Why do humans go to war?

Saturday 14 February 2026

War is older than memory. It precedes parchment and precedes scripture. Before law codes were chiselled into stone, before diplomats drafted treaties in careful ink, men assembled in ranks and advanced towards one another with sharpened metal and trembling conviction. The question is not merely why particular wars are fought — over territory, honour, resources or revenge — but why humanity, across millennia and continents, has so persistently returned to organised violence as a means of settling disputes.

The philosopher Thomas Hobbes, writing in his 1651 work Leviathan, offered perhaps the starkest diagnosis. In the absence of an overriding authority, he argued, human life tends towards “a condition of war of every man against every man”, in which existence is “solitary, poor, nasty, brutish, and short”. Hobbes did not believe that men relish bloodshed for its own sake. Rather he thought they are driven by fear, by competition and by a restless desire for security. War, in his account, is not the eruption of madness but the logical extension of insecurity in a world without guaranteed order.

Yet Hobbes’s view — bleak and mechanistic — sits alongside a contrasting tradition. Jean-Jacques Rousseau insisted that “man is born free, and everywhere he is in chains”. For Rousseau it was not human nature but human institutions that corrupted mankind. War, in his analysis, is not an expression of innate savagery but a product of property, hierarchy and political organisation. Tribes may clash, but large-scale warfare requires states — and states require ambition.

Between these poles lies a third perspective, articulated with austere clarity by Carl von Clausewitz. In his unfinished masterpiece On War, he wrote that “war is merely the continuation of policy by other means”. Clausewitz stripped war of mysticism. He rejected the idea that it is solely a moral failing or a biological impulse. Instead he regarded it as an instrument — a rational tool employed by political communities when other tools have failed. If war is an instrument, then its persistence reflects not only human aggression but human calculation.

These philosophical diagnoses illuminate different aspects of a single phenomenon. Fear, ambition and calculation intertwine. The ancient Greek historian Thucydides, describing the Peloponnesian War, identified three motives that drive states to conflict: “fear, honour and interest”. Two and a half millennia later, those categories retain an uncanny explanatory power. Nations fight because they fear encirclement, because they perceive affronts to dignity, and because they seek material advantage. Rarely does one motive appear alone.

But there is more to war than motives. There is also the human capacity for abstraction. Animals fight for territory or mates, but they do not fight for flags or ideologies. Humans, uniquely, are willing to die — and to kill — for symbols. Benedict Anderson described nations as “imagined communities”. That imagination is potent. A border on a map, a language, a historical grievance passed down through generations — these can mobilise millions. The philosopher Ernst Cassirer observed that man is not merely a rational animal but a symbolic one. War often arises when symbols are perceived to be under threat.

Religion too has provided both restraint and justification. Saint Augustine developed the theory of the “just war”, arguing that violence may be morally permissible under strict conditions. He did not glorify war; he lamented its necessity in a fallen world. Yet once criteria are established for righteous violence, they may be invoked by those convinced of their own virtue. The line between moral duty and moral delusion is perilously thin.

Modernity did not abolish war; it industrialised it. The Enlightenment promise that reason would tame passion proved fragile. Immanuel Kant, in his essay Perpetual Peace, envisioned a federation of republics that would gradually eliminate war through commerce and law. “The spirit of commerce”, he wrote, “cannot coexist with war”. There is some truth in this. Economic interdependence raises the cost of conflict. Yet the twentieth century demonstrated that trade and treaties do not extinguish nationalist fervour or ideological absolutism. When leaders persuade populations that survival or identity is at stake, commerce yields to cannon.

Psychology adds another layer. Sigmund Freud, in correspondence with Albert Einstein in 1932, speculated about a human “death drive” — a destructive impulse that finds expression in war. Einstein asked whether humanity could be freed from the menace of war. Freud’s reply was cautious: civilisation restrains aggression, but it cannot eliminate it. Aggression may be redirected, sublimated, channelled into competition or art, but it remains latent.

Anthropologists have debated whether prehistoric societies were largely peaceful or chronically violent. The evidence suggests neither Eden nor constant carnage, but a complex mosaic. Violence appears wherever groups compete over scarce resources. Yet co-operation appears wherever mutual survival depends upon it. The capacity for war is paired with an equally profound capacity for solidarity. Indeed war often strengthens internal cohesion even as it destroys external relations.

Why then have humans “all gone to war”? Perhaps because war is not an aberration but a possibility embedded in the structure of human social life. We form groups; we attach identity to those groups; we fear their vulnerability; we calculate advantages; we invest meaning in symbols. When these elements align under conditions of stress — economic collapse, demographic pressure, political instability — conflict becomes conceivable, then probable, then actual.

And yet to describe war as structural is not to excuse it. The same faculties that enable war also enable restraint. Law, diplomacy and international institutions are fragile achievements, but they are achievements nonetheless. The United Nations, the Geneva Conventions, regional alliances and economic unions represent attempts to civilise power — to bind Hobbes’s warlike impulses within rules. They do not abolish conflict, but they alter its calculus.

The persistence of war may ultimately reflect a tragic paradox. Humans are imaginative enough to conceive of justice, honour and destiny — and powerful enough to pursue those visions with organised violence. We are neither angels nor beasts, but creatures suspended between aspiration and fear. As long as communities exist, and as long as they value security, identity and survival, the temptation to war will endure.

Yet history also records long periods of relative peace, expanding zones of commerce and unprecedented global prosperity. The very fact that we ask why humans go to war suggests that we recognise war as a problem to be solved rather than a destiny to be embraced. Kant’s vision of perpetual peace remains unrealised, but it has not vanished. It hovers as an aspiration — fragile, contested, but persistent.

War is therefore not inevitable in each instance, although it may be perennial as a possibility. It arises from fear and pride, from miscalculation and ambition, from symbolic attachment and material need. It flourishes where institutions fail and where leaders persuade populations that violence is necessary.

The deeper question is not only why we go to war, but whether we can cultivate the habits, institutions and moral imagination required to prevent it. That question remains open. It has accompanied humanity since the first organised battle — and it will likely accompany her as long as she endures.