Sam Seitz

With the 100th anniversary of the Battle of the Somme and the 240th anniversary of the outbreak of the Revolutionary War occurring this week, I figured I would write about war. Specifically, I want to consider the reasons that wars break out. As Dale Copeland summarizes, “The central puzzle is why states fight wars when any ex post outcome—the terms of a peace agreement—comes at the cost of fighting the war. Short of wars of annihilation, rational leaders should bargain to reach an outcome that avoids the cost of fighting the war.” In other words, one side always wins, one side always loses, and the costs are usually astronomical. Why, then, do the two sides not simply negotiate a settlement and avoid the unnecessary bloodshed? For example, why didn’t France just immediately sue for peace during the Franco-Prussian War, give up Alsace-Lorraine, and avoid the embarrassment of being thoroughly dismantled by Germany (a result, by the way, that I hope is repeated on Thursday when Die Mannschaft plays France in the European semifinals)? In short, it comes down to two things: credible commitments and incomplete information.


Credible Commitments – The credible commitment problem emerges when states are unable to ensure that their enemies will not renege on certain agreements, thus necessitating the use of force as a means of ensuring compliance. Consider, for example, the issue of Iranian nuclearization. Currently, a diplomatic treaty (JCPOA) regulates and constrains Iran’s ability to acquire nuclear weapons. However, Iran still has incentives to seek a nuclear deterrent, thus making their commitment to nonproliferation lack complete credibility. There are ways of ameliorating this problem – intrusive monitoring, creating incentives to comply, etc. – but ultimately it’s impossible to guarantee with 100% certainty that Iran won’t renege. If Iran does decide to acquire nuclear weapons, then, the U.S. may be forced to resort to violence in order to secure its policy goals.

Incomplete Information – States have an interest in hiding certain information. For example, the U.S. does not reveal exactly where its SSBNs are located or what technologies DARPA is researching because revealing those capabilities would allow adversaries to develop counters. However, by keeping certain strategies and capabilities concealed, it becomes harder for adversaries to accurately assess the strength and resolve of the United States. This is true not just of the U.S. Every country faces the problem of trying to balance its need to reveal enough information to prevent miscalculations with its need to ensure that important military technologies and secrets aren’t compromised. When states are too opaque, and adversaries evaluate their capabilities inaccurately, war can occur. For example, Britain was ambiguous about its commitments during the lead up to World War I, causing Kaiser Wilhelm to erroneously believe that the U.K. might actually fight on the side of Germany. The problem of incomplete information reared its head again during the Second Gulf War, causing the Bush administration to think that Iraq was developing WMDs and triggering an unnecessary war. Incomplete information is particularly dangerous because it can lead to false optimism, a situation in which “At least one side, and all too often both, commonly expects to fare better from war than it actually does.” If one or both sides think a war will be easy to wage and relatively cheap, they will be incentivized to fight instead of compromise.

Of course, wars can also occur because leaders are insane and irrational, fighting even when it is not in their best interest. For example, Hitler’s questionable strategic choices during World War II suggest that his aggressive expansion was driven not by careful calculation but instead by lunacy. Nonetheless, most political scholars argue that it is best to assume that leaders are largely rational for two reasons. One, most leaders are relatively somber individuals who try to make informed, reasoned decisions. Even if they occasionally act in irrational ways, the nature of the international system forces them to revert to rationality or face severe consequences. Second, if every state and national leader is truly irrational, the whole field of political science is useless because it’s impossible to derive predictable and universal theories from incoherent and nonsensical actions.

Ultimately, it’s impossible to know exactly when wars will happen. While one can say that certain actions and conditions make war more likely, each war is triggered by a unique spark that is impossible to foresee in advance. Understanding why events as costly and ruinous as wars occur is interesting for academic reasons, of course. But it is also important because by understanding what causes wars, we can work to prevent them.