Whether economic interdependence is a cause of war or peace constitutes a central debate in international politics. Two major approaches advance diametrically opposed claims: liberal theory holds that interdependence between states promotes peace by increasing the costs of war; realist theory argues that interdependence is just another word for vulnerability, a condition that states may try to escape by seizing the resources and markets they need for self-sufficiency. Considerable evidence supports both of these claims. In Economic Interdependence and War , Dale Copeland proposes to resolve this stalemate by showing that interdependence promotes peace when states expect mutually beneficial trade to continue, but creates incentives for war when at least one of the states expects that trade trends will leave it dangerously vulnerable. Notwithstanding this book's major theoretical contributions and its impressive historical research, it leaves open several important questions about how to move forward with its agenda of theoretical development and testing.

One reason why Europe went to war in 1914 is that all of the continental great powers judged it a favorable moment for them to fight, and all were more pessimistic about postponing the fight until later. Not only is this historical paradox an interesting puzzle in its own right, but it sheds light on what is arguably the reigning theory of the causes of wars in general: James Fearon's rational bargaining theory. None of Fearon's three main mechanisms—private information, commitment problems, or indivisibility of stakes—can explain the paradox of the universal, simultaneous view of 1914 as a favorable year for war. Two mechanisms that play a marginal role in his analysis, however—bounded rationality in multidimensional power assessments and attempts to mitigate power shifts through coercive diplomacy—help to explain how Europe's powers became trapped in a choice between war now and war later. These mechanisms were set in motion by background strategic assumptions rooted in the culture of militarism and nationalism that perversely structured the options facing Europe's political leaders in 1914. Whereas Fearon's theory assumes that states are paying equal attention to all relevant information, in 1914 each power's strategic calculations produced disproportionate levels of self-absorption in its own domestic concerns and alliance anxieties.