Summa Theologica

Objection 1: It seems that the knowledge of God is not the cause of things. For Origen says, on Rom. 8:30, "Whom He called, them He also justified," etc.: "A thing will happen not because God knows it as future; but because it is future, it is on that account known by God, before it exists."

Objection 2: Further, given the cause, the effect follows. But the knowledge of God is eternal. Therefore if the knowledge of God is the cause of things created, it seems that creatures are eternal.

Objection 3: Further, "The thing known is prior to knowledge, and is its measure," as the Philosopher says (Metaph. x). But what is posterior and measured cannot be a cause. Therefore the knowledge of God is not the cause of things.

On the contrary, Augustine says (De Trin. xv), "Not because they are, does God know all creatures spiritual and temporal, but because He knows them, therefore they are."

I answer that, The knowledge of God is the cause of things. For the knowledge of God is to all creatures what the knowledge of the artificer is to things made by his art. Now the knowledge of the artificer is the cause of the things made by his art from the fact that the artificer works by his intellect. Hence the form of the intellect must be the principle of action; as heat is the principle of heating. Nevertheless, we must observe that a natural form, being a form that remains in that to which it gives existence, denotes a principle of action according only as it has an inclination to an effect; and likewise, the intelligible form does not denote a principle of action in so far as it resides in the one who understands unless there is added to it the inclination to an effect, which inclination is through the will. For since the intelligible form has a relation to opposite things (inasmuch as the same knowledge relates to opposites), it would not produce a determinate effect unless it were determined to one thing by the appetite, as the Philosopher says (Metaph. ix). Now it is manifest that God causes things by His intellect, since His being is His act of understanding; and hence His knowledge must be the cause of things, in so far as His will is joined to it. Hence the knowledge of God as the cause of things is usually called the "knowledge of approbation."

Reply to Objection 1: Origen spoke in reference to that aspect of knowledge to which the idea of causality does not belong unless the will is joined to it, as is said above.

But when he says the reason why God foreknows some things is because they are future, this must be understood according to the cause of consequence, and not according to the cause of essence. For if things are in the future, it follows that God knows them; but not that the futurity of things is the cause why God knows them.

Reply to Objection 2: The knowledge of God is the cause of things according as things are in His knowledge. Now that things should be eternal was not in the knowledge of God; hence although the knowledge of God is eternal, it does not follow that creatures are eternal.

Reply to Objection 3: Natural things are midway between the knowledge of God and our knowledge: for we receive knowledge from natural things, of which God is the cause by His knowledge. Hence, as the natural objects of knowledge are prior to our knowledge, and are its measure, so, the knowledge of God is prior to natural things, and is the measure of them; as, for instance, a house is midway between the knowledge of the builder who made it, and the knowledge of the one who gathers his knowledge of the house from the house already built.

Objection 1: It seems that God has not knowledge of things that are not. For the knowledge of God is of true things. But "truth" and "being" are convertible terms. Therefore the knowledge of God is not of things that are not.

Objection 2: Further, knowledge requires likeness between the knower and the thing known. But those things that are not cannot have any likeness to God, Who is very being. Therefore what is not, cannot be known by God.

Objection 3: Further, the knowledge of God is the cause of what is known by Him. But it is not the cause of things that are not, because a thing that is not, has no cause. Therefore God has no knowledge of things that are not.

On the contrary, The Apostle says: "Who... calleth those things that are not as those that are" (Rom. 4:17).

I answer that, God knows all things whatsoever that in any way are. Now it is possible that things that are not absolutely, should be in a certain sense. For things absolutely are which are actual; whereas things which are not actual, are in the power either of God Himself or of a creature, whether in active power, or passive; whether in power of thought or of imagination, or of any other manner of meaning whatsoever. Whatever therefore can be made, or thought, or said by the creature, as also whatever He Himself can do, all are known to God, although they are not actual. And in so far it can be said that He has knowledge even of things that are not.

Now a certain difference is to be noted in the consideration of those things that are not actual. For though some of them may not be in act now, still they were, or they will be; and God is said to know all these with the knowledge of vision: for since God's act of understanding, which is His being, is measured by eternity; and since eternity is without succession, comprehending all time, the present glance of God extends over all time, and to all things which exist in any time, as to objects present to Him. But there are other things in God's power, or the creature's, which nevertheless are not, nor will be, nor were; and as regards these He is said to have knowledge, not of vision, but of simple intelligence. This is so called because the things we see around us have distinct being outside the seer.

