More than a Difference of Opinion

Immigration is a central axis of political conflict in Western Europe, yet its role in intensifying intergroup animosity remains underexplored. This paper studies affective polarization between supporters and opponents of immigration across six Western European countries. I argue that polarization is amplified by distorted perceptions of political debate: citizens overestimate the prevalence of ideologically extreme and unrepresentative arguments on the other side. To test this claim, I field a survey experiment with open-ended questions that elicit which arguments respondents attribute to their opponents, which they consider the strongest for the opposing side, and how both compare to the arguments that opponents actually use. Preliminary results show systematic mischaracterization of opponents’ reasoning and a corresponding increase in negative affect toward them. A complementary vignette experiment isolates the causal effect of perceived argument profiles on affective evaluations. Together, the findings indicate that people on both sides distinguish between legitimate and illegitimate arguments for the other side, but disproportionately attribute illegitimate arguments to opponents—thereby fueling affective polarization over immigration.