Multiparty Disputes and the Probability of War, 1816—1992

Previous theory and research have suggested that multiparty disputes might be significantly more likely to escalate to war than bilateral disputes, because of the difficulty of reaching a mutually acceptable agreement as the number of parties increases. This study presents a systematic test of this hypothesis. Efforts to provide such a test have been hampered by the absence of data that distinguish the number of participants in a militarized interstate dispute prior to the outbreak of war from the number of participants after the war breaks out. We find that multiparty disputes do have an increased probability to escalate to war. In addition, we find that the issue over which the disputants contend has an important effect on the probability that the dispute will escalate to war; multiparty disputes that are over territory have a higher probability of escalating to war than multiparty disputes in general. Lastly, it is found that the effects related to the number of parties in a dispute and to whether the dispute is over territory are independent, and one does not eliminate the effect of the other. In order to contribute to future scholarship on this topic, the data for the new classification scheme of multiparty disputes are published in the appendices.