WHEN EVERYONE gets preferred treatment, no one does. That not-so-profound thought occurred to us the other morning when we read that the Supreme Court had upheld a state veterans-preference law against a plaintiff's claim that it discriminated against women. And it struck us again in connection with the Court's hearing of the Bakke case, which turns on the question of racial preferences for minority students and whether this unconstitutionally denies opportunity to whites. There are preferences nowadays of one kind or another - required by law or voluntary, in government and in private employment - for women, blacks and other ethnic minorities, the handicapped, veterans - and even discharged Capitol Hill employees. There are so many, in fact, that if you don't have a preference, you may be out in the cold - indeed, you may be out of luck even if you do have one, since someone else's preference may be given preference over yours.

What this suggests to us is that the coinage of preference is gradually being debased. Somehow, somewhere along the line, if preferences are any longer going to be of any use to anybody in school admissions, hiring and promotion, housing and all the rest, they are going to have to be cut back in number or there will have to be established some formal system of preferences among preferences. Merely to contemplate the latter is to recognize its infeasibility; can you imagine trying to establish as a general rule some sort of super-preference for any of the groups now given preferential treatment? So while we await the day when there is an abundance of everything for which preferences are now granted, it occurs to us that the best course may be some sort of system that would at least provide for the elimination of preferences that have outlived their purpose - a sunset law, in effect.

Take, for example, compensatory special treatment for blacks in the educational system. Given the systematic way blacks have been discriminated against in this country, it is clearly justified in certain circumstances. But at some point, when our society has discharged its obligations to equity and fair play, the need for preferential treatment will run out. In some cases it already may have. The next problem, of course, would be persuading the preferred that their need for preference had, in fact, run out.

Presumably it wouldn't be easy.But one place to start with this sunset proposal might be the range of preferences that government gives to veterans. We are not talking here about education, housing and other financial benefits that are designed to compensate veterans for time spent in service, and are supposed to help ease their passage back into a productive civilian life. Nor, of course, are we talking of health benefits to compensate for service-connected disabilities. Rather, we are thinking of special treatment having to do with such matters as going to the head of the line for government jobs and federal loans - preferences that remain available years after many eligible veterans have reestablished themselves with government assistance and have been pretty generously compensated for their years in the service. Our hunch is that by this time a sunset provision could reasonably be applied to most preferences for most veterans of wars up to, let's say, the Korean conflict - but most certainly not including the Vietnam war. Vietnam veterans, as we have been regularly arguing in this space, have suffered a particular neglect related to the bitter and enduring controversy that marked that war; many are precisely at that stage in their lives, and in relation to their release from the service, when veterans preferences can do the most good.

But once the basic purpose of any of these preferences - for veterans or any other group - is fulfilled, they ought to be eliminated. The General Accounting Office has urged Congress to curtail veterans preference in government hiring, primarily because it works so great a disadvantage on female applicants. We would go a step further and urge Congress (and the state legislatures) to apply the "sunset" principle (where they are by law free to) to all the preferences on the books. That way it will be possible to determine whether they still meet a valid need or have in fact outlived their original purpose.