Kant and the Question of Noumenal Ontology

A Critical Assessment of Kant's Antithetic of Pure Reason in View of his Denial of a Metaphysical Proof for the Existence of God

by Mario Derksen

Nothing is more repulsive to a scholastic spirit than an antinomy of pure reason. Throughout the middle ages, philosophers inspired by the Platonic and Aristotelian traditions were convinced that the proper use of reason could lead the intellect to the attainment of the highest and profoundest metaphysical truths. With the advent of the 18th-century British skeptic David Hume, however, this position seemed no longer able to be justified. A radical empiricist, Hume proposed to demonstrate that non-trivial knowledge is in fact impossible. Intimidated by the devastating epistemological conclusions of Hume’s seemingly air-tight logic, the critical idealist Immanuel Kant saw only one way out to save knowledge from utter destruction—by limiting it immensely, basing it on a revolutionary hypothesis, which proved to have a fatal outcome as far as the most important kind of philosophical study—metaphysics—was concerned: it made metaphysics, at least as it had been traditionally understood, impossible, reducing it to mere unverifiable and therefore meaningless speculation.

This forlorn outcome of Kant’s critical philosophy was, though originally unintended, a slap in the face for those metaphysicians who immediately preceded Kant, such as Wolff, Locke, and Leibniz, but it also would have met with serious criticism in the ancient and medieval days of Aquinas, Averroës, Aristotle, and Plato. In fact, throughout the middle ages, metaphysics was considered the “Queen of all the sciences,”[1] and to hurl against it, as Kant did, the charge that it yields only paradoxical conclusions and therefore mere nonsense—at least as far as true knowledge is concerned—would have been the height of impudence for the great scholastics, most notably St. Thomas Aquinas.

It shall be the purpose of this paper to examine Kant’s accusations against traditional metaphysics in light of two of his four “antinomies of pure reason” to see how they, if valid, nullify pre-Kantian metaphysical claims. I shall also attempt to offer a possible neo-scholastic critique of Kant’s antinomies to show a way to rehabilitate the pre-Kantian conceptions of metaphysics at least to a limited extent.

For a philosopher like St. Thomas Aquinas, it would have been unthinkable to admit of Kant’s position that any traditional metaphysical claim must result in an antinomy, an “affirmation and negation of the same statement.”[2] This is not to say that St. Thomas thought human reason was unlimited, or that any question whatsoever could be answered by reason alone. In fact, to use a popular example, Thomas was quite insistent upon the fact that philosophical reasoning alone, unaided by divine revelation, could not prove either that the world has always existed or that it had a beginning: “For the world to be always . . . cannot be proved by demonstration”[3]; “By faith alone do we hold, and by no demonstration can it be proved, that the world did not always exist.”[4] In other words, “[p]hilosophical reasoning leaves both options as logical possibilities. Divine revelation . . . resolve [sic] the question; philosophy does not.”[5] This is a classic example to demonstrate that even though Aquinas believed metaphysical knowledge to be possible, by this he didn’t imply that we can solve all metaphysical problems using reason alone.

However, while Thomas admitted that not every question can be solved by reason alone, Kant insisted that any application of the categories of the understanding beyond the sensible world must necessarily lead to an antinomy. He says:

A completely [perplexing] situation arises when reason is applied to the objective synthesis of appearances. For in this domain, however it may endeavour to establish its principle of unconditioned unity, and though it indeed does so with great though illusory appearance of success, it soon falls into such contradictions that it is constrained, in this cosmological field, to desist from any such pretensions.[6]


This extreme view, namely that as far as dogmatic metaphysics is concerned, one thesis can be proved by reason, and its very antithesis can equally be so proved, was quite a novel idea in the world of philosophy, but it is not surprising that Kant endorsed it, given his revolutionary hypothesis in the theory of knowledge, which had arisen from his reflection on Hume’s skeptical challenge. For Kant, however, sacrificing metaphysical knowledge in order to rehabilitate knowledge of the sensible world seemed like a fair price to pay. He saw himself forced to choose between a Humean skepticism and complete denial of knowledge on the one hand, and synthetic a priori knowledge on the other, which would exclude dogmatic[7] metaphysics. For Kant, then, the choice was easy.

Before Hume and Kant, however, metaphysics was flowering in the ancient, scholastic, and even the pre-Kantian modern traditions. With the advent of Christianity, the question soon arose whether the new faith was compatible with reason, or whether they were rivals,[8] and much of the Christian medieval metaphysics was dedicated to demonstrating that philosophy could play a great role in aiding the belief of Christians and in convincing unbelievers by using elements of Greek philosophy. It is not of great surprise, then, that the middle ages produced such great works as St. Augustine’s De Trinitate, Boethius’ De Consolationæ Philosophiæ, and St. Thomas’ Summa Contra Gentiles and Summa Theologica.

 In this paper, I shall be concerned primarily with the metaphysical views of St. Thomas Aquinas, for he represents the epitome of medieval Christian philosophy, a philosophy which made use of dogmatic metaphysics to a large extent. A critique like Kant’s, which makes dogmatic metaphysics meaningless or impossible if valid, would be detrimental to Christian philosophy. Though Kant himself asserted that he “found it necessary to deny knowledge, in order to make room for faith,”[9] it is important to emphasize that the Christian scholastics would have seen his “faith” as a pure fideism, a distortion of faith, and radically different from that faith which has to rely on divine revelation to come to the knowledge of those truths which reason alone cannot attain, e.g. that God is a Trinity. For Thomas and the Catholic Church, [10] the existence of God does not belong to this category: “There are some truths which the natural reason . . . is able to reach. Such are that God exists, that He is one, and the like.”[11] Such truths as the existence of God, which are demonstrable by reason alone, do not belong to the articles of faith but to the “preambles of faith”: “The existence of God and other like truths about God, which can be known by natural reason, are not articles of faith, but are preambles to the articles.”[12]

Kant’s critical philosophy, by denying dogmatic metaphysics, of course denies the Thomistic proofs for God’s existence. It is in his antinomies of pure reason that Kant attempts to demonstrate why metaphysics in its traditional sense cannot lead to knowledge but only to confusion and illusion. But before taking a look at Kant’s antinomies and transcendental dialectic, let me first turn to the Thomistic proofs themselves.

