Abstract
This paper studies social conflicts where both groups that engage in appropriative activities and groups that are passive in this respect participate. The introduction of passive groups results in two onmonotonicities with respect to the effectiveness of appropriative activities. The first relates to the share of their resources that active groups allocate to appropriative activities when they cooperate with each other. The second concerns the payoffs of active groups when they are unable to cooperate. We show that these results hold under different methods of cooperation and different types of behavior of passive groups in response to appropriative activities. We also offer an explanation as to why passive groups remain passive.