Reply to Objection 1: Those things that are not actual are true in so far as they are in potentiality; for it is true that they are in potentiality; and as such they are known by God.

Reply to Objection 2: Since God is very being everything is, in so far as it participates in the likeness of God; as everything is hot in so far as it participates in heat. So, things in potentiality are known by God, although they are not in act.

Reply to Objection 3: The knowledge of God, joined to His will is the cause of things. Hence it is not necessary that what ever God knows, is, or was, or will be; but only is this necessary as regards what He wills to be, or permits to be. Further, it is in the knowledge of God not that they be, but that they be possible.

Objection 1: It seems that God does not know evil things. For the Philosopher (De Anima iii) says that the intellect which is not in potentiality does not know privation. But "evil is the privation of good," as Augustine says (Confess. iii, 7). Therefore, as the intellect of God is never in potentiality, but is always in act, as is clear from the foregoing (A[2]), it seems that God does not know evil things.

Objection 2: Further, all knowledge is either the cause of the thing known, or is caused by it. But the knowledge of God is not the cause of evil, nor is it caused by evil. Therefore God does not know evil things.

Objection 3: Further, everything known is known either by its likeness, or by its opposite. But whatever God knows, He knows through His essence, as is clear from the foregoing(A[5]). Now the divine essence neither is the likeness of evil, nor is evil contrary to it; for to the divine essence there is no contrary, as Augustine says (De Civ. Dei xii). Therefore God does not know evil things.

Objection 4: Further, what is known through another and not through itself, is imperfectly known. But evil is not known by God; for the thing known must be in the knower. Therefore if evil is known through another, namely, through good, it would be known by Him imperfectly; which cannot be, for the knowledge of God is not imperfect. Therefore God does not know evil things.

On the contrary, It is written (Prov. 15:11), "Hell and destruction are before God [Vulg: 'the Lord']."

I answer that, Whoever knows a thing perfectly, must know all that can be accidental to it. Now there are some good things to which corruption by evil may be accidental. Hence God would not know good things perfectly, unless He also knew evil things. Now a thing is knowable in the degree in which it is; hence since this is the essence of evil that it is the privation of good, by the fact that God knows good things, He knows evil things also; as by light is known darkness. Hence Dionysius says (Div. Nom. vii): "God through Himself receives the vision of darkness, not otherwise seeing darkness except through light."

Reply to Objection 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 to Objection 2: The knowledge of God is not the cause of evil; but is the cause of the good whereby evil is known.

Reply to Objection 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 to Objection 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.

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.

Objection 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.

Objection 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."

I answer that, God knows singular things. For all perfections found in creatures pre-exist in God in a higher way, as is clear from the foregoing (Q[4], A[2]). Now to know singular things is part of our perfection. Hence God must know singular things. Even the Philosopher considers it incongruous that anything known by us should be unknown to God; and thus against Empedocles he argues (De Anima i and Metaph. iii) that God would be most ignorant if He did not know discord. Now the perfections which are divided among inferior beings, exist simply and unitedly in God; hence, although by one faculty we know the universal and immaterial, and by another we know singular and material things, nevertheless God knows both by His simple intellect.

Now some, wishing to show how this can be, said that God knows singular things by universal causes. For nothing exists in any singular thing, that does not arise from some universal cause. They give the example of an astrologer who knows all the universal movements of the heavens, and can thence foretell all eclipses that are to come. This, however, is not enough; for singular things from universal causes attain to certain forms and powers which, however they may be joined together, are not individualized except by individual matter. Hence he who knows Socrates because he is white, or because he is the son of Sophroniscus, or because of something of that kind, would not know him in so far as he is this particular man. Hence according to the aforesaid mode, God would not know singular things in their singularity.

On the other hand, others have said that God knows singular things by the application of universal causes to particular effects. But this will not hold; forasmuch as no one can apply a thing to another unless he first knows that thing; hence the said application cannot be the reason of knowing the particular, for it presupposes the knowledge of singular things.

Therefore it must be said otherwise, that, since God is the cause of things by His knowledge, as stated above(A[8]), His knowledge extends as far as His causality extends. Hence as the active power of God extends not only to forms, which are the source of universality, but also to matter, as we shall prove further on (Q[44], A[2]), the knowledge of God must extend to singular things, which are individualized by matter. For since He knows things other than Himself by His essence, as being the likeness of things, or as their active principle, His essence must be the sufficing principle of knowing all things made by Him, not only in the universal, but also in the singular. The same would apply to the knowledge of the artificer, if it were productive of the whole thing, and not only of the form.

