Here are some highlights from this 2020 paper in the Annual Review of Political Science:
* Does ethnic diversity erode social trust? Continued immigration and corresponding growing ethnic diversity have prompted this essential question for modern societies, but few clear answers have been reached in the sprawling literature. This article reviews the literature on the relationship between ethnic diversity and social trust through a narrative review and a meta-analysis of 1,001 estimates from 87 studies.* Does ethnic diversity erode social trust? This question is the quintessential derivative of the wider debate about whether the positive interpersonal ties characteristic of socially cohesive societies can be preserved when societies’ inhabitants to a decreasing extent share a common ethnic background. The answer to this question is crucial for understanding the potential challenges that developed societies are facing from increasing ethnic diversity stemming from immigration and refugee settlement. It also provides a potential explanation for the challenges to governance in countries that have historically been ethnically heterogeneous (Alesina et al. 1999, Alesina & Glaeser 2004). Further, because social trust stimulates cooperation between individuals (Gächter
et al. 2004), the link between ethnic diversity and trust provides a plausible explanation for why ethnic diversity has been found to inhibit the enactment of redistributive welfare policies…* One account posits that mere exposure to people of different ethnic background erodes social trust (Dinesen & Sønderskov 2015). This approach does not impose any assumptions regarding the mode or form of interaction between people in a given context. It is simply “being around” interethnic others that is proposed to influence trust, although this influence might be accentuated or mitigated by specific forms of interactions (e.g., competition or positive contact). This account builds on the assumption that people display heterogeneity—or out-group—aversion (Alesina & La Ferrara 2002, Olsson et al. 2005). That is, they trust those who are different from themselves less than those who are more similar, because similarity is an indicator of shared norms and other behavior-regulating features relevant for trust. By implication, because ethnicity is one—often highly visible—cue of similarity, social trust is predicted to be lower in ethnically diverse settings, where cues of dissimilarity are more frequent.
* In his much discussed “constrict theory,” Putnam (2007) presents an argument for why ethnic diversity may erode social trust, independent of the specific target. This is premised on the idea that ethnic diversity leads to social isolation. That is—using Putnam’s famous metaphor—people “hunker down” in more ethnically diverse areas. Because ethnic diversity is expected to induce such general anomie, this mechanism predicts that ethnic diversity lowers all forms of social trust, including both out- and in-group trust. As such, constrict theory is the most daring and wideranging account suggested to link ethnic diversity and social trust.
* First, as a consequence of people’s inherent preference to interact with people like themselves (i.e., homophily) (Lazarsfeld & Merton 1954), ethnically diverse settings might be less socially integrated (e.g., in terms of density of acquaintanceship and friendship networks). This reduces both the flow of information and the potential for sanctioning freeriders, which lay the foundation for trusting others. Second, ethnic diversity might result in preference diversity (i.e., fewer shared collective goals), thereby lowering people’s expectations that collective endeavors are possible while also creating incentives to manipulate process and agenda (Page 2008). Both set people further apart. Third, ethnic diversity with its associated linguistic and cultural differences might inhibit communication—and ultimately coordination—which makes trusting others more risky. Importantly, other people who live in such disintegrated environments are considered less trustworthy,
irrespective of whether they are in- or out-group members themselves, because their behavior is not constrained by the social structure in the local environment. These inferences may—in an attenuated form—extend beyond the local area to trust in specific groups as well as to trust in other people more generally.
