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Part I
Contributions to the understanding of the causes of conflict![]()
1 Multiparty disputes and the probability of war, 1816–1992
Karen K. Petersen, John A. Vasquez, and Yijia Wang
Authors' note: Our thanks to anonymous referees for valuable comments. Research reported in this article has been supported in part by NSF Grant #SES-9818557 (John Vasquez and Paul Senese, principal investigators).
Introduction
Among the most important legacies of Stuart Bremer were his completion of the Militarized Interstate Dispute (MID2.1) data set and the theoretical and methodological changes he helped bring about in light of the possibilities created by these data. His work on MIDs resulted in two key shifts in the intellectual history of peace research. The first was the shift from systemic analyses of why war occurs to an emphasis on what distinguishes militarized disputes that escalate to war from those that do not. The second was the shift from the correlates of war to what factors increase the probability of war. Each of these shifts has made research within the field much more successful and cumulative than it was before Bremer's work.
A focus on the question, "What distinguishes MIDs that escalate to war from those that do not?" has been a new theoretical approach within international relations research, and it has given rise to a new research program centered on a particular way of conceptualizing how war arises. Much of the theoretical edifice for this approach was first laid out in Bremer and Cusack (1995), which sets out several stages or sequences that depict the various factors that might affect the process by which war emerges. The mere fact of looking at war as a process that emerges from the interaction of states was in itself somewhat revolutionary, given the systemic emphasis of the previous two decades. In this analysis, we examine the possible effect of multiple parties on the probability that an MID might escalate to war.
If we think about the factors that might distinguish MIDs that escalate to war from those that do not, we can see that there are four obvious sets of characteristics that should be examined: first, the attributes of the MID itself – e.g. the kind of issue under contention, such as territory; second, the characteristics of the actors in the disputes, e.g. whether they are neighbors or democracies; third, what these states actually do to each other, e.g. the nature of their bargaining and the history of their prior interactions; and lastly, the systemic context in which the MID occurs, e.g. whether the norms of the system are restrictive or permissive (see Raymond 2000).
Much of the research associated with the second set of variables has been framed in terms of dyadic analyses, and here again Bremer (1992) led the way by looking at the attributes that would distinguish the dangerous dyads from the ones that would be less likely to go to war or, in some cases, "never" or rarely go to war. Of course, some of the variables used in his analysis of dangerous dyads actually included factors that reflected behavior that states had previously taken and not just static attributes. These would include variables like whether states were allied to each other or militarized, and in Bremer (2000) whether they had a history of militarized confrontations.
The dyadic analyses brought about by Bremer's (1992) work have resulted in a major research design breakthrough for peace science in that they have produced a number of important findings, best illustrated by the work on the democratic peace, but also by the work on rivalry (Dielil and Goertz 2000) and on territorial disputes (Hensel 1996; Vasquez and Henehan 2001; Senese and Vasquez 2003). The extensive popularity of dyadic analyses, however, has diverted attention away from characteristics of MIDs that may increase the probability of war that are associated with the dispute itself and not the dyad. In particular, researchers have tended not to think about the various specific characteristics of disputes that might account for its escalation to war. Perhaps the variable that has been most forgotten by dyadic analyses is the number of actors involved in a dispute, i.e. whether an MID involves multiple parties. This is the subject of this study.
Previous research, particularly that of Cusack and Eberwein (1982) on a forerunner of the MID data, has found a significant relationship between multiparty disputes and the onset of war. Analyzing the relationship between multiparty disputes and the probability of war, however, is not easily done with the current MID data, primarily because no distinction has been made in the data as to whether the MID becomes multiparty before or after the onset of war.
In what is regarded by most as a seminal article in the scientific study of international conflict, Stuart Bremer commented on a data limitation that we correct herein. When laying out the research design for Dangerous Dyads he claimed:
If all wars began as one-on-one confrontations, then for each of the 56 interstate wars that began during the period under study there would be one dyad of original participants, but the historical record is not quite so simple. In 13 of the 56 qualifying wars, two or more states became involved in war with one or more other state on the very first day of the war. These may be instances of genuine collusion or very fast joining behavior (I favor the former interpretation), but unfortunately the available historical record does not allow us to distinguish reliably between the two.