In his Summa Theologica, St. Thomas advances five proofs, commonly referred to collectively as the “cosmological argument,” to demonstrate that God exists. Curiously, however, none of these entirely originated with Thomas himself:

The first two reflect the influence of Aristotle’s Physics and Metaphysics; the third suggests Thomas’ indebtedness to the Guide for the Perplexed by the Jewish philosopher Maimonides; the fourth echoes the Platonic Dialogues; and the fifth should be considered in light of St. John Damascene’s On the Orthodox Faith.[13]


The first proof is the argument from motion, and is more easily cited from his Summa Contra Gentiles. St. Thomas argues that since some things are in motion, there must be a prime mover that is itself not moved. He says:

Everything that is moved is moved by another. That some things are in motion . . . is evident from sense. Therefore, it is moved by something else that moves it. This mover is itself either moved or not moved. If it is not, we have reached our conclusion—namely, that we must posit some unmoved mover. This we call God. If it is moved, it is moved by another mover. We must, consequently, either proceed to infinity, or we must arrive at some unmoved mover. Now, it is not possible to proceed to infinity. Hence, we must posit some prime unmoved mover.[14]


It is quite important here to understand how Thomas uses the term “motion.” He is not referring to motion as thought of in a modern sense, i.e. in the sense that a moving car is in motion. Rather, he uses motion in an Aristotelian sense, i.e., for him motion is change, “any kind of transition from potency to act,”[15] and that would include, for instance, a human being’s development from infancy to adulthood.

Of course, Thomas recognized that in his first proof “there are two propositions that need to be proved, namely, that everything that is moved is moved by another, and that in movers and things moved one cannot proceed to infinity.”[16] In the Summa Contra Gentiles, he proves both propositions at great length, but they shall not concern us here, for our focus right now is not on whether the proof is valid, but only on giving a few examples of dogmatic metaphysics as practiced by Aquinas, hundreds of years before Kant.

The second argument St. Thomas adduces in support of the existence of God is the proof from efficient causality:

In the world of sense we find there is an order of efficient causes.  There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible.  Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several, or only one.  Now to take away the cause is to take away the effect.  Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause.  But if in efficient causes it is possible to go on to infinity, there will be no first efficient cause, neither will there be an ultimate effect, nor any intermediate efficient causes; all of which is plainly false.  Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.[17]


In other words, St. Thomas claims that every event is caused, and thus we must admit of a first cause that is itself uncaused, namely God. The only other alternative would be to admit of an infinity of efficient causes, with no first cause at all; but this is impossible, for then nothing would exist, since nothing arises from nothing: “If one holds that this series of causes and effects goes back endlessly, then he is forced to hold that it never started. And it is as foolish to hold this as it is to hold that there can be a stick with only one end.”[18] In other words, if there is a series of effects which all depend on causes prior to them, there must be one uncaused cause, or else there would not be any effects to begin with, for to take away the cause is to take away the effect.

Now, it is crucial to understand Thomas correctly: “It is not the possibility of an infinite series as such which St. Thomas denies, but the possibility of an infinite series in the ontological order of dependence.”[19] That is to say, “the essentially ordered causes are hierarchically arranged,” and hence “the impossibility of an infinite regress must not be taken as an infinite regress in time, but as applying to the present consideration of the universe.”[20] Consequently, there must be something outside the chain of cause-and-effect to account for the fact that there’s a chain at all: “If there is no first cause, then the universe is like a great chain with many links; each link is held up by the link above it, but the whole chain is held up by nothing.”[21] Thus, the Angelic Doctor concludes, there must be a first cause that is itself uncaused, i.e. that exists outside the chain of cause-and-effect.

The third of Thomas’ proofs for the existence of God argues from contingency:

We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they are possible to be and not to be.  But it is impossible for these always to exist, for that which is possible not to be at some time is not.  Therefore, if everything is possible not to be, then at one time there could have been nothing in existence.  Now if this were true, even now there would be nothing in existence, because that which does not exist only begins to exist by something already existing.  Therefore, if at one time nothing was in existence, . . . even now nothing would be in existence - which is absurd.  Therefore, not all beings are merely possible, but there must exist something the existence of which is necessary.[22]


One may, with a certain justification, inquire just why St. Thomas claims that “that which is possible not to be at some time is not.” The reason is that if there is no Creator, then time must be infinite, and if this is so, then every possibility is eventually actualized: “If there has been infinite time, then every possibility must have already had enough time to have been actualized, including the possibility of simultaneous non-existence for all contingent beings.”[23] Since no one, at least in Thomas’ days, would dare make the grotesque assertion that nothing exists, his third way does indeed prove the existence of a necessary being, which is called God.[24]

The fourth of Thomas’ ways to prove the existence of God is the proof from the grades of perfection of things:

Among beings there are some more and some less good, true, noble and the like.  But "more" and "less" are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being, as it is written in De Metaphysica ii.  Now the maximum in any genus is the cause of all in that genus. . . . Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God.[25]


This is probably the least convincing argument to the modern mind. Not only does it rest on Aristotle’s teaching that “the things which possess the highest degree of truth, possess also the highest degree of being,”[26] i. e. that there is a hierarchy of being corresponding to a hierarchy of truth, but it is also open to a few other objections which modern and postmodern philosophers would be tempted to make, which, however, shall not concern us here. Given that Aquinas’ fourth way does not have wide appeal and is open to extensive criticism, I shall not touch upon it any further.

