Mutual Optimism and War, and the Strategic Tensions of the July Crisis

The forthcoming article “Mutual Optimism and War, and the Strategic Tensions of the July Crisis” by Alexandre Debs is summarized by the author below. 

Is mutual optimism a rationalist explanation for war?  

Leaders routinely express confidence in their odds of victory on the eve of battle. When Russia ordered the general mobilization of its troops during the July Crisis of 1914, a move which would certainly trigger a European war, both its French allies and its German enemies celebrated.  

It seems reasonable that if enemies are mutually optimistic, they may not find a peaceful compromise. But it is not clear how rational countries could be mutually optimistic in the first place. If a country attacks only when it receives a favorable signal about the balance of power, then a country’s enthusiasm for war should temper its enemy’s preference for conflict. It doesn’t seem possible for both countries to be optimistic about their odds of winning, while being aware of their enemy’s preference for war.  

Whether mutual optimism stands as a rationalist explanation for war has been hotly contested among International Relations scholars, with some of the seminal work published in the pages of the American Journal of Political Science (Fey and Ramsay 2007; Slantchev and Tarar 2011).  

I argue that a key solution to this strategic tension is to recognize that there are multiple reasons for a preference to attack: favorable information about the balance of power as well as a high resolve. A country may find it optimal to attack because it has a high resolve, even if it believes that it is unlikely to prevail. Because of these multiple motivations for an attack, countries cannot infer from their enemy’s eagerness to fight that they received favorable intelligence. Countries would also have reasons to discount their enemy’s public statements predicting a quick victory. Of the two reasons to fight, favorable information about the balance of power is politically more expedient, helping to preserve a leader’s honor and motivate troops. Countries may even celebrate the news of their enemy’s decision to attack, if it helps justify their own decision to attack. 

I present this logic in a game-theoretic model, and I argue that it captures important features of the July Crisis, shedding new light on the causes of the First World War. Russian officials arguably lacked confidence in their odds of victory, but they still preferred war due to their high resolve. German and French decisionmakers celebrated their enemy’s decision for war, convinced that it justified their offensive plans. 

In sum, mutual optimism does stand as a rationalist explanation for war, if we recognize the difficult inference problem that countries face when divining their enemy’s motivations. Looking ahead, there is great value in further investigating the complex strategic calculations that leaders make when choosing whether to go to war. When do leaders on opposite sides of a crisis both conclude that their enemy’s actions amount to a declaration of war, justifying their own aggressiveness? This is an important question for future research.  

About the Author: Alexandre Debs is Associate Professor, Department of Political Science at Yale University. Their research “Mutual Optimism and War, and the Strategic Tensions of the July Crisis” is now available in Early View and will appear in a forthcoming issue of the American Journal of Political Science.