There appear to be only three important lines of argument against the conclusion reached in question E, that sins of weakness in grave matter of the third and fourth kinds always are mortal.

First, it can be argued that when sins of weakness and the need to struggle against them are considered in Scripture, in traditional pastoral practice, and in the recent teaching of the magisterium, the main point is to insist upon the necessity of the struggle and the inescapably grave guilt involved if one surrenders entirely—for example, refuses even during sober periods to seek help to overcome alcoholism. The question of the guilt of the sinner fighting the good fight but not yet winning is not directly confronted. Therefore, the argument concludes, nothing in these sources really shows that sins of weakness of the fourth type always are mortal sins. Sinners have been allowed to think of them as such, since this belief has helped them in their struggle, but the theoretical question remains open.

But this line of argument implies that past pastoral practice was based either on a mistake or on deception. Neither is acceptable. The faithful were told that the choice to do certain things, even under the pressure of strong emotion, is a mortal sin. The inability of the Church as a whole to mistake God’s mind and will, the certitude that what is bound on earth also is bound in heaven—this excludes mistake in a matter of this sort. A fortiori, deception is excluded; pastoral practice in the whole Church cannot have involved a noble lie told for the spiritual welfare of the faithful.

If surrender to such temptations in some circumstances were not mortal sin, Christian teaching could easily have made this fact clear, and Christians could have been reassured that consistent faithfulness during normal states of mind is sufficient for salvation. Such reassurance would remove much of the fear and trembling, much of the subjective concern, from Christian life. But the contrary of such reassurance seems to be given (see Lk 9.23; 13.24; 1 Cor 9.27; Phil 2.12; 3.12–16). Anxiety concerning salvation is opposed not by any such reassurance but rather by the assurance of hope: Since God is faithful, the seemingly impossible demands of Christian life can be met by human persons, weak in themselves but strong by the all-powerful Spirit (see Jn 14.10–18; 15.1–8; Rom 8.14–17).

A second line of argument arises from reflection upon pastoral experience in the light of modern thinking about the limits of human freedom and responsibility. Many quasi-compulsive sinners go through the cycle of sin and repentance time and again, sometimes in a very regular pattern through many years. Sound and pastorally experienced moral theologians have doubted for a long time that such sinners really are alternating repeatedly between mortal sin and grace. Even fairly soon after considering the statement of Pius XII, quoted in question E, they tended to exclude the likelihood of grave guilt in at least some cases of quasi-compulsive sin of weakness.⁹

The answer to this line of argument is threefold.

In the first place, modern thinking about the limits of freedom and responsibility does help us see that many acts involving grave matter do not involve sufficient reflection and a definite choice. But no psychological insight shows in the least that when one really does know—at the level of moral truth, not merely superego and social convention—that a matter is grave and when one really does choose to do it, one is not really determining oneself inconsistently with charity. Many theologians apparently confused two very different questions: (1) whether the usual conditions for mortal sin are met; (2) whether these conditions are sufficient for mortal sin. Psychology and experience can throw light on the first question but not the second.

Furthermore, some apparent quasi-compulsive sinners through weakness might not be committing repeated mortal sins, for the conditions might well not in fact be met, even if the sinners themselves think they are committing mortal sins. Others might not really be sinners through weakness; perhaps they have abandoned a serious struggle against sin, and carry out a pretense of struggle, putting up token resistance to temptation only to satisfy superego and social convention. Pastoral intuitions could reflect these facts without accurately interpreting them. Pastoral intuitions also could be mistaken. How can anyone know that a person cannot sin mortally and repent sincerely on a regular basis for years? Analogies with other interpersonal relationships do not necessarily hold for one’s relationship with God, since in other relationships one can be endlessly ambivalent without being insincere, whereas the relationship with God is susceptible to only limited ambivalence.¹⁰

Finally, perhaps some whose pastoral intuitions suggest to them that quasi-compulsive sinners through weakness cannot be guilty of grave sin are misled by a false assumption concerning the frustration experienced both by such sinners and by confessors committed to helping them. The false assumption is that the frustration is a sign of impossibility, and the impossibility a sign that the sin cannot be mortal. However, failure and frustration need not signify impossibility; perhaps they signify inadequately directed effort.

A third line of argument against the conclusion reached above is as follows. As has been explained (16‑G), the gravity of an act depends upon its inconsistency with specific implications of one’s act of faith. However, it is not easy to see how certain quasi-compulsive sins of weakness, committed as such, interfere with the life of the Church or with the carrying out of one’s Christian duties. A plausible argument can be made that any sexual sin, accepted as an integral part of one’s lifestyle, will have an impact incompatible with implications of faith. But, it might be suggested, at least certain quasi-compulsive sins of weakness, when specified to be the kinds of acts described in question D, should be considered light matter.

In considering this suggestion, one wonders what would happen if the Church were to teach that the specific kind of act chosen in a quasi-compulsive sin of weakness is light matter—for example, that when the act of fornication was chosen as fornication now to end temptation with repentance immediately afterwards it is not the matter of grave sin. One suspects this act would become very attractive, but many who tried to commit it would not in fact meet the conditions of quasi-compulsive sin of weakness.

Beyond this, there is an intrinsic reason why such acts should not be considered light matter. As has often been pointed out, classical modern moral theology was too interested in isolated acts and insufficiently aware of the profound dynamisms of moral life. If acts are considered in their context, one can more easily see why acts gravely wrong in kind must remain so even if they are chosen as quasi-compulsive sins of weakness.

The person who freely commits sexual sins in adolescence also phantasizes other sins, later continues to indulge such phantasy and begins to carry it out, approaches adulthood with adolescent attitudes toward sexuality, and never learns how to integrate sexual activity in sincere self-giving. The sexual sins of adults cannot be isolated from the sexual struggle of the adolescent, for the more obviously evil sexual sins of adulthood are an outgrowth of an inadequate or abandoned moral effort at an earlier stage. Thus, one must either maintain the entire traditional norm or accept its entire reversal; the dynamic unity of sexual life permits no middle position.