The National Catholic Bioethics Quarterly vol:13 issue:4 pages:611-616
This essay is an attempt to clarify Aquinas’ position on "the moral object" by examining three difficulties in understanding a "per se" order. A correct understanding of a "per se" order is critical for moral reasoning because if an action (the external object) is "per se" ordered to the end intended by the agent, then the species of the object is formally derived from that aim. This differs from a "per accidens" order where an action is only related accidentally to the end; it is only related in the agent’s mind and therefore the action does not draw its moral species from the aim (end). After discussing the difficulties in distinguishing the two different orders, this essay will compare the act of craniotomy with the act of lethal self-defense. The essay argues that the moral species are different because craniotomy involves only a "per accidens" order to the good end of saving the mother, while lethal self-defense is "per se" ordered to the good end of preserving one’s life.