His fifth and final proof is the argument from design:

We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result.  Hence it is plain that not fortuitously, but designedly, do they achieve their end.  Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.[27]


This explanation is otherwise known as the teleological argument, because it argues from the purposes, or ends, of things. Frederick Copleston rephrases it very lucidly:

We behold inorganic objects operating for an end, [which] must be the result of intention. But inorganic objects . . . cannot . . . tend towards an end unless they are directed by someone who is intelligent and possessed of knowledge. . . . Therefore there exists an intelligent Being, by whom all natural things are directed to an end; et hoc dicimus Deum.[28]


To make the argument more forceful, it is prudent to use an example of inanimate matter working towards an end: the organs of our own human body. Certainly, no one can sensibly deny that all these organs work toward a man’s health. But this is an example of design and as such lends itself to supporting the teleological argument of St. Thomas, namely that where there is design, there must be a designer.

There are really only two ways to demolish Aquinas’ teleological argument: (1) by claiming that design doesn’t need a designer but could be the result of chance; or (2) by claiming, as Kant did, that there is no design in the world, that it is something merely imposed by the mind.

The first assertion is perhaps best countered by emphasizing that while some people may attempt to deny that all design needs a designer, this cannot realistically be done, because “everyone admits this principle in practice.”[29] Neo-Thomist Peter Kreeft gives a good example to illustrate this:

When the first moon rocket took off from Cape Canaveral, two U.S. scientists stood watching it, side by side. One was a believer, the other an unbeliever. The believer said, “Isn’t it wonderful that our rocket is going to hit the moon by chance?” The unbeliever objected, “What do you mean, chance? We put millions of manhours of design into that rocket.” “Oh,” said the believer, “you don’t think chance is a good explanation for the rocket [hitting the moon]? Then why do you think it’s a good explanation for the universe? . . .”[30]


Kant’s objection, on the other hand, may be answered by pointing out that what he is claiming is absurd. He basically maintains that “we must think about reality in terms of order and intelligibility, but things may not exist that way in fact.”[31] But to assert this is to find oneself in an extremely awkward position, for it implies that our mind can think about something in a way in which it cannot think about it (“must,” after all, implies “can”). That is to say, Kant asks us to think about how reality might be while at the same time insisting that the only way in which we can think about reality is in terms of transcendentally imposed order and design—which, a priori, eliminates the very possibility of thinking of reality as undesigned and chaotic.

Having given a brief survey of St. Thomas Aquinas’ five proofs for the existence of God as representative of pre-Kantian dogmatic metaphysics, I shall now turn to Immanuel Kant’s critique of dogmatic metaphysics as such, precipitated by his “Copernican revolution” in the theory of knowledge.

When David Hume died in 1776, he left traditional epistemology and metaphysics in ruins through his excessive skepticism. Hume, who had divided all claims to knowledge into the categories of relations of ideas and matters of fact, presented a major problem to modern philosophy: the absence of knowledge. This struck quite a blow to the optimism of the Enlightenment, which had hitherto been fostered since the scientific revolution and Descartes’ attempts to make philosophy indubitably certain. After Kant finally woke up from his “dogmatic slumber”[32] after reading Hume’s Enquiry Concerning Human Understanding, however, part of the optimism was restored with the publication of Kant’s Critique of Pure Reason, claiming to rehabilitate certain knowledge.

The price Kant and his followers had to pay for this “rehabilitation” was the possibility of metaphysics as the philosophical world had known it, but this seemed to be fair enough to the philosophers of the time, who were relieved that at least scientific knowledge, with its assumptions of the existence of causality and substance, for instance, was validated once again, in response to Hume’s devastating criticism.[33]

It was Kant’s “Copernican revolution,” the novel idea that “objects must conform to our knowledge,”[34] together with his insistence that the “true method of metaphysics is fundamentally the same as that which Newton has introduced into natural science,”[35] which eliminated the possibility of traditional metaphysics. Just as Descartes had assumed the proper philosophical method to be mathematical, so Kant attempted to put the method of Newtonian physics in its stead. “But,” as neo-Thomist Etienne Gilson observes, “metaphysics is no more capable of physical than of mathematical demonstration,”[36] and thus it is not surprising that Kant, before long, had to admit that metaphysics, which he called the “battle-field of these endless controversies,”[37] was not capable of giving us certain knowledge but only “illusory speculation.”[38]

However, the mere fact that there are controversies in metaphysics, even if they seem “endless,” does not prove that metaphysics is impossible or that no metaphysical assertion can add to our knowledge. James Rachels, who can hardly be accused of being biased towards the scholastic philosophical tradition, observes:

If we think of [difficult] questions . . ., it is easy to believe that “proof” in [metaphysics] is impossible. But the same could be said about the sciences. There are complicated matters that physicists cannot agree on; and if we focused entirely on them, we might conclude that there is no “proof” in physics.[39]


But Kant was quite convinced that proof in physics is possible, even though there are many disagreements among physicists. As the history of science shows, theory after theory has been refuted and replaced, and the same could happen to Newtonian physics. Yet these events do not argue against the possibility of scientific proof—rather, it is the very possibility of such proof that is the precondition for there to be any progress, any science, at all. Thus, Kant can hardly argue, at least on this premise, that the myriad metaphysical battles throughout the history of pre-Kantian philosophy demonstrate that metaphysics does not generate any convincing conclusions about reality.

