IN MY article on A Common Destiny, I distinguished between a discrimination model of black-white differences in American society and what I called a distributional model. According to the former, differences in average levels of education, income, infant mortality, and so on are the results of racial discrimination—past or present, intentional or unintentional. In the distributional model, differences in those average levels may be traced to differences between the populations that are due to factors other than discrimination. The individuals who constitute the populations may, for example, differ in intelligence, personality, habits, customs, value systems, physical circumstances, and so on. And these differences may not be explained entirely by discrimination.