The premise of the affirmative-action case currently before the Supreme Court is that ethnic diversity improves higher education. But how do we know the premise is true? It is surprisingly difficult to find solid evidence in the case documents. The original UT–Austin brief refers me to the Joint Appendix. The Joint Appendix in turn cites the “Affidavit of N. Bruce Walker,” admissions director for UT–Austin. In that affidavit, Mr. Walker says that diversity improves race relations “in the University’s judgment.” He also assures us that, “I have read studies that tout other benefits.” Those studies are not listed.
The amicus briefs in the case are more forthcoming, but the barrage of studies they cite often have tiny effect sizes and narrowly focused results, making them more suggestive than convincing. A good example of narrow focus is yesterday’s New York Times op-ed by Sheen Levine and David Stark. The authors describe how the distrust and friction generated by ethnic diversity can be beneficial in avoiding the groupthink that creates stock-market bubbles. Interesting point. But then they go way beyond their empirical findings to conclude: “Ethnic diversity is like fresh air: It benefits everybody who experiences it.”
In fact, Levine and Stark’s research demonstrates how theoretically ambiguous the impact of diversity can be. Interpersonal friction may have some benefits, but it also carries obvious costs. It is especially difficult to reconcile the diversity benefits that Levine and Stark describe – which depend on people distrusting each other – with the supposed improvements in cross-racial understanding that come from diversity. The literature contains evidence of diversity producing undesirable conflict, and the uproar over Halloween costumes at Yale could probably be a new case study.
What we need is better data. All else equal, do students who attend more diverse colleges score higher on the GRE? Earn more money? Find better jobs? Go on to live in more integrated neighborhoods? Send their kids to more integrated schools? I understand the Supreme Court’s legal deference on these questions, but it would be nice for the public to have answers that are more reassuring than “in the University’s judgment.”