Before we can evaluate Kant’s critique of dogmatic metaphysics, however, it is essential to investigate some of his antinomies of pure reason, pairs of paradoxes which, so Kant thought, disprove the possibility of metaphysics as a science producing knowledge because they yield opposite conclusions. The inquiry into the antinomies of pure reason he called “transcendental antithetic,”[40] and this is the heart of Kant’s critique of traditional metaphysics, especially as far as causality and the existence of God are concerned. In his prelude to the actual four antinomies, Kant insists that it is our task to be “impartial umpires,” following the “sceptical method,” which is a way of “provoking . . . a conflict of assertions . . . for the purpose of investigating whether the object of controversy is not perhaps a deceptive appearance.”[41] Kant believes that the conclusion arrived at by means of this method indeed demonstrates that there is a “deceptive appearance” at work, that dogmatic metaphysical assertions are nothing other than “pseudo-rational doctrines which can neither hope for confirmation in experience nor fear refutation by it.”[42]

Kant’s point here is not to say that when we have a metaphysical thesis contradicted by its very antithesis, neither can be proved, but rather that both can be proved, and this, according to him, is an indication that we’re engaging in hollow reasoning, trying to extend our own understanding to the noumenal sphere, by using categories and concepts meant only to synthesize experienceable data, i.e. phenomena. Thus, Kant dismisses the scholastic reasoning of the medievals[43] on the grounds that his antithetic of pure reason shows that two contrary metaphysical assertions can both be shown to be true, thus demonstrating that reason is limited to the phenomenal realm. Hence, since the metaphysical doctrines of Aquinas and other pre-Kantian metaphysicians all claim to extend knowledge to the noumenal realm, these doctrines are, in effect, meaningless or at least devoid of any ontological significance.[44] They do not tell us anything about reality, because we are unable to access this reality.

It is extremely important to understand the weight of Kant’s antinomies of pure reason—and, by extension, his entire transcendental dialectic—, for they rationally demonstrate why he rejects traditional metaphysics as sophistry and illusion. It is largely on this conviction—that understanding necessarily fails when it comes to the noumenal realm—that Kant bases his denial of the possibility of any metaphysical proof for the existence of God. For purposes of this paper, it will suffice to refer to and discuss only two of Kant’s four antinomies, namely the first and the fourth, because it is these two that touch upon Aquinas’ arguments for God’s existence most directly.

Kant’s first antinomy of pure reason, then, is as follows: Thesis: “The world has a beginning in time, and is also limited as regards space.” Antithesis: “The world has no beginning, and no limits in space; it is infinite as regards both space and time.”[45] Kant explains the first assertion, as far as time is concerned,[46] in terms of the infinite regress—it is impossible that an infinite amount of time should have elapsed, and therefore “a beginning of the world is . . . a necessary condition of the world’s existence.”[47]

The counter-assertion, the antithesis, Kant defends by pointing out that if the world—defined as the “sum-total of all appearances”[48]—began in time, then before the world began, there must have been what he calls “empty time.” Yet, by definition, nothing can come to exist in empty time, and hence no world could start to exist either. Therefore, Kant reasons, the world has no beginning but extends infinitely into the past.

The fourth antinomy consists of the following two contrary assertions: Thesis: “There belongs to the world, either as its part or as its cause, a being that is absolutely necessary.” Antithesis: “An absolutely necessary being nowhere exists in the world, nor does it exist outside the world as its cause.”[49] This antinomy relates directly to Aquinas’ cosmological proof, particularly the way of efficient causality and the way arguing from the contingency of the world. Kant justifies the thesis by arguing that the sensible world contains alterations, each of which stands under a preceding condition and thus is conditioned. “Now every conditioned that is given presupposes . . . a complete series of conditions up to the unconditioned, which alone is absolutely necessary.”[50] Kant then goes on to argue that this absolutely necessary being cannot be outside the sensible world but must be a part of it.

The antithesis of the fourth antinomy Kant seeks to justify by incorporating the first antinomy to an extent, saying that if we assume the opposite, i.e. that the world is necessary or contains a necessary being, then either the series of alterations we experience “is absolutely necessary, and therefore without a cause, or the series itself is without any beginning, and although contingent and conditioned in all its parts, none the less, as a whole, is absolutely necessary and unconditioned.”[51]

The second option Kant dismisses as absurd because it would require us to accept the obviously problematic proposition that the world as such can be necessary even though none of its members, or parts, is necessary. Thus, according to Kant, we are left only with the first alternative, namely that “there is a beginning in the series of alterations which is absolutely necessary, and therefore without a cause.”[52] However, so the great German thinker objects, to admit this would be to contradict the “dynamical law of the determination of all appearances in time,”[53] which basically says that anything that has a beginning in time must be caused, for else it couldn’t have a “beginning.” Thus, we are left with our having to admit that there cannot be an absolutely necessary being, either inside or outside the world.

