The Rational Partisan

Abstract Our politics are increasingly polarised. Polarisation takes many forms. One is increasing clustering, whereby people hold down-the-line liberal or conservative views on a wide range of orthogonal issues. Some philosophers think that such clustering is indicative of irrationality, and so finding yourself in one of several clusters gives you evidence that not all your political beliefs are true. I argue that the reverse is true, presenting a simple model of belief-formation in which finding yourself in one of several clusters of opinion on orthogonal issues should increase, rather than decrease, your confidence that all your beliefs are true.