In his work on the 1994 genocide in Rwanda, Mamdani (2001: 224) relates how a respondent named Mectilde described mass Hutu participation in the violence: ‘She gave me a rough count: ten percent helped; 30 percent were forced to kill; 20 percent killed reluctantly; 40 percent killed enthusiastically.’1 The response illustrates that the Hutu population was not monolithic in its propensity to engage in Tutsidirectedviolence, in spite of which, hundreds of thousands of Hutu did participate in the genocide.2 So whereas for Mamdani (2001: 224), ‘It is the 40 percent, those who “killed enthusiastically,” who represent the real moral and political dilemma of the Rwandan genocide’, I am concerned with explaining why another 50% of Hutus participated, albeit reluctantly or under duress. What, in other words, explains mass participation by reluctant Hutu in violence against Tutsis? A related puzzle concerns the scale and intensity of violence, which was simply unprecedented. Why were previous episodes of Hutu–Tutsi violence localized and contained, while the episode in 1994 consumed the entire country?
I argue that the compulsion and resultant participation of the reluctant in the killing constituted a dramatic behavior shift, with related consequences for the scale and intensity of anti-Tutsi violence. As such, the unprecedented magnitude of violence in 1994 can, to a large extent, be attributed to the emergence of a violence-promoting norm among Rwandan Hutu, a norm that compelled all Hutu – reluctant or otherwise – to participate in the violence. Simply put, Hutu who opposed the genocide and were reluctant to participate in the killing, killedn the hundreds and thousands because they were left with no other choice: ‘kill or be killed’.3 If, as I argue, a violence-promoting norm did emerge in Rwanda and engender mass participation, this raises a number of related questions: Why, for instance, do norms that engender mass participation in violence emerge within some ethnic groups and not others? Can these behavioral norms vary in strength within a given episode of violence? Can these norms also promote nonviolent outcomes such as intergroup cooperation? Is norm formation equally likely in ethnic groups with similar aggregate characteristics? It is equally likely with weak or no punishments?
In this article, I analyze the emergence of ethnic norms – rules instituted and enforced within an ethnic group to shape the behavior of its members toward rivals.4 By delineating behavioral expectations in times of conflict and cooperation, norms constitute one mechanism to shape group behavior by increasing cohesiveness among co-ethnics and enlarging the set of participants in group action. Therefore, I do not claim that ethnic norms are the only mechanism that matters in episodes of mass violence. Rather, I seek to determine the conditions under which expectations of mass participation will emerge by analyzing the dynamics of within- group interaction. Using the Rwandan genocide as a foil, my framework under- scores (1) the initial proclivity of group members to engage in interethnic violence and punish co-ethnics who fail to engage in violence; (2) the structure of social networks within the group; and (3) the strength of punishments imposed on individuals whose behavior deviates from emergent group behavior.
My usage follows Kuran (1998: 1), who defines ‘ethnic norms’ as ‘the behavioral codes that individuals must follow to retain the acceptance of their ethnic groups . . . sustained partly by sanctions’. It also follows Axelrod (1986: 1097), insofar as ‘a norm exists in a given social setting to the extent that individuals usually act in a certain way and are often punished when seen not to be acting in this way’. Both definitions make it possible to study the growth and decay of norms based on how often a particular course of action is followed and the frequency of punishment for those who do not follow it.
To emphasize, my immediate interest is in norms that engender mass participation, rather than outcomes – whether an episode of interethnic conflict yielded a particular level of violence – though the latter are obviously a latent concern.5 In order, then, to explore variation in the strength of ethnic norms both within and across episodes of interethnic violence – and thus extend my analysis beyond Rwanda to derive a set of general propositions about the emergence of ethnic norms – I utilize complex systems theory and its simulation by agent-based modeling (ABM). This methodology, in particular, lends itself well to the study of emergent phenomena (Axelrod, 1997; Holland, 1999; Page, 1999). By repeating simulations and observing trajectories of participation, one can learn about the distribution of outcomes associated with different initial conditions, as well as about processes of norm formation and change within ethnic groups. Moreover, ABM makes it possible to tie variation in individual characteristics, interaction, and behavior to variation in the strength of norms that engender mass participation in ethnic violence, thereby reveal- ing how micro-level dynamics generate macro-level events.
The article is organized as follows. In the next section, I analyze the puzzle of mass participation in the Rwandan genocide in greater detail. I then discuss the norm-based framework in relation to other intra group mechanisms used to engender collective behavior, before specifying an agent-based model of norm formation and change. I then present the model’s results, and conclude with a discussion of my findings.