Abstract

The principle of double effect is often used in bioethics as a tool to evaluate significant cases in obstetrics and gynecology. In this article the author, a Catholic priest, presents and interprets St. Thomas Aquinas’s delineation of the principle and discusses several classical applications, namely, to hysterectomy during pregnancy, ectopic pregnancy, and craniotomy. He explains the medical anatomy and physiology of the conjoined Maltese twins, Jodie and Mary, and then examines the arguments of four moralists on their separation. He concludes by arguing that the principle morally justified the surgical separation of Jodie and Mary. National Catholic Bioethics Quarterly 9.1 : 85–96.