Let us now consider how Aristotle applies his own theory of justice to the social problem of alleged superiors and inferiors, before attempting a brief critique of that theory. While Plato accepted slavery as a legitimate social institution but argued for equal opportunity for women, in his Politics , Aristotle accepts sexual inequality while actively defending slavery. Anyone who is inferior intellectually and morally is properly socio-politically inferior in a well-ordered polis . A human being can be naturally autonomous or not, “a natural slave” being defective in rationality and morality, and thus naturally fit to belong to a superior; such a human can rightly be regarded as “a piece of property,” or another person’s “tool for action.” Given natural human inequality, it is allegedly inappropriate that all should rule or share in ruling. Aristotle holds that some are marked as superior and fit to rule from birth, while others are inferior and marked from birth to be ruled by others. This supposedly applies not only to ethnic groups, but also to the genders, and he unequivocally asserts that males are “naturally superior” and females “naturally inferior,” the former being fit to rule and the latter to be ruled. The claim is that it is naturally better for women themselves that they be ruled by men, as it is better for “natural slaves” that they should be ruled by those who are “naturally free.” Now Aristotle does argue only for natural slavery. It was the custom (notice the distinction, used here, between custom and nature) in antiquity to make slaves of conquered enemies who become prisoners of war. But Aristotle (like Plato) believes that Greeks are born for free and rational self-rule, unlike non-Greeks (“barbarians”), who are naturally inferior and incapable of it. So the fact that a human being is defeated or captured is no assurance that he is fit for slavery, as an unjust war may have been imposed on a nobler society by a more primitive one. While granting that Greeks and non-Greeks, as well as men and women, are all truly human, Aristotle justifies the alleged inequality among them based on what he calls the “deliberative” capacity of their rational souls. The natural slave’s rational soul supposedly lacks this, a woman has it but it lacks the authority for her to be autonomous, a (free male) child has it in some developmental stage, and a naturally superior free male has it developed and available for governance (ibid., pp. 7-11, 23; 1254a-1255a, 1260a).