1. In committing sin one does not choose its sinfulness as such. Rather, one chooses a certain good. A man who steals a watch chooses to enjoy the watch; he accepts the injustice of taking what belongs to somebody else. Even in violations of the seventh and eighth modes of responsibility, where one does choose something bad (the destruction, damage, or impeding of a human good), one does not choose the sin as such. Rather, one accepts its sinfulness, while pursuing revenge or seeking, through violating some good, to attain some other good or avoid some evil (see S.t., 1–2, q. 73, a. 1; q. 78, a. 1).
There are exceptional cases in which someone does choose moral evil as a means to some ulterior end. For example, Hamlet thinks of avenging himself on the king at a time when the king is in sin, in order to send him to hell. A choice to do this would include sin in the proposal adopted. Similarly, a wife outraged by her husband’s adultery might choose to commit adultery to get even with him. In making this choice, she might include the very immorality of her own act in the proposal she adopts, for she can wish not only to make her husband suffer but even to wound the marital relationship itself.
2. To a person who is not conscious of living in a religious framework which embraces every choice, it seems that all or most morally evil acts are only violations of the dictates of reason. In the fallen human condition, however, consistent reasonableness is likely to seem pointless. For one thing, although being reasonable is a human good, it is only one good among others and it is incommensurable with the others. Furthermore, one may very well question the point of being always reasonable, for no matter how reasonable one is, one is faced with tension and conflict, disappointment and unfulfillment, suffering and death. This explains the Church’s teaching that apart from the light of faith and the help of grace, morally evil choices are inevitable (see DS 241/132, 383–85/186–88, 389/192, 391/194, 393/196).
3. Even one who considers the possibilities in a situation of temptation in the light of faith does not face a choice between God and the wrongly desired good. True, one fully realizes in the light of faith that every morally evil choice is an offense against God. But the choice is between the wrongly desired good and one’s actual, present relationship with God. This relationship is not God himself. It appeals to us as one human good among others, and usually we think that in sinning we will disrupt it only for the time being, not forever.6
4. Thus, when tempted to sin, we do not see our relationship with God as absolutely and in every respect a greater good than that which tempts us. In fact, here and now the relationship with God does not offer something promised by the tempting alternative. If it were otherwise, if the relationship with God were understood as being absolutely and in every respect better than anything else we might choose, there would be no choice, and sin would be impossible (see S.t., 2–2, q. 34, a. 1).
5. Although in sinning one does not choose the sin as such, still one does choose to do what is in fact sinful. How does one come to do this? If this question asks for the reason why one chooses sinfully rather than uprightly, no answer is possible, because one sins by free choice. But if the question asks only about the genesis of the sinful choice, the answer begins with sentient awareness and emotion. (This was considered in 7‑G.) Emotions, although good in themselves, are not in themselves rational, and these nonrational motivations can make sinful possibilities appealing (see S.t., 1–2, q. 75, a. 2).7 (The many ways in which they do this were described in chapter eight, where the modes of responsibility were articulated.)
6. Still, emotional appeal is not enough for choice. One only chooses what one understands as good in some respect. Thus, some aspect of intelligible goodness must be found in the possibility which emotion urges in its own nonrational way (see S.t., 1–2, q. 74, a. 4). But this is not difficult: Sinful possibilities always offer at least a certain realization of the good of self-integration, specifically the satisfaction of the emotional drive itself.
7. To the extent a possibility is sinful, however, its choice cannot be consistent with all the principles of practical reason (see 7‑F). Thus, by giving in to temptation one gains some aspect of self-integration at the expense of a certain self-mutilation. The peace, the temporary inner harmony, which comes in sinning is only an apparent good, for it blocks the attainment of a deeper and more inclusive self-integration (see S.t., 1–2, q. 75, a. 2).
8. In sum, one does not choose moral evil as such. Rather, one chooses to do that which is morally evil only by choosing a certain good and accepting the immorality of the choice as something accompanying it. Emotion promotes the morally excluded possibility, urging it on one’s attention and encouraging its acceptance. One who is tempted understands this possibility as offering a certain good—at least the experience of temporary inner peace which comes with emotional satisfaction. In a morally evil choice, however, such peace is only an apparent good. One satisfies part of oneself but sacrifices the more inclusive integration of one’s whole self.
6. In the case of mortal sin, one’s participation in divine life, which is more than a merely human good, also is implicitly at stake. But this fact is known only by faith, since grace does not present itself as something humanly fulfilling except insofar as it affects the human good of religion. Thus, only the latter appears directly threatened when one is tempted to commit a mortal sin.
7. See St. Thomas Aquinas, S.t., 1–2, q. 71, a. 2, esp. ad 3; in showing that every vice is against nature, he explains that emotion provides the natural foundation for the irrationality of sin. One might object that angels also can sin, and that Thomas elsewhere (S.c.g., 3, 109) suggests that human beings can sin as the angels do, by refusing to subordinate their proper good to divine goodness itself, which is the ultimate end. I think that Thomas is inconsistent in this matter. For in the same work (S.c.g., 3, 122) he holds that “we do not offend God except by doing something contrary to our own good.” To refuse to subordinate one’s proper good to divine goodness will not be contrary to our own good unless this subordination is essential for an immanent order constitutive of one’s proper good. But if ordering one’s proper good to God is essential to one’s proper good itself, then there can be no choice between standing in one’s proper good and ordering that good to God—the two are not genuine alternatives. So one will naturally love God more than oneself provided one does not violate one’s proper good, and Thomas teaches precisely this to be the case, both with respect to angels and human persons (S.t., 1, q. 60, a. 5). In dealing with the angels and with human persons in the condition of original justice, Thomas holds that sanctifying grace is required to order the created will to the supernatural end (S.t., 1, q. 62, a. 2; q. 95, a. 1). Here the subjection of human reason to God is a matter of grace, and one might suppose that sin in the case of the angel (and the parallel case for human persons) is simply a refusal of grace, without any immanent violation of a proper, natural good (cf. De malo, q. 16, a. 5). But there can be no choice without an alternative, and so if grace can be rejected without a violation of the natural good of the creature, then that good itself must be an alternative to grace; in that case, grace would not perfect nature, but annul it. I think that this inconsistency in Thomas underlies the unsatisfactory situation among Thomists on the sin of the angels. See Jacques Maritain, The Sin of the Angel (Westminster, Md.: Newman Press, 1959), v–vii; but his own resolution is inadequate, since he supposes (30) that in opting for God the proper good of the creature must be set aside and (90) that the violation in angelic sin is simply disobedience, for obedience is always required by nature. How, then, can angels sin? I think we must stop assuming that we know what angels are—simple spiritual substances. This is only a theological hypothesis. If we assume in them some complexity of nature, analogous to that of our own, then we can suppose that they might sin as we do, by preferring their own partial good. Supposing this, we no longer need suppose either that there can be an option with no genuine alternative or that grace is a genuine alternative to the perfection possible to finite persons according to their nature. Chapters twenty-four and twenty-five propose a resolution to the underlying difficulty about the distinction and unity in created persons of nature and grace.