Article III: On the External Sin of Commission, Indirectly or in the Cause Voluntary

St. Thomas, I-II, q. 71, a. 6; q. 74, a. 2; De Malo, q. 2, a. 2 and 3.

422. What the external sin of commission is. - Sin of commission properly so called is not only the interior will of evil, but also an evil external work commanded by the will or not impeded, for example, homicide, theft, an external movement of anger: for the external act, although it does not have the notion of fault except from the will, nevertheless of itself has the notion of evil because it has deformity or discordance with right reason and the law of God, on account of undue matter or undue circumstances. Whence it also is prohibited by God: but everything which is prohibited by God is sin (and therefore to be declared in confession).

External sin is begun interiorly in affection when its cause is voluntarily placed, and is consummated exteriorly in effect when the external act is really present, in the same mode as was said concerning omission.

423. External sin can be voluntary in the cause or only indirectly. - For sin is an evil human act; whence, just as for a human act, so that an evil external work may be sin, it is required, but also suffices, that it be voluntary in some way. Therefore it is not required that it be voluntary in itself, but it suffices that it be voluntary in a positive cause (for example, anger from drunkenness), or indirectly in a preceding omission insofar as the will ought to prohibit it and does not do so (for example, damage from the fact that a father does not prohibit his son from stealing).

424. Question: Is actual advertence to malice required for sin? - The response is that from the aforesaid the question is easily solved: for sin some voluntary thing suffices, whether in the cause or indirect from omission; but for such a voluntary thing advertence at the moment at which such a cause or omission is placed suffices. Hence:

a) Actual advertence to malice is not always required here and now, that is, at the moment at which the external sin is consummated or the external act is effectively placed: for this is not required so that it may be voluntary, since evil effects or acts are rightly imputed to man which are placed with culpable inadvertence and proceed from a voluntary cause from which they are foreseen as going to follow, as from culpable ignorance on account of negligence (for example, damage to a sick person from a physician negligent in learning the things which he is bound to know), from a passion which someone deliberately wills to follow (for example, homicide from drunkenness or anger), from an evil habit (for example, blasphemy from custom), from voluntary inconsideration, as by acting precipitously (for example, a hunter negligent in considering whether a man or beast is present, and killing a man).

b) Nevertheless that inadvertence and the act placed with it will not be voluntary and culpable, unless at the moment at which the cause was placed there was actual advertence by which in some way the effect or evil act was foreseen at least confusedly, obscurely, and indistinctly, insofar as someone at least doubted or suspected that evil would follow, or knew the obligation of attending to it or of applying greater caution; otherwise they would in no way be voluntary. At this moment sin is begun interiorly and committed as to affection and fault.

From the explanation given, the opposed opinions of theologians are easily reconciled, of whom some always require actual advertence, while others, on the contrary, affirm that sometimes virtual and interpretative advertence suffices (n. 60, II and 63).