Partisan Homogeneity Does Not Increase Collaborative Corruption

Abstract This study examines the behavioral consequences of partisan group composition on cooperation in a setting where cooperation is mutually beneficial but unethical. Collaborative corruption highlights that corruption is not a solitary act but necessitates cooperation. Based on the premise that partisanship serves as a social identity, leading ordinary citizens to reward co-partisans and penalize out-partisans, we expect that collaborative corruption is higher in partisan-wise homogeneous groups. To test this expectation, we conducted a preregistered, large-scale experiment among U.S. voters playing an online version of the collaborative cheating game by Weisel and Shalvi. We find no evidence that partisan homogeneity affects collaborative cheating. These results suggest a critical scope condition: while partisan homogeneity improves cooperation in social dilemmas, it does not extend to contexts of unethical collaboration. They also refute common concerns that partisan homogeneity may facilitate cooperative corruption.