Aristotle on Sexual Difference examines Aristotle’s conception of sexual difference—the differences between male and female, men and women—both in his biological works and in his political philosophy. For Aristotle, the problem of sexual difference emerges from the tension between his assertions that the female is imperfect relative to the male and that men by nature should rule over women, and his commitment to two other claims: (1) that sex is a division in the matter and not in the form of the genus animal—so there is no difference in essential form between the male and female members of a sexually differentiated species, and (2) that sexual difference, and therefore the existence of sexed individuals, is good, both for generation and for the political life characteristic of human beings. This book analyzes how Aristotle would describe both the physiological and the psychological defects of women, and then asks how those defects might also be benefits on his account, and how the different defects might be causally connected. It has three aims. The first is to provide a comprehensive analysis of Aristotle’s conception of sexual difference in animal bodies and in political life. The second is to demonstrate that Aristotle takes sexual difference to be valuable to an animal species as well as to the city-state. The third is to establish the link between the explanation Aristotle offers for the deficiencies of the female body and his justification of distinct roles for the sexes in the household and the city.