The Complexity of Interdependence

“Interdependence” has long been a cardinal element in theoretical analyses of international politics, but its utility has been hampered by disagreements over both the meaning of the term and its links to changes in state behavior. This article provides a general framework for resolving those debates by using a game-theoretic analysis developed by Kelley and Thibaut. Their work demonstrates that past calls for choosing between the concepts of vulnerability and sensitivity are misplaced. The first measures dependence, the second interdependence. Only by using both—and by combining them with a third measure, independence—can we fully model the interactions of states in international politics. With such a complete model we can then begin to understand why some seemingly baneful issues in international politics (such as Mutual Assured Destruction) can still lead to cooperative outcomes, while some apparently benign issues (such as free trade) often lead to conflict. Finally, the article offers some preliminary propositions on the connection between interdependence and cooperation, tying those propositions to the measures of interdependence developed by earlier analysts.