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G D His Existence And His Nature -Rev. R. Garigou-Lagrange, O.P.


7) We are here concerned with a philosophical or, more precisely, a metaphysical demonstration. In the rigor of its proof and its power to convince, it must surpass the so-called scientific demonstrations of the present day.


It seems hardly necessary for us to point out that we do not claim to give a scientific demonstration for the existence of God, if by that term is understood, as is often the case nowadays, a process that does not go beyond the data of observation and experience. But if reason tells us that