Thomas Aquinas, Disputed Questions on Truth (De Veritate)

1. It belongs to higher reason to cling to the eternal norms of conduct. Therefore, sin can be in it only in so far as it turns away from these eternal norms. But to turn away from them is a mortal sin. Therefore, there can be only mortal sin in higher reason.

2. Through contempt venial sin becomes mortal. But there seems to be contempt when one considers something to be evil and to be punished by God and, nevertheless, consents to commit it. Therefore, it seems that there is a mortal sin whenever one consents to the act even of a venial sin after the consideration of higher reason.

3. There is something in the soul, sensuality, in which there can be only venial sin, and something in which there can be venial and mortal sin, namely, lower reason. Therefore it seems that there is also something in the soul in which there can be only mortal sin. But this is not synderesis, because in that there is no sin. Therefore, this description fits higher reason.

4. In angels and in man in the state of innocence there could not be venial sin, because venial sin arises from the weakening of the flesh, and this did not then exist. But higher reason is apart from the weakening of the flesh. Therefore, there can be no venial sin in it.

To the Contrary:

1'. Consent to the act of sin is not more serious than the act of sin itself. But consent to the act of venial sin belongs to higher reason. Therefore so does venial sin.

2'. An unpremeditated movement of infidelity is a venial sin, and this takes place only in higher reason. Therefore, there is venial sin in it.

REPLY:

There can be venial and mortal sin in the higher part of reason. Nevertheless, there is some subject matter concerning which there can be only mortal sin in higher reason. This is plain in what follows. For higher reason has an act concerning some matter directly, that is, concerning eternal norms, and an act concerning some matter indirectly, that is, temporal norms, about which it judges according to eternal norms. With reference to its proper matter, eternal norms, it has a double act, one unpremeditated and one deliberate. But, since mortal sin is committed only after the act of deliberation, there can be venial sin in higher reason when there is an unpremeditated movement, and mortal when there is deliberate movement, as we see in the sin of infidelity. But it has only a deliberate act with reference to the matter of temporal things because it is directed to them only when it compares the eternal norms with them. Consequently, the act of higher reason will always be a mortal sin in this matter, if such matter is by nature a mortal sin. But, if it is by nature a venial sin, it will be venial, as is clear when one gives consent to an idle word.

Answers to Difficulties:

1. Higher reason sins in this, that it turns away from eternal norms not only by acting against them, but by acting outside them, which is a venial sin.

2. Not every contempt makes a sin mortal, but contempt of God. And through this alone man is turned away from God. But, when one consents to a venial sin after any deliberation, no matter how much, he does not have contempt of God, unless, perhaps, he would judge that the sin is contrary to a divine commandment. Thus, the conclusion does not follow.

3. That there can be only venial sin in sensuality comes from its imperfection. But reason is a perfect power and, therefore, there can be sin in it according to every difference of sin. For its act can be complete in any genus. Hence, if it is by nature a venial sin, it is venial; if it is by nature a mortal sin, it is mortal.

4. Although higher reason is not directly connected with the flesh, the weakening of the flesh reaches it, inasmuch as higher powers receive something from the lower powers.