ction on the part of its inordinateness. Nevertheless, as an
act it can have natural perfection: and thus it can be the cause of
another sin.

Reply Obj. 3: Not every cause of one sin is another sin; so there is
no need to go on indefinitely: for one may come to one sin which is
not caused by another sin.
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QUESTION 76

OF THE CAUSES OF SIN, IN PARTICULAR
(In Four Articles)

We must now consider the causes of sin, in particular, and (1) The
internal causes of sin; (2) its external causes; and (3) sins which
are the causes of other sins. In view of what has been said above (A.
2), the first consideration will be threefold: so that in the first
place we shall treat of ignorance, which is the cause of sin on the
part of reason; secondly, of weakness or passion, which is the cause
of sin on the part of the sensitive appetite; thirdly, of malice,
which is the cause of sin on the part of the will.

Under the first head, there are four points of inquiry:

(1) Whether ignorance is a cause of sin?

(2) Whether ignorance is a sin?

(3) Whether it excuses from sin altogether?

(4) Whether it diminishes sin?
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FIRST ARTICLE [I-II, Q. 76, Art. 1]

Whether Ignorance Can Be a Cause of Sin?

Objection 1: It would seem that ignorance cannot be a cause of sin:
because a non-being is not the cause of anything. Now ignorance is a
non-being, since it is a privation of knowledge. Therefore ignorance
is not a cause of sin.

Obj. 2: Further, causes of sin should be reckoned in respect of sin
being a _turning to_ something, as was stated above (Q. 75, A. 1).
Now ignorance seems to savor of _turning away_ from something.
Therefore it should not be reckoned a cause of sin.

Obj. 3: Further, every sin is seated in the will. Now the will does
not turn to that which is not known, because its object is the good
apprehended. Therefore ignorance cannot be a cause of sin.

_On the contrary,_ Augustine says (De Nat. et Grat. lxvii) "that some
sin through ignorance."

_I answer that,_ According to the Philosopher (Phys. viii, 27) a
moving cause is twofold, direct and indirect. A direct cause is one
that moves by its own power, as the generator is the moving cause of
heavy and light things. An indirect cause, is either one that removes
an impediment, or the removal itself of an impediment: and it is in
this way that ignorance can be the cause of a sinful act; because it
is a privation