In the struggle over the tax laws, you are going to hear a great deal about the contribution that this or that endangered provision makes to economic growth and the standard of living. Some of it will be true. Capital investment is a highly important factor in any country's standard of living -- but it's not as important as the quality of education and young people's access to it.

The House and now the Senate have passed higher education bills that represent modest improvement. Neither imposes the large cuts that the Reagan administration wanted. Both would tighten eligibility a little, to provide slightly more support for slightly fewer students. But Congress, under great pressure to reduce budget deficits, is simply trying to defend the present programs. It is deferring all of the large and threatening questions about aid that changing circumstances have raised.

Over the past five years, federal aid for college students has declined -- after adjustment for inflation -- by about 10 percent. Meanwhile, the cost of attending college -- also adjusted for inflation -- has continued to rise two or three times as fast as personal income, according to figures compiled by the College Board. In this atmosphere, attempts to increase aid only invite the objection that more aid will simply encourage even faster increases in tuition.

Federal aid for college students began expanding in the mid-1960s, in the context of the war on poverty, to open the opportunity of further education to youngsters who would otherwise have had no hope of it. But over the succeeding two decades, the emphasis has shifted from grants to loans and from very poor families to the middle class. This shift, together with the steady rise in tuitions, means that students increasingly incur substantial debts as they go through college. The proportion of black high school graduates who go on to college has been declining since the mid-1970s. The reasons are not entirely clear, but certainly the high costs and the prospect of a burden of debt must be among them.

The massive expansion of the colleges and universities following World War II has brought incalculable benefits to every aspect of American life. Over the past decade, unfortunately, there's been little further progress in widening access, and perhaps even some backsliding. Federal aid alone can't fix it. But the decisions that determine who can go to college and at what cost are likely to affect the country's prosperity and the character of its society even more profoundly than tax legislation can.