In our capacity as political scientists, historians, or philosophers we all have had occasion at one time or another to engage in debate with ideologists – whether communists or intellectuals of a persuasion closer to home. And we have all discovered on such occasions that no agreement, or even an honest disagreement, could be reached, because the exchange of argument was disturbed by a profound difference of attitude with regard to all fundamental questions of human existence – with regard to the nature of man, to his place in the world, to his place in society and history, to his...