With the exception of a few primitive cultures without time perspectives, a curiosity about the future has infected all major civilizations. Each culture has had its seers, prophets, shamans, and oracles and virtually all cultures have developed images of the future (both utopian and dystopian) as mechanisms of self-renewal and self-correction. Plagued by uncertainty and driven by curiosity, human beings have been particular inventive in their search for predictive tools, using such approaches as hepatoscopy (the inspection of animal livers), cleromancy (divination by lot), lithology (divination by throwing stones), astrology, and the visiting of oracles. Mesopotamian priests, long before the time of Christ, regularly evaluated the possible impacts of proposed technological projects. The Judeo-Christian tradition of prophecy was built on the conditional if-then exploration of future actions. Finally, the development and explorations of alternative futures is within the broad tradition of scientific objectivity described by philosopher Israel Scheffler as requiring the "possibility of intelligible debate over the merits of rival paradigms."