Appeared in Vol. 3 No. 3  Download PDF here

One of the most difficult problems in human understanding centers on the relationship among God’s knowledge, His providential direction of the universe, and human freedom. In the commentary which follows, Kristin Popik examines the arguments on God’s perfect knowledge advanced by St. Thomas Aquinas, and shows how such knowledge need neither force events nor violate free will. The article makes a number of valuable distinctions regarding both knowledge and time which enable the reader to perceive rightly that God knows all things, including ourselves and our future actions, without controlling our free response to His grace. In an age characterized by determinism on the one hand and insecurity on the other, the author’s conclusion is reassuring. It is also fully compatible with the teachings of the Church.

 The question of God’s foreknowledge of our future actions, and the problem it poses with respect to human free will, has often bewildered not only thoughtful laymen but also philosophers and theologians. We cannot exclude from God’s knowing power the knowledge of future contingent beings and events, for even we humans have a type of foreknowledge with reference to our friends and relatives: if we know someone well, we can often predict even with certainty what he will do in a future circumstance. Surely God’s knowing abilities cannot be less than our own-He must have the capability to know future contingents. And yet a moment’s reflection will cause us to doubt: if His knowledge is necessarily right, if He cannot be in error, does this not force the future actions, does this not make these future contingents not really contingent after all but rather necessary? Doesn’t the necessity or infallibility of God’s knowledge destroy human free choice? If these future events or beings are truly contingent, God’s knowledge must be subject to error, but if He cannot err, they are forced into necessity by the necessity of His knowledge being true.

A similar dilemma is posed by the related problem of God’s knowledge of non-beings-things that do not, and never will, exist. Since they do not even exist, these things are literally nothings-and how can there be knowledge of a nothing, a something which is not? Clearly such knowledge would be erroneous and contradictory: to know something which actually is not, is not to know anything. And yet since God’s knowledge is perfect and limitless, we hesitate to place on its object any limit, even the limit of being, especially since we humans experience a type of knowledge of these non-beings, such as the children we might have had, fanciful animals, and fantastic other-worlds.

St. Thomas Aquinas treats and solves these two problems with his characteristic lucidity in his Quaestiones Disputatae de Veritate. The context in which his treatment is located is the second question which is devoted to God’s knowledge: whether or not He properly can be said to know, how He knows and what He knows, and how His knowledge compares to that of man. A brief examination of these other articles will introduce us to the general problem of God’s knowledge and prepare us for a more detailed study of his knowledge of non-beings and future contingent beings. Besides the arguments of the De Veritate, additional confirmatory solutions are found in Aquinas’ monumental Summa Theologiae and Summa Contra Gentiles, beneficial in rounding out our grasp of the master’s thought.


God’s knowledge is not, St. Thomas tells us, either something added to his essense, nor merely a metaphorical attribution, nor do we attribute knowledge to God only because He is the cause of knowledge in us. God properly knows and His knowledge is one of the Divine attributes, like His goodness and His wisdom, constituting his very essence, which is simple.(1) Because God is supremely immaterial and actual, He is both most able to know and most knowable in Himself; and since His existence is absolutely identified with His nature He has immediate and perfect knowledge of Himself.(2) But He also knows things, since He is the cause of them. From our experience of things as tending towards an end we can conclude that they are thus directed by an intellect, which of course must know the things in order to direct them to an end. God’s knowledge of things is also proved by the fact that every effect is in the agent according to the mode of the agent. Since God is immaterial, his effects (all things) must be in Him according to His mode, that is immaterially or as knowledge.(3)

His knowledge of things is proper determinate knowledge because although God is only the ultimate cause of things (and for proper determinate knowledge of a thing one must know it in all of its causes), God is the cause of all things and hence of all the proximate causes of any one thing. He therefore knows all the causes, Himself as ultimate cause and all the proximate causes, of everything.(4)

Nor is His knowledge of things merely universal. He of course knows the (universal) form of everything He makes just as an artist knows the form of his creation. But unlike an artist God does not merely form already-existing matter; He is also the creator of the matter which individuates and hence, as its cause, knows it and consequently the singular. While we know singulars only indirectly through sensation, by reference to our phantasms, God knows singulars directly as the cause of both their form and their matter.(5) God even knows these singulars united to all their accidents, since instead of abstracting the form of the object known from its matter as we do, He apprehends also the matter and hence the proper essence of each singular with all its accidents, as we analogously know all the essential properties of a species by knowing universally the essence of the species.(6)

