What causes people in large numbers to step outside their daily routines and gather in public to voice demands on issues that affect a group much larger than themselves?

If we’re to believe a recent article in Time on the protests bursting across Brazil, then the answer is, well, a lot of things. Here’s a list of all the “causes” of the recent Brazilian protests identified in the space of just a few hundred words:

Social inequality

World Cup spending

Police violence

A nine-cent rise in bus fares

Corruption

A lack of return on high taxes

Inadequate government spending on infrastructure, education, and health care

“The country’s dramatic rise on the world stage”

“The incapacity of traditional political representation to deal with the new and unheard of demands of a changing society”

Youth

Inflation

I don’t mean to pick on Time, which does a lot of solid international reporting, or on the authors of that particular piece. As Christian Davenport observes in a recent post on the blog Political Violence @ a Glance, press coverage of social unrest often gives us “a blow-by-blow account of the street battles taking place” without carefully connecting those events or their alleged causes to prior theory or empirical research. When comparisons are made, it’s usually by analogy, with strong bias toward cases that are recent, geographically proximate, and emotionally salient. As a result, “It all just seems to be new and eventful without much rhyme or reason.”

I realize that journalism isn’t rigorous social science, and it’s not supposed to be. Still, one of the intellectual dangers of laundry-list explanations is that they make it even easier to succumb to confirmation bias—that is, to pick through the list and pull out the items that support our prior beliefs. In the Time piece on Brazil alone, for example, there’s “evidence” to support many different and potentially competing hypotheses about causes of mass protest, from neo-Marxist claims about the centrality of economic inequality to socio-demographic theories emphasizing youth bulges and an expanding middle class to “homo economicus” models focused on price hikes and public spending.

We can’t learn a whole lot about the causes of mass protest by simply cataloging the conditions and things participants tell us about their motivations in cases where they occur. That information is useful, but not so much on its own.

To make real headway on causal analysis, we have to engage in contrasts. To learn about the origins of mass protest, for example, we need to compare cases where uprisings occur with ones where they don’t. Yes, income inequality is high in Brazil, but the same can be said for many of its regional neighbors. If inequality foments uprisings, why aren’t we seeing waves of mass protest in Honduras or Bolivia or Colombia or Paraguay? Meanwhile, inequality was comparatively low in many countries touched by the “Arab awakening.” According to World Bank data, income inequality is lower in Tunisia, Egypt, and Syria than in virtually every country in Latin America. Together, these contrasts imply that high inequality is neither necessary nor sufficient for mass protest, but that’s probably not what you’d expect if you saw the Time headline proclaiming that “Social Inequality and World Cup Spending Fuel Mass Unrest.”

In general, laundry lists of concerns and plausible causes like the one proffered in that Time article can be useful as fodder for what Alex George and Andrew Bennett call “heuristic case studies,” which “inductively identify new variables, hypotheses, causal mechanisms, and causal paths.” What they most certainly don’t do is test theory. These analyses are the social-science equivalent of ambulance chasing. When we hear the noise of the crowd, we rush toward it, ask the participants why they’re angry, read their signs and banners, and try to spin a coherent story from what we see and hear. That’s fine as far as it goes—which, it turns out, isn’t very far.

PS. If you’re interested in my thoughts on what does cause mass protest, see this later post.