Thomas Aquinas believed that human actions have kinds or species. He divided human actions into good, evil, or indifferent, and subdivided them into more particular kinds such as almsgiving, murder, fraternal correction, or theft. From his earliest consideration of this topic in the Commentary on the Sentences to his latest in the Summa Theologiae, he used five different terms — end, object, matter, circumstance, and motive — to identify what gives species to human actions. Some difficulties have been noted with respect to his thinking on this subject. A first such difficulty is that his teach ... More

Thomas Aquinas believed that human actions have kinds or species. He divided human actions into good, evil, or indifferent, and subdivided them into more particular kinds such as almsgiving, murder, fraternal correction, or theft. From his earliest consideration of this topic in the Commentary on the Sentences to his latest in the Summa Theologiae, he used five different terms — end, object, matter, circumstance, and motive — to identify what gives species to human actions. Some difficulties have been noted with respect to his thinking on this subject. A first such difficulty is that his teaching on a few of these terms seems at times inconsistent. For example, although Aquinas maintains in some texts that circumstances can give species to human actions, he seems to deny that they can in other texts. Further, although on some occasions he holds that a remote end is irrelevant for the specification of human actions, on other occasions, he seems to assert that a remote end is the most important principle for such specification. It is not easy to see at first how these seemingly contradictory statements can be true at the same time. A second difficulty is that it is hard to grasp how end, object, matter, circumstance, and motive could all refer to what specifies human actions. Although certain similarities in meaning can be recognized among them, no term seems to be a strict synonym of any other, ruling out an easy reconciliation. This monograph examines Aquinas’s understanding of these five terms to resolve these difficulties and propose a coherent account of his teaching on the specification of human actions.