Admissions policies that take class into account, rather than race, are getting a renewed push as a win-win solution. The contention is that they more fully serve the goal of diversity in higher education and provide a progressive way to resolve an enduring conflict that has now returned to the Supreme Court in a case about race-conscious admissions at the University of Texas at Austin.

But a crucial premise of the class-over-race argument is wrong. It is not possible to maintain the same level of racial diversity in higher education while applying a race-blind admissions policy. Class-based admissions generally reduce the number of black and Hispanic students. To maintain or build the levels of racial diversity on selective campuses, it is necessary to maintain race-conscious admissions.

While there are higher shares of blacks and Hispanics among low-income Americans, their smaller shares of the whole population mean that whites make up by far the largest portion of low-income families. As Alan Krueger, now head of President Obama’s Council of Economic Advisers, and his co-authors wrote in 2006, “The correlation between race and family income, while strong, is not strong enough to permit the latter to function as a useful proxy for race in the pursuit of diversity.”

Class-based policies can maintain the share of blacks and Hispanics at selective colleges and universities only if admissions policies also give an advantage to blacks and Hispanics that is not race-blind. That is also the finding of Anthony Carnevale and his co-authors, researchers relied on by advocates for class-based policies. Advocates may broaden the definition of social and economic disadvantage to include other factors, like speaking a foreign language at home, but these are proxies for ethnicity or race.