Later in the second question of the De Veritate, St. Thomas proves that God’s knowledge must be cause of things, since it is impossible both that the things cause His knowledge (because temporal things cannot be the cause of something eternal as His Knowledge) and that both His knowledge and things themselves are caused by some further cause (since in Him nothing can be caused). His knowledge then is a cause of things, through the mediation of His will and that of secondary causes.(7)

This last point, that God’s knowledge is the cause of things is precisely the reason given by St. Thomas for God’s knowing all things, even those that do not exist or will never exist. The relation between things and our knowledge of them is the reverse of that relation between things and God’s knowledge. Our knowledge is received from things and even in a sense caused by them (although the primary efficient cause of our act of knowing is our intellect’s ability to abstract from sensation). Since our knowledge is dependent on the existence of things, the things are antecedent to our knowing them, and as St. Thomas says, “When what is antecedent is removed, what is subsequent is likewise removed.”(8) It is hence impossible for us to know natural things unless they exist since our knowledge is received from things and by its nature comes after them.

On the other hand, God’s knowledge is not caused by things but rather is itself antecedent to them, since it causes the things: He causes or creates all beings according to His prior knowledge of them. The Creator’s knowledge of creatures is like that an artist has of his art: it precedes the thing which is known, and the thing comes to be according to the knowledge. Hence if the thing does not exist, or does not exist yet, this in no way removes the possibility of knowledge of the thing. “The actual existence or non-existence of a thing is a matter of indifference to the intellect of God or that of an artist. “(9) In fact, since the knowledge of God or of an artist necessarily precedes the thing made, they must have knowledge of these things before they exist; before the things are made to exist (whether natural things in the case of God or artistic things in the case of the artist) they are known and it is according to this knowledge that they are subsequently made.


However, St. Thomas continues, this knowledge of the artist or of God can be either speculative or practical. The speculative or theoretical knowledge of an artist is knowledge of the intimate nature of a possible work, without the intention of applying this knowledge to production. Practical knowledge of a possible work follows on this speculative knowledge with the addition of an intention, an ordination of the knowledge to the end of making or effecting the thing. It is evident that the practical knowledge depends on the speculative: one cannot know a thing which he intends to make without knowing it first in itself. Employing the principle used above,(10) we can conclude that the absence of practical knowledge in no way violates the speculative, which is antecedent to it. An artist then has knowledge not only of things that are not yet made, but also of those which he may never make, either because he has not the intention or because he is unable to make them. Human knowledge, then, with reference to natural things depends on their prior existence and cannot know non-existent natural things; with reference, however, to things of our own making it is prior, and can know them either before they exist or even in the case that they may never exist. So too, God has knowledge of non-beings: of those which do not now exist but He intends to make in the future He has practical knowledge; of those which will never be He has a type of speculative knowledge, since He knows them as possible ways of communicating His goodness. Thus St. Thomas says:

He sees them in His goodness, the end of all that is made by Him;for He sees that there are many ways of communicating His goodness, besides those He has already communicated to existing things, having existence, past, present, or future, because all created things cannot equal His goodness, no matter how much they seem to participate in it.(11)

To the objection suggested by Dionysius (that knowledge is only of existing things), St. Thomas responds, “Things which neither have been, are, nor will be, exist in some way in God’s power as in an active principle, or in His goodness as in a final cause.”(12) St. Thomas responds to a similar objection in the Summa Theologiae, saying that “Things which are not actually existent have a truth corresponding to their potentiality; i.e., it is true that they are potentially existent; and God knows them in that way.”(13) To the objection that God cannot know non-existents because His knowledge is only of the true, and the true is interchangeable with being, St. Thomas responds in a similar vein:

Things which neither have been, are, nor will be possess truth in so far as they possess existence, namely, in so far as they are in their active principle or final cause. As such, they are also known by God. (14)

In the Summa Theologiae(15) the principle proof for God’s knowledge of non-existents is this same argument that even non-beings have some type of existence. Things which are not actually existent in the unqualified sense exist potentially as producible either by God or by man, and God knows all things that are in any way whatever.

