Rationality in Fragmented Belief Systems

This chapter deals with the question of which notion of rationality best fits with a fragmentation picture of belief that holds that we are mostly rational. According to this picture, coherence is not a requirement of rationality for the entire belief system. Coherence is only rationally required within belief fragments. The chapter argues, however, that fragmentation still needs to offer a different rationality criterion across belief fragments to account for a variety of cases in which we would intuitively ascribe irrationality to the subject. It proposes that the requirement of evidence responsiveness is a good candidate for making sense of the idea that there are certain normative relations in place among beliefs from different belief fragments.