If human beings are observed within just one culture, therefore, one may derive a sharply limited notion of human potential. For instance, even such broad-minded visionaries as Jefferson and Lincoln were unable to imagine black people as fully equal to whites in intellectual and moral potential. In order to understand the limited viewpoints of these idealists, we must recognize that people under conditions of slavery do not exhibit the full range of their capacities as rational beings.

Although most Americans today do not live in such extreme conditions of constraint and deprivation, their behavior nevertheless reflects the limitations of our institutions. Just as the institutions of today are very different from those of other centuries and other parts of the world, they can (if we choose) be very different tomorrow. If we are to plan for the twenty-first century, we cannot allow our view to be restricted by the here and now, but must ask ourselves what is possible generally to human nature.     Continue...