Ph.d.-forsvar: Allan Anders Balsgaard:"Arms Races and War a game theoretic analysis

This thesis uses game theoretic analysis to study international relations and the behavior of states. The first part of the thesis consists of a dynamic arms race model where states decide whether to acquire a nuclear weapon or not. We derive an equilibrium in which the fear of being left behind in the arms race is counterbalanced by the fear of setting off an arms race. Surprisingly, we find that increasing the proportion of pacifistic states makes an arms race more likely. The model provides an explanation for the remarkable absence of nuclear proliferation in the post-war period.  The second part of the thesis explores the contradictions between a weaker state and its stronger ally. The states wish to counter a common threat to their security, however mutual mistrust makes it difficult for the weaker ally to rely on the stronger state for protection and the weaker ally may therefore decide to attack on its own. This compels the stronger ally to preempt in order to forestall the adverse effects of an uncoordinated attack. The model provides a theoretical mechanism for the power curse. The third part of the thesis asks whether better information makes war less likely. Using a three type ultimatum game, we show that this is not necessarily so.  Despite that complete information implies peace, better information does not always make war less likely.