); it is evident that when ignorance causes an act to be
involuntary, it takes away the character of moral good and evil; but
not, when it does not cause the act to be involuntary. Again, it has
been stated above (Q. 6, A. 8) that when ignorance is in any way
willed, either directly or indirectly, it does not cause the act to
be involuntary. And I call that ignorance "directly" voluntary, to
which the act of the will tends: and that, "indirectly" voluntary,
which is due to negligence, by reason of a man not wishing to know
what he ought to know, as stated above (Q. 6, A. 8).

If then reason or conscience err with an error that is voluntary,
either directly, or through negligence, so that one errs about what
one ought to know; then such an error of reason or conscience does
not excuse the will, that abides by that erring reason or conscience,
from being evil. But if the error arise from ignorance of some
circumstance, and without any negligence, so that it cause the act to
be involuntary, then that error of reason or conscience excuses the
will, that abides by that erring reason, from being evil. For
instance, if erring reason tell a man that he should go to another
man's wife, the will that abides by that erring reason is evil; since
this error arises from ignorance of the Divine Law, which he is bound
to know. But if a man's reason, errs in mistaking another for his
wife, and if he wish to give her her right when she asks for it, his
will is excused from being evil: because this error arises from
ignorance of a circumstance, which ignorance excuses, and causes the
act to be involuntary.

Reply Obj. 1: As Dionysius says (Div. Nom. iv), "good results from
the entire cause, evil from each particular defect." Consequently in
order that the thing to which the will tends be called evil, it
suffices, either that it be evil in itself, or that it be apprehended
as evil. But in order for it to be good, it must be good in both ways.

Reply Obj. 2: The eternal law cannot err, but human reason can.
Consequently the will that abides by human reason, is not always
right, nor is it always in accord with the eternal law.

Reply Obj. 3: Just as in syllogistic arguments, granted one
absurdity, others must needs follow; so in moral matters, given one
absurdity, others must follow too. Thus suppose a man to seek
vainglory, he will sin, whether he does his duty for vainglory or
whether he omit to do it. Nor is he in a dilemma about the