Group identification, uncertainty, and the duration of genocide and politicide

Episodes of genocide and politicide show remarkable variation in how long they last. Some end within months; others continue for decades. Why do some persist while others end soon after they start? I argue that uncertainty influences the duration of killing. When a government has difficulty identifying members of a target group, it is less certain that it has accomplished its violent goals vis-à-vis the group. Therefore, the more uncertain the government is about the source of the threat it faces, the longer its killing will last. Statistical analysis of all episodes of genocide and politicide from 1955 to 2011 supports these claims.