Bargaining Over Power: When Do Shifts in Power Lead to War?

37 Pages Posted: 13 Aug 2009 Last revised: 4 Sep 2009

See all articles by Thomas Chadefaux

Thomas Chadefaux

Trinity College Dublin, Department of Political Science

Date Written: 2009


Students of international relations have long argued that rapid shifts in relative power can lead to war. Fighting is rational, it is argued, when the declining state fears that the rising one will exploit its increased power once the shift has occurred. However, I demonstrate that this explanation is insufficient to explain war. Indeed, the rising state should be willing to alleviate the declining states concern by reducing its expected future power, such that a commitment problem never emerges. For example, states often limit their ability to launch preemptive attacks by withdrawing weapons (e.g., the Cuban missile crisis) or creating demilitarized zones; they abandon armament programs to avoid preventive wars (e.g., the Washington Naval Treaty); and they disarm to help bring about the trust necessary to end wars. By giving up today the attributes that will increase its power tomorrow, then, the rising state can credibly commit now to a future partition of the pie. Indeed, I show that war never occurs in equilibrium when countries can negotiate over the determinants of their power (their capabilities), no matter how fast relative power shifts. This result is robust to uncertainty about growth rates, and to any bargaining protocol in which war is an option. War occurs only when there are constraints on the players ability to change their relative power caused by: (i) indivisible or intangible capabilities and (ii) costs in relation to third parties.

Keywords: Bargaining, Negotiations, War, Capabilities, Power, Conflict, Fighting, Commitment Problems, Preventive Wars, Preemptive Wars, Stochastic Game, Markov Process, Markov Perfect Equilibrium, Disarmament, Shifts in Power, Growth Rate, Rationalist Explanations for War

Suggested Citation

Chadefaux, Thomas, Bargaining Over Power: When Do Shifts in Power Lead to War? (2009). APSA 2009 Toronto Meeting Paper, Available at SSRN:

Thomas Chadefaux (Contact Author)

Trinity College Dublin, Department of Political Science ( email )

College Green 2-3
Dublin 2


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