Immediate and Permissive Causes of War in Waltz’s Theory

In his biggest publication, Man, the State and War, Political theorist Kenneth Waltz distinguishes between what he calls the immediate causes of war and the permissive causes of war. “War may result because state A has something that state B wants,” Waltz writes. “The efficient cause of the war is the desire of state B; the permissive cause is the fact that there is nothing to prevent state B from undertaking the risks of war.”¹ Waltz uses the words “efficient” and “immediate” interchangeably when describing this cause. The former refers to specific triggers that directly cause conflict, such as the desire for more territory. Immediate causes are what Waltz identifies as first and second image explanations. The first image is human nature, and the second is the internal organization of individual states.

On the other hand, the permissive cause of war is not about the impulses or institutions of individual states, but instead about the structure of the international system itself. This is the third image. According to Waltz, war is made possible by the international system of anarchy, which means a lack of overarching authority to restrain states or enforce peace.

This essay argues that the permissive cause, the structural condition of anarchy, is ultimately the most convincing explanation for war and competition between states. While domestic and individual-level factors can shape a state’s wartime strategies or influence whether it pursues conflict at a given moment, it is the absence of a higher authority in the international system that allows war to happen in the first place. Through an examination of the causes of World War II, nuclear competition during the Cold War, and the creation and failure of international organizations after World War II, the permissive cause consistently proves to be the most convincing explanation for continuous global insecurity.

Nuclear Deterrence and the Logic of the Anarchic System

One of the clearest demonstrations of how permissive causes shape the behavior of states is found in the nuclear competition that emerged during and after the Cold War. The deterrence that comes with nuclear weapons exemplifies the power of structural constraints in preventing war. In chapter 1, “More May Be Better,” in The Spread of Nuclear Weapons: A Debate Renewed, co-authored with Scott Sagan, Waltz argues that the spread of nuclear weapons promotes peace by reinforcing deterrence.² In a world where no centralized government exists to police aggression, nuclear weapons act as a substitute: their destructive potential imposes constraints on behavior by making the cost of war too high for states to risk engaging in it. In this sense, the threat of mutual destruction serves as a functional stand-in for a world government by punishing states through fear. This is only necessary because the system itself is anarchic: if a global authority existed with the power to enforce rules and mediate disputes, deterrence through mass destruction would not be required.

Organizational Failure or Structural Success? The Cuban Missile Crisis

Some scholars argue that immediate causes, mainly the internal structures of states, are the true drivers of war. Scott Sagan, arguing his side of the debate, emphasizes how domestic factors cannot be ignored when examining the causes of war. For example, Sagan cites the Cuban Missile Crisis as an example for his organizational theory, which claims that nuclear silos are controlled by branches of the state (the military, for example), and those branches are vulnerable to making mistakes. Therefore, the proliferation of nuclear weapons is extremely risky. The Soviet military intended to keep its missile deployment in Cuba secret, but the construction crews followed standard routines that left obvious signs for American intelligence officers: air defense missile batteries arranged in a “Star of David” pattern and missile pads marked with distinctive “slash marks.” These features allowed U.S. intelligence to quickly identify that the Soviets were behind the operation.³ Sagan uses this example to explain how the organizations that are tasked with deploying nuclear weapons make mistakes, and in the case of the Cuban Missile Crisis, it almost led to war.

Nevertheless, despite Sagan’s concerns, the most important takeaway from the crisis is that even in the face of mistakes, high tensions, and two states that did not trust each other, deterrence still prevailed. In fact, the Cuban Missile Crisis serves as proof of nuclear deterrence prevailing, and this has held strong to the present day. While accepting that relying on nuclear deterrence is fear-inducing for many, it currently serves as the next best option for stopping the spread of war, as the world remains anarchic. Therefore, the example of deterrence and debates surrounding nuclear proliferation put further emphasis on the importance of restructuring the international system in order to avoid war.

