Q: Whether the Sin of Consent to the Act Is in the Higher Reason?

A: On the contrary,
Augustine says (De Trin. xii, 12): "If the consent to the evil use of things that can be perceived by the bodily senses, so far approves of any sin, as to point, if possible, to its consummation by deed, we are to understand that the woman has offered the forbidden fruit to her husband."

I answer that,
Consent implies a judgment about the thing to which consent is given. For just as the speculative reason judges and delivers its sentence about intelligible matters, so the practical reason judges and pronounces sentence on matters of action. Now we must observe that in every case brought up for judgment, the final sentence belongs to the supreme court, even as we see that in speculative matters the final sentence touching any proposition is delivered by referring it to the first principles; since, so long as there remains a yet higher principle, the question can yet be submitted to it: wherefore the judgment is still in suspense, the final sentence not being as yet pronounced. But it is evident that human acts can be regulated by the rule of human reason, which rule is derived from the created things that man knows naturally; and further still, from the rule of the Divine law, as stated above (Q. 19, A. 4). Consequently, since the rule of the Divine law is the higher rule, it follows that the ultimate sentence, whereby the judgment is finally pronounced, belongs to the higher reason which is intent on the eternal types. Now when judgment has to be pronounced on several points, the final judgment deals with that which comes last; and, in human acts, the action itself comes last, and the delectation which is the inducement to the action is a preamble thereto. Therefore the consent to an action belongs properly to the higher reason, while the preliminary judgment which is about the delectation belongs to the lower reason, which delivers judgment in a lower court: although the higher reason can also judge of the delectation, since whatever is subject to the judgment of the lower court, is subject also to the judgment of the higher court, but not conversely.

Reply Obj. 1: Consent is an act of the appetitive power, not absolutely, but in consequence of an act of reason deliberating and judging, as stated above (Q. 15, A. 3). Because the fact that the consent is finally given to a thing is due to the fact that the will tends to that upon which the reason has already passed its judgment. Hence consent may be ascribed both to the will and to the reason.

Reply Obj. 2: The higher reason is said to consent, from the very fact that it fails to direct the human act according to the Divine law, whether or not it advert to the eternal law. For if it thinks of God's law, it holds it in actual contempt: and if not, it neglects it by a kind of omission. Therefore the consent to a sinful act always proceeds from the higher reason: because, as Augustine says (De Trin. xii, 12), "the mind cannot effectively decide on the commission of a sin, unless by its consent, whereby it wields its sovereign power of moving the members to action, or of restraining them from action, it become the servant or slave of the evil deed."

Reply Obj. 3: The higher reason, by considering the eternal law, can direct or restrain the internal delectation, even as it can direct or restrain the external action: nevertheless, before the judgment of the higher reason is pronounced the lower reason, while deliberating the matter in reference to temporal principles, sometimes approves of this delectation: and then the consent to the delectation belongs to the lower reason. If, however, after considering the eternal law, man persists in giving the same consent, such consent will then belong to the higher reason.

Reply Obj. 4: The apprehension of the power of imagination is sudden and indeliberate: wherefore it can cause an act before the higher or lower reason has time to deliberate. But the judgment of the lower reason is deliberate, and so requires time, during which the higher reason can also deliberate; consequently, if by its deliberation it does not check the sinful act, this will deservedly be imputed to it.