Reply Obj. 4:  Evil of fault must not be done, that good may ensue; but evil of punishment must be inflicted for the sake of good. ________________________

QUESTION 80

OF THE CAUSE OF SIN, AS REGARDS THE DEVIL
(In Four Articles)

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

(1) Whether the devil is directly the cause of sin?

(2) Whether the devil induces us to sin, by persuading us inwardly?

(3) Whether he can make us sin of necessity?

(4) Whether all sins are due to the devil’s suggestion?
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FIRST ARTICLE [I-II, Q. 80, Art. 1]

Whether the Devil Is Directly the Cause of Man’s Sinning?

Objection 1:  It would seem that the devil is directly the cause of man’s sinning.  For sin consists directly in an act of the appetite.  Now Augustine says (De Trin. iv, 12) that “the devil inspires his friends with evil desires”; and Bede, commenting on Acts 5:3, says that the devil “draws the mind to evil desires”; and Isidore says (De Summo Bono ii, 41; iii, 5) that the devil “fills men’s hearts with secret lusts.”  Therefore the devil is directly the cause of sin.

Obj. 2:  Further, Jerome says (Contra Jovin. ii, 2) that “as God is the perfecter of good, so is the devil the perfecter of evil.”  But God is directly the cause of our good.  Therefore the devil is directly the cause of our sins.

Obj. 3:  Further, the Philosopher says in a chapter of the Eudeme[a]n Ethics (vii, 18):  “There must needs be some extrinsic principle of human counsel.”  Now human counsel is not only about good things but also about evil things.  Therefore, as God moves man to take good counsel, and so is the cause of good, so the devil moves him to take evil counsel, and consequently is directly the cause of sin.

On the contrary, 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.

I answer that, 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 (Q. 9, AA. 3, 4, 6), 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 (Q. 9, AA. 3, 4, 6).  Now God cannot be the cause of sin, as stated above (Q. 79, A. 1).  Therefore it follows that in this respect, a man’s will alone is directly the cause of his sin.