Species of Human Actions in Aquinas Determined by Both Object and End Joseph Pilsner C.S.B. In his moral writings, St. Thomas Aquinas dedicates much effort to identifying various kinds of human actions (e.g., almsgiving, murder, liberality, robbery, etc.) and to examining what determines such species.1 Among the various aspects of human action, the two he considers most important for determining moral species are "object" (what an agent is doing) and "end" (an agent's purpose in acting).2 Objects specify for Aquinas when they possess a morally relevant formal character (ratio) revealed by a comparison to right reason. An object with such a formal character will either realize or oppose some moral good if willed. Suppose that a married man is considering "having sexual relations with a woman." This description of his possible action may be accurate, but it is insufficient for a determination about whether it would be good or evil in kind. When the action under consideration is compared with right reason—in this case, a correct understanding of how sexual powers ought to be used—aspects of the man's action relevant to this comparison will come to light; St. Thomas holds that these aspects should be included in the object's formal character. Sometimes the comparison will reveal [End Page 565] aspects which indicate conformity with right reason; for example, the man's object might be "having sexual relations with his own spouse." This object (with its formal character now identified) will determine a morally good human action of marital love. At other times, however, the comparison with right reason might reveal something discordant: the object might be "having sexual relations with another's spouse." This object has a distinctive opposition to the good of marriage as discerned by right reason; it defines or specifies an evil kind of human action, adultery.3 What role does an end play in specification? For Aquinas, in some cases, a human action will receive a moral species from its object, and no further determination relevant to this moral species will be added by an end. For example, a man may have as his object "to present himself as other than he is." If the man wills this object simply from the pleasure of carrying out this deception and for no further end, then according to St. Thomas, this object by itself will determine the moral species of dissimulation (simulatio).4 On another occasion, this man might have a further end for dissimulating, but if this end has no special relation to right reason, then here too, the object will determine the action's only moral species. If, however, the end on account of which some object is chosen possesses its own distinctive relation to right reason, then, according to Aquinas, this end would determine an additional moral species. For example, in a case where a man is "having sexual relations with another's spouse" (object) as a means to "appropriating secretly some possession" of his paramour (end), the human action would have the species of adultery from its object and theft from its end.5 The end, like the object, is opposed to right reason, but the evil brought about by willing the end is essentially distinct from the evil brought about by willing the object. An end in such a case has a special importance in specifying the human action: since the object is willed for the end's sake, the species from the end has a certain formal primacy over the species from the object. Note, however, that for St. Thomas, the species from this end does not subsume, alter, or contribute to the species that the action receives from its object. The human action in this case remains adultery from its object, even when it is determined to be theft (the more prominent species) from its end. [End Page 566] There is a third way, according to St. Thomas, in which an object and end can be related to the specification of human actions, and this third way is the primary concern of this article. In certain species of human action, Aquinas holds that an object and end together contribute to...