Our studies show that people are often unable to escape the pull of their prior attitudes and beliefs, whichguide the processing of new information in predictable and sometimes insidious ways. But what does this mean for citizens in a democracy? From one perspective the average citizen would appear to be both cognitively and motivationally incapable of fulfilling the requirements of rational behavior in a democracy. Far from the rational calculator portrayed in enlightenment prose and spatial equations, homo politicus would seem to be a creature of simple likes and prejudices that are quite resistant to change. Can this possibly be rational? The normative question, it seems, turns on whether the processing of new information and the updating of one’s attitude needs to be independent of one’s priors.