WAR EXPANSION AND WAR OUTCOME

Most wars do not expand beyond the initial two participants. Why is th is so? We argue that wars remain small because initiators select as ta rgets states that they believe will not receive third-party help and t hat they can defeat without such help. Drawing on the idea of selectio n effect, a model of this choice is presented and a hypothesis is deri ved in which initiators (1) will win most often in wars of one against one and (2) will win least often when the target receives any help. T his hypothesis is tested against war outcomes for initiators and targe ts in the period 1816-1975 using probit regression. The expectation is supported. The authors conclude that initiators act as predators and are likely to attack target states they know they can defeat if these targets are not joined by coalition partners. This selection pattern t ends to make small wars likely.