Appeasement as a Symptom of Structural Weakness

A second historical example that reinforces the importance of the permissive cause is the outbreak of World War II. At first glance, it might seem that domestic ideological factors or the personal ambitions of leaders like Adolf Hitler were the decisive drivers of conflict. These explanations have merit, but they cannot account for why aggressive states were able to expand unchecked for years before war broke out. The real explanation lies in the permissive cause: the anarchic nature of the international system and the absence of an effective authority to prevent aggression.

In a system with no worldwide government or no nuclear deterrence, states must assume the role of penalizing other states. One of the most powerful examples of this occurred not long after the First World War ended. After realizing that the League of Nations clearly held no power, the burden should’ve fallen on Britain, France, and the United States to balance the power and prevent German expansion. Instead, they appeased Hitler. A.J.P. Taylor’s interpretation in The Origins of the Second World War is particularly instructive here. Taylor argued that Hitler’s foreign policy was not a radical change from traditional German objectives, but was rather a rational reaction to power politics. In his view, the real failure lay with Britain and France, who failed to be effective balancers in the European system. Germany’s first big expansionist move was the reoccupation of the Rhineland in 1936, but this was met by no pushback. Two years later, British Prime Minister Neville Chamberlain ceded the Sudetenland territory of Czechoslovakia to Hitler, hoping to diffuse tensions after an invasion. By failing to challenge German expansion early on, they signaled that there would be no consequences for Germany for war-mongering. In Taylor’s words, “any guilt left over after Hitler had been condemned could be passed on to the French for failing to expel him from the Rhineland in 1936 or on to Chamberlain for flinching in September 1938.”⁴ Britain and France, as the only powers capable of checking Germany, were unwilling to act, leaving nobody to stop Hitler from taking over more and more territory. Appeasement was a flawed policy choice, but more importantly, it was a symptom of the underlying permissive cause: a system that depends on states to maintain the balance of power, but offers no guarantee that they will do so.

This reinforces the truth that large-scale war requires the permissive conditions of an anarchic system. Had Britain and France acted decisively to restore the balance of power, or had the League of Nations possessed real enforcement power, the chain of Hitler’s opportunistic expansions might have been broken before becoming a global conflict. Instead, the absence of any effective overarching authority allowed grievances, ambitions, and miscalculations to escalate unchecked, making World War II inevitable.

Attempts at Managing Anarchy: International Institutions After 1945

After World War II, the world seemed to recognize the dangers of an unregulated international system. In an effort to mitigate the risks of war, states formed institutions such as the United Nations and NATO. The United Nations was established in 1945, founded by 51 different states, hoping that the international organization would help to avoid a repeat of World War II. However, while the U.N. has made important contributions to humanitarian relief, it lacks the authority to prevent war. The United Nations Security Council includes five major members (the U.S., China, Russia, the U.K., and France), any one of which can veto whatever they want, meaning it’s extremely hard for the U.N. to penalize warmongering states. Additionally, the U.N. is resource-dependent on its member states, meaning, at times, the very states it would need to constrain.

A second international organization that was established after the end of World War II was the North Atlantic Treaty Organization, created in 1949. NATO wasn’t founded to be a world government, as would be needed to abolish the anarchical system, but instead was made to be a strong treaty and powerful counter to the Soviet Union. It’s noteworthy that current-day Russia has shown no hesitancy to invade Ukraine, a state that is not a part of NATO. As pointed out by Stacie Goddard in “The Outsiders: How the International System Can Still Check Russia and China,” Moscow has not, and likely will not, attack any NATO members, as that would risk dragging in all thirty-two countries that make up the alliance.⁵

The existence of these organizations shows that states are beginning to acknowledge the importance of the third image. However, Goddard explains how these institutions have struggled to fulfill their peacekeeping missions. In part, this is because the United States and its allies have used these institutions not as neutral frameworks for cooperation, but as instruments for promoting liberalization, particularly concerning China and Russia: “U.S. officials turned to multilateral institutions to deal with these incipient threats. These policymakers believed that membership in liberal institutions would make China and Russia more liberal themselves and thus less inclined to buck the existing international order.”⁶ This is not the correct way to utilize these institutions, as Goddard herself later in her piece explains how international institutions “are a tool to manage power politics.”⁷ Where the United States has gotten it wrong is trying to use these institutions to change the domestic politics of states that they’re uncomfortable with. Essentially, they’ve been attempting to stop the “immediate causes of war” by hoping to tame states that pose ideological challenges to liberal states. But all this has done is exacerbate conflict, not diffuse it. Great powers have been unwilling to conform to the United States’ expectations for how they should govern themselves.