Reply to Objection 1: Our intellect abstracts the intelligible species from the individualizing principles; hence the intelligible species in our intellect cannot be the likeness of the individual principles; and on that account our intellect does not know the singular. But the intelligible species in the divine intellect, which is the essence of God, is immaterial not by abstraction, but of itself, being the principle of all the principles which enter into the composition of things, whether principles of the species or principles of the individual; hence by it God knows not only universal, but also singular things.

Reply to Objection 2: Although as regards the species in the divine intellect its being has no material conditions like the images received in the imagination and sense, yet its power extends to both immaterial and material things.

Reply to Objection 3: Although matter as regards its potentiality recedes from likeness to God, yet, even in so far as it has being in this wise, it retains a certain likeness to the divine being.

Objection 1: It seems that God cannot know infinite things. For the infinite, as such, is unknown; since the infinite is that which, "to those who measure it, leaves always something more to be measured," as the Philosopher says (Phys. iii). Moreover, Augustine says (De Civ. Dei xii) that "whatever is comprehended by knowledge, is bounded by the comprehension of the knower." Now infinite things have no boundary. Therefore they cannot be comprehended by the knowledge of God.

Objection 2: Further, if we say that things infinite in themselves are finite in God's knowledge, against this it may be urged that the essence of the infinite is that it is untraversable, and the finite that it is traversable, as said in Phys. iii. But the infinite is not traversable either by the finite or by the infinite, as is proved in Phys. vi. Therefore the infinite cannot be bounded by the finite, nor even by the infinite; and so the infinite cannot be finite in God's knowledge, which is infinite.

Objection 3: Further, the knowledge of God is the measure of what is known. But it is contrary to the essence of the infinite that it be measured. Therefore infinite things cannot be known by God.

On the contrary, Augustine says (De Civ. Dei xii), "Although we cannot number the infinite, nevertheless it can be comprehended by Him whose knowledge has no bounds."

I answer that, Since God knows not only things actual but also things possible to Himself or to created things, as shown above(A[9]), and as these must be infinite, it must be held that He knows infinite things. Although the knowledge of vision which has relation only to things that are, or will be, or were, is not of infinite things, as some say, for we do not say that the world is eternal, nor that generation and movement will go on for ever, so that individuals be infinitely multiplied; yet, if we consider more attentively, we must hold that God knows infinite things even by the knowledge of vision. For God knows even the thoughts and affections of hearts, which will be multiplied to infinity as rational creatures go on for ever.

The reason of this is to be found in the fact that the knowledge of every knower is measured by the mode of the form which is the principle of knowledge. For the sensible image in sense is the likeness of only one individual thing, and can give the knowledge of only one individual. But the intelligible species of our intellect is the likeness of the thing as regards its specific nature, which is participable by infinite particulars; hence our intellect by the intelligible species of man in a certain way knows infinite men; not however as distinguished from each other, but as communicating in the nature of the species; and the reason is because the intelligible species of our intellect is the likeness of man not as to the individual principles, but as to the principles of the species. On the other hand, the divine essence, whereby the divine intellect understands, is a sufficing likeness of all things that are, or can be, not only as regards the universal principles, but also as regards the principles proper to each one, as shown above. Hence it follows that the knowledge of God extends to infinite things, even as distinct from each other.

Reply to Objection 1: The idea of the infinite pertains to quantity, as the Philosopher says (Phys. i). But the idea of quantity implies the order of parts. Therefore to know the infinite according to the mode of the infinite is to know part after part; and in this way the infinite cannot be known; for whatever quantity of parts be taken, there will always remain something else outside. But God does not know the infinite or infinite things, as if He enumerated part after part; since He knows all things simultaneously, and not successively, as said above(A[7]). Hence there is nothing to prevent Him from knowing infinite things.

Reply to Objection 2: Transition imports a certain succession of parts; and hence it is that the infinite cannot be traversed by the finite, nor by the infinite. But equality suffices for comprehension, because that is said to be comprehended which has nothing outside the comprehender. Hence it is not against the idea of the infinite to be comprehended by the infinite. And so, what is infinite in itself can be called finite to the knowledge of God as comprehended; but not as if it were traversable.

