The Specification of Sex/Gender in the Human Species: A Thomistic Analysis

To develop a philosophical framework to address the specification of sex/gender in humans, I will begin by summarizing what we know about the biology of sex determination in human beings. Basically, sex/gender is specified by several networks of genes anchored in the genetic interaction between the two genes, Sry and Sox9. Next, I will propose that this biological mechanism is best understood within a philosophical anthropology that embraces insights taken from systems biology to articulate a hylomorphism that explains the integrity, dynamism, and teleology of the human organism. The systems perspective described here represents one attempt to reformulate the received philosophical framework of classical Aristotelian-Thomistic hylomorphism so that it incorporates the insights of modern biology. Finally, I will use the systems perspective and key principles articulated by St. Thomas Aquinas in his philosophy of nature to identify criteria that could be used to specify the sex/gender of a particular human being: The most certain criterion for maleness would be the capacity to produce sperm while the most certain criterion for femaleness would be the complementary capacity to produce eggs. Deviations from this criterion would decrease the certitude of our judgment regarding the sex/gender of the individual.