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.
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 (Q. 10, AA.
1, 2). 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.
Reply Obj. 1: All these, and other like authorities, if we meet with
them, are to be understood as denoting that the devil induces man to
affection for a sin, either by suggesting to him, or by offering him
objects of appetite.
Reply Obj. 2: This comparison is true in so far as the devil is
somewhat the cause of our sins, even as God is in a certain way the
cause of our good actions, but does not extend to the mode of
causation: for God causes good things in us by moving the will
inwardly, whereas the devil cannot move us in this way.
Reply Obj. 3: God is the universal principle of all inward movements
of man; but that the human will be determined to an evil counsel, is
directly due to the human will, and to the devil as persuading or
offering the object of appetite.
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