Can we please, PLEASE stop it with the assertions that a country’s income inequality tells us a lot about its propensity for social unrest?

This claim pops up all the time. Exhibit A from an article I read this morning, on China’s official Gini coefficient for 2012:

China’s reality of inequality – and the challenge to narrowing the gap – remains unchanged: the current coefficient of 0.474 poses a high risk for social unrest.

I understand, and am even sympathetic to, the claim that gross disparities in wealth are unjust, particularly in societies where the poorest want for basic needs like food and shelter. I also recognize that organizers of, and participants in, contemporary social unrest often call out economic inequality as one of their chief grievances.

What I’m just not seeing, though, is empirical evidence that countries with higher economic inequality are more susceptible to social unrest.

For starters, there’s the general observation that economic inequality is common and persistent, but large-scale social unrest is uncommon and usually fleeting. What Jim Fearon and David Laitin wrote in 1996 about inter-group tensions and ethnic violence applies just as well here:

Among existing theories of ethnic conflict, accounts focusing on past tensions between groups that are memorialized in narratives of blame and threat tend to dramatic overprediction of violence. Such narratives are almost always present, but large-scale interethnic violence is extremely rare.

The same goes for inequality and popular rebellion. The former is ubiquitous while the latter is scarce, so it’s hard to see how the presence of the one can be said to predict the risk of the other.

Okay, so maybe inequality doesn’t help explain the timing of social unrest, but it does predispose certain societies to erupt when other forces come together. It’s not the spark that starts the fire; it’s the dry tinder that helps the spark catch and spread.

Well, I’m just not seeing this, either.

To look at the association between inequality and unrest, I started by downloading the World Bank’s data on income inequality from Hans Rosling’s Gapminder site. These data summarize occasional national surveys on income or consumption in a Gini coefficient. The higher the Gini coefficient, the more unequal the distribution of incomes in that society. Because the data are only updated occasionally—many countries have just one or two reported values since 1979, the start of the World Bank’s observation period for this measure—I reduced the time series into a single value by taking the maximum (or, in some cases, lone) value for each country. Then I used Erica Chenoweth and Maria Stephan’s data on nonviolent uprisings to identify which countries had seen at least one civil-resistance campaign emerge between 1980 and 2006. Finally, I used the ‘sm‘ package in R to produce kernel density plots that visually compare the distribution of Gini coefficients across those two sets of countries.

The results are shown below. As you can see, there seems to be virtually no difference in the level of income inequality among countries that have and have not produced popular uprisings since 1980. In a bivariate logistic regression model estimated from these same data, the coefficient for the Gini index is <0.01. Not exactly the powerful discriminator we keep hearing about, eh?

That chart only looks at nonviolent uprisings, but published research on violent conflict suggests that the association isn’t especially strong there, either. In a 2008 paper (h/t Cyrus Samii), political scientist Gudrun Østby finds only a weak link between income inequality among individuals and the risk of civil-war onset in 36 developing counties. Interestingly, she does find evidence that higher levels of inequality between ethnic groups increase the risk of violent rebellion, suggesting that inter-group comparisons play a role in fomenting conflict. Still, this isn’t the rich vs. poor narrative on which the conventional wisdom about inequality and rebellion depends, and on that score, Østby’s analysis only strengthens my prior belief.

In light of that empirical evidence, it’s hard to put much stock in the oft-heard claim that highly unequal countries are especially prone to social unrest. Given how noisy the data on income inequality are, it seems particularly absurd to treat small fluctuations in a single country’s Gini coefficient as a useful indicator of rising or falling prospects for a popular uprising or civil war. I don’t think this blog post is going to do much damage to the conventional wisdom, but if there are any takers out there, I would be happy to bet against anyone who wants to use Gini coefficients to predict where the next rebellion will occur.

Update: In the Comments, Rex Brynen suggested I also compare the distributions of Gini coefficients in a couple of subsets where inequality would arguably have a stronger effect: poorer countries, and poorer countries with no history of democracy before 1980 (the start of my period of observation). The plots below do that, where “poorer” is defined broadly as countries that weren’t OECD members as of 1980. As you can see, there’s still virtually no separation in the broader non-OECD subset (the plot on the left). When we limit our view to non-OECD countries with no democratic experience before 1980 (the plot on the right), we get a little bit of separation in the expected direction, but the difference is still rather marginal. (In a bivariate logistic regression estimated from this subset, the coefficient is 0.03 with an s.e. of 0.04.)