This book explores some implications of studying international relations from a systemic perspective. This chapter takes on the preliminary tasks of defining systems, identifying distinctive characteristics of systemic explanations, and situating systems approaches in a broader context of relational framings. A system is a bounded set of components of particular types, arranged in definite ways, operating in a specific fashion to produce characteristic outcomes, some of which are emergent. The arrangement and operation of the components produce “emergent” “systems effects;” properties and outcomes that cannot be fully understood through knowledge of the parts considered separately. I emphasize the relational character of systemic explanations and their reliance on mechanisms and processes, in order to foster developing a relational processual systemic perspective within a pluralistic IR.

Multilevel multicomponent complex adaptive systems are not reducible to the sum of the causal effects of independent variables. Causal inference, which has a privileged place in contemporary IR (and many other social sciences) cannot address systems effects, which arise from interdependent elements and operations (not the impact of independent variables on dependent variables). Systems effects explanations explain why by showing how. They identify mechanisms and processes of causation. They thus are able to establish causal efficacy; that is, show how processes produce – actually cause – outcomes (rather than merely identify some elements that are part of an unspecified causal process). Such an understanding leads us away from a “laws and theories” conception of science, which remains popular in Physics and Chemistry, towards a “models and mechanisms” understanding, which predominates in the life sciences (which, on their face, seem a much better model for the social sciences).