Identity massively shapes how citizens understand and behave in democracy. As Mason and Versteegen explain, both partisanship and ideology are particularly pertinent influences that can make politics an issue of personal and group status. In extreme cases, this can lead to partisans prioritizing their partisan group's success over the nation's. However, next to partisanship and ideology, other identities, like ethnic, cultural, and religious belonging influence political behavior as well.
The effect of these identities on affective polarization is especially interesting when considering them in parallel. Research from both social psychology and political science shows that the relationship between an individual’s various identities affects their biases towards others. Mason and Versteegen highlight the overlap between both fields’ theories on the matter. In social psychology, social identity can be defined as an individual’s affective membership in a social group. “Identity complexity theory” posits that the degree of overlap between the social groups an individual belongs to affects their tolerance of others. On the one hand, "high complexity identities" are considered to have little overlap of members between the various groups an individual belongs to. "Low complexity identities", on the other hand, denote a high overlap between members of the various groups. As the authors explain, this is politically relevant insofar as high-complexity identities raise tolerance, while low-complexity identities decrease it.
Similar dynamics have been described in political behavioral research on “cross-cuttingness.” Here, scholars found that cross-cutting social identities can reduce the biasing effects of partisanship, such that people may be more likely to engage with a political opponent if they have at least some overlapping social identity (e.g., gender, education) despite different partisan identities. Of course, the chances of finding overlap differ by the extent of sorting and the type of party system. Nevertheless, considering the evidence from both fields, it is clear that identities – and in particular the alignment between them – influence political behavior.
From this vantage point, the authors take a closer look at the process of social sorting in the United States. They describe how social sorting occurred, particularly along racial lines in the US, resulting in white Americans becoming sorted into the Republican Party and a more racially diverse group in the Democratic Party. Interestingly, this sorting caused affective polarization mainly among White Americans and shows little effect among Black Americans. Further, religious identity has been increasingly influential, with Christianity tied tightly to the Republican Party over the last decades. As Mason and Versteegen explain, the process of social sorting affects affective polarization: the deeper the divisions between citizens are (or at least are perceived to be), the higher the stakes of political competition. Therefore, social sorting makes individuals more extreme in their partisan identity and attitudes, while cross-cutting identities mitigate emotional hostility. Interestingly, the polarizing effect of social sorting as well as the attenuating effect of cross-pressures occur more strongly among supporters of the Republican party.
There are multiple approaches to reducing the effects of social sorting: Firstly, Mason and Versteegen discuss contact theory, which describes the notion that social contact with others can, under certain circumstances, reduce people’s prejudices towards those belonging to different groups. To achieve this positive effect, the two individuals must be of equal status, in pursuit of common goals, and the situation should be authorized by institutional support. Secondly, cross-pressures tend to reduce intolerance and excessive partisan thinking. They may even produce “secondary transfer effects” in which the increased tolerance for one group spills over to others. Lastly, the authors explain that emphasizing shared, “superordinate” identities (e.g., the national, rather than partisan identity) can increase communication between groups. While all these approaches are promising, the authors note that the implementation of each is challenging, also because all require the collaboration of partisans and the motivation of political leaders.
As outlined, both social psychology and political behavior research have shown that social sorting can drive political division, animosity, and even violence. In turn, such hostility may encourage even further social sorting. To further understand the relevance of this phenomenon, Mason and Versteegen argue that future research should consider the effects of social sorting through causal designs, in multi-party contexts, and in contexts outside the United States. Additionally, scholars should investigate interventions to slow and/or reduce the effects of social sorting. Finally, the authors stress that, normatively speaking, social sorting is not just negative. That is, social sorting is often the consequence of previously marginalized groups becoming empowered through political representation, thus reshaping the partisan lines of a society. They argue: “Hatred and contempt already exist between groups – social sorting makes those dynamics more relevant to politics” (Mason & Versteegen, 2025, p. 378)
For a more detailed read, find the Handbook of Affective Polarization here.
References
Mason, L. & Versteegen, P.L. (2025). Social Sorting. In M. Torcal & E. Harteveld (Eds.), Handbook of Affective Polarization (pp. 232–249). Edward Elgar Publishing.
