Augustine’s view marked a clear departure from Aristotle’s about property and slavery. Both property and slavery, according to the saint, are contrary to original human nature. But they become necessary in the actual condition of the fallen man. In the natural condition property is held in common. After the ‘Fall’, in view of man’s avarice and instinct of self-possession it becomes almost impossible for common ownership to work satisfactorily.
Thus, state control and organisation become necessary. In the words of A.J. Carlyle: “Private property is therefore practically the creation of the state, and is defined, limited and changed by the State.” But while the legal right to private property is recognised by the Fathers, “as a suitable and necessary concession to human infirmity the institution cannot override the natural right of a man to obtain what he needs from the abundance of that which the earth brings forth.”
Augustine’s views on war and slavery are also explicated in the context of the sinful condition of man after Adam’s fall. In the ideal conditions of idyllic innocence and eternal peace, war would be unthinkable, but in the present state of strife and insecurity war becomes a necessity.
Even from the moral and religious point of view, the state must wage war to protect the Empire and to destroy the heretics. St. Augustine, as against the early Christians, approves of military service for the Christians.
He lays the foundation for the theory of “just war” which was developed by medieval thinkers. Like war, enslavement of man by man is also not strictly in accordance with Eternal law. But it is also justified by what Troeltsch calls the Augustinian doctrine of “relative natural law”.
It is both a punishment and a corrective for the sinful act of men. St. Augustine’s views on slavery are opposed to Aristotle’s; they are more akin to Stoicism modified in the light of Christian theology, that is, the notion of the fall of man.