Still, the very effort to build such institutions is revealing. States are beginning to understand that war will persist so long as states operate in an environment with no legitimate central authority. The failure of international organizations is not proof that permissive causes are irrelevant, but rather that attempts to overcome anarchy remain incomplete. Until the system itself changes, wars will remain possible, regardless of the motives or restraint of individual states.

If the permissive cause is the most convincing explanation for war, then the key to reducing conflict lies not only in addressing the motives of individual states, but in altering or mitigating the conditions that make war possible.

So, What are Possible Solutions?

First, giving real power to collective security mechanisms is essential. The failures of the League of Nations and the partial successes of the United Nations demonstrate that institutions can shape state behavior, but only if they possess both legitimacy and enforcement capacity. On the other hand, the alliance of NATO has proven a strong partnership between nations, deterring Russia from advancing into territory outside of Ukraine. However, it lacks the scope that would be needed to overhaul the international state system completely. The focus must shift from creating international organizations that rely on purely voluntary commitments to creating international organizations that have the means to successfully penalize aggressors. Additionally, policymakers should recognize the limits of ideological transformation as a strategy. As Goddard notes, using international organizations primarily as tools to liberalize other states can weaken their possible use as structures for managing conflicts. In a permissive system, the priority should be preventing escalation and managing competition, not expecting to change the ideology and domestic policy of other states.

Secondly, the balance of power paired with nuclear deterrence is the most powerful current constraint on war. As Taylor’s account of World War II suggests, when capable states fail to act as balancers, revisionist powers will exploit the opportunity. Waltz’s argument shows that in the absence of a world government, the threat of catastrophic retaliation can stabilize rivalries. Yet deterrence is only effective if communication is clear, command-and-control systems are secure, and proliferation is contained to avoid increasing the risk of miscalculation.

In short, the constantly lingering permissive cause of war has forced states to compensate for the absence of a world government by finding other ways to constrain aggressive states. As states attempt to work towards the elimination of anarchy, these other measures are the best that the world can do. However, it’s necessary to recognize that organizations such as the United Nations and NATO are important first steps towards a more successful force that can ultimately reduce, if not eliminate, the threat of going to war.

Therefore, the natural next step for policymakers to take is building on the concepts of the United Nations and NATO to supersede the current anarchic system. NATO offers the best blueprint for this, as it’s shown to have real power and the ability to counterbalance states that present a threat to NATO members. Creating a “Worldwide NATO” may seem like an impossible task, and it certainly would require overcoming tremendous complexities and challenges. But it may be the only way towards a world where the threat of war is an afterthought.

References

Kenneth N. Waltz, Man, the state, and war: a theoretical analysis, New York: Columbia University Press, 2001, 201. ↩︎
Kenneth N. Waltz, The Spread of Nuclear Weapons: A Debate Renewed, (2nd ed.) New York: W.W. Norton, 2002, 45. ↩︎
Scott Sagan, The Spread of Nuclear Weapons: A Debate Renewed, (2nd ed.) New York: W.W. Norton, 2002, 67-8. ↩︎
A. J. P. Taylor,The Origins of the Second World War. London: Hamilton, 1961, 11. ↩︎
Stacie Goddard, “The Outsiders: How the International System Can Still Check China and Russia,” Foreign Affairs (New York, N.Y.), Council on Foreign Relations, Inc, 2022, 37. ↩︎
Goddard, “The Outsiders,” 31. ↩︎
Goddard, “The Outsiders,” 37. ↩︎

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