Therefore whatever can be produced or thought or said by a creature, and also whatever God Himself can produce, all is known by God, even if it is not actually existing. In this sense it can be said that He has knowledge even of non-existent things.(16)

St. Thomas continues, saying that God’s knowledge of the things that will never be produced is called knowledge of simple understanding, whereas His knowledge of things that either were in the past or will be in the future is called knowledge of vision, because vision for us signifies that the thing seen has a separate existence outside the person who sees.

The Summa Contra Gentiles(17) contains yet another proof of God’s ability to know things which do not and will never exist. God knows all things other than Himself by His own essence, since by His essence He causes all other things, and the likeness of every effect exists in its cause. However, all things are limited in being and in perfection, while God’s essence is infinitely perfect. It is impossible then that all things together would equal the perfection of the Divine Essence. Hence, the Divine Intellect has the capacity to know many things besides those which exist. We can further conclude that God does in fact know things which do not exist because God must know the whole power and perfection of His essence; therefore, “His knowledge extends not only to those things that are, but also to those that are not.”(18)

Also in this chapter of the Summa Contra Gentiles, St. Thomas offers a demonstration of God’s knowledge of specifically those things which are not yet. Since effects can be foreknown in their causes even before they exist, He knows these things through their cause (which is Himself) in the very act of knowing Himself. “God’s knowledge is of all things through their causes: for in knowing Himself, Who is the cause of all, He knows other things as His effects.”(19)

In summary, St. Thomas says: “Wherefore God knows non-beings insofar as they have being after a fashion, either in the Divine Power, or in their causes, or in themselves. And this is not contrary to the essential conditions of knowledge.”(20) The things which will never exist He knows as existing within His power; those which will exist in the future and those which have existed He knows in their causes and in themselves by knowledge of vision


Having proved that God is in no way limited in His knowledge and can know not only things which are not yet, but also those which will never be, we must still determine precisely how God can know future contingents without, by His infallibility, violating their contingency. This problem is of the utmost importance, for in our resolution of it we must safeguard both Divine Providence and the freedom of the human will.

In the beginning of his treatment of this problem in the De Veritate,(21) St. Thomas refutes the two opinions which violate these doctrines. It cannot be said that God has no knowledge of future contingents because this would eliminate providence over human affairs which are contingent. Yet if we admit that God knows them, and to safeguard the truth of his knowledge say that they are not contingent but necessary, we destroy free choice and also their nature as contingent beings. We must find an explanation affirming God’s knowledge of contingents which does not reduce the contingents to necessity.

A knowing habit or power which is always true must know things which would never fall short of what the knowing power apprehends about them. With reference to future things, a knowing power of this type could always know in a truthful manner future necessary things because the necessary cannot be prevented from happening before it happens: necessary means that its causes are unchangeably ordained to its production, and these things can therefore be known in their causes without error. But since contingents by their very nature may be impeded before they are brought into being, because their causes may be prevented from producing their effect, a knowing power which was always true could not know them. The possibility of error accrues to foreknowledge of contingents because of this possibility that, after all, they may be impeded and not come to exist. However, a power of knowing in which there is no falsity can know contingents after they have been brought into being, for then they can no longer be prevented; they already are in themselves, not just in their causes. So a knowing power which is always true can know only future necessity and present contingents, but not future contingents.

Even after this examination of the objects of necessarily true knowledge (which of course is the kind God has), we seem to be without a solution. Future contingents cannot be known by a knowing power which does not err, if they are really future and really contingent: to be known by such a power they must be either present or necessary.

St. Thomas solves the dilemma by recalling that God is outside time or eternal: things which are future for us are all immediately present in the simultaneity which is eternity. Eternity includes all of time but is not measured by it; for God there is no future, nor past, but eternal present.

