WHEN PRESIDENT Carter promised during the 1976 campaign to select federal judges "on the basis of merit," his proposal sounded both wise and simple. But now that his administration is involved in actually choosing scores of new judges, it is clear that "merit selection" is not simple. There is a conflict between merit selection strictly defined, as many are now defining it, and a diversified judiciary. Until that conflict is resolved, the administration is likely to have more problems of the kind it faces in Virginia, where the attorney general has found unacceptable the list of candidates submitted by a nominating commission.

The problem is that merit selection means different things to different people. Some define it in terms of technical qualifications -- training, experience, knowledge of the law and temperament.Others define merit selection as meaning only that politics and past political activity will be eliminated as factors in picking judges. They think non-technical factors like race, sex and diversity of experience must be considered in the selection process to produce a balanced judiciary.

Thus the knid of list that is produced by a nominating commission, or anyone else asked to recommend judicial candidates to the president, depends heavily on what the commission conceives its mission to be. If it sets out to find the five people with the best technical qualifications, it may end up with, as did a commission in Virginia, a list of five white males. That's because the upper reaches of the law in many states were preserves for white men until 10 or 15 years ago. Women and minority males of the appropriate age to be federal judges were short-changed in their earlier years. That doesn't mean there are no women or b lacks in such states qualified to be judges; it simply means that few or none of them have the credentials -- on paper -- that stack up with those held by the five "best qualified" white males. The irony is that the line between the five best qualified people for any job and the next five or 25 is usually quite thin.

The goal of merit selection -- particularly when discrimination is not yet far behind us -- should not be an attempt to choose judges only from among those lawyers who have the best paper credentials and technical qualifications. If ought to be an attempt to remove politics from the selection process and to ensure that those who are chosen are well-qualified for the job. The strength of the judiciary re sts in the way it is perceived by those over whom it sits in judgment. That perception will be infinitely better if the bench is populated with well-qualified men and women of all races, chosen without regard to politics, than if it is populated only by the "best" qualified lawyers, particularly if most of them turn out to be white males.