Reply Obj. 1: The saying of the Philosopher must be understood as meaning that the intellect which is not in potentiality, does not know privation by privation existing in it; and this agrees with what he said previously, that a point and every indivisible thing are known by privation of division. This is because simple and indivisible forms are in our intellect not actually, but only potentially; for were they actually in our intellect, they would not be known by privation. It is thus that simple things are known by separate substances. God therefore knows evil, not by privation existing in Himself, but by the opposite good.
Reply Obj. 2: The knowledge of God is not the cause of evil; but is the cause of the good whereby evil is known.
Reply Obj. 3: Although evil is not opposed to the divine essence, which is not corruptible by evil; it is opposed to the effects of God, which He knows by His essence; and knowing them, He knows the opposite evils.
Reply Obj. 4: To know a thing by something else only, belongs to imperfect knowledge, if that thing is of itself knowable; but evil is not of itself knowable, forasmuch as the very nature of evil means the privation of good; therefore evil can neither be defined nor known except by good. _______________________
ELEVENTH ARTICLE [I, Q. 14, Art. 11]
Whether God Knows Singular Things?
Objection 1: It seems that God does not know singular things. For the divine intellect is more immaterial than the human intellect. Now the human intellect by reason of its immateriality does not know singular things; but as the Philosopher says (De Anima ii), "reason has to do with universals, sense with singular things." Therefore God does not know singular things.
Obj. 2: Further, in us those faculties alone know the singular, which
receive the species not abstracted from material conditions. But in
God things are in the highest degree abstracted from all materiality.
Therefore God does not know singular things.
Obj. 3: Further, all knowledge comes about through the medium of some likeness. But the likeness of singular things in so far as they are singular, does not seem to be in God; for the principle of singularity is matter, which, since it is in potentiality only, is altogether unlike God, Who is pure act. Therefore God cannot know singular things.
On the contrary, It is written (Prov. 16:2), "All the ways of a man are open to His eyes."