Someone might object that strong emotion can directly affect the will even though the fact and extent of such an effect cannot be verified by experience. This objection can be answered only by an analysis of what is meant by “will.” Since will is a spiritual power, it cannot be moved directly by nonspiritual factors. As an appetitive power proper to persons, who transcend the world of nonspiritual causality, will is determined only by intellectual judgment proposing something as intelligibly good or, in the case of free choices, by its own self-determination concerning which judgment to follow.

The will can indirectly affect the emotions. One can choose what to think, what to imagine, and what to do. By such choices, one can alter one’s emotional actuations. Thus, one who wishes to love God wholeheartedly, including emotionally, can meditate upon his goodness, and especially upon those evidences of it which are sensibly moving. One who wishes to banish sadness can think of happy things and, especially, can engage in some activity which is not too difficult and is fulfilling to the whole person—in other words, can do the most enjoyable thing possible which also is genuinely worthwhile and in all respects good to do.

Underlying every choice is some emotion. Very often, however, one is not especially conscious of emotions. One becomes aware of them only when they are unusual enough in their strength or some other respect to call attention to themselves by their physiological consequences. The ordinary desire to eat or drink is not noticed as an emotion; the craving of a person dying of hunger and thirst is noticed. The emotional satisfaction of walking across campus is not usually noticed; the joy with which one walks on a beautiful day in spring is noticed.

Similarly, every sinful choice involves emotion. One would not choose to determine oneself otherwise than in a fully reasonable way except that emotions dispose one to act otherwise. Each mode of responsibility excludes certain emotions from serving as nonrational principles of self-determination. But it does not follow that every sin is a sin of weakness. If one considers possibilities with an upright conscience and decides to do what is right, one normally has little or no difficulty directing one’s attention to carrying out one’s good decision. Sin of weakness becomes possible only when the strength of emotion is such that one’s normal will to act reasonably is rebelliously resisted by emotion.

The situation is analogous to that in a deliberative assembly. Within the rules of procedure, members are entitled to propose anything they please. Many proposals are voted down, because they would not be in the common interest. Usually, the negative vote is accepted and the proposal disposed of. But at times the desire of some to have their own way is so great that they keep bringing up a rejected proposal, insisting on its acceptance lest the work of the assembly be bogged down and its harmony be disrupted. Under these conditions, there is a tendency to give in for the sake of peace. Similarly, the temptation to commit a sin of weakness arises when emotions are strong and unruly enough to resist a reasonable decision, distract attention from other matters, and keep demanding reconsideration for a rejected proposal.

In the fallen human condition, there is hardly any member of any assembly who is altogether impartial, who is not somewhat unreasonable and disruptive. The same thing is true of the emotions of fallen humankind. The whole human emotional complex is distorted by the fear of death consequent upon original sin (see 14‑G). The “normal” human condition is somewhat abnormal and perverse. This state of affairs is what is called “concupiscence,” which refers to a residual effect of original sin (see DS 1515/792). Consequently, very often emotions are not easy to integrate, and one experiences in one’s members a law at odds with the law of one’s mind (see Rom 7.23). Hence, emotional resistance to reasonable decisions cannot be accepted as humanly normal and healthy, even though in our actual condition it is virtually universal and not pathological.

Some contemporary psychologies, based upon a denial of free choice, tend to reduce the whole moral problem to the dimensions of emotional health and sickness, maturity and immaturity.³ However, sickness and immaturity can be distinguished from sinful weakness and malice. Those who are emotionally sick or immature experience emotions which are not well integrated even at the level of sentient nature. For example, the neurotic has emotions out of proportion to the situation which arouses them, and the smooth flow of behavior as a whole tends to be disrupted. The adolescent likewise experiences emotional extremes which cause distress and cannot easily be explained by the actual situation and the content of consciousness. Thus the conscious and the unconscious minds are not functioning harmoniously in cases of emotional sickness and immaturity.

In cases of sinful weakness and malice, by contrast, the emotions can be perfectly well proportioned to the situation which arouses them and integrated into a smooth pattern of behavior, and so they can be explained by the actual situation and content of consciousness. One need not assume any hidden condition creating disharmony between the conscious and unconscious minds. The disharmony primarily is within consciousness itself, between the law of one’s members and the law of one’s mind—that is, between the emotionally appealing possibility which promises sentient satisfaction and the freely eligible possibility which reason proposes as intelligibly good (see S.t., 1–2, q. 75, a. 2; q. 77, a. 2; q. 91, a. 6).

Obviously, in most of us both types of disorder and disharmony often are present in some proportion. This fact complicates matters and helps render plausible determinism’s explaining away of human moral responsibility. However, one must reject this rationalization, for it is absolutely at odds both with reason and with faith. Immoral acts, including sins of weakness, are not a product of emotional immaturity and/or neurosis. Just to the extent that they are done by free choice, immoral acts are a product of nothing other than one’s self freely choosing to be less than one could and ought to be.