The Causes and Consequences of Arms Races

This chapter reviews the literature on causes of arms races, their consequences, and when a state should build up arms and engage in an arms race if necessary. The literature tends to equate external causes with threats; the chapter argues for a broader understanding that includes all causes of rational arming behavior. Internal causes of arms races are then understood to be factors within the state that lead it to adopt suboptimal policies. Although the causes and consequences of arms races are usually dealt with separately, in fact they are closely connected. When a state engages in an arms race because this is its best option, the state is acting rationally, the causes of the arms race are external, and the arms race has no consequences of its own. In contrast, when a state arms because domestic interests have distorted its policy, the arms race produces negative consequences. Research on the consequences of arms races has been hindered by the lack of a fully developed theory of when a state shouldrace; progress on defensive realism is helping to fill this gap.