This paper examines the views of a number of late scholastic moral theologians, with emphasis on Francisco Suárez, about the limits of the duty to refrain from those otherwise permissible actions which make it difficult for people to choose uprightly. In so doing, the paper singles out and analyses a number circumstantial factors capable of excusing ordinary agents for giving others an occasion of sin.

Critics of homosexual activity often appeal to some form of natural law theory as a basis for their arguments. According to one version of natural law theory, actions that “pervert” or misuse a bodily faculty are immoral. In this paper, I argue that this “perverted faculty argument” provides a successful account of good and evil action. Several objections are assessed and found inadequate.