Each stage in the model presents a different sort of society than that which came before it. Very basic social and economic questions—including subsistence strategy, family type, mechanisms for mate selection, and so forth—change substantially as societies move through one stage to the next. Customs and norms that are adaptive for individuals in stage two societies may not be adaptive for individuals in living in stage four societies.
If the transition between these stages was slow this would not matter much. But it is not. Once stage two begins, each stage is only two or three generations long. The children of Europeans, Japanese, Taiwanese, and South Koreans born today look forward to spending their teenage years in stage five societies. What traditions could their grandparents give them that might prepare them for this new world? By the time any new tradition might arise, the conditions that made it adaptive have already changed.
This may be why the rationalist impulse wrests so strong a hold on the modern mind. The traditions are gone; custom is dying. In the search for happiness, rationalism is the only tool we have left