Or so Kant thought. The reason Kant finds an antinomy of pure reason in the fourth conflict is, I believe, due to a failure on his part to understand the gravity of St. Thomas’ cosmological argument, i.e. precisely what the different proofs establish and how they are interrelated. I shall now proceed, in light of St. Thomas’ philosophy, to spell out my own critique of Kant’s attempt to destroy Aquinas’ metaphysics—and traditional metaphysics in general—in the first and fourth antinomies. If this critique be successful, one of Kant’s great pillars, namely the one denying the possibility of doing ontology within the noumenal realm, will be significantly undermined.

As far as the first antinomy is concerned, i.e. as regards the question of whether or not the world has always existed, St. Thomas, unlike his contemporary St. Bonaventure, was insistent that neither thesis could be proved, whereas Kant demanded that they both can be proved. Hence, as Frederick Copleston observes:

At first sight Kant seems to adopt a position diametrically opposed to that of St. Thomas Aquinas. For while the latter maintained that it had never been philosophically demonstrated either that the world had a beginning in time or that it had no beginning in time, Kant appears to be saying that both theses can be demonstrated.[54]


However, in a way, both Kant and Aquinas actually agree—they both concede that it is not possible to discern from reason alone whether the world had a beginning; the difference being, of course, that for Kant, the explanation is that both theses can be proved, whereas for Aquinas, neither can. So what we have here—in terms of why it is not possible to know whether the world has always existed—is indeed two diametrically opposing viewpoints: Aquinas’ insistence that neither thesis can be proved, and Kant’s claim that they both can be proved. Obviously, from a merely pragmatic point-of-view, only Kant’s assertion is truly problematic because, if Aquinas is correct, this only means that reason has simply not yet found a way to solve this particular problem; if, however, Kant is correct, then, when it comes to metaphysics, reason can prove too much and therefore invalidates itself because it demonstrates that our minds are not fit for metaphysical endeavors.

Had St. Thomas been alive to hear Kant’s claims, he would have found them most curious, to say the least. There is no question that, for Aquinas, the inquirer who ends up proving two completely opposite assertions must have gone wrong somewhere along the way. There are theses we cannot prove by reason alone, he would concede. But to suggest that we can prove too much—i.e. thesis and antithesis—is totally unacceptable. Says Frederick Copleston: “The only really satisfactory way of showing that there can be metaphysical knowledge is to produce examples.”[55] In other words, in order to defend Aquinas’ view and prove Kant wrong, one must find a way to demonstrate that his antinomies of pure reason are only specious—that they can be resolved in a way different from Kant’s critical solution of limiting reason to the phenomenal sphere. It is precisely this endeavor with respect to the first and fourth antinomies that shall fill the remainder of my essay.

I will now turn to the first antinomy of pure reason, which deals with the question of whether the world has always existed. One of the advantages of St. Thomas’ cosmological argument is that the conclusion is not altered by whether or not one believes the world to have always existed or to have been brought into existence at some particular point in time. Thus, whether or not the world is considered to stretch back into the past infinitely is irrelevant, from Thomas’ point-of-view, for God’s existence is neither confounded nor established thereby. Now, Kant uses St. Bonaventure’s argument to prove that the world had a beginning in time, which is the thesis of the first antinomy. While St. Thomas objects to the Bonaventurian argument as being inconclusive,[56] I feel compelled to side with Bonaventure on this issue, for it seems to me that the proof the Seraphic Doctor advances does indeed establish that the world cannot possibly be infinite.

So the thesis can be proved—Kant agrees; but what about the antithesis? According to Kant, it, too, can be proved, whereas both Aquinas and Bonaventure are most emphatic about this not being possible. Incidentally, were Kant alive today, he would assuredly be interested to see that natural science tends to agree, based on empirical evidence, that the world had a beginning in time.[57] But be that as it may, to show that the two medieval saints were correct in claiming that one cannot prove the world to have existed always, I must now demonstrate that Kant’s reasoning in the proof for the antithesis is flawed.

As he does with the fourth antinomy, Kant uses reductio ad absurdum to reach his conclusion; he assumes the opposite of the proposition and then shows that it cannot be true. So Kant presupposes that the world does have a beginning in time. If that is true, Kant argues, then there must have been a period before the beginning of the world called “empty time,” or else the world would not be limited temporally by anything and hence be infinite.[58] But if the world, then, had a beginning, it had to be brought into existence. But in empty time, nothing can come to exist: “No coming to be of a thing is possible in an empty time, because no part of such a time possesses . . . a distinguishing condition of existence rather than of non-existence.”[59] And thus Kant believes he has shown that it is impossible that the world should have begun to exist some time in the past. But it is in this conclusion that he is mistaken for precisely two reasons: (1) he holds to the notion of an “empty time,” which is contradictory, and (2) he does not consider a third alternative, namely, that time itself began to exist with the beginning of the world. I shall elaborate on these two points of criticism now.

Regarding the first item, there simply is no such thing as “empty time.” It makes no sense to speak of time before time existed—yet this is precisely what Kant does, calling it “empty time.” But there is no “before” outside of time, at least not as far as temporality is concerned. Hence, his assertion that “the beginning is an existence which is preceded by a time in which the thing is not”[60] is false. While his assertion is true generally, it is not true when it comes to the beginning of time, since it is absurd to talk about something temporally preceding time since temporality implies time.

