Is Affective Polarization Driven by Identity, Loyalty, or Substance?

Partisan Americans like members of their own party more than members of the opposing party. Scholars often interpret this as evidence that party identity or loyalty influence interpersonal affect. First, we reassess previous studies and demonstrate that prior results are also consistent with what we would predict if people cared only about policy agreement. Next, we demonstrate the difficulty of manipulating perceptions of party identity without also manipulating beliefs about policy agreement and vice versa. Finally, we show that partisans care much more about policy agreement than they do about party loyalty when the two come into conflict. Our analyses suggest that partisan Americans care about policy agreement; we have little convincing evidence that they care about partisan identity or loyalty per se, and scholars will have to find new research designs if they want to convincingly estimate the effects of identity or loyalty independent of policy substance.