In the wake of the renewal of « virtue » ethics, works on Thomas Aquinas’ propositions on the human act and agency and his version of “virtue” have been published. This seminar proposes a different perspective of the idea of the human act and its structure that is rather centered on the notions of “vice” and “sin”. Hence, it offers a more complex vision of Aquinas’ understanding of the human act. During this seminar, students will analyze the issues linked to concepts and perspectives of the vicious act, according to Aquinas. By reading the Summa Theologiae and other writings in Aquinas’ corpus of texts, students will examine and refine their personal reflection on the idea of vice. Students will be assessed periodically in this course on the outcomes and interpretation of their reading assignments, on their communication skills and attitudes by means of oral presentations and by active participation in classroom discussions and debates.