Rousseau's law of war

Rousseau's law of war distinguishes conflict between States from violence against individual people, making the political purpose and limits of war central to its legitimacy. Since war is a relation between States rather than persons, combatants are enemies only while acting as defenders; surrender restores their status as human beings beyond the enemy relation. The rule also denies that conquest or force can create a rightful title to life, liberty, or obedience.

War Between States, Not Individuals

Rousseau rejects the idea that people are naturally enemies simply because they live independently of one another. In the state of nature, they lack stable mutual relations sufficient to constitute either peace or war. Nor does an isolated duel or encounter establish a state of war: war arises from a relation between political entities, not from personal antagonism alone.

The distinction also rules out private war within civil society, where relations fall under the authority of laws. Individual combats cannot constitute a state, and private wars once authorized by the establishments of Louis IX of France are presented as feudal abuses, contrary to natural right and good polity. War, in the relevant political sense, is therefore between State and State; individuals become enemies only accidentally, through their public role as soldiers and defenders.

The Status of Individuals in War

The object of war is the destruction of the hostile State, not the destruction of its population. A State may have other States, but not individual men, as enemies. Accordingly, a just prince who takes public property in enemy territory respects the lives and goods of individuals, whose rights are connected to the rights on which his own authority depends.

The opposing side may kill defenders while they bear arms, because they then act as instruments of the enemy State. But when they lay down their arms and surrender, they cease to be enemies and become men again; war provides no right to take their lives. Rousseau adds that it may be possible to defeat a State without killing any of its members. The permissions of war are limited by what is necessary to achieve its political object.

Conquest, Slavery, and Force

This account undercuts the claim that conquest gives a victor a right to enslave the conquered. The supposed right to kill an enemy cannot supply a foundation for enslavement, because Rousseau denies that war grants a general right to massacre a people. Nor can the right to kill be justified by first assuming a right to enslave: each claim would depend on the other, forming a circle rather than establishing legitimate authority.

More broadly, force cannot turn obedience into a moral duty. If force alone created right, each stronger force would inherit the supposed right, and obligation would disappear whenever resistance became possible. Such a rule would make power, not right, the only measure. A person compelled to obey yields from necessity or prudence; compulsion by itself does not establish a legitimate political bond.

The Peaceful Basis of Political Obligation

Rousseau sets the limits of war against the problem that the social contract is meant to solve: how people can unite their strength for common protection while remaining free. The compact joins each associate to the whole community under terms common to all, rather than placing one person under another's arbitrary authority. It creates a basis for mutual obligations that naked force cannot provide.

The compact's assurance that a member who refuses the general will may be compelled by the whole body belongs to this shared political order. Such enforcement is presented as securing citizens against personal dependence, not as a victor's entitlement over a defeated enemy. The distinction matters: public authority founded on a common compact is not equivalent to domination founded on conquest.

Political Limits and Significance

The war rule belongs to Rousseau's larger distinction between facts and rights. The fact that a State has conquered another, or that a ruler has enough force to command obedience, cannot by itself establish a legitimate right. Political theory must ask what can be justified, not treat existing power as its own proof.

The same standard applies when government turns against the political order that authorizes it. If a prince usurps sovereignty, the State contracts into a body made up only of the government, which becomes master and tyrant to the rest. The social compact is then broken, and citizens recover their natural liberty: they may be forced to obey, but are no longer bound by a legitimate obligation. Across warfare and government alike, Rousseau separates compulsion from right and limits authority by the political conditions that make it legitimate.