(Bremer 1992: 320-321)
We do, in fact, believe that distinguishing between collusion and joining is both empirically important and feasible. In our discussion herein dealing with multiparty disputes, "collusion" refers to instances when three or more states are party to a dispute that leads to war, whereas "joining" refers to instances when two states go to war and are subsequently joined by one or more additional states.
Distinguishing between collusion and joining is important because previous studies have attempted to distinguish between bilateral and multiparty dispute escalation without explicitly discussing the distinction. Cusack and Eberwien (1982: 25) found evidence that the expansion of disputes makes war more likely and conclude that "the entrance of third parties into ongoing serious international disputes has been associated with the escalation of such disputes to war." Gochman and Mao2 (1984: 602) analyze Militarized Interstate Disputes (MIDs) from 1816 to 1976 and find that 22 percent of the multiparty disputes escalated to war, compared to 5 percent of the dyadic disputes. They posit several reasons for the war-proneness of multiparty disputes. First, they claim that the larger aggregate of capabilities makes the sustenance of full-scale conflict possible. Second, major states tend to intervene more, and major states have greater capacity to sustain hostilities. Finally, they claim that "the decision-making dynamics of multiparty disputes may make it difficult to control the escalatory potential of conflict spirals" (Gochman and Maoz 1984: 602). Likewise, Vasquez (1993: 190—193) argues that the size of a dispute affects its probability of war because it is more difficult to negotiate among several parties and that outcomes from multiparty disputes are more apt to leave one or more parties less satisfied than a bilateral negotiation would.
The crisis literature also addresses the issue of multiple participants. In his work on international crises, Brecher (1993: 151) finds that "the larger the number of parties in a bargaining sequence, the more difficult it is to attain a solution that will satisfy all concerned. Under such circumstances, there is reason to expect that one or more actors will resort to violence in the escalation phase." Brecher (1993: 245, 331) also finds that crises of short duration are more likely to involve only two participants and that crises with multiple actors are more intense and more likely to have a high impact. Additionally, Brecher and Wilkenfeld (1997: 858) find that crises with multiple actors are significantly more likely to experience intervention by global organizations than crises with only two actors. Likewise, James and Wilkenfeld (1984) find that crises that involve three or more parties tend to be longer because the bargaining dynamics are more complicated.
While the ICB crisis data is not directly comparable to the MID data, it is encouraging that the findings from the crisis data indicate that there is in fact a difference between bilateral and multiparty disputes/crises. However, within the MID data there is not an explicit distinction between original participants and joiners to the ensuing war (or collusion and joining). Given the existing coding rules, it is not possible to tell whether all the actors enter the MID before or after the MID escalates to war. Because joining and collusion are indistinguishable in the current MID data, it is not possible to make valid claims about the escalation of multiparty disputes. Since it is clear that a distinction should be made between bilateral and multiparty disputes, we posit that it is important that multiparty disputes be properly classified so as to be able to clearly and confidently state the effect that multiple participants have on escalation.
Theoretical rationale
The conflict literature contains some discussion of the difficulty of conflict resolution when multiple parties are involved in a dispute. Both Gochman and Mao2 (1984) and Brecher (1993) briefly address the issue of conflict resolution and how multiple participants might make resolution more difficult. Additionally, in her study of the impact of alliances on conflict behavior, Leeds (2003: 8) notes that "it is reasonable to assume that all else equal, increasing the number of parties that must be satisfied by a bargain to avoid war makes the negotiation of a successful settlement less likely, and war correspondingly more likely."1 Negotiations in situations of militarized conflict, whether mediated through a third party or resolved among the participants to the dispute, require consideration of the issues underlying the dispute in order to understand the nature of the escalation to, or termination short of, war.2 It then follows that the more participants, the less similarity of interests, and hence the lower the probability for a settlement depending on the issue at stake.
The inability to reach negotiated settlements inevitably leads to prolonged and protracted conflicts that produce more battle casualties and become "wars" under the Correlates of War ope...
