Every age, every civilisation and every continent has spoken about peace. From Greek philosophers to Roman jurists, from medieval theologians to modern state-builders, and from presidents and diplomats to today’s activists, the desire for peace seems universal and constant. Yet the idea of a “just peace” – a peace that is not merely the end of hostilities, but an ethical result – has always been ambiguous and controversial. A just peace appears to be a sublime moral goal, but throughout history it has often been a political tool used to justify wars, conquests, imperial orders and punishments. It is a noble aspiration, but also a language of power.
Human history offers a permanent paradox: there is no word more celebrated than peace, and no word more ambiguous. Everyone calls for peace, yet the peace proposed by others is almost never considered just. For some, peace means freedom; for others, security; for others still, order and stability. For some, peace is self-determination; for others, territorial integrity. Every side defines justice according to its own interests, values, memories and traumas. This is why speaking about a just peace means speaking about perspectives, conflict, power relations and legitimacy. Peace is always a relationship. It does not exist in a vacuum. And whenever we try to imagine peace outside the realm of power, we discover that peace itself becomes fragile and often illusory.
This long essay explores the history of the concept of a just peace, showing how it has been used, interpreted and transformed across civilisations. From Greek origins to Imperial Rome, from medieval Christianity to modernity, from colonial empires to international orders, and into our globalised world, the idea of just peace appears as an ideal that reinvents itself, evolves and adapts to historical conditions. Yet one feature remains constant: relativity. A just peace is never objective. It is always defined by someone, for someone, against someone else.
Peace as a Conceptual Problem
In modern imagination, we tend to think of peace as an intrinsic value, a universal good that does not need justification. But for the ancients this was not the case. Peace was not a moral end in itself. It was a moment, a social and political condition that allowed the community to flourish. Yet the ancients did not regard peace as superior to war. War was part of nature and part of political order.
In Thucydides, peace is not the absence of violence but a temporary suspension. History is a cycle of conflicts. The Greek poleis lived in unstable equilibrium, constantly drawn toward war. Peace came when war was no longer sustainable, or when a superior power imposed order. The Greeks debated justice, but they rarely imagined perfect peace. Conflict was natural, and peace was a product of strength.
Plato introduced another dimension. Peace is the consequence of just order. If the city is governed according to virtue and reason, if each class occupies its rightful place, peace is achieved. But this does not mean that the city is free of external conflict. Plato admits that war can be necessary. Internal order and peace do not exclude the use of force externally.
Aristotle deepens the connection between peace and virtue. Peace results from good government. Social justice is what enables cohesion. Yet Aristotle also recognises that war can be just when it secures what is owed. Already in Greek philosophy, just peace is relative: it concerns the just city, not humanity as a whole.
The Stoics shift the axis. True peace is not outside but within. It is the imperturbability of the soul that accepts fate. External peace can be broken by events, wars and catastrophes, but inner peace remains accessible. This idea will have a long life in Christian tradition. Nevertheless, the political dimension of peace is not eliminated. Societies continue to organise their order through force. In Greece, peace was never separated from power. It existed as political practice, not universal myth.
Rome and Peace as Domination
If Greece provides the intellectual foundations, Rome builds the political architecture. The concept of Pax Romana is one of antiquity’s most powerful inventions. Rome did not think of peace as abstention from war. Peace was the order that followed victory. Roman war was always just, because Rome fought to punish injustice. But injustice was defined by the empire. Rome recognised no higher authority. A just peace was a Roman peace.
The entire civilised world was conceived as potential space for Roman order. Latin authors insisted on this idea. Livy, Virgil and Horace celebrated peace as the fruit of imperium. Without Rome there was barbarism and chaos. With Rome there were roads, trade, law and prosperity.
The Ara Pacis Augustae is a symbolic monument. It portrays peace as abundance, continuity and sacredness. But that peace was won through civil wars, proscriptions, campaigns in Spain, Germany and the East. Augustus celebrated peace only after eliminating his rivals. Peace was always the consequence of victory. Propaganda presented this order as natural, just and eternal. But peace had a price. The defeated had to accept conditions, tribute and discipline. The empire appeared peaceful because its peripheries were subdued.
Rome proves that just peace is almost always the peace of the victor. Yet this model has been admired for centuries. The idea that peace coincides with the order of a universal power reappears from medieval Europe to modern empires, and even in the American peace of the twentieth century. Rome did not eliminate war; it turned it into a structural instrument. Peace was organisation: law, infrastructure, unification. War was the means. Peace, the end. But both were part of the same project.
Christianity and the Middle Ages: Peace as Morality
With Christianity, peace acquires a moral dimension. War is no longer merely political but becomes a religious matter. Saint Augustine formulates the doctrine of just war. War can be just if it defends order, punishes injustice and protects the innocent. Peace is superior to war, but war is sometimes necessary to achieve it. Thomas Aquinas codifies the criteria: legitimate authority, just cause, right intention. This theological framework will legitimise crusades, expansions and repressions.
The Middle Ages are often portrayed as a time of religious peace, yet history reveals constant warfare. Kings fought each other, cities laid siege, feudal lords contested land. The Treuga Dei were attempts to limit violence by imposing sacred truces. Yet war remained normal. Christian peace was fragile because it depended on human morality. Order was unstable. Just peace was an ideal, not reality.
