Abstract: In the literature on polarization, it is axiomatic that hostility and negative

affect between groups are heightened by within-group homogeneity and clarity of

purpose. However, this paper argues the opposite for political parties in democ-

racies: when voters are risk-averse, negative affect toward out-parties should

increase with their internal heterogeneity or ambiguity. We use data from a

number of surveys to demonstrate that both within countries and across coun-

tries, voters express more negative affect toward parties whose policies are most

unpredictable. Affective polarization is associated not with homogeneous par-

ties that credibly commit to rigid, fixed platforms, but rather, by heterogeneous

parties whose policies are viewed by voters as dangerous policy lotteries.