1
Introduction
Is war the rational and well-calculated pursuit of states, or are decisions for war more
often dominated by miscalculation and misperception? This is an important question because
assumptions about the extent of rationality of nations heading into war underlie policy debates on
a range of subjects from deterrence and missile defense to peacekeeping. Deterrence uses arms,
alliances, and deployments to shift the costs and benefits of war away from combat. Those who
argue that deterrence works assume that decisions to initiate war are rational and deliberate. On
the other hand, arguments for greater transparency, for arms control, and against militarism and
hypernationalism often assume that war is rooted in miscalculation and misperception. In this
view, opacity, arms races and spirals, and malignant sources of misperception may cause
unnecessary or inadvertent wars. Supporters of U.S. missile defenses often argue that ‘rogue’
states are irrational and not deterrable. Opponents of missile defense counter that ‘states of
concern’ are deterrable. Light peacekeeping assumes that combatants do not really want to fight,
and that peace can be kept once miscalculations and misperceptions are sorted out. Yet if the
combatants have good reasons for fighting, peacekeeping must be heavy or avoided altogether
(Betts 1994). Successful prescriptions for reducing the likelihood of war depend on accurate
diagnoses of the causes of war. These diagnoses in turn often rely on assumptions about the
prevalence of rationality and the quality of deliberation in the lead up to war.
Differing assumptions about rationality constitute a huge and largely implicit debate in
the causes of war literature. Most offensive and neo-realists, rational choice analysts, and
materialists argue that war tends to be rational and deliberate. In contrast, some defensive
Convention