The coronation of Charlemagne marks a decisive moment. Imperial power is presented as an instrument of divine peace. The empire becomes guarantor of Christian order. But to impose this order, Charlemagne wages relentless campaigns. The medieval model repeats the paradox: one fights for peace. Justice is not defined universally; it is defined by God through His representatives. Peace is subordinate to religious and political order.
When the Protestant Reformation breaks Christian unity, the concept of just peace explodes. There is no longer a single truth. The wars of religion show that justice is relative to confessions. Peace must be negotiated, not imposed. This paves the way to modernity.
Modernity: Peace as Balance of Power
The Peace of Westphalia (1648) is the founding event of the modern international system. Peace no longer derives from a universal authority or a global empire, but from balance between sovereign states. Each state has the right to rule itself. Just peace becomes peace through equilibrium. There is no justice above the states. Powers negotiate, fight and form alliances. Peace is compromise.
War remains legitimate. Treaties are made after wars, not before. The Westphalian system produces relative stability, but not universal peace. European powers fight constantly: dynastic wars, colonial wars, national wars. Peace is always fragile. Justice is negotiated at the table. Diplomacy becomes an art. Modernity invents the ambassador, the congress and protocol. Yet all of this serves to manage conflict, not eliminate it.
The Enlightenment tries to change the paradigm. Reason should found peace. Kant imagines a federation of republican states. The idea of perpetual peace becomes a philosophical ideal. But history quickly contradicts optimism. The Napoleonic wars show that peace is still domination. Napoleon builds a European empire, presenting it as rational order. But other powers see him as a threat. Peace remains subordinate to force.
The 19th Century: Empires, Nations and Armed Peace
The nineteenth century is dominated by empires and nationalism. Peace is often frozen conflict. European powers colonise Africa and Asia in the name of civilisation. Colonial peace is imposed order. The colonised are pacified. Colonial wars are presented as civilising missions. Europe experiences a long period of equilibrium, but beneath the surface rivalry grows. Peace is maintained through arms. Alliances serve as deterrence. Peace is deterrence.
The First World War reveals that this armed peace was unstable. European powers explode into total war. After the war, the League of Nations tries to create an international order. Peace must be organised institutionally. But it lacks coercive power. Aggression is not stopped. The Second World War arrives as definitive catastrophe.
The twentieth century is the century of organised peace. The United Nations is born from the idea that peace can be guaranteed by international law. But superpowers immediately enter ideological conflict. The Cold War is an armed peace. The two blocs avoid direct confrontation, but fund proxy wars. Both speak of peace. The United States speaks of democratic peace. The USSR speaks of socialist peace. Peace becomes propaganda. Each bloc feels just. Every action is presented as defensive.
The Contemporary World: Just Peace and Multipolarism
In the twenty-first century, the concept of just peace returns to the centre. Contemporary conflicts are often presented as moral wars. Fighting is done against terrorism, aggression and injustice. But the international order is multipolar. There is no universal consensus. The war in Ukraine, conflicts in the Middle East, tensions in the Pacific show that peace is still a conceptual battlefield. Every side speaks of peace. Every side accuses the other of aggression. Every side feels morally right.
Just peace becomes a matter of narrative. Whoever controls discourse controls legitimacy. Powers invest in communication, public diplomacy and propaganda. Public opinion becomes battleground. Peace is language and perception. Justice is not objectively verifiable. It depends on values, media, interpretation. In a globalised world, war is not only military: it is symbolic, economic and informational.
Just Peace as Necessary Myth
Despite its relativity, just peace remains a fundamental ideal. Societies need to believe in it. Without a horizon of peace, politics becomes pure struggle. Just peace is a productive myth. It functions as regulator of conflict. It enables negotiations, compromises and agreements. Without justice, peace would be a technical truce. The myth creates legitimacy. Parties accept conditions because they believe peace is just. Even when it is not entirely true, it must appear so. This is why the rhetoric of peace is so powerful. Peace is always presented as moral good. But morality is relative.
Just Peace as Dynamic Balance
Just peace is fragile balance. It requires reciprocal recognition, proportionality and shared security. But these conditions rarely occur. Peace is often reached through exhaustion, attrition or impossibility of victory. Peace signed after war is often imperfect. Wounds remain. Memories continue to fester. Communities cultivate resentment. Peace is temporary. When it breaks, war returns. Yet this does not mean peace is illusion. It is necessary reality. It is constant construction. It is process, not state.
Conclusion: Is a Just Peace Possible?
There is no simple answer to whether just peace is possible. Certainly no perfectly just peace exists. Every peace is relative, historical, situated. Every peace has winners and losers. Every peace is compromise. But this does not diminish the value of the ideal. Just peace is continuous work. It is gradual improvement. It is reduction of violence. It is recognition of the other’s humanity. It is the ability to negotiate, listen and yield. It is awareness that no one possesses the truth. It is the will to coexist.
Just peace is not a gift. It is choice. And that choice must be renewed every day. History shows that societies that seek just peace are more stable, prosperous and secure. Societies that live in permanent war destroy themselves. Just peace is not utopia. It is discipline. It is pragmatism. It is minimal ethics. It is reciprocal recognition. The contemporary world needs this awareness. Just peace will never be definitive. But it can be built, lived and defended. Its relativity is not a flaw. It is the condition of the human. Peace is fragile because human beings are fragile. But it is also powerful, because it is the only alternative to destruction.
Just peace is a path, not a destination. History teaches that peace is always provisional. But war is also provisional. No conflict is eternal. No order is immutable. Just peace is what survives extremes. It is what remains when violence ends. It is the place where human beings choose to begin again.