Secondly, Kant does not consider another alternative, namely the one Aquinas proposes, which says that “God brought into being both the creature and time together.”[61] Thus, instead of there being “empty time” before the beginning of the world, let us posit an eternal God outside the world, as the Angelic Doctor does, and recognize that:

Prior to the initial existence of the totality of created being there is no diversity of parts of any duration . . . [for] nothingness has neither measure nor duration. Now, God’s duration, which is eternity, does not have parts, but is utterly simple, without before or after; since God is immovable. . . . Therefore, the beginning of the whole of creation is not to be thought of in comparison to any diverse parts designated in some pre-existing measure [e.g. empty time]. . . .[62]


Thus, the God we ought to posit, according to St. Thomas, is a God outside of all time: “[O]utside the entire universe of creatures there is no time, time having been produced simultaneously with that universe. . . .”[63] It would then be this infinite God who limits the universe in space and time.

If we accept this and reject Kant’s notion of “empty time” as absurd or self-contradictory, then we have found at least one half of the necessary resolution to the first antinomy. The other half may be supplied by a resolution to the antithesis of the fourth antinomy, where Kant argues that there cannot be a first cause. It is to an examination of this fourth antinomy, therefore, that we must now turn. If the notion of God as first cause can be established and its antithesis refuted, the possibility of God as first cause in the hypothesis of my critique of the antithesis in the first Kantian antinomy would be vindicated, and a possible solution to refute the proof of the antithesis would be offered.

In proving the thesis of the fourth antinomy, Kant draws very much on Aquinas’ third proof of the cosmological argument, reasoning that contingent entities in the world depend for their existence on another being which, if contingent itself, must also depend on another being, and thus eventually a first cause in the order of being must be admitted, an entity that is unconditioned and thus necessary.

However, Kant makes what I consider to be a crucial mistake. He claims that the being which causes the first conditioned being must precede it in time, “since the beginning of a series in time can be determined only by that which precedes it in time.”[64] Not only does this premise seem questionable—in fact, I consider it to be not true at all; yet Kant presupposes it, indeed, seems to accept it almost dogmatically. St. Thomas’ cosmological proof, however, avoids this pitfall. Ed Miller points out:

It should be apparent by now that it misses the point entirely to represent the most classical theistic argument (St. Thomas’) as reducing the world to antecedent states that originate in a being who stands at the beginning of the spatio-temporal process. The inevitable picture of falling dominoes or bumping billiard balls is wholly out of place here. What the argument leads to is an ultimate being who at this moment (as at every moment) underlies the whole structure of the cosmic process. As someone has expressed it, God is arrived at not by noting what has gone before something, but by looking into it. . . . It is all a matter of what must exist right now in order to account for the way the world exists right now.[65]


In other words, it is quite possible that A precedes B not in the order of time but in the order of logical necessity. A can be logically prior to B while not being temporally prior. A flame that casts beams of light is not temporally prior to the light beams, but logically so. Hence, the flame is the cause of the light beams without any reference to time.[66] Thus, I consider Kant to be simply wrong in his assertion that “the beginning of a series in time can be determined only by that which precedes it in time.”

As far as the antithesis is concerned, Kant again uses reductio ad absurdum to come to the conclusion that there could not exist a necessary being, either outside the world as its cause or within the world. He says: “If . . . we assume that an absolutely necessary cause of the world exists outside the world, then this cause . . . must itself begin to act, and its causality would therefore be in time, and so would belong to . . . the world.”[67]

Again, the Thomist answer is simply that something absolutely necessary exists outside of the world as its logical—not temporal—cause. Just like the flame in our analogy doesn’t have to begin emitting light, neither does God have to begin causing the world. As Miller pointed out, the picture of falling dominoes does not apply here, for God’s causation is not horizontal but vertical or hierarchical; his causation and the existence of creation are one reality occurring simultaneously, in a way similar that the cutting of an apple is simultaneous with that apple’s being cut.

Does it follow, then, that creation, God’s effect, is eternal, just as he is eternal? Not at all, says St. Thomas, knowing that claiming otherwise would contradict his position that neither the eternity of the world nor its finitude could be proved by reason alone. Says the saintly doctor: “Although God is the sufficient cause of bringing things into being, it is not necessary to hold that because He is eternal His effect is eternal”[68] for the very reason that “[p]rior to the initial existence of the totality of created being there is no diversity of parts of any duration.”[69] Again, however, the cosmological argument works regardless of whether we presuppose the eternity of the world or its finitude; Thomas is merely saying that its eternity does not follow from the fact that God is eternal.

By means of demonstrating that Kant’s proof for the antithesis of the fourth antinomy is flawed, then, we have paved the way for knowing that there is—nay, must be—a God who is the first cause in the order of being, causing both creation and time. Now, this God can be used to validate the critique of Kant’s proof for the antithesis of the first antinomy which I had proposed earlier. Again, Kant’s original position that “empty space outside the world and empty time prior to it . . . have to be assumed if we are to assume a limit to the world in space and time”[70] is therefore invalidated; it is this God, whose existence we have just established, who limits the world before it began; it is a God who is first in the order of being, not in the order of time, as demonstrated especially by the second and third proofs of the cosmological argument. If we accept, then, that this God, and not Kant’s “empty time,” existed before the creation of the world—and this God Kant has not refuted[71]—, then we can dismiss Kant’s proof for the antithesis of the first antinomy and thereby deliver the antithetic from its conflict in this regard.

Now, some may argue that the notion of God here is merely a hypothesis, one only used to explain what would have to obtain so that Kant’s proof for the antithesis fails. But even if this were true, certainly Kant couldn’t object to it, for his entire theory of knowledge is based on a hypothesis the merit of which can only be judged after we can evaluate its impact. Secondly and more importantly, however, it seems to me that the existence of an eternal God is the only possible way to explain the beginning of a world in time, for if we assume the opposite, then the world would not be limited in space and time but infinite, which, however, has been disproved in the thesis of the first antinomy; and the only other alternative would be Kant’s notion of “empty time,” which, as we have seen, is self-contradictory.

