other words, a winnowing process by the legislators, who know their fellow lawmakers. In the United States the public finds out about candidates from the press then proceeds to the nomination through a series of state caucuses and primaries.

I hear worries expressed these days about the unique US process. Does it pick the best men? Lord Bryce thought the US actually wanted and selected ''non-great'' men for presidents. On the whole the American system has worked pretty well and has strong public support. But can it keep up with a changing world?

Another aspect of the system was invented by the Founding Fathers - the division of powers. This, too, has worked reasonably well. It was crafted to thwart tyrants: The president can block the Senate, the Senate can block the House, the Supreme Court can block all three, and behind is the slow federal bureaucracy and quasi-independent commissions like the Federal Reserve Board. But what if action is needed in a hurry?

In the old days a political party gave some cohesion. But parties have languished in recent years. Looking at Washington today, there are times when nobody quite knows who's in charge. Something should be done but do we have the cohesion to do it? James Sundquist, senior fellow at the Brookings Institution, says, ''Citizens, seeing their government besieged by seemingly uncontrollable events, have lost confidence in their leadership and institutions. Some trends have been positive. (Improved civil protection, accountability, and public participation are examples.) But the picture as a whole suggests a society unable to cope with current events. Polls reveal that the traditionally buoyant, optimistic American has become fearful of the future and doubtful of the competence of politicians to prevent disaster.''

Yes, there is a highbrow, public-spirited, privately financed group working on this problem. The bipartisan Committee on the Constitutional System has been considering it for a couple of years. Sen. Nancy Landon Kassebaum of Kansas is chairman, with C. Douglas Dillon, former secretary of the Treasury, Lloyd N. Cutler, former counsel to President Carter, and others, including Williams College professor James MacGregor Burns. A thoroughly worthy, idealistic public-interest group. Can they do anything? The anniversary of the Constitution is in 1987. Will America greet this great event with a split foreign policy, with a deadlocked government, with a huge deficit? At a conference in Washington last week leaders of the Committee on the Constitutional System declared that the group ''hopes to decide by September of 1985 what actions - if any - should be recommended for public consideration.'' Well - just in time for the nation's birthday.