“The way to stop discrimination on the basis of race,” Chief Justice John Roberts wrote in 2007, “is to stop discriminating on the basis of race.” Those words as much as any may define the chief justice’s jurisprudential philosophy today. In that 2007 opinion, he wrote for five justices that two urban school systems could not take account of the race of students, even in a small minority of cases, in order to prevent certain magnet schools from becoming racially isolated because of neighborhood housing patterns.