Abstract

Aquinas opens the second part of the ST by arguing, in a series of careful steps, that there is one and only one ultimate end for all human actions. The placement of this argument is no accident, since the notion of an end is of fundamental importance not only in Aquinas’s theory of human action but in his accounts of practical reasoning, law, and the virtues. Yet the interpretation of Aquinas’s argument in ST 1a2ae, q.1, is a matter of considerable controversy. I shall first follow the argument through its successive steps and then briefly consider three possible ways of understanding Aquinas’s claim that all human actions have exactly one ultimate end. Aquinas first argues that every human action is for the sake of some end. That is, every human action is purposive in some way; it is done for the sake of attaining some goal or realizing some desired state of affairs. To the obvious objection that we do things all the time without any purpose at all, Aquinas replies by distinguishing between a human action (actus humanus) and an action of a human being (actio hominis). Human actions, properly so called, are those that proceed from human beings in virtue of their distinguishing power, which is to be in control of their own actions (dominus suorum actuum) through reason and will. Anything else that a human being does can be called the action of a human being, but not (in the proper sense) a human action. Human actions, then, are those that are willed on the basis of rational deliberation. And since “the object of the will is an end and a good, it follows that all human actions are for the sake of an end.”1 What, precisely, is meant by the “end” of a human action? Aquinas tells us in a. 2 that an end is something cognized as good. It must be something cognized because otherwise we just have “natural appetite,” the sort of built-in directedness by which heavy objects are moved..