Thomas Aquinas on Sexual Difference: The Metaphysical Biology and Moral Significance of Human Sexuality

Thomas Aquinas offers for his time a novel take on human sexual difference, in that he grounds human sexuality in what we might term a metaphysical biology and accords it a privileged role in the moral life. Though his biology is drawn from Aristotle, which leads Aquinas to make problematic statements on sexual difference, he nonetheless offers a perspective that remains deeply relevant and significant for today. His method or approach of tethering sexual difference first and foremost to our animal-like biological design remains perennial, particularly at a time when many seek to dismiss biology as irrelevant to sexual identity and gender difference. The latest findings of the emerging field of neurobiology, which have uncovered structural differences between the male and female brains, offer key support to Aquinas’s approach. Even more important, he holds, in an unprecedented move, that sexual design and inclination provide a veritable source of moral excellence. He goes so far as to locate the mean of virtue in our sexual design and appetites.