Review: Rationalist Explanations For War

Published: 2023-10-01

Author: James D. Fearon
International Organization Volume 49, Issue 3, Summer 1995 pp. 379-414
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One of the core mysteries of neorealist international relations (IR) is the question of war. Namely: why do states persist in engaging in armed conflict? Is it merely a matter of irrationality, or bounded rationality on the part of leaders? Or is there a positive logic that compels states to go to war? If such a logic exists, under what conditions is the bloodshed and expense of armed conflict a preferable outcome to a negotiated settlement? This is the question that James Fearon attempts to answer in "Rationalist Explanations For War".

Fearon begins by noting that existing IR literature is strangely silent on the topic of whether it is ever rational for states to choose to go to war. War is held to be the natural consequence of international relations occurring in a state of anarchy, where there is no supranational authority capable of wielding force in order to deter states from engaging in war to settle disputes. Wars, then, are merely a Pareto-efficient outcome that occurs whenever there is no negotiated conflict that either side would prefer to the gamble of armed conflict.

However, this explanation is incomplete. Wars impose enormous costs on both participants, and result in one side winning, and the other side losing. How is it possible that both parties to an armed conflict, expect, ex-ante, a positive expected value? And given that wars impose enormous deadweight losses, even on the victorious party, shouldn't both parties prefer a negotiated outcome that gives them a significant fraction of what they want, without war? A true explanation for the occurrence of war needs to not just show that war can be allowed. It must show that war can be wanted.

Here, existing IR literature tends to throw up its hands. Wars are held to be the result of incomplete information or bounded rationality on the part of leaders. Nobody truly wants war. Instead it is the result of miscalculation caused by incomplete information, leaders' limited reasoning abilities, or domestic factors that are not captured by the unitary rational calculating actor model of states used by neorealist IR.

Fearon doesn't accept this argument, and in this paper, he comes up with three main findings

First Fearon shows that wars are never Pareto efficient, or, equivalently, there will always exist a bargain that will be preferable to war. He shows that given two states, \(A\) and \(B\), negotiating over a set of outcomes from \([0, 1]\), with costs of war \(c_A\) and \(c_B\) respectively and a probability of victory for \(A\), \(p\), there will always exist an interval, \(p - c_A, p + c_B\) that will have higher expected value for both A and B than going to war.

If there is always a bargain that states would prefer to war, why would a perfectly rational unitary state ever choose to go to war? One possibility is that issues don't divide up neatly over a continuous interval from 0 to 1. Fearon acknowledges this, but dismisses it out of hand. While it is true that outcomes in international relations are often discrete, there is nothing preventing states from linking multiple outcomes together into a single "basket" order to approximate a continuous interval. If nothing else, they ought to be able to use cash as the counterweight, with \(A\) offering a monetary payment in order to induce \(B\) to accept its terms without fighting.

Even if a particular outcome is truly discrete (such as the question of which person occupies a given monarchy), perfectly rational unitary states can use rotations or lottery systems to create equitable outcomes without resorting to war. Fearon cites an example of mafia bosses allocating contracts by lot among themselves and their allied business interests as an example of state-like entities using probabilistic processes to equitably allocate discrete outcomes.

In Fearon's opinion, a more significant causes of inter-state armed conflict is informational asymmetries. States have more information about themselves than their adversaries, and thus might overestimate their military power relative to a given opponent. While strictly rational leaders would understand that their counterpart would also have access to private information, they are not incentivized to engage in an exchange of information to resolve their uncertainties about their relative strengths, as doing so would undermine their own bargaining positions. Similarly, even if they have a certainty about each others military capabilities, leaders may misrepresent their willingness to commit to costly conflict in order to improve their bargaining position. These incentives to misrepresent lead states to come up with differing probabilities of victory or estimates of war costs, which narrows the visible range of mutually beneficial negotiated outcomes. In extremis, the range of mutually beneficial outcomes is concealed entirely, and even perfectly rational leaders can be led to believe that war has greater expected utility than any negotiated settlement.