Therefore, since the vision of divine knowledge is measured by eternity, which is all simultaneous and yet includes the whole of time without being absent from any part of it, it follows that God sees whatever happens in time, not as future, but as present. For what is seen by God is, indeed, future to some other thing which it follows in time; to the divine vision, however, which is not in time but outside time, it is not future but present.(22)

In other words, God, being outside of time does not have to wait to discover whether or not His predictions about some future thing will be right. He already sees the thing which will be, as it will be, already present to his vision which is outside time. Nor does His preknowledge force the thing to be according to His knowledge. His knowledge of future contingents is properly a knowledge of vision, a seeing all of the future as already present. He sees all of history not as it unfolds for us, but as past-present-future all fused in the present. Just as our sense of sight is not deceived when it sees present contingents, neither may God’s sight be in error when He sees as present all the contingents which for those of us in time are future. Just as our vision of present contingents in no way prevents them from happening contingently, neither does God’s vision of them prevent them from happening contingently.

In the chapter of the Contra Gentiles(23) dealing with God’s knowledge of non-existents, St. Thomas describes this relation between eternity and time as similar to that between the center and the circumference of a circle: the center is outside the circumference (as eternity is outside time) in the sense that it forms no part of it; yet each point in the circumference is coexistent with, opposite to, or present to the center. Similarly every point of time is present to eternity even though it is related to all other points by temporal duration, and even though eternity itself plays no part in this temporal relation. According to St. Thomas, “A thing cannot be present to, and coexistent with, the eternal, except with the whole eternal, since this has no successive duration. Therefore whatever happens throughout the whole course of time is seen as present by the divine intellect in its eternity.”(24)

St. Thomas devotes the next chapter of the Summa Contra Gentiles(25) to this problem of God’s knowledge of future contingents, giving a number of demonstrations in addition to those suggested in the previous chapter on God’s knowledge of non-beings in general. Contingents differ from the necessary only with respect to their causes, not with respect to the being they have in themselves; and since God’s knowledge is not limited to the being which things have in their cause (rather He knows the being they have in themselves), He knows the thing itself, irrespective of whether it is necessary or contingent with respect to its causes. Necessary and contingent refer to the thing in relation to its causes; since God is not limited to the knowledge of things in their causes, He knows them in themselves whether they are necessary or contingent.

Another reason which St. Thomas gives for God’s knowledge of future contingents is that He knows all causes, not only the causes of the things themselves which are either necessary or contingent, but also the causes of those things which may hinder the contingent beings from being effected according to their own causes; for contingents differ from necessary beings only and precisely in this possibility of hindrance or interruption in the process of their following from their causes. For if it is not thus hindered, a contingent unfolds according to its own causes in the same way that a necessary being does. So God knows not only the causes of the things, but also the hindering causes, and which contingents will come to be according to their causes and which will be altered.(26)

It is precisely this difference between necessary and contingent things, namely the mediation of secondary or proximate causes (or the possibility of interruption of the causes of a thing) which allows that, while God’s knowledge of future contingents is necessarily true, the things still happen contingently. God is the ultimate cause of all things, while the proximate or secondary causes mediate between God and the thing, making the thing contingent. But not only is God the ultimate cause, but also He knows all the secondary causes, in addition of course to knowing the things themselves as present to His vision.

In the Summa Theologiae(27) St. Thomas explains in a most lucid way his primary reason for affirming God’s knowledge of future contingents, by distinguishing between the contingent considered in itself, in the state of actuality (that is, as present, not as future), and the contingent in its causes, as potential, or as future, in which latter consideration the contingent cannot be the subject of certain knowledge for us. But God knows contingents in both ways and with certainty in both ways: since they are all present to Him, He sees certainly that of which we can only have conjectural knowledge; and He, in knowing all the causes of things which are future for us, knows not only the causes which may produce something but also those which may hinder those causes, and what the outcome will be, or rather is.

This is why, then, St. Thomas tells us in the Summa Contra Gentiles(28) that while God knows some non-beings (those that will never be) insofar as they have being in the Divine Power, He knows those which are future for us, and which depend on secondary contingent causality insofar as they have being in their causes or in themselves. He knows future contingents, then, in two ways: in themselves by His vision which is eternal, and in His knowledge of their causes, by knowing all causes.

To summarize, we may say that while St. Thomas uses the fact that God’s knowledge, unlike ours, is not caused by the things known to explain why his knowledge is not limited to existing things, he uses the fact that God’s visionary knowledge of contingent future beings is caused by them (since God sees them as present) to show that the infallibility of this knowledge does not force the events.


