Of the Cause of Sin, as Regards the Devil

Of the Cause of Sin, as Regards the Devil — St. Thomas Aquinas asks: Whether the devil is directly the cause of man's sinning?; Whether the devil can induce man to sin, by internal instigations?; Whether the devil can induce man to sin of necessity?; Whether all the sins of men are due to the devil's suggestion?.

We must now consider the cause of sin, as regards the devil; and under this head there are four points of inquiry:

Article 1: Whether the devil is directly the cause of man's sinning?

Augustine proves (De Lib. Arb. i, 11) that "nothing else than his own will makes man's mind the slave of his desire." Now man does not become a slave to his desires, except through sin. Therefore the cause of sin cannot be the devil, but man's own will alone.

Sin is an action: so that a thing can be directly the cause of sin, in the same way as anyone is directly the cause of an action; and this can only happen by moving that action's proper principle to act. Now the proper principle of a sinful action is the will, since every sin is voluntary. Consequently nothing can be directly the cause of sin, except that which can move the will to act.

Now the will, as stated above (), can be moved by two things: first by its object, inasmuch as the apprehended appetible is said to move the appetite: secondly by that agent which moves the will inwardly to will, and this is no other than the will itself, or God, as was shown above (). Now God cannot be the cause of sin, as stated above (). Therefore it follows that in this respect, a man's will alone is directly the cause of his sin.

As regards the object, a thing may be understood as moving the will in three ways. First, the object itself which is proposed to the will: thus we say that food arouses man's desire to eat. Secondly, he that proposes or offers this object. Thirdly, he that persuades the will that the object proposed has an aspect of good, because he also, in a fashion, offers the will its proper object, which is a real or apparent good of reason. Accordingly, in the first way the sensible things, which approach from without, move a man's will to sin. In the second and third ways, either the devil or a man may incite to sin, either by offering an object of appetite to the senses, or by persuading the reason. But in none of these three ways can anything be the direct cause of sin, because the will is not, of necessity, moved by any object except the last end, as stated above (). Consequently neither the thing offered from without, nor he that proposes it, nor he that persuades, is the sufficient cause of sin. Therefore it follows that the devil is a cause of sin, neither directly nor sufficiently, but only by persuasion, or by proposing the object of appetite.

Article 2: Whether the devil can induce man to sin, by internal instigations?

In that case, the devil would never tempt man, unless he appeared visibly; which is evidently false.

The interior part of the soul is intellective and sensitive; and the intellective part contains the intellect and the will. As regards the will, we have already stated (; ) what is the devil's relation thereto. Now the intellect, of its very nature, is moved by that which enlightens it in the knowledge of truth, which the devil has no intention of doing in man's regard; rather does he darken man's reason so that it may consent to sin, which darkness is due to the imagination and sensitive appetite. Consequently the operation of the devil seems to be confined to the imagination and sensitive appetite, by moving either of which he can induce man to sin. For his operation may result in presenting certain forms to the imagination; and he is able to incite the sensitive appetite to some passion or other.

The reason of this is, that as stated in the , the corporeal nature has a natural aptitude to be moved locally by the spiritual nature: so that the devil can produce all those effects which can result from the local movement of bodies here below, except he be restrained by the Divine power. Now the representation of forms to the imagination is due, sometimes, to local movement: for the Philosopher says (De Somno et Vigil.) [*De Insomn. iii, iv.] that "when an animal sleeps, the blood descends in abundance to the sensitive principle, and the movements descend with it, viz. the impressions left by the action of sensible objects, which impressions are preserved by means of sensible species, and continue to move the apprehensive principle, so that they appear just as though the sensitive principles were being affected by them at the time." Hence such a local movement of the vital spirits or humors can be procured by the demons, whether man sleep or wake: and so it happens that man's imagination is brought into play.

In like manner, the sensitive appetite is incited to certain passions according to certain fixed movements of the heart and the vital spirits: wherefore the devil can cooperate in this also. And through certain passions being aroused in the sensitive appetite, the result is that man more easily perceives the movement or sensible image which is brought in the manner explained, before the apprehensive principle, since, as the Philosopher observes (De Somno et Virgil.: De Insomn. iii, iv), "lovers are moved, by even a slight likeness, to an apprehension of the beloved." It also happens, through the rousing of a passion, that what is put before the imagination, is judged, as being something to be pursued, because, to him who is held by a passion, whatever the passion inclines him to, seems good. In this way the devil induces man inwardly to sin.

Article 3: Whether the devil can induce man to sin of necessity?

It is written (1 Pet. 5:8): "Your adversary the devil, as a roaring lion, goeth about seeking whom he may devour." Now it would be useless to admonish thus, if it were true that man were under the necessity of succumbing to the devil. Therefore he cannot induce man to sin of necessity.

Further, it is likewise written (Jam. 4:7): "Be subject . . . to God, but resist the devil, and he will fly from you," which would be said neither rightly nor truly, if the devil were able to compel us, in any way whatever, to sin; for then neither would it be possible to resist him, nor would he fly from those who do. Therefore he does not compel to sin.

The devil, by his own power, unless he be restrained by God, can compel anyone to do an act which, in its genus, is a sin; but he cannot bring about the necessity of sinning. This is evident from the fact that man does not resist that which moves him to sin, except by his reason; the use of which the devil is able to impede altogether, by moving the imagination and the sensitive appetite; as is the case with one who is possessed. But then, the reason being thus fettered, whatever man may do, it is not imputed to him as a sin. If, however, the reason is not altogether fettered, then, in so far as it is free, it can resist sin, as stated above (). It is consequently evident that the devil can nowise compel man to sin.

Article 4: Whether all the sins of men are due to the devil's suggestion?

It is written (De Eccl. Dogm. lxxxii): "Not all our evil thoughts are incited by the devil; sometimes they are due to a movement of the free-will."

the devil is the occasional and indirect cause of all our sins, in so far as he induced the first man to sin, by reason of whose sin human nature is so infected, that we are all prone to sin: even as the burning of wood might be imputed to the man who dried the wood so as to make it easily inflammable. He is not, however, the direct cause of all the sins of men, as though each were the result of his suggestion. Origen proves this (Peri Archon iii, 2) from the fact that even if the devil were no more, men would still have the desire for food, sexual pleasures and the like; which desire might be inordinate, unless it were subordinate to reason, a matter that is subject to the free-will.