Asking who won a particular war is like asking who won the San Francisco earthquake. Such senseless destruction and indiscriminate violence make the question absurd. But how far can we stretch this analogy? Are wars also like earthquakes in the sense that their occurrence is unpredictable? Or is warfare a human activity, subject to social-scientific explanation?

Kenneth Waltz begins Man, the State, and War (1959) with this incredibly illuminating analogy. Just as seismologists study earthquakes, a student of international relations studies the causes of war. Unlike earthquakes, however, we hope that studying war will help us prolong peace. To achieve peace, we must first ask: what causes war? Waltz is not interested in what caused any particular war, but what causes war in general.

Asking what caused World War One is, to an extent, an empirical question. Asking what causes war in general is a theoretical one. Waltz is unashamed about his reliance on political theory. “The empirical approach, though necessary, is not sufficient. The correlation of events means nothing”, Waltz argues. Empiricism does not tell us about the interrelation between data points, nor which factors are most salient. Establishing any kind of causality requires interpretation. Good interpretation requires theoretical clarity. It is precisely this kind of clarity that Waltz feels is missing from international relations. Most explanations of war tend to rely on unarticulated assumptions about which factors to study, and why. Some theorists, in seeking to explain war, blame individuals, or human nature writ large. Waltz calls this “the first image”. Other theorists, recognising that humans are shaped by their social environment, explain war in reference to the political make up of states. Basically, certain kinds of states are more warlike than others. Waltz calls this the “second image”. Finally, a handful of theorists recognise that states are just like individuals, they too are shaped by their external environment. At the level of international politics, anarchy prevails. There is no structured, regulated environment between states. Each must ensure its own survival. Power politics is the lingua franca of international relations.

In case you hadn’t already guessed, Waltz favours the third image. This does not mean neglecting the first two images. Instead, they should be interpreted through the prism of the third image. Waltz thus inaugurates what has come to be known as “structural” or “neo” realism. To understand the causes of war, look first to the structure (or lack thereof) of international politics. Waltz’s reasons for emphasising the third image are subtle and theoretically nuanced. Stop here if you are content with knowing Waltz’s conclusion. Read on if you want to know how he got there.

The First Image

Humans have an innate capacity and natural proclivity towards violence. We are selfish, greedy, and power-hungry. Humanity in the state of nature wages a “war of all against all.” Life is “nasty, brutish, and short.” Thomas Hobbes, just quoted, provides the pithiest description of the first image. War is caused by flaws buried deep within human nature itself. We are the problem, war is merely a symptom of our inherent sickness. Preventing war requires, if possible, a reformation of the human condition. Hobbes, though the most famous proponent of this view today, is the inheritor of a long tradition blaming war on humanity’s fallen nature. Hobbes’ innovation was to secularise a deeply religious argument. Saint Augustine, writing in the fourth century, expressed profound scepticism that heaven could ever be realised on Earth. To be human is to be sinful. Humans sin not just to survive, but to experience the joys of sinning. We are fallen creatures, as expressed by the Christian idea of original sin.

What are we to make of these arguments? They clearly speak to a deep truth about the human condition. Everyone has felt tempted to sin. It is thrilling. But can this impulse really explain war? Waltz reminds us that “the search for causes is an attempt to account for differences.” War broke out in 1914, but there was peace in 1913. And yet human nature (by definition) was the same across both years. Herein lies the basic problem with first-image analysis: “the importance of human nature…is reduced by the fact that the same nature, however defined, has to explain an infinite variety of social events (Waltz, p.29). In explaining everything, it explains nothing. In any case, the first image must logically give way to the second. If human nature is irredeemably violent, we need strong political structures to contain it. If human nature is redeemable, social structures can help reform individuals. Either way, our attention is drawn towards the importance of politics.  

The Second Image

Only certain kinds of states – bad states – go to war. Ridding the world of war amounts to ridding the world of violent, warlike states. Ultimately, this amounts to a truism: bad states do bad things. But what kind of states are bad, and once identified, how do we get rid of them? Can we wage a war against war, as many liberals advocate? Paradoxically, this might have the effect of increasing, not decreasing, the incidence of war. This is the great dilemma faced by those who believe that war is a problem caused by problem states. Liberals and Marxists both agree on the second image frame but disagree on which states make war.

