My colleague Macartan Humphreys recently came out with book, Coethnicity (with James Habyarimana, Daniel Posner, and Jeremy Weinstein, addresses the question of why public services and civic cooperation tend to be worse in areas with more ethnic variation. To put it another way: people in homogeneous areas work well together, whereas in areas of ethnic diversity, there’s a lot less cooperation.

I’ll give my comments, then at the end I posted a response from Macartan.

From one perspective, this one falls into the “duh” category. Of course, we cooperate with people who are more like us! But it’s not so simple. Macartan and his colleagues discuss and discard a number of reasonable-sounding explanations before getting to their conclusion, which is that people of the same ethnic group are more able to enforce reciprocity and thus are more motivated to cooperate with each other.

But, looking at it another way, I wonder whether it’s actually true that people in homogenous societies cooperate more. I think of the U.S. is pretty ethnically diverse, compared to a lot of much more disorganized places. One question is what counts as ethnicity. Fifty or a hundred years ago in the U.S., I think we’d be talking about Irish, English, Italians, etc., as different ethnic groups, but now they’d pretty much all count as white. To what extent is noncooperation not just the product of ethnic diversity but also a contributor to its continuation?

Macartan and his collaborators address some of these issues in their concluding chapter, and I’m sure there’s a lot more about this in the literature. This is an area of political science that I know almost nothing about. When a researcher such as myself writes a book in American politics, we don’t have to explain much–our readers are already familiar with the key ideas. Comparative politics, though, is a mystery to the general reader such as myself.

I should say something about the methods used by Macartan and his collaborators. They went to a city in Uganda, told people about their study, and performed little psychology/economics experiments on a bunch of volunteers. Each experiment involved some task or choice involving cooperation or the distribution of resources, and they examined the results by comparing people, and pairs of people, by ethnicity, to see where and how people of the same or different ethnic groups worked together in different ways.

One thing that was cool about this study, and which reminded me of research I’ve seen in experimental psychology, was that they did lots of little experiments to tie up loose ends and to address possible loopholes. Just for example, see the discussion on pages 137-139 of how they rule out the possibility that their findings could be explained by collusion among study participants.

I was also thinking about the implications of their findings for U.S. politics. (Macartan has told me that he doesn’t understand how there can be a whole subfield of political scientist specializing in American politics, but he told me that he’ll accept “Americanists” by thinking of us as comparative politics scholars who happen to be extremely limited in what we study.) The authors allude to research by Robert Putnam and others comparing civic behavior in U.S. communities of varying ethnic homogeneity, but I also wonder about public opinion at the national level, not just local cooperation but also to what extent people feel that “we’re all in this together” and to what extent people evaluate policies and candidates based on how they effect their ethnic group (however defined). I’m also interested in the sometimes-vague links between ethnicity and geography, for example the idea that being a Southerner (in the U.S.) or a Northerner (in England) seems like an ethnic identity. Even within a city, different neighborhoods have different identities.

If I haven’t made the point clear enough already, I think the book is fascinating, and it looks like it will open the door to all sorts of interesting new work as well.

P.S. While typing up these notes, I realized that “sanction” is one of those funny words with two nearly completely opposite definitions. According to, the first definition of this verb is “to authorize, approve, or allow.” But “sanction” also is used in the opposite sense, to mean “punish.” Similarly, the noun can either mean “permission” or “penalty.” It can get confusing at times, to read that some behavior is being sanctioned.

P.P.S. In one of the experiments in the book involves two people and a combination lock. Person A is shown how to use the lock (apparently, these are common in the U.S. but not in Uganda), then person B is given the lock and is given ten minutes to open it. Person A is allowed to give instructions but not to touch the lock. I was surprised to read that 40% of the pairs in this experiment did not succeed in opening the lock! I mean, how hard it be to say, “Turn to the right a few times until you reach the number 17, then turn to the left, . . .”? Was it a language barrier, or was person A sometimes not helping at all, or was there something else going on? Not having ever conducted or participated in such an experiment, I don’t know how to think about this at all.

