He suggests studying the functions of political violence. In this way the issues of social structure will be incorporated in the conflict resolution process. With this definition he combines an instrumental concept of violence with structural perspectives. Tilly distinguishes between reactive and proactive violence. Reactive violence is a response to a threat to the established power system.
Proactive violence challenges the established power structure.
These types of violence belong to hierarchical social systems. In horizontal relations, groups engage in competitive collective actions. There is a reciprocal relation between social structures and their transformation, and collective violence. These concepts cannot be examined separately from each other. The problem-solving model often assumes conflict and its elements such as parties, issues and interests are static.