THIRD ARTICLE [I, Q. 15, Art. 3]
Whether There Are Ideas of All Things That God Knows?
Objection 1: It seems that there are not ideas in God of all things that He knows. For the idea of evil is not in God; since it would follow that evil was in Him. But evil things are known by God. Therefore there are not ideas of all things that God knows.
Obj. 2: Further, God knows things that neither are, nor will be, nor have been, as has been said above (A. 9). But of such things there are no ideas, since, as Dionysius says (Div. Nom. v): "Acts of the divine will are the determining and effective types of things." Therefore there are not in God ideas of all things known by Him.
Obj. 3: Further, God knows primary matter, of which there can be no idea, since it has no form. Hence the same conclusion.
Obj. 4: Further, it is certain that God knows not only species, but also genera, singulars, and accidents. But there are not ideas of these, according to Plato's teaching, who first taught ideas, as Augustine says (Octog. Tri. Quaest. qu. xlvi). Therefore there are not ideas in God of all things known by Him.
On the contrary, Ideas are types existing in the divine mind, as is clear from Augustine (Octog. Tri. Quaest. qu. xlvi). But God has the proper types of all things that He knows; and therefore He has ideas of all things known by Him.
I answer that, As ideas, according to Plato, are principles of the knowledge of things and of their generation, an idea has this twofold office, as it exists in the mind of God. So far as the idea is the principle of the making of things, it may be called an "exemplar," and belongs to practical knowledge. But so far as it is a principle of knowledge, it is properly called a "type," and may belong to speculative knowledge also. As an exemplar, therefore, it has respect to everything made by God in any period of time; whereas as a principle of knowledge it has respect to all things known by God, even though they never come to be in time; and to all things that He knows according to their proper type, in so far as they are known by Him in a speculative manner.
Reply Obj. 1: Evil is known by God not through its own type, but through the type of good. Evil, therefore, has no idea in God, neither in so far as an idea is an "exemplar" nor as a "type."
Reply Obj. 2: God has no practical knowledge, except virtually, of things which neither are, nor will be, nor have been. Hence, with respect to these there is no idea in God in so far as idea signifies an "exemplar" but only in so far as it denotes a "type."