Abstract

This paper shows that the medieval concept synderesis comes from Origen’s endorsement of the Stoic theory of rational “self-affiliation” (oikeiōsis). Synderesis is a term that medieval authors inherited from Jerome, who was reporting Origen. Most famously, Aquinas made synderesis central to his moral epistemology, claiming that it is a natural mental habit whereby all humans have an implicit and vague understanding of axiomatic norms of morality. However, the identity of the original Greek word and its conceptual content have been debated since the ninth century. I show that the word must have been suntērēsis (“safeguarding”), employing as evidence recently (2012) discovered texts by Origen. I compare Origen to Chrysippus, Hierocles, and Epictetus. I also compare Aquinas to Origen. I point out three implications. First, the latest critical edition of Jerome (CCL) is incorrect, because it prints suneidēsis (“conscience”) instead of suntērēsis. Second, some of Aquinas’ core assertions about the characteristics of synderesis and its “place” within the mind are consistent with Origen’s account. Third, Stoic suntērēsis and Aquinas’ synderesis share certain metaethical associations.