Whether Sin Has an Internal Cause?
Objection 1: It would seem that sin has no internal cause. For that
which is within a thing is always in it. If therefore sin had an
internal cause, man would always be sinning, since given the cause,
the effect follows.
Obj. 2: Further, a thing is not its own cause. But the internal
movements of a man are sins. Therefore they are not the cause of sin.
Obj. 3: Further, whatever is within man is either natural or
voluntary. Now that which is natural cannot be the cause of sin, for
sin is contrary to nature, as Damascene states (De Fide Orth. ii, 3;
iv, 21); while that which is voluntary, if it be inordinate, is
already a sin. Therefore nothing intrinsic can be the cause of the
first sin.
_On the contrary,_ Augustine says (De Duabus Anim. x, 10, 11;
Retract. i, 9) that "the will is the cause of sin."
_I answer that,_ As stated above (A. 1), the direct cause of sin must
be considered on the part of the act. Now we may distinguish a
twofold internal cause of human acts, one remote, the other
proximate. The proximate internal cause of the human act is the
reason and will, in respect of which man has a free-will; while the
remote cause is the apprehension of the sensitive part, and also the
sensitive appetite. For just as it is due to the judgment of reason,
that the will is moved to something in accord with reason, so it is
due to an apprehension of the senses that the sensitive appetite is
inclined to something; which inclination sometimes influences the
will and reason, as we shall explain further on (Q. 77, A. 1).
Accordingly a double interior cause of sin may be assigned; one
proximate, on the part of the reason and will; and the other remote,
on the part of the imagination or sensitive appetite.
But since we have said above (A. 1, ad 3) that the cause of sin is
some apparent good as motive, yet lacking the due motive, viz. the
rule of reason or the Divine law, this motive which is an apparent
good, appertains to the apprehension of the senses and to the
appetite; while the lack of the due rule appertains to the reason,
whose nature it is to consider this rule; and the completeness of the
voluntary sinful act appertains to the will, so that the act of the
will, given the conditions we have just mentioned, is already a sin.
Reply Obj. 1: That which is within a thing as its natural power, is
always in it: but that which is within it, as the internal act of the
appetitive or apprehensive power, is not always in it. Now the power
of the will is the potential cause of sin, but is made actual by the
preceding movements, both of the sensitive part, in the first place,
and afterwards, of the reason. For it is because a thing is proposed
as appetible to the senses, and because the appetite is inclined,
that the reason sometimes fails to consider the due rule, so that the
will produces the act of sin. Since therefore the movements that
precede it are not always actual, neither is man always actually
sinning.
Reply Obj. 2: It is not true that all the internal acts belong to the
substance of sin, for this consists principally in the act of the
will; but some precede and some follow the sin itself.
Reply Obj. 3: That which causes sin, as a power produces its act, is
natural; and again, the movement of the sensitive part, from which
sin follows, is natural sometimes, as, for instance, when anyone sins
through appetite for food. Yet sin results in being unnatural from
the very fact that the natural rule fails, which man, in accord with
his nature, ought to observe.
________________________