But the united states is no longer a nation of joiners. As the political scientist Robert Putnam famously demonstrated in Bowling Alone, participation in civic groups and organizations of all kinds declined precipitously in the last decades of the 20th century. The trend has, if anything, accelerated since then; one study found that from 1994 to 2004, membership in such groups fell by 21 percent. And even that likely understates the real decline, as a slight uptick in passive memberships has masked a steeper fall in attendance and participation. The United States is no longer a nation of presidents, either. In a 2010 census survey, just 11 percent of respondents said that they had served as an officer or been on a committee of any group or organization in the previous year.

Putnam was concerned about the effects of this decline on “social capital,” which he defined as the “norms of reciprocity and networks of civic engagement.” His financial metaphor values civic life primarily for the assets it provides individuals. This perspective lends itself to a certain optimism. Not every measure of social capital is in decline: Americans still volunteer and attend religious services at relatively high rates. They can also use social media to connect with one another in new ways, forging communities of interest across vast geographic distances. In these ways, individuals can still accrue substantial social capital. The metaphor has its limits, however: In focusing on the importance of ties between individuals, it neglects the intrinsic benefits of participating in civic life.

Volunteerism, church attendance, and social-media participation are not schools for self-government; they do not inculcate the habits and rituals of democracy. And as young people participate less in democratically run organizations, they show less faith in democracy itself.