Reply to Objection 3: The knowledge of God is the measure of things, not quantitatively, for the infinite is not subject to this kind of measure; but it is the measure of the essence and truth of things. For everything has truth of nature according to the degree in which it imitates the knowledge of God, as the thing made by art agrees with the art. Granted, however, an actually infinite number of things, for instance, an infinitude of men, or an infinitude in continuous quantity, as an infinitude of air, as some of the ancients held; yet it is manifest that these would have a determinate and finite being, because their being would be limited to some determinate nature. Hence they would be measurable as regards the knowledge of God.

Objection 1: It seems that the knowledge of God is not of future contingent things. For from a necessary cause proceeds a necessary effect. But the knowledge of God is the cause of things known, as said above(A[8]). Since therefore that knowledge is necessary, what He knows must also be necessary. Therefore the knowledge of God is not of contingent things.

Objection 2: Further, every conditional proposition of which the antecedent is absolutely necessary must have an absolutely necessary consequent. For the antecedent is to the consequent as principles are to the conclusion: and from necessary principles only a necessary conclusion can follow, as is proved in Poster. i. But this is a true conditional proposition, "If God knew that this thing will be, it will be," for the knowledge of God is only of true things. Now the antecedent conditional of this is absolutely necessary, because it is eternal, and because it is signified as past. Therefore the consequent is also absolutely necessary. Therefore whatever God knows, is necessary; and so the knowledge of God is not of contingent things.

Objection 3: Further, everything known by God must necessarily be, because even what we ourselves know, must necessarily be; and, of course, the knowledge of God is much more certain than ours. But no future contingent things must necessarily be. Therefore no contingent future thing is known by God.

On the contrary, It is written (Ps. 32:15), "He Who hath made the hearts of every one of them; Who understandeth all their works," i.e. of men. Now the works of men are contingent, being subject to free will. Therefore God knows future contingent things.

I answer that, Since as was shown above(A[9]), God knows all things; not only things actual but also things possible to Him and creature; and since some of these are future contingent to us, it follows that God knows future contingent things.

In evidence of this, we must consider that a contingent thing can be considered in two ways; first, in itself, in so far as it is now in act: and in this sense it is not considered as future, but as present; neither is it considered as contingent (as having reference) to one of two terms, but as determined to one; and on account of this it can be infallibly the object of certain knowledge, for instance to the sense of sight, as when I see that Socrates is sitting down. In another way a contingent thing can be considered as it is in its cause; and in this way it is considered as future, and as a contingent thing not yet determined to one; forasmuch as a contingent cause has relation to opposite things: and in this sense a contingent thing is not subject to any certain knowledge. Hence, whoever knows a contingent effect in its cause only, has merely a conjectural knowledge of it. Now God knows all contingent things not only as they are in their causes, but also as each one of them is actually in itself. And although contingent things become actual successively, nevertheless God knows contingent things not successively, as they are in their own being, as we do but simultaneously. The reason is because His knowledge is measured by eternity, as is also His being; and eternity being simultaneously whole comprises all time, as said above (Q[10], A[2]). Hence all things that are in time are present to God from eternity, not only because He has the types of things present within Him, as some say; but because His glance is carried from eternity over all things as they are in their presentiality. Hence it is manifest that contingent things are infallibly known by God, inasmuch as they are subject to the divine sight in their presentiality; yet they are future contingent things in relation to their own causes.

Reply to Objection 1: Although the supreme cause is necessary, the effect may be contingent by reason of the proximate contingent cause; just as the germination of a plant is contingent by reason of the proximate contingent cause, although the movement of the sun which is the first cause, is necessary. So likewise things known by God are contingent on account of their proximate causes, while the knowledge of God, which is the first cause, is necessary.

Reply to Objection 2: Some say that this antecedent, "God knew this contingent to be future," is not necessary, but contingent; because, although it is past, still it imports relation to the future. This however does not remove necessity from it; for whatever has had relation to the future, must have had it, although the future sometimes does not follow. On the other hand some say that this antecedent is contingent, because it is a compound of necessary and contingent; as this saying is contingent, "Socrates is a white man." But this also is to no purpose; for when we say, "God knew this contingent to be future," contingent is used here only as the matter of the word, and not as the chief part of the proposition. Hence its contingency or necessity has no reference to the necessity or contingency of the proposition, or to its being true or false. For it may be just as true that I said a man is an ass, as that I said Socrates runs, or God is: and the same applies to necessary and contingent. Hence it must be said that this antecedent is absolutely necessary. Nor does it follow, as some say, that the consequent is absolutely necessary, because the antecedent is the remote cause of the consequent, which is contingent by reason of the proximate cause. But this is to no purpose. For the conditional would be false were its antecedent the remote necessary cause, and the consequent a contingent effect; as, for example, if I said, "if the sun moves, the grass will grow."

