The Policy Basis of Measured Partisan Animosity in the United States

Understanding and addressing the consequences of partisan animosity requires knowledge of its foundations. To what extent is animosity between partisan groups motivated by dislike for partisan outgroups per se, policy disagreement, or other social group conflicts? In many circumstances, including extant experimental research, these patterns are observationally equivalent. In a series of vignette evaluation experiments, we estimate effects of shared partisanship when additional information is or is not present, and we benchmark these effects against shared policy preference effects. Partisanship effects are about 71% as large as shared policy preference effects when each is presented in isolation. When an independently randomized party and policy position are presented together, partisanship effects decrease substantially, by about 52%, whereas policy effects remain large, decreasing by about 10%. These results suggest that common measures of partisan animosity may capture programmatic conflict more so than social identity–based partisan hostility. Verification Materials: The materials required to verify the computational reproducibility of the procedures and analyses in this article are available on the American Journal of Political Science Dataverse within the Harvard Dataverse Network. The data required to verify the computational reproducibility of the results are available from Dataverse, the National Election Studies website (https://electionstudies.org), and NORC at the University of Chicago, under protected access, as described on the American Journal of Political Science Dataverse, at: (https://doi.org/10.7910/DVN/RFECVH). Partisanship in the contemporary United States is widely understood as a social identity (e.g., Green, Palmquist, and Schickler 2002), which for many individuals defines a partisan ingroup in conflict with an opposing outgroup (Tajfel 1974). Recent scholarship shows that partisan animosity expressed on surveys has grown substantially in recent decades (Iyengar, Sood, and Lelkes 2012; Mason 2015). Such animosity appears to be spilling out of the purely political realm into private interpersonal relationships (e.g., Iyengar and Westwood 2015), much as ethnic conflict has widespread political and social consequences. Growing partisan animosity is feared to reinforce political segregation, exacerbate polarization, and hinder bipartisan cooperation. While partisanship is correlated with policy positions (e.g., views on social issues) and many other identities (e.g., race), recent scholarship has focused on the direct Lilla V. Orr is Graduate Student, Department of Political Science, Yale University, PO Box 208301, New Haven, CT 06520-8301 (lilla.orr@yale.edu). Gregory A. Huber is Forst Family Professor of Political Science, Yale University, 77 Prospect Street, PO Box 208209, New Haven, CT 06520-8209 (gregory.huber@yale.edu). We thank Jonathon Baron, Peter Aronow, and Alex Coppock for generously sharing data and collaborating on data collection. We are grateful for comments from Doug Ahler, Matthew Graham, Annabelle Hutchinson, Shanto Iyengar, Samara Klar, Yanna Krupnikov, Yphtach Lelkes, Matthew Levendusky, Neil Malhotra, Ana De La O, Kyle Peyton, Fredrik Savje, Susan Stokes, Gaurav Sood, Steven Webster, Sean Westwood, anonymous reviewers, New York Area Political Psychology Meeting participants, and seminar participants at Yale. We acknowledge financial support from the Institution for Social and Policy Studies and Center for the Study of American Politics at Yale University. role of partisan orientations in shaping evaluations of other private citizens. For example, Iyengar, Sood, and Lelkes (2012) show that Americans are less excited about their child marrying a member of the opposition party than their own party. The magnitude of this difference has grown since 1960, and discrimination on the basis of partisanship may have surpassed racial discrimination in some contexts (Iyengar, Sood, and Lelkes 2012; Iyengar and Westwood 2015). This (survey) experimental evidence provides an unbiased estimate of the total effect of partisanship on these evaluations, but what explains this effect? Some work interprets these effects through the lens of partisanship itself (e.g., Sunstein 2015), whereas other work has suggested either that partisanship proxies other social identities (e.g., Abramowitz and Webster 2018) or conveys information about issue positions that underlie increasingly American Journal of Political Science, Vol. 00, No. 00, xxxx 2019, Pp. 1–18 C ©2019, Midwest Political Science Association DOI: 10.1111/ajps.12498