P.P.P.S. Some minor comments:

p.6, line 2: They write, “this book departs form the typical social science concern with whether, rather than why, one thing causes another” [italics in original]. This reminds me of something I’ve been thinking about recently, which is that, in social settings, everything “causes” everything else. To put it another way, no effects are zero, and apparent near-zeroes can arise from effects that are positive in some cases and negative in others. (To consider an example from educational research, a new teaching method might work for some students but be counterproductive for others.)

p. 6-7: A related point goes here: the authors give several possible explanation for greater cooperation among coethnics, but I’m suspicious because all these stories go in the same direction. A positive effect need not be composed solely of positive components.

p.8: They discuss that one reason for avoiding cooperation is to avoid being a “sucker.” This reminds me of one of my favorite psychology articles, The norm of self-interest, by Dale Miller.

p.15: Robert Axelrod’s work on the prisoner’s dilemma is mentioned here. I’d just like to point out that, as interesting as that work is, I don’t think it actually applies to the example that Axelrod discussed in his book.

p.51: One of my pet peeves is the presentation of tables that you have to turn the book to read. With a bit of care, this and the other such tables could be formatted to fit right-side-up on the page. (In this case, you could start by removing all the initial zeroes (“0.41” becomes “.41”, etc.) I also admit to finding these tables extremely difficult to read, because I have to distinguish between “Baganda,” “Bagisu,” “Bakiga,” “Basoga,” and several other similarly-named groups. Also, how are these groups ordered in the table? The natural ordering would be from largest to smallest in population, but that doesn’t seem to be what they’re doing here. And is “Munyankole” (p.50) the same as “Banyankole” (p.51)?

Overall, I think the graphical presentations of model estimates throughout the book are excellent.

P.P.P.P.S. Macartan answers some of my questions:

There seems a bit of a contradiction in you seeing the US a pretty diverse place but also using it as example of how development undercuts diversity. Two substantive points though, one for each side of the contradiction: First, the coethnicity/cooperation relationship is also found *within* the US, possibly the best known study is by Alesina, Baqir and Easterly, but there are others. The second is that our study does still agree with your main point; reciprocity norms seem to be particularly important when there aren’t stronger institutions, and even in the context of our study we find that the introduction of a fairly minimal institution (a third party enforcer) is enough to remove the coethnic effect.

A minor point is that the subjects weren’t volunteers but were randomly sampled from the study area, with very low non-response and attrition rates; so there is some claim here that they are representative at least of this region, which is often not true for lab style experiments.

I agree that we didn’t think through what negative effects could contribute to overall positive effects, that’s a better way to think about it. Elster talks about that in his article on mechanisms also. Also, in light of the work on mediation (by Kosuke and others) it’s clearer to me now that a zero average relation (or, “small”) does not necessarily mean that the mechanism is unimportant.

Munyankole is the singular for Banyankole, just like Mugelman and Bagelman are singular and plural.

4 thoughts on “Coethnicity

  1. Fifty or a hundred years ago in the U.S., I think we'd be talking about Irish, English, Italians, etc., as different ethnic groups, but now they'd pretty much all count as white.

    Actually, 100 years ago, these were all considered different races, and this led to significant problems during WW1 and on into the 1920s, esp. with regard to both the Irish and Germans. See this article:

    By the time WW2 rolled around, there was an almost conscious decision to adopt the South's 1 drop rule, and begin treating as white everyone whose ancestry was entirely European. Part of this was expressed in having top military leaders be of German heritage (e.g., Eisenhower, Nimitz & Spaatz). Wilkie, although or perhaps because of his, German background, expressed support for the UK over Germany. The transition continued through the 1950s and into the 1960s, as quotas limiting Jews at prestigious educational institutions persisted for awhile.

  2. Macartan et al argue that, "Ethnically homogenous communities often do a better job than diverse communities of producing public goods such as satisfactory schools and health care, adequate sanitation, and low levels of crime." However, often doing a "better job" requires (1) a significant redistribution of wealth from the upper income (minority) to the middle and lower income (majority) groups which require negotiation between these groups via some institutional structure and (2) the capacity of the community to develop and implement these public goods. I would be curious to know how much Macartan et al focused on class structure within ethnically homogenous vs heterogenous groups and from an organizational theory perspective how ethnically homogenous communities develop and implement better public services. I look forward to reading the book and finding out.

  3. From what I recall of Putnam, his findings on ethnic differences applied even to Swedish-Americans vs Norwegian-Americans in the great plains.

    I had a different take on the effect of diversity on the production of public goods.

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