Another cause of conflict among perfectly rational unitary states is the lack of enforcement mechanisms in an anarchic international system. In other words, the fact that there is no "world police" means that the threat of war is the only thing that prevents states from reneging on agreements that they have agreed to with other states. Even if both sides have resolved information asymmetries at a particular portion in time, changing levels of military strength and willingness to commit to armed conflict can create incentives for a rising power, e.g. \(A\), to present the other with a fait accompli that resolves a particular issue completely in favor of the presenting side. In order to the prevent this, a declining power, e.g. \(B\), has an incentive to engage in preemptive war. The international state of anarchy presents no mechanisms by which \(A\) can bind its future self, so \(B\) has strong incentives to intervene in the present in order to secure its advantages. One important thing to note here is that unlike in traditional conceptions of conflict between rising and declining powers, it's possible here for states to come into conflict even when neither side is afraid of a direct attack from the other. The source of the conflict isn't that \(A\) might directly threaten \(B\)'s territory. Instead conflict comes from \(B\) concern that it might be forced to accept a disadvantageous bargain in the future, when \(A\) is more powerful.

Thus Fearon has shown that even in the most abstract case, where states have perfect information about themselves, zero transaction costs, and are led by leaders possessing unbounded rationality, circumstances can still lead to war. But what significance does this have for the real world, where rationality is bounded, transaction costs can be enormous, and states are embodied not as single leaders but a vast plethora of factions, all of whom have imperfect information about each other?

The most important lesson from Fearon's paper is that, even under ideal circumstances, war is sometimes unavoidable. While there is always an outcome that would result in lower expected costs to both sides than armed conflict, this outcome isn't always perceptible to the participants. Both of these facts should be taken into account by state leaders. When another state appears to be irrationally intransigent, it might be due to the fact that they're fearing that accepting a bargain now would reduce their ability to bargain for future concessions in the future.

Another lesson from the paper is that more work should be done to make issues divisible. One of the reasons that Fearon discounts indivisibility of issues as a potential cause in his theoretical framework is that wars are often started for territory, and, in theory, territory can be split up. If \(A\) wants to extend their border by 5 kilometers, but \(B\) wants the border to stay where it is, then, in theory, there is a settlement where \(A\) and \(B\) can agree on a compromise border, in exchange for an exchange of cash payment or other compensatory measures.

In the real world, however, national borders have increasingly been viewed as inviolable, making finding such compromises difficult. Even in cases where borders aren't agreed upon by both parties, such as the border between India and Pakistan, India and China, North and South Korea, or Armenia and Azerbaijan, states view lines of control, armistice lines, etc. as de facto borders, and become loath to accept changes. While a return to the "Great Game" era of international geopolitics, where borders were seen as the playthings of various (British, French, Russian, etc) imperial powers is undesirable, I think there is a case to be made that national borders today have become too fixed and rigid, and there should be more negotiation regarding territorial boundaries and concessions between nation-states.

In this framework the primary utility of supra-national entities, such as the European Union, is the prevention of war through the provision of mechanisms by which states can bind their future actions. The loss of sovereignty thus entailed is a positive feature of the system, not a limitation, as it enables states to make credible commitments in negotiations with other states. The much decried demilitarization of Europe, exposed by the current conflict in Ukraine, serves a similar purpose. By ensuring that their military capabilities do not grow to the point where they can win easy victories over other European nations, France and (more importantly) Germany allow themselves to be viewed as equal participants in a system that resolves international disputes through coordination and negotiation rather than war.

The problem with the EU system as it stands is that it suffers from a free-rider problem. Every nation has incentives to reduce its military strength in order to participate in the EU. But if all nations reduce their military forces to negligible amounts, the EU as whole will be vulnerable to external pressure. Currently this contradiction is resolved by the EU's collective reliance on the United States as a global security guarantor. The US is, from the perspective of the EU, a disinterested third party which will ensure that contract disputes among EU nations do not rise to the level of military violence. In addition, the membership of the majority of EU nations in NATO safeguards the EU against external threats, underwritten once again by the United States.

EU member states are attempting to solve this problem by investing in their own armies. This risks undermining the EU itself, as any nation whose military grows strong enough to resist the coercive pressure of other nations grows strong enough to undermine its future commitments. The solution is for the EU itself to have a pan-European military force, devoted to securing its borders and enforcing contractual agreements among its members. Unfortunately, this is viewed as an unacceptable loss of sovereignty. This interlocking set of contradicting priorities ensures that, for the foreseeable future, the EU will continue to rely on the US as the ultimate provider of security.

While Fearon's analytical model for the causes of war seems powerful, it's important to keep in mind its limitations. The model treats states as unitary entities, ruled by all-powerful, highly rational leaders who treat various demands as commensurable claims that can be assigned values using a common currency. It assumes a level of calculation that is in little evidence when states actually make decisions to go to war. Nevertheless, as a theoretical framework, it is important, as it demonstrates that, even under idealized conditions, war is not just permitted, but can be actively desired.