Article 3. Whether sin has an external cause?

Objection 1. It would seem that sin has no external cause. For sin is a voluntary act. Now voluntary acts belong to principles that are within us, so that they have no external cause. Therefore sin has no external cause.

Objection 2. Further, as nature is an internal principle, so is the will. Now in natural things sin can be due to no other than an internal cause; for instance, the birth of a monster is due to the corruption of some internal principle. Therefore in the moral order, sin can arise from no other than an internal cause. Therefore it has no external cause.

Objection 3. Further, if the cause is multiplied, the effect is multiplied. Now the more numerous and weighty the external inducements to sin are, the less is a man’s inordinate act imputed to him as a sin. Therefore nothing external is a cause of sin.

On the contrary, It is written (Numbers 21:16): “Are not these they, that deceived the children of Israel by the counsel of Balaam, and made you transgress against the Lord by the sin of Phogor?” Therefore something external can be a cause of sin.

I answer that, As stated above (Article 2), the internal cause of sin is both the will, as completing the sinful act, and the reason, as lacking the due rule, and the appetite, as inclining to sin. Accordingly something external might be a cause of sin in three ways, either by moving the will itself immediately, or by moving the reason, or by moving the sensitive appetite. Now, as stated above (I-II:9:6; I-II:10:4), none can move the will inwardly save God alone, who cannot be a cause of sin, as we shall prove further on (I-II:79:1. Hence it follows that nothing external can be a cause of sin, except by moving the reason, as a man or devil by enticing to sin; or by moving the sensitive appetite, as certain external sensibles move it. Yet neither does external enticement move the reason, of necessity, in matters of action, nor do things proposed externally, of necessity move the sensitive appetite, except perhaps it be disposed thereto in a certain way; and even the sensitive appetite does not, of necessity, move the reason and will. Therefore something external can be a cause moving to sin, but not so as to be a sufficient cause thereof: and the will alone is the sufficient completive cause of sin being accomplished.

Reply to Objection 1. From the very fact that the external motive causes of sin do not lead to sin sufficiently and necessarily, it follows that it remains in our power to sin or not to sin.

Reply to Objection 2. The fact that sin has an internal cause does not prevent its having an external cause; for nothing external is a cause of sin, except through the medium of the internal cause, as stated.

Reply to Objection 3. If the external causes inclining to sin be multiplied, the sinful acts are multiplied, because they incline to the sinful act in both greater numbers and greater frequency. Nevertheless the character of guilt is lessened, since this depends on the act being voluntary and in our power.

Article 4. Whether one sin is a cause of another?

Objection 1. It would seem that one sin cannot be the cause of another. For there are four kinds of cause, none of which will fit in with one sin causing another. Because the end has the character of good; which is inconsistent with sin, which has the character of evil. In like manner neither can a sin be an efficient cause, since “evil is not an efficient cause, but is weak and powerless,” as Dionysius declares (Div. Nom. iv). The material and formal cause seems to have no place except in natural bodies, which are composed of matter and form. Therefore sin cannot have either a material or a formal cause.

Objection 2. Further, “to produce its like belongs to a perfect thing,” as stated in Meteor. iv, 2 [Cf. De Anima ii.]. But sin is essentially something imperfect. Therefore one sin cannot be a cause of another.

Objection 3. Further, if one sin is the cause of a second sin, in the same way, yet another sin will be the cause of the first, and thus we go on indefinitely, which is absurd. Therefore one sin is not the cause of another.

On the contrary, Gregory says on Ezechiel (Hom. xi): “A sin that is not quickly blotted out by repentance, is both a sin and a cause of sin.”

I answer that, Forasmuch as a sin has a cause on the part of the act of sin, it is possible for one sin to be the cause of another, in the same way as one human act is the cause of another. Hence it happens that one sin may be the cause of another in respect of the four kinds of causes. First, after the manner of an efficient or moving cause, both directly and indirectly. Indirectly, as that which removes an impediment is called an indirect cause of movement: for when man, by one sinful act, loses grace, or charity, or shame, or anything else that withdraws him from sin, he thereby falls into another sin, so that the first sin is the accidental cause of the second. Directly, as when, by one sinful act, man is disposed to commit more readily another like act: because acts cause dispositions and habits inclining to like acts. Secondly, after the manner of a material cause, one sin is the cause of another, by preparing its matter: thus covetousness prepares the matter for strife, which is often about the wealth a man has amassed together. Thirdly, after the manner of a final cause, one sin causes another, in so far as a man commits one sin for the sake of another which is his end; as when a man is guilty of simony for the end of ambition, or fornication for the purpose of theft. And since the end gives the form to moral matters, as stated above (I-II:1:3; Question 18, Articles 4 and 6), it follows that one sin is also the formal cause of another: because in the act of fornication committed for the purpose of theft, the former is material while the latter is formal.

Reply to Objection 1. Sin, in so far as it is inordinate, has the character of evil; but, in so far as it is an act, it has some good, at least apparent, for its end: so that, as an act, but not as being inordinate, it can be the cause, both final and efficient, of another sin. A sin has matter, not “of which” but “about which” it is: and it has its form from its end. Consequently one sin can be the cause of another, in respect of the four kinds of cause, as stated above.

Reply to Objection 2. Sin is something imperfect on account of its moral imperfection on the part of its inordinateness. Nevertheless, as an act it can have natural perfection: and thus it can be the cause of another sin.

Reply to Objection 3. Not every cause of one sin is another sin; so there is no need to go on indefinitely: for one may come to one sin which is not caused by another sin.

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