Abstract

The distinction between actus humanus and actus hominis is the best-known distinction in Thomas Aquinas’ theory of action. A human action (actus humanus) is a special case of an act of a human being (actus hominis). Several acts of our intellect and will form a human action and thereby put it from the realm of pure natural happenings (genus naturae) into the moral realm (genus moris). The paper at hand shows the character and main parameters of Thomas Aquinas’ action theory, especially in the Summa theologiae I-II, quaestiones 6-17. Moreover, it presents Thomas Aquinas’ central idea of what is the essence of a human action. The analysis especially makes use of the element of command (imperium) It shows that, according to Aquinas, acting consists in the intellectually comprehensible self-disclosure of a person and therefore builds the basis for the moral evaluation of human actions.