If we thus suppose that God causes the beginning of the world—and of time, simultaneously—, it seems to me that we have found a way to show that Kant’s antithesis of the first antinomy is not conclusive after all. Hence, as regards Kant’s first and fourth antinomies, they are not really antithetical—the conflict Kant seeks to draw out is merely specious and vanishes after critical examination.

What does all of this mean for Kant’s theory of knowledge? It means that if what I have presented is accepted, then at least two of Kant’s four antinomies are invalid, because his proofs for the antitheses have been shown to be flawed, and this demonstrates that it is not possible to rationally prove a metaphysical thesis and its very antithesis. This, however, is what Kant relied on practically in his attempt to debunk whatever metaphysical ventures had come before him, and so by proving Kant wrong in this respect, at least part of pre-Kantian metaphysics has been vindicated and rehabilitated.

To complete a critique of Kant’s denial of traditional metaphysics, of course, one would have to go very much beyond these two antinomies; after all, the entire Critique of Pure Reason is full of challenges to the medieval and early modern mind. But even a refutation of merely two antinomies is already a step in the right direction for the neo-Thomist or anyone else engaging in pre-Kantian metaphysics.

However, an attack on Kant’s antinomies is not the only nor perhaps even the best way to critique him, of course. Catholic phenomenologist Dietrich von Hildebrand points out that Kant’s entire epistemology is problematic from the bottom up:

Kant dissolves the authentic meaning of knowledge as the grasping of a being such as it is objectively . . . by replacing it with the notion of the construction of the object. We must stress again and again that this implies an immanent contradiction . . . in the interpretation of knowledge. . . . In claiming to reveal to us the real nature of knowledge, Kant presupposes the notion of knowledge which he denies in the content of his thesis.[72]


Why is it, then, one may wonder, that Kant’s Copernican revolution has found such wide appeal? Why was it so influential? I believe the answer to this is simply that most people thought and continue to think that the only way out of Hume’s dilemma is through Kant, which, however, is not true at all. The true answer to Hume has always laid in the abandoned scholasticism, which seemed obsolete and dry to the moderns, and which, for that reason, they never deigned to look upon or search through in order to find answers. Now it is up to them and to their successors to deal with the Kantian legacy.


Works Cited

Alexander, Anthony F. College Apologetics: Proof of the Truth of the Catholic Faith. Rockford, IL: TAN Books and Publishers, 1994.

Aquinas, St. Thomas. Summa Contra Gentiles. Book I, God. Ed. Anton C. Pegis. Notre Dame, IN: University of Notre Dame Press, 1975.

———. Summa Contra Gentiles. Book II, Creation. Ed. James F. Anderson. Notre Dame, IN: University of Notre Dame Press, 1975.

Carus, Paul, ed. Kant’s Prolegomena. La Salle, IL: Open Court Publishing Co., 1947.

Copleston, Frederick. A History of Philosophy. Vol. II, Medieval Philosophy: From Augustine to Duns Scotus. New York, NY: Doubleday, 1993.

———. A History of Philosophy. Vol. VI, Modern Philosophy: From the French Enlightenment to Kant. New York, NY: Doubleday, 1994.

de la Torre, Teodoro. Popular History of Philosophy. Houston, TX: Lumen Christi Press, 1988.

Gilson, Etienne. The Philosophy of St. Thomas Aquinas. Ed. G. A. Elrington. Trans. Edward Bullough. New York, NY: Dorset Press, 1948.

———. The Unity of Philosophical Experience. San Francisco, CA: Ignatius Press, 1999.

Kant, Immanuel. Critique of Pure Reason. Trans. Norman Kemp Smith. New York, NY: St. Martin’s Press, 1965.

Kreeft, Peter. Fundamentals of the Faith: Essays in Christian Apologetics. San Francisco, CA: Ignatius Press, 1988.

———. A Summa of the Summa: The Essential Philosophical Passages of St. Thomas Aquinas’ Summa Theologica Edited and Explained for Beginners. San Francisco, CA: Ignatius Press, 1990.

Kreeft, Peter, and Ronald K. Tacelli. Handbook of Christian Apologetics. Downers Grove, IL: Intervarsity Press, 1994.

Miller, Ed. L. God and Reason: An Invitation to Philosophical Theology. 2d ed. Englewood Cliffs, NJ: Prentice Hall, 1995.

Rachels, James. The Elements of Moral Philosophy. 3d ed. Boston, MA: McGraw-Hill College, 1999.

Reith, Herman. The Metaphysics of St. Thomas Aquinas. Milwaukee, WI: The Bruce Publishing Company, 1958.

Taylor, Richard. Metaphysics. 3d ed. Englewood Cliffs, NJ: Prentice Hall, 1983.

von Hildebrand, Dietrich. The New Tower of Babel: Modern Man’s Flight from God. Manchester, NH: Sophia Institute Press, 1994.

[1] Immanuel Kant, Critique of Pure Reason, trans. Norman Kemp Smith (New York, NY: St. Martin’s Press, 1965), 7.

[2] Teodoro de la Torre, Popular History of Philosophy (Houston, TX: Lumen Christi Press, 1988), 232.

[3] S. T., I q. 46 a. 1.

[4] S. T., I q. 46 a. 2.

[5] Peter Kreeft, A Summa of the Summa (San Francisco, CA: Ignatius Press, 1990), 197, n. 15.

[6] Kant, Critique of Pure Reason, 385; italics given.

