Analyzing the Causes of War: Theoretical Perspectives

Few questions in political science have occupied scholars as persistently as this one: why do states go to war? Conflict has shadowed human civilisation across every era, every continent, and every form of government. Yet the reasons behind any single war are rarely simple. A war may erupt from a leader’s ambition, a country’s internal politics, an economic struggle for resources, or the basic insecurity that comes from living in a world without a central authority. To make sense of this complexity, theorists have developed structured frameworks that sort the causes of war into distinct levels. This post examines those theoretical perspectives, helping you understand not just why wars happen, but how scholars think about the question itself.

The levels of analysis framework 🔗

The most influential way of organising the causes of war comes from Kenneth Waltz, whose 1959 book Man, the State, and War classified theories of the causes of war into three categories. Waltz called these categories “images,” and each one locates the root cause of war at a different level: within the individual human being, within the internal structure of states, or within the international system as a whole.

Waltz himself never used the phrase “levels of analysis.” That term came later, largely through the political scientist J. David Singer, who suggested that Waltz had identified different levels at which world politics could be analysed. Singer’s key insight was that the level you choose to examine shapes the conclusions you reach. Looking at the same war, an analyst focused on individuals might blame a reckless leader, while one focused on the system might point to a shift in the balance of power. Both can be correct because they are answering slightly different questions.

It is worth being precise about what Waltz actually asked. According to one careful reading of his work, his three images were not about what causes war so much as where the major causes of war are to be found. This is a subtle but important distinction. Waltz was building a map of where to look, not a single definitive explanation. With that map in hand, we can examine each level in turn.

System-level analysis: the structure of world politics 🔗

The system level, which Waltz called the third image, locates the cause of war in the structure of the international system itself. The central feature of this structure is anarchy. In international relations, anarchy does not mean chaos or disorder. It refers to the absence of a sovereign authority above states. There is no world government, no global police force, and no higher power that can reliably stop one country from attacking another.

This single structural fact has enormous consequences. Because no one guarantees their safety, states must provide for their own security. Waltz argued that the anarchic structure of the international system is the root cause of war. Wars do not require evil leaders or aggressive nations to break out; the permissive conditions of anarchy are enough to make war a recurring possibility. This is why the third image is so central to realist thinking, and why it later shaped the school known as neorealism.

The security dilemma 🔗

One of the most powerful ideas to emerge from system-level analysis is the security dilemma, developed in its modern form by Robert Jervis. The logic is tragic. When one state builds up its military to feel safer, neighbouring states cannot be certain whether those weapons are defensive or offensive. They respond by arming themselves, which in turn makes the first state feel less secure. The result is an arms race that no one truly wanted.

The security dilemma is structural in origin, rooted in states’ uncertainty and fears about each other’s present and future intentions. What makes it so unsettling is that war can result from purely defensive actions, with no aggressor required. However, scholars are careful to note that the security dilemma can cause war but is not the cause of all wars. The Second World War, fought against a genuinely expansionist Nazi Germany, is often cited as a case where there was no real dilemma at all, since one side was clearly bent on conquest.

Power, alliances, and the balance of power 🔗

System-level analysis also examines how the distribution of power shapes state behaviour. When power shifts dramatically between major states, the risk of conflict tends to rise. Some theorists argue that a balance of power keeps the peace, while others contend that clear dominance by a single state does so. These debates run through much of modern strategic studies. The Cold War rivalry between the United States and the Soviet Union is frequently read as a system-level story, where two superpowers competed for security and influence within an anarchic order rather than because either nation was inherently warlike.

State-level analysis: the character of nations 🔗

The state level, Waltz’s second image, shifts the focus inward. Here the argument is that the domestic makeup of states causes wars. Two countries facing identical international pressures may behave very differently because of their internal structures. The type of government, the strength of nationalism, the influence of the military, and the health of the economy can all push a state towards or away from conflict.

Government type and democratic peace theory 🔗

One of the most studied ideas at this level is democratic peace theory, which holds that democracies rarely if ever go to war with one another. Explanations vary, but most accounts focus on domestic political institutions, domestic political norms, and constructed identities. The reasoning is that democratic leaders face elections and public scrutiny, which raise the political costs of starting a war, while shared liberal norms encourage democracies to resolve disputes peacefully among themselves.

The evidence here is nuanced. The finding that democracies do not fight each other is strong at the level of pairs of states, but the broader claim that democracies are generally more peaceful than other states is far weaker. This distinction matters for any student evaluating the theory, because it shows how the same data can support a narrow conclusion while undermining a sweeping one.

Diversionary war and domestic distraction 🔗

A darker state-level theory is the idea of diversionary war, sometimes called the “rally round the flag” effect. The argument is that leaders facing trouble at home, such as an economic crisis or sagging popularity, may start or escalate conflicts abroad to unite the public and distract from domestic problems. A leader may have an incentive to divert attention from domestic economic problems by becoming involved in military conflict abroad.

