ARE BLACK AMERICANS gradually becoming part of mainstream society? Or is the nation following the Kerner Commission’s prophecy and moving toward separate black and white societies? There are plenty of facts, but not all point in the same direction.  During the last twenty-five years, earnings of black men and women rose much faster than those of whites. But black poverty is three times more prevalent than white poverty. We see blacks becoming teachers, reporters, lawyers, judges, and mayors, but we also read about high rates of black crime, illegitimacy, welfare dependency, and drug abuse. In most big cities, people are afraid to venture into poor black neighborhoods or to have their children attend largely black schools.