By David E. Campbell, Ph.D. (University of Notre Dame)

As the 2024 presidential election approaches, we are reminded that Americans are deeply polarized. But while the term “polarization” is widely used, with apologies to The Princess Bride, that word does not always mean what you think it means. The American public is not polarized in the sense that they are divided into two ideological camps with little middle ground (although that is the case for our politicians). Rather, they experience affective polarization, which refers not to their views on public policy—as Americans are generally centrists—but instead a personal dislike of people who support the “other” party. This is a relatively recent development, for as recently as the 1980s, partisan differences did not usually translate to personal antipathy. Nor is it limited to one party; Republicans and Democrats express nearly identical dislike of each another.

“...social capital can strengthen our communities. And make democracy work.”

It is no coincidence that mutual partisan antipathy has risen sharply over the same time that there has been a steep decline in social capital—that is, personal connections and networks that foster trust and reciprocity. As famously documented by Robert Putnam, Americans are “bowling alone.” That is, they are spending less time together, and are less likely to trust one another. Writing almost twenty-five years ago, Putnam predicted that less social capital would lead to greater political polarization or, as he put it at the time, “our politics will become more shrill.” At the risk of understatement, our politics today is shrill indeed. A high state of affective polarization is the seedbed for conspiracies, disinformation, and an unwillingness to accept the outcome of a presidential election in which your party’s candidate lost. In other words, partisan antipathy makes it difficult—perhaps impossible—for American democracy to work.

Social capital comes in two flavors: bonding and bridging. To bond is to make connections with people like you; to bridge is to connect with those with a different identity or background. Both are important for a healthy society, but it is bridging that fosters trust across social lines that are otherwise divisive. At least, that is the theory. In practice, it has been difficult to distinguish between bonding and bridging, as they are not mutually exclusive. For example, many organizations foster both—think of a religious congregation in which people share common bonds of faith but are economically diverse. Thus, past studies showing the positive consequences for communities with higher social capital have not been able to isolate the effect of bridging specifically.

Recently, however, the economist Raj Chetty and his colleagues have been able to measure one especially important type of bridging social capital: personal connections among people with different socioeconomic backgrounds. They do so with data from many millions of Facebook users with billions of friendships—so many, in fact, that they can measure the degree of socioeconomic bridging down to the level of their ZIP code, a good approximation of a neighborhood. They find that people who are raised in neighborhoods with more bridging across socioeconomic lines are more economically mobile. That is, they are more likely to live the “American dream” of greater financial prosperity than their parents’ generation.

What, though, about politics? Does greater bridging social capital among people of different class backgrounds lessen affective polarization? In a word, yes. In a recent article, I show that people who live in neighborhoods (technically, ZIP codes) with more socioeconomic connectedness—bridging social capital—are less likely to be affectively polarized. Republicans rate Democrats more highly, and vice-versa. Similarly, each group is less likely to ascribe negative stereotypes to the other side, such as being selfish, hypocritical, mean, and close-minded.

Importantly, the key to lower affective polarization is the social capital within a community, and not just the social connections made by any given individual. It is in communities, especially neighborhoods, that a culture of trust and mutual reciprocity is developed. Furthermore, the data suggests that this effect is greatest among high-income Americans, and affluent Republicans most of all.

The implications of these findings for socioeconomic bridging are profound. They suggest that efforts to nurture greater economic integration will not only improve social mobility but also the health of American democracy. We should not be under any illusions that this will be easy, as economic segregation in the United States is both widespread and growing. Here again research into social capital is illuminating. This is not the first time that the United States has experienced high income inequality and economic segregation. In the wake of the first Gilded Age, America experienced a boom in civic groups, many of which fostered socioeconomic mixing. What the nation requires now is a similar civic revival. Granted, the forms of social connection today will differ from a century ago, but the need to bridge our class divides has not.

Why social science? Because social capital can strengthen our communities. And make democracy work.

David Campbell is the Packey J. Dee Professor of American Democracy at the University of Notre Dame and the director of the Notre Dame Democracy Initiative. His research focuses on civic and political engagement, with particular attention to religion and young people. Campbell’s most recent book is Secular Surge: A New Fault Line in American Politics (with Geoff Layman and John Green), which received the Distinguished Book Award from the Society for the Scientific Study of Religion. Among his other books is American Grace: How Religion Divides and Unites Us (with Robert Putnam), winner of the award from the American Political Science Association for the best book on government, politics, or international affairs. His work has appeared in a variety of scholarly journals including the American Political Science Review, American Journal of Political Science, Journal of Politics, Public Opinion Quarterly, and Daedalus. In addition, he has been featured in publications such as the New York Times, Washington Post, Wall Street Journal and—every political scientist’s dream—Cosmopolitan.

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