We offer a theory of polarization as an optimal response to ambiguity. Suppose individual A's beliefs first-order stochastically dominate individual B's. They observe a common signal. They exhibit polarization if A's posterior dominates her prior and B's prior dominates her posterior. Given...

Two players choose hawkish or dovish actions in a conflict game with incomplete information. An "extremist," who can either be a hawk or a dove, attempts to manipulate decision making. If actions are strategic complements, a hawkish extremist increases the likelihood of conflict, and reduces...