I was reading Robert Putnam’s now rather famous paper from the journal Scandinavian Political Studies, “E Pluribus Unum: Diversity and Community in the Twenty-first Century,” the one that found, to the dismay of people like Putnam himself, that “new evidence from the US suggests that in ethnically diverse neighbourhoods residents of all races tend to ‘hunker down’. Trust (even of one’s own race) is lower, altruism and community cooperation rarer, friends fewer.”
There has been, as you might imagine, a lot of response to Putnam’s work, which I won’t get into here. But I was struck to notice, half-way through the paper, this fragment:
“Across American census tracts, greater ethnic heterogeneity is associated with lower rates of car-pooling, a social practice that embodies trust and reciprocity.”
The source is this paper, by Charles and Kline. It’s fire-walled, so I can’t read it. But Tim Harford gives the gist, noting how car-pooling as an activity is an interesting proxy for the elusive concept of “social capital”:
“And so we return to car-pooling. It is not a bad measure of a certain kind of social capital: car-pooling does not work without trust. Can you trust your fellow travellers not to be late, drive badly, or murder you? Whatever it is, social capital would seem to help you get a lift. Economists Kerwin Charles and Patrick Kline have just published a paper about car-pooling and social capital, and there’s a twist. Charles and Kline want to understand how the local racial mix affects social capital. They predict that, for instance, African-Americans will find it easier to car-pool if they live in an area with lots of other African-American, following a battery of tedious but handy statistical tests, this is exactly what they find.
They also find that not all racial differences present the same barrier to car-pooling. Asians who are a minority in a chiefly white area car-pool more than Asians who are a minority in a chiefly African-American area. African-Americans and Hispanics seem to find it similarly easy to get along. But neither whites in a largely African-American area nor African-Americans in a largely white area tend to car-pool. There is such a thing as social capital, and if you live in an area full of people with the same colour skin as you, it seems you will enjoy more of it.”
I’m not sure how good the data are, etc., or what other factors might be lurking there, but it’s a curious finding nonetheless. And I’m not how sure how this data relates to informal car-pooling, like “slugging” in San Francisco.
Traffic in general presents perhaps an extreme version of what Putnam is describing: You’re surrounded by people you don’t know, who are different from you, and in general there’s few outlets for trust and reciprocity, because you’ll never see these strangers again. As Putnam writes, “Social psychologists and sociologists have taught us that people find it easier to trust one another and cooperate when the social distance between them is less.”