Agent-based computational modeling (ABM, for short) is a formal and supplementary methodological approach used in international relations (IR) theory and research, based on the general ABM paradigm and computational methodology as applied to IR phenomena. ABM of such phenomena varies according to three fundamental dimensions: scale of organization—spanning foreign policy, international relations, regional systems, and global politics—as well as by geospatial and temporal scales. ABM is part of the broader complexity science paradigm, although ABMs can also be applied without complexity concepts. There have been scores of peer-reviewed publications using ABM to develop IR theory in recent years, based on earlier pioneering work in computational IR that originated in the 1960s that was pre-agent based. Main areas of theory and research using ABM in IR theory include dynamics of polity formation (politogenesis), foreign policy decision making, conflict dynamics, transnational terrorism, and environment impacts such as climate change. Enduring challenges for ABM in IR theory include learning the applicable ABM methodology itself, publishing sufficiently complete models, accumulation of knowledge, evolving new standards and methodology, and the special demands of interdisciplinary research, among others. Besides further development of main themes identified thus far, future research directions include ABM applied to IR in political interaction domains of space and cyber; new integrated models of IR dynamics across domains of land, sea, air, space, and cyber; and world order and long-range models.
Caroline A. Hartzell
Civil wars typically have been terminated by a variety of means, including military victories, negotiated settlements and ceasefires, and “draws.” Three very different historical trends in the means by which civil wars have ended can be identified for the post–World War II period. A number of explanations have been developed to account for those trends, some of which focus on international factors and others on national or actor-level variables. Efforts to explain why civil wars end as they do are considered important because one of the most contested issues among political scientists who study civil wars is how “best” to end a civil war if the goal is to achieve a stable peace. Several factors have contributed to this debate, among them conflicting results produced by various studies on this topic as well as different understandings of the concepts war termination, civil war resolution, peace-building, and stable peace.
Richard Ned Lebow
Counterfactuals seek to alter some feature or event of the pass and by means of a chain of causal logic show how the present might, or would, be different. Counterfactual inquiry—or control of counterfactual situations—is essential to any causal claim. More importantly, counterfactual thought experiments are essential, to the construction of analytical frameworks. Policymakers routinely use then by to identify problems, work their way through problems, and select responses. Good foreign-policy analysis must accordingly engage and employ counterfactuals.
There are two generic types of counterfactuals: minimal-rewrite counterfactuals and miracle counterfactuals. They have relevance when formulating propositions and probing contingency and causation. There is also a set of protocols for using both kinds of counterfactuals toward these ends, and it illustrates the uses and protocols with historical examples. Policymakers invoke counterfactuals frequently, especially with regard to foreign policy, to both choose policies and defend them to key constituencies. They use counterfactuals in a haphazard and unscientific manner, and it is important to learn more about how they think about and employ counterfactuals to understand foreign policy.
Shannon Carcelli and Erik A. Gartzke
Deterrence theory is slowly beginning to emerge from a long sleep after the Cold War, and from its theoretical origins over half a century ago. New realities have led to a diversification of deterrence in practice, as well as to new avenues for its study and empirical analysis. Three major categories of changes in the international system—new actors, new means of warfare, and new contexts—have led to corresponding changes in the way that deterrence is theorized and studied. First, the field of deterrence has broadened to include nonstate and nonnuclear actors, which has challenged scholars with new types of theories and tests. Second, cyberthreats, terrorism, and diverse nuclear force structures have led scholars to consider means in new ways. Third, the likelihood of an international crisis has shifted as a result of physical, economic, and normative changes in the costs of crisis, which had led scholars to more closely address the crisis context itself. The assumptions of classical deterrence are breaking down, in research as well as in reality. However, more work needs to be done in understanding these international changes and building successful deterrence policy. A better understanding of new modes of deterrence will aid policymakers in managing today’s threats and in preventing future deterrence failures, even as it prompts the so-called virtuous cycle of new theory and additional empirical testing.
Sabine C. Carey and Neil J. Mitchell
Pro-government militias are a prominent feature of civil wars. Governments in Colombia, Syria, and Sudan recruit irregular forces in their armed struggle against insurgents. The United States collaborated with Awakening groups to counter the insurgency in Iraq, just as colonizers used local armed groups to fight rebellions in their colonies. An emerging cross-disciplinary literature on pro-government non-state armed groups generates a variety of research questions for scholars interested in conflict, political violence, and political stability: Does the presence of such groups indicate a new type of conflict? What are the dynamics that drive governments to align with informal armed groups and that make armed groups choose to side with the government? Given the risks entailed in surrendering a monopoly of violence, is there a turning point in a conflict when governments enlist these groups? How successful are these groups? Why do governments use these non-state armed actors to shape foreign conflicts whether as insurgents or counterinsurgents abroad? Are these non-state armed actors always useful to governments or perhaps even an indicator for state failure?
We examine the demand for and supply of pro-government armed groups and the legacies that shape their role in civil wars. The enduring pattern of collaboration between governments and these armed non-state actors challenges conventional theory and the idea of an evolutionary process of the modern state consolidating the means of violence. Research on these groups and their consequences began with case studies, and these continue to yield valuable insights. More recently, survey work and cross-national quantitative research contribute to our knowledge. This mix of methods is opening new lines of inquiry for research on insurgencies and the delivery of the core public good of effective security.
Regional Politics and Powers: Hierarchy and Comparative Regional Analysis in International Relations
Jon Patrick Rhamey, Jr. and Thomas J. Volgy
Comparative regionalism constitutes a new frontier of international relations analysis that provides a more focused theoretical lens for understanding the localized phenomena dominant in international politics. However, as is often the case with a relatively new area of academic inquiry, the subfield currently suffers from a number of challenges in conceptual agreement and operationalization conventions that have slowed progress. Having perhaps finally caught up with area specialists and researchers in the field of comparative politics in recognizing the relative importance of regional spaces, the question remains as to how to most effectively understand the extent regions—as either levels of analysis or units unto themselves—are substantively integral in generating the outcomes studied by international relations scholars. Following almost four decades of theorizing, future steps lie in clearer conceptual definitions followed by generating novel empirical findings that may complement, or contradict, existing international relations theories.
While some early attempts at engaging comparative regionalism exist prior to the Cold War’s conclusion, most theorizing begins at the point at which the region as a concept is able to emerge from the shadow of international relations research’s emphasis on the bipolar order of the American–Soviet rivalry. These early explorations, however, were frequently limited to either qualitative discussion of emerging trading behaviors and political institutions or, alternatively, the exploration of “non-Western” types of political engagement that challenged the traditional Anglo-European understanding of both international relations and the conduct of political science. Building on the backdrop of this conceptual theorizing, empirical work highlighting regional distinctions began to emerge as well. This renewed emphasis on comparing regional spaces is often undertaken from a small-N comparative methodological approach to identify similarities and differences between regions, with a very specific interest in developing an understanding for the causal variation behind how regional spaces’ trajectories develop and diverge.
Finally, one of the greatest theoretical challenges of comparative regionalism is the applicability of theories designed to understand the interactions of the entire international system (with primary focus on the major powers) to more localized spaces and conflicts. This is not to claim that politics necessarily follows different rules within different regions, but instead that because regional-local contexts are sufficiently unique, the combination of causal variables present may lead to very different outcomes for many phenomena of interest that scholars seek to understand. As regional importance has risen over the past 20 years, a clear set of criteria upon which theoretical development and empirical analysis can proceed is required in order to delineate the effects of regions on states and international politics.