[7] The word “dogmatic” is here used in the sense of being “pre-critical,” i.e. pre-Kantian.

[8] Cf. Frederick Copleston, A History of Philosophy, Vol. II, Medieval Philosophy: From Augustine to Duns Scotus (New York, NY: Doubleday, 1993), 15.

[9] Kant, Critique of Pure Reason, 29; italics given.

[10] Cf. Vatican Council I, Dogmatic Constitution Concerning the Catholic Faith, Canon 2.1.

[11] St. Thomas Aquinas, Summa Contra Gentiles, Book I, God, ed. Anton C. Pegis (Notre Dame, IN: University of Notre Dame Press, 1975), 63.

[12] S. T., I q. 2 a. 2.

[13] Ed. L. Miller, God and Reason: An Invitation to Philosophical Theology, 2d ed. (Englewood Cliffs, NJ: Prentice Hall, 1995), 48.

[14] Aquinas, Summa Contra Gentiles, Book I, God, 86.

[15] Herman Reith, The Metaphysics of St. Thomas Aquinas (Milwaukee, WI: The Bruce Publishing Company, 1958), 178.

[16] Aquinas, Summa Contra Gentiles, Book I, God, 86; italics given.

[17] S. T., I q. 2 a. 3.

[18] Anthony F. Alexander, College Apologetics: Proof of the Truth of the Catholic Faith (Rockford, IL: TAN Books and Publishers, 1994), 18.

[19] Copleston, A History of Philosophy, Vol. II, 342.

[20] Etienne Gilson, The Philosophy of St. Thomas Aquinas, ed. G. A. Elrington, trans. Edward Bullough (New York, NY: Dorset Press, 1948), 82, 76; italics given.

[21] Peter Kreeft, Fundamentals of the Faith: Essays in Christian Apologetics (San Francisco, CA: Ignatius Press, 1988), 30.

[22] S. T., I q. 2 a. 3.

[23] Kreeft, A Summa of the Summa, 67, n. 24.

[24] I shall come back to this later when I discuss Kant’s critique of metaphysics.

[25] S. T., I q. 2 a. 3.

[26] Gilson, The Philosophy of St. Thomas Aquinas, 86.

[27] S. T., I q. 2 a. 3.

[28] Copleston, A History of Philosophy, Vol. II, 344.

[29] Kreeft, Fundamentals of the Faith, 25.

[30] Ibid.

[31] Peter Kreeft and Ronald K. Tacelli, Handbook of Christian Apologetics (Downers Grove, IL: Intervarsity Press, 1994), 58.

[32] Paul Carus, ed., Kant’s Prolegomena (La Salle, IL: Open Court Publishing Co., 1947), 7.

[33] Of course, Kant’s rehabilitation produced the two opposing currents of scientific realism vs. scientific anti-realism, but to discuss this now would be to open a Pandora’s box.

[34] Kant, Critique of Pure Reason, 22.

[35] Qtd. in Etienne Gilson, The Unity of Philosophical Experience (San Francisco, CA: Ignatius Press), 182f.

[36] Gilson, The Unity of Philosophical Experience, 183.

[37] Kant, Critique of Pure Reason, 7.

[38] Gilson, The Unity of Philosophical Experience, 185.

[39] James Rachels, The Elements of Moral Philosophy, 3d ed. (Boston, MA: McGraw-Hill College, 1999), 49.

[40] Kant, Critique of Pure Reason, 393.

[41] Ibid., 395.

[42] Ibid., 394.

[43] Kant never makes explicit mention of Thomas or the medievals, but the nature of his critique is such that it would include these philosophers.

[44] Cf. Carus, Kant’s Prolegomena, 120.

[45] Kant, Critique of Pure Reason, 396.

[46] The part that mentions space is irrelevant for the purpose of this paper, so I shall not discuss it.

[47] Ibid., 397.

[48] Ibid., 415.

[49] Ibid., 415.

[50] Ibid., 416.

[51] Ibid., 415f.

[52] Ibid., 415; italics added.

[53] Ibid., 416.

[54] Frederick Copleston, A History of Philosophy, Vol. VI, Modern Philosophy: From the French Enlightenment to Kant (New York, NY: Doubleday, 1994), 287-88.

[55] Ibid., 434.

[56] St. Thomas Aquinas, Summa Contra Gentiles, Book II, Creation, ed. James F. Anderson (Notre Dame, IN: University of Notre Dame Press, 1975), 112-14.

[57] Miller, God and Reason, 52f.

[58] Kant, Critique of Pure Reason, 400f.

[59] Ibid., 397.

[60] Ibid.

[61] Aquinas, Summa Contra Gentiles, Book II, Creation, 104.

[62] Ibid.

[63] Ibid., 104f.

[64] Kant, Critique of Pure Reason, 416.

[65] Miller, God and Reason, 58; italics given.

[66] Analogy taken from Richard Taylor, Metaphysics, 3d ed. (Englewood Cliffs, NJ: Prentice Hall, 1983), 94f.

[67] Kant, Critique of Pure Reason, 416.

[68] Aquinas, Summa Contra Gentiles, Book II, Creation, 103.

[69] Ibid., 104.

[70] Kant, Critique of Pure Reason, 400.

[71] The God Kant has refuted is the God who is part of the world. I am aware that Kant criticizes the cosmological proof later in his first Critique, but since the scope of this paper is limited, I am unable to discuss and probe his further assertions here.

[72] Dietrich von Hildebrand, The New Tower of Babel: Modern Man’s Flight from God (Manchester, NH: Sophia Institute Press, 1994), 81; italics given.