Hobbesian War and Separation of Powers

Abstract

If a political authority cannot commit to sparing anyone from domination, will everyone be attracted to fight over it? What institutions can help preempt such a risk? We analyze a dynamic game for a king’s council, where, in each period, each member can contest the kingship for its authority to persecute surviving council members, whereas any persecution is subject to the council’s approval by a voting rule, which measures the degree of such authority. Focusing on Markov perfect equilibria, we show that, compared with non-unanimity rules, only unanimity rule can preempt the risk of perpetual Hobbesian wars, in which every member would contest the kingship in each period. In two extensions, respectively, we show that, when persecution incurs little externality, unanimity rule and peace will be resilient only if, whenever the council decides on its voting rule, the king is prohibited from setting the agenda; when the externality is high and a judiciary is introduced to review persecution, peace can be secured under a non-unanimity rule, but only if sufficiently many justices are prohibited from joining the executive council in the future. Besides providing implications on other political-economic issues, these results help explain the shift in separation of powers in European history from between the executive and legislative branches to between the executive and judicial branches.