Interestingly, the empirical support for this theory is less robust than its intuitive appeal would suggest. Scholars continue to debate which kinds of leaders are most likely to use this strategy. Some argue democratic leaders avoid it because they anticipate higher political costs, while authoritarian leaders who expect fewer consequences may have more incentive to externalise domestic conflict. This reminds us that an explanation can feel compelling and still struggle to hold up under careful testing.

Individual-level analysis: human nature and leadership 🔗

The individual level, Waltz’s first image, finds the cause of war within human beings themselves. This can mean human nature in general or the specific personalities and decisions of particular leaders. At this level, international politics is driven primarily by the actions of individuals or the outcomes of psychological forces.

Human nature and leadership 🔗

The oldest version of this argument holds that humans are inherently aggressive or power-seeking, and that war is therefore a permanent feature of human affairs. A related but narrower view focuses on individual leaders. Waltz pointed to figures like Napoleon, and the example of Adolf Hitler is often used to show how one person’s ambitions and ideology can drive a nation into catastrophic war. When we say a war was caused by a particular tyrant’s recklessness, we are reasoning at the individual level.

Misperception and the psychology of decision-making 🔗

Modern individual-level analysis goes beyond blaming leaders and examines how the human mind processes information under pressure. Robert Jervis showed that misperception, rooted in psychological factors, errors of judgment, and other systematic mistakes, can push states towards conflict. Leaders often misread the intentions of their rivals, overestimate threats, or convince themselves that a risky policy is both necessary and certain to succeed.

This psychological dimension links back to the security dilemma. When two sides each misread the other’s defensive moves as aggression, they can spiral into a confrontation that neither side intended. The build-up to the First World War is often described as exactly this kind of spiral, where mutual suspicion and miscalculation outran any deliberate plan for war. Psychology, in other words, can turn a manageable rivalry into an uncontrollable one.

Economic explanations of war 🔗

Cutting across the three levels is a body of theory that places economics at the centre of war’s causes. The most famous version is the theory of imperialism, associated with the British economist J. A. Hobson and later developed by Vladimir Lenin. Hobson argued that imperialism was linked to the growth of monopoly capital and a subsequent underconsumption crisis. In his view, wealth concentrated in too few hands at home, so capitalists looked abroad for new markets and investments, drawing their nations into colonial competition and conflict.

Lenin pushed this argument towards revolutionary conclusions. For him, war was not an accident but a structural feature of advanced capitalism. As Waltz noted when discussing the second image, Lenin’s theory of imperialism argued that the main cause of war lay in the need for capitalist states to continue opening up new markets to perpetuate their economic system at home. In this Marxist framework, inter-imperialist wars were essentially struggles to redraw the terms of global economic exploitation. Whether or not one accepts the conclusions, these theories usefully remind us that the competition for resources and markets has been a persistent driver of conflict throughout history.

Why the levels matter together 🔗

It would be a mistake to treat the three levels as rival theories where only one can be correct. Waltz himself did not see them this way. He assessed the first two images as generally less influential than the third, yet ultimately necessary for a full understanding of war. The system level, in his view, describes the framework of world politics, while the individual and state levels determine the specific policies a state actually adopts within that framework.A complete explanation of any real war usually draws on all three. Consider how the levels combine. The anarchic system creates the permanent possibility of war. A state’s internal politics and economy shape whether it is inclined to fight. And the perceptions, fears, and ambitions of individual leaders determine the moment a crisis tips into open conflict. This is precisely why wars are so difficult to predict and prevent, and why they keep recurring despite humanity’s repeated vows to end them. Each level captures something real, and ignoring any one of them leaves the picture incomplete.

For students of peace and conflict studies, the value of this framework is not that it hands you a single answer. Its value is that it gives you a disciplined way to ask better questions. When you encounter a war, you can interrogate it at every level: What was the structure of power around it? What was happening inside the states involved? Who were the decision-makers, and what did they believe? Working through these questions is the first step towards understanding conflict well enough to imagine how it might be avoided.

What do you think? If you had to explain a recent international conflict, which level of analysis would you reach for first, and why? And do you believe wars are ultimately a product of flawed systems, flawed states, or flawed individuals?

References

1. https://en.wikipedia.org/wiki/Man,_the_State,_and_War
2. https://wwnorton.com/college/polisci/lenses/protect/print/main_intro.htm
3. https://ir101.co.uk/wp-content/uploads/2018/11/Suganami-Understanding-Man-The-State-and-War.pdf
4. https://www.tandfonline.com/doi/full/10.1080/09636410903133050
5. https://politicalscienceblog.com/3-levels-of-analysis-in-international-relations/
6. https://www.researchgate.net/publication/344789255_Democratic_Peace_Theory
7. https://academic.oup.com/isq/article/50/4/755/1838527
8. https://www.nber.org/system/files/working_papers/w31681/w31681.pdf
9. https://en.wikipedia.org/wiki/Theories_of_imperialism