In conclusion, then, it is easily seen that there is no contradiction between God’s knowledge and the freedom of the human will. His knowledge of these contingent events by eternal vision certainly cannot force or cause the events since it is knowledge caused by the vision of the events themselves. The knowledge is consequent to and dependent on the things, and hence cannot cause them.

Similarly, his knowledge of these events in their causes cannot force the events. He has absolutely perfect and complete knowledge of all causes, including accidental causes. But His knowledge of things in their causes is not foreknowledge either: it is present knowledge of present realities, absolute knowledge (as ultimate cause of all causes) of the make-up of all reality, some of which, from our point of view, is still future possibility. Those of us who are constrained to living in the present by the temporal mode of our existence can speak of the future as “not yet”, but we must not forget that this is a peculiarity of our type of existence. For God, all of being is right now; and God knows it all in itself and in its causes as it is.


1 D.V. II, 1.

2 Ibid., II, 2. 3 Ibid., II, 3.

4 Ibid., 11,4. 5 Ibid., II, 5.

6 Ibid., II, 7.

7 Ibid., II, 14.

8 Ibid., II, 8. “Remoto autem priori removetur posterius ….”

9 Ibid.

10 See above, note 8.

11 Ibid., II, 8. “. . . intueatur ea in sua bonitate, quae est finis omnium quae ab eo fiunt; secundum, scilicet, quod intuetur multos alios modos esse communicationis propriae bonitatis, quam sit communicata rebus existensibus, praeteritis, praesentibus, vel futurus; quia omnes res create eius bonitatem aequare non possunt, quantumcumque de ea participare videantur.”

12 Ibid., ad L”. .. illa quae nee fuerunt, nee sunt, nee erunt, sunt aliquo modo existentia in potentia Dei sicut in principio activo, vel in bonitate eius sicut in causa finali.”

13 S.T., I, 14, 9, ad 1. “. . . secundum quod sunt in potentia, sic habent veritatem ea quae non sunt in actu: verum est enim ea esse in potentia; et sic sciuntur a Deo.”

14 D.V., II, 8, ad 5. “. . . illa quae nee fuerunt, nee sunt, nee erunt, secundum hoc habent veritatem secundum quod habent esse, prout scilicet in suo principio activo vel finali sunt; et sic etiam cognoscuntur a Deo.”

15 S.T., 1, 14, 9.

16 Ibid. “Quaecunque igitur possunt per creaturam fieri vel cogitari vel dici, et etiam quaecumque ipse facere potest, omnia cogniscit Deus, etiam si actu non sint. Et pro tanto dici potest quod habet etiam non entium scientiam.”

17 S.C.G., I, 66.

18 Ibid., “Suae cognoscit extendid se eius cognitio non solum ad ea quae sunt, sed etiam ad ea quae non sunt.”

19 Ibid. “Sed cognitio Dei est de rebus omnibus per causam: se enim cognoscendo, qui est omnium causa, alia quasi suos effectus cognoscit . . . .

20 Ibid., “Sic igitur non entia cognoscit Deus inquantum aliquo modo habent esse: vel in potentia Dei, vel in causis suis, vel in seipsis. Quod rationi scientiae non obsistit.”

21 D.V., II, 12.

22 Ibid., “Unde, cum visio divinae scientiae aeternitate mensuretur, quae est tota simul, et tamen totum tempus includit, nee alicui parti tempori deest, sequitur ut quidquid in tempore geritur, non ut futurum, sed ut praesens videat: hoc enim quod a Deo visum est, futurm est rei alteri, cui succedit in tempore; sed ipsi divinae visioni; quae non in tempore, sed extra tempus est, non est futurum, sed praesens.”

23 S.C.G., I, 66.

24 Ibid., “Aeterno autem non potest aliquid praesentialiter coexistere nisi toti: quia successionis durationem non habet. Quidquid igitur per totum dicursum temporis agitur divinus intellectus in tota sua aeternitate inuentur quasi praesens.”

25 S.C.G., 1, 67.

26 Ibid.

27 S.T., 1, 14, 13.

28 S.C.G., I, 66.