The past two decades have been punctuated by instances of mass mobilization. 2011 saw the start of the revolutionary wave in the Middle East and North Africa. Later that same year, the Occupy Wall Street movement emerged in New York City and became a global phenomenon. The 2013 Gezi Park protests erupted in Istanbul, but quickly spread throughout the country with solidarity protests occurring around the world. In 2020, millions of people mobilized on almost every continent to protest police violence after George Floyd was murdered by officer Derek Chauvin in Minneapolis while three other police officers looked on. These and other similar events have reshaped social and political landscapes. While the initial triggers of these protests are often evident, explaining how they gained momentum to become mass mobilizations has proven more challenging, raising the question: how does mass mobilization occur?

In his book, “Rise of the Masses: Spontaneous Mass Mobilization and Contentious Politics”, Benjamin Abrams proposes a compelling answer to this question in the form of affinity-convergence theory. At the heart of affinity-convergence theory is the notion that whether a person mobilizes for a cause depends on their affinity for the cause in question. Abrams defines affinity as a predisposition to participate in a cause, and identifies several types of affinities. He distinguishes broadly between social affinities—which are based on patterns of activity, social status, resources and obligations—and psychological affinities––which refer to internal dispositions and drivers including identities, attitudes, perceptions, interests and needs. Together, these various affinities form the basis for common ground among people engaged in mass mobilization.

Affinities are, however, necessary but insufficient conditions for mass mobilization: whether people mobilize in mass depends on the presence of certain social conditions that make it both possible and desirable for large groups of people to come together. Abrams refers to these as convergence conditions. Drawing on existing literature on contentious politics, he identifies three different subtypes of convergence conditions: convergence can take the form of opportunities that make protest more feasible (what Abrams refers to as opportune conditions), exceptional conditions that make the moment unique, or paramount conditions where the scale and significance of the issue prompt participation. These three conditions are further mediated by the different contexts in which they occur. Here Abrams distinguishes between structural, cognitive, and physical/spatial contexts. The result is a taxonomy of nine different types of convergence conditions.

Taken together, affinity-convergence theory explains mass mobilization as the product of widely shared affinities that are catalyzed into mass mobilization by various social conditions. After introducing his theoretical framework, Abrams spends most of the book illustrating the utility of affinity-convergence theory through empirical analyses of four cases of mass mobilization. Three of the cases are from the 21st century—the 2011 Egyptian revolution, the 2011 Occupy Wall Street movement, and the 2020 protests for Black lives—while the fourth looks back in history to explore the causes of the 1789 French Revolution. For each case, Abrams explains the background of the events, then analyzes the salient affinities and the conditions that led to their convergence. For both the Egyptian revolution and Occupy Wall Street, he also devotes considerable attention to how the movements declined.

There are striking differences between the four cases Abrams analyzes, which illuminate important facets of affinity-convergence theory. Specifically, the cases highlight the range of ways that various affinities and convergence conditions are manifested. For instance, in the context of the Egyptian revolution, Abrams finds evidence of all nine types of convergence conditions identified in his taxonomy. In contrast, he finds only three in his analysis of Occupy Wall Street, seven in his analysis of the mobilization for Black lives, and eight in the context of the French Revolution.

Focusing specifically on the first two cases, the Egyptian revolution emerged from a seemingly perfect storm of convergence conditions. Tahrir Square represented a uniquely powerful spatial context that provided safety and a forum for interaction and community building, while also taking on symbolic importance as a site of resistance. The uprisings in Tunisia that sparked the revolutionary wave in the Middle East and North Africa created a set of cognitive conditions that made the moment exceptional, while persistent poverty and corruption bolstered the framing that it was “payback time”. Moreover, changes in the structural conditions in Egyptian society drew more people into mobilization, as initial victories over the police led to a moment where people felt they could participate without fear of direct repression. In contrast, there were relatively few conditions underpinning the emergence of Occupy Wall Street. Two of the conditions identified focus specifically on the physical space, as Abrams highlights how Zuccotti Park provided protection from police and facilitated open participation. Occupy Wall Street was also bolstered by a national moment where opposition to economic elites (i.e. the 1%) was particularly high.

Both the Egyptian revolution and Occupy Wall Street accommodated diverse affinities but the way those affinities manifested varied. For instance, in the Egyptian revolution, Abrams focuses on the salience of national identities, deprivation, government corruption, widespread oppression and anti-regime hatred as key psychological dispositions. In Occupy Wall Street, he points to identification with the 99% and perceived injustices following the 2008 financial crisis as key psychological dispositions. In doing so, he highlights the range of identities, injustices, and attitudes that can serve as a basis for social affinity.

Affinity-convergence theory thoughtfully synthesizes insights from scholarship on social movements and collective behavior. Readers familiar with these literatures will recognize the centrality of framing, political opportunity, and identity, among other factors that influence and motivate people to mobilize for causes. Through his synthesis, Abrams provides a relatively simple framework that nevertheless allows for the complexities underpinning mass mobilization.

While affinity-convergence theory represents an elegant synthesis and extension of existing scholarship, there are opportunities for further theoretical development. One point that struck me as I read had to do with the breadth of the affinities illustrated in the empirical analysis. At times it seemed as though almost anything could be an affinity. However, if anything can be an affinity, then affinities are always going to be present in one form or another. If affinities are always present, it raises questions about the extent to which a focus on affinities is useful in explaining mass mobilization. With that in mind, I found myself wondering if the concept of affinities could be more clearly bounded such that we can also identify what is not a basis for affinity. Another question that struck me was whether mass mobilization depends on the co-occurrence of multiple convergence conditions. Empirically, every instance of mass mobilization analyzed in the book exhibited a combination of opportune, exceptional, and paramount conditions. I found myself wondering whether each of these subtypes must be present for mass mobilization to occur or if it is possible for a single convergence condition to act as a catalyst. This is arguably an empirical question, but answering it stands to yield valuable theoretical insights. A final question that I believe warrants further consideration is the extent to which affinity-convergence theory can distinguish between the presence versus absence of mass mobilization. Consistent with the rich tradition of macro-comparative sociology that this book builds on, Abrams draws insights from cases where mobilization was present. Moreover, he is meticulous in showing how the conditions that resulted in mass mobilization waned in several of his cases, thereby demonstrating their importance. However, given the range of possible affinities and the broad nature of the convergence conditions, I found myself wondering whether the theory is capable of explaining why mass mobilization doesn’t occur more often.

The Rise of the Masses is a major contribution to scholarship on mobilization. While Abrams’s contributions are theoretically generative, the empirical analyses also represent meaningful substantive contributions to scholarship on each of the four cases covered. Consequently, I believe this book will appeal to a broad readership of scholars interested both in the dynamics of contentious politics and in these four transformative cases.