Prevailing norms, which only move a modicrum to the left or right despite the best efforts of partisans on both sides. Some imortant world events can push it left or right for a little while, but like water it usually finds it's level.
For example: When you think about it, the war on terror has done more in modern times to push the center to the right than anything that Ronald Reagan ever did.
Who esablishes prevailing norms?
Who establishes prevailing norms?