Can someone expand Rousseau's proper definition of war?

Question

Rousseau, in his 'Of the Social Contract', chapter IV, 'Slavery', puts that:

Men, from the mere fact that, while they are living in their primitive independence, they have no mutual relations stable enough to constitute either the state of peace or the state of war, cannot be naturally enemies. War is constituted by a relation between things, and not between persons; and, as the state of war cannot arise out of simple personal relations, private war, or war of man with man, can exist neither in the state of nature, where there is no constant property, nor in the social state, where everything is under the authority of the laws.

Well, to me this seems a rather obscure definition of what war is. I can't see how a relation is necessary for war to exist. To me it seems likely that any conflict of interest, even between previously unrelated entities, is prone to generate war - e.g two previously unrelated princes interested in the same territory.

I can find his logic behind there not being a possibility of war between two persons, by assuming a conflict between both would be a fight and not a war, but that is as far as I got in following his logic. But what he means by "real relations" and how these relate to the legitimacy of war, within his logic, that's far from being clear to me.

Answer 1

Just to supplement Mauro's answer, which brings out perfectly the central conceptual point about war, there's an associated point that relates to why wars occur between states when the roots of war are not authentic to human nature. Only because of the degraded condition to which 'civilization' has reduced us, so Roussseau thinks, are states predisposed to war.

For Hobbes, violence is an expression of human nature, whenever it is not repressed by a Leviathan; international war remains inevitable because man is an asocial animal, even after the establishment of civil societies. For Rousseau, war is not a human necessity or drive, because man is not social by nature. "One kills in order to win; no man is so ferocious that he tries to win in order to kill."* War is a social institution: hence Rousseau's famous insistence on the idea that wars are, by nature, contests between states (i.e., artificial bodies) but not between individuals, and consequently ought to be waged as such. This idea was directly inspired by Montesquieu's writings; but Rousseau formulated it more categorically, so as to make clear that man, dénaturé by bad social institutions, is alienated man, whose acts spring not from his true self but from a distorted self which society has manufactured and for which society alone is responsible. Since nothing in human nature forces a man to kill another, the objects of wars are always far removed from the citizens' lives: the stakes of war are not man's needs, but the frills and fancies grafted on those needs by society. (Stanley Hoffmann, 'Rousseau on War and Peace', The American Political Science Review, Vol. 57, No. 2 (Jun., 1963), pp. 317-333: 321.)

*https://oll.libertyfund.org/titles/rousseau-the-political-writings-of-jean-jacques-rousseau-vol-1--5: On tue pour vaincre; mais il n'y point d'homme si féroce qu'il cherche à vaincre pour tuer.

Answer 2

War is not a relation between individuals, but between States.

See The Social Contract, Book I: Chapter IV :

Private combats, duels, and encounters are acts that do not constitute a state of war; [...] War, then, is not a relation between man and man, but a relation between State and State, in which individuals are enemies only by accident, not as men, nor even as citizens, but as soldiers; not as members of the fatherland, but as its defenders.

See also The Philosophy of War.