For decades America’s universities have made extensive efforts to achieve racial diversity within their student bodies. The official justifications for these efforts have changed depending on political currents and Supreme Court whims: What began as explicit redress for African-Americans eventually morphed into a commitment to diversity as an educational good unto itself. But the implicit goal has always been a kind of elite legitimation, a demonstration that the meritocracy is actually fair and open and representative of the society that it aspires to rule.

For a long time this system was challenged mostly from the right, by critics of affirmative action who argued that it legitimized meritocracy at the expense of academic merit.

But lately the critiques have come from all directions. Asian-Americans have noticed that the current racial balance on campuses is sustained, in part, by suppressing Asian numbers. Populists of the left and right have pointed out that meritocracy often has racial diversity without socioeconomic diversity, reproducing a multi-hued but still immensely privileged elite. And the new progressivism has attacked that racial diversity as insufficient, because it still leaves blacks and Hispanics alienated within a system dominated by rich white kids.

In general I think the meritocracy deserves almost all the criticism it gets. But in this column I want to strike one note of sympathy for its mandarins: There is no obvious reform that would satisfy all of these objections, no simple step that would bring the idea of meritocracy, the diversity of class and race, and the need to attract tuition dollars into balance.