The U.S. Commission on Civil Rights heard important testimony on Friday — two witnesses arguing that social science evidence shows that racial balancing in K-12 classrooms has important educational benefits, and two saying that such evidence is lacking (see here and here). The testimony is very timely, since the Supreme Court has granted review in a pair of cases, one from Seattle and one from Louisville, that raise the question whether racial preferences in student assignments to ensure such balance is constitutional. It seems dubious that social science could ever justify racial discrimination; certainly if there is a division of opinion among social scientists such discrimination cannot be justified.