Liberals blame war on non-democratic, illiberal regimes. A tyrant who nervously hangs onto power is constantly looking for ways to unite and distract his people. By constructing a foreign enemy, blaming them for domestic problems, and waging an external war of aggression, the unelected leader shores up his political legitimacy. For a contemporary example of this kind of analysis, simply read mainstream accounts of Russia’s invasion of Ukraine. According to liberals, Russia invaded Ukraine because the existence of a burgeoning democracy next door makes Russian elites fearful that democracy will spread to Russia. Putin’s solution is to construct a foreign enemy in the United States and NATO, blame them for Russia’s economic woes, and wage a nationalistic war claiming to defend Russian interests. Russia’s authoritarian political system makes war a more likely tool of foreign policy.

For Marxists, capitalist states are the problem, be they nominally democratic or authoritarian. Capitalists only have one motive: profit. Cutting production costs is the surest way to maximise profit. Left unattended, capitalists will attempt to pay workers as little as possible. This runs into an immediate problem: if workers’ purchasing power is reduced, who is left to consume the finished product? Capitalists must also therefore constantly seek newer and bigger markets to dump their goods. Hijacking the state, the capitalist convinces his or her country to get involved in overseas ventures. The most obvious historical example is Britain’s opium war against China. In a desperate attempt to reverse Britain’s trade deficit with China, Britain began selling opium to the Chinese. However, China had banned opium and quickly seized British shipments. Using this as a pretext for war, Britain attacked China and forced it to open up its markets to British opium in return for peace. A similar Marxist reading can be made of the ongoing US-China trade war.    

Waltz has two primary objections to second image analysis. First, those convinced that they are on the right side of history tend to wage wars as if they were crusades. Ironically, in waging a war against war, they themselves become the chief cause of human suffering. As A.J.P. Taylor said: Bismarck fought ‘necessary’ wars and killed thousands, idealists of the twentieth century fought ‘just’ wars and killed millions. Second, holding down or destroying “bad states” (however one construes them) requires a preponderance of force and an overarching authority that simply does not exist at the international level. Quite naturally, we move onto the third image.

The Third Image

Just as society conditions individuals, international society conditions states. Nation-states are born into and conditioned by anarchy. There is no international authority to enforce decisions. This environment gives rise to a certain kind of rationality, a rationality which does not easily incorporate domestic notions of morality. Machiavelli made this point well: “if a prince wants to maintain his rule, he must be prepared not to be virtuous.” But it is Rousseau, according to Waltz, who offers the best explanation of why Machiavelli is right. Imagine a group of hunters who band together to catch and eat a stag. Working alone, no one can catch the stag and each will die of starvation. Cooperation is a necessity for survival. Except that during the hunt, one of the hunters notices a hare. He can catch and eat the hare by himself, avoiding the hard work of catching a stag. Viewed from his perspective alone, it would be rational for him to do this. The same hunter, however, knows that he will be punished for breaking rank. Furthermore, he knows that all the other hunters are having the exact same thoughts as him. If he decides to cooperate, what if another hunter steals the hare and he is left starving? Rationally, he is better off by being the first to stop cooperating. Through the stag hunt analogy, Rousseau shows why conflict arises from the structure of social activity itself, regardless of the intentions of individual actors.

At the domestic level, this problem of trust can be overcome by developing institutions which facilitate cooperation and punish those who break the social contract. No such institution exists at the international level. One solution might be an international federation of states. Practically speaking, establishing such a federation would run into the same problems as waging a war against war: it would surely prompt fierce backlash. Furthermore, our liberties might be at risk under such a globally powerful institution. Short of establishing world government, the most prudent way of securing peace is to ensure a balance of power between states. If one state – or a coalition of states – grows too powerful, it will be tempted to exploit others; enforcing the rules when it suits them, disregarding them when it does not. As Thucydides said: the strong do what they can and the weak suffer what they must. States must avoid being too weak and prevent others from becoming too strong. It has always been so.