Therefore we must reply otherwise; that when the antecedent contains anything belonging to an act of the soul, the consequent must be taken not as it is in itself, but as it is in the soul: for the existence of a thing in itself is different from the existence of a thing in the soul. For example, when I say, "What the soul understands is immaterial," this is to be understood that it is immaterial as it is in the intellect, not as it is in itself. Likewise if I say, "If God knew anything, it will be," the consequent must be understood as it is subject to the divine knowledge, i.e. as it is in its presentiality. And thus it is necessary, as also is the antecedent: "For everything that is, while it is, must be necessarily be," as the Philosopher says in Peri Herm. i.

Reply to Objection 3: Things reduced to act in time, as known by us successively in time, but by God (are known) in eternity, which is above time. Whence to us they cannot be certain, forasmuch as we know future contingent things as such; but (they are certain) to God alone, whose understanding is in eternity above time. Just as he who goes along the road, does not see those who come after him; whereas he who sees the whole road from a height, sees at once all travelling by the way. Hence what is known by us must be necessary, even as it is in itself; for what is future contingent in itself, cannot be known by us. Whereas what is known by God must be necessary according to the mode in which they are subject to the divine knowledge, as already stated, but not absolutely as considered in their own causes. Hence also this proposition, "Everything known by God must necessarily be," is usually distinguished; for this may refer to the thing, or to the saying. If it refers to the thing, it is divided and false; for the sense is, "Everything which God knows is necessary." If understood of the saying, it is composite and true; for the sense is, "This proposition, 'that which is known by God is' is necessary."

Now some urge an objection and say that this distinction holds good with regard to forms that are separable from the subject; thus if I said, "It is possible for a white thing to be black," it is false as applied to the saying, and true as applied to the thing: for a thing which is white, can become black; whereas this saying, " a white thing is black" can never be true. But in forms that are inseparable from the subject, this distinction does not hold, for instance, if I said, "A black crow can be white"; for in both senses it is false. Now to be known by God is inseparable from the thing; for what is known by God cannot be known. This objection, however, would hold if these words "that which is known" implied any disposition inherent to the subject; but since they import an act of the knower, something can be attributed to the thing known, in itself (even if it always be known), which is not attributed to it in so far as it stands under actual knowledge; thus material existence is attributed to a stone in itself, which is not attributed to it inasmuch as it is known.

Objection 1: It seems that God does not know enunciable things. For to know enunciable things belongs to our intellect as it composes and divides. But in the divine intellect, there is no composition. Therefore God does not know enunciable things.

Objection 2: Further, every kind of knowledge is made through some likeness. But in God there is no likeness of enunciable things, since He is altogether simple. Therefore God does not know enunciable things.

On the contrary, It is written: "The Lord knoweth the thoughts of men" (Ps. 93:11). But enunciable things are contained in the thoughts of men. Therefore God knows enunciable things.

I answer that, Since it is in the power of our intellect to form enunciations, and since God knows whatever is in His own power or in that of creatures, as said above(A[9]), it follows of necessity that God knows all enunciations that can be formed.

Now just as He knows material things immaterially, and composite things simply, so likewise He knows enunciable things not after the manner of enunciable things, as if in His intellect there were composition or division of enunciations; for He knows each thing by simple intelligence, by understanding the essence of each thing; as if we by the very fact that we understand what man is, were to understand all that can be predicated of man. This, however, does not happen in our intellect, which discourses from one thing to another, forasmuch as the intelligible species represents one thing in such a way as not to represent another. Hence when we understand what man is, we do not forthwith understand other things which belong to him, but we understand them one by one, according to a certain succession. On this account the things we understand as separated, we must reduce to one by way of composition or division, by forming an enunciation. Now the species of the divine intellect, which is God's essence, suffices to represent all things. Hence by understanding His essence, God knows the essences of all things, and also whatever can be accidental to them.

Reply to Objection 1: This objection would avail if God knew enunciable things after the manner of enunciable things.

Reply to Objection 2: Enunciatory composition signifies some existence of a thing; and thus God by His existence, which is His essence, is the similitude of all those things which are signified by enunciation.