GEORG HEGEL was a German philosopher of the early 19th century. Hegel believed that history unfolds through a "dialectical" process, in which each stage is the product of the contradictions inherent in the ideas that defined the preceding one. Within these tensions and contradictions, Hegel believed, the philosopher can discern a comprehensive, evolving, rational unity. He called that unity "the absolute idea." History consists of an inevitable and progressive march to that idea.Until recently it appeared that Marxism (which borrowed Hegel's dialectic but replaced "ideas" with economic systems and classes--hence "dialectical materialism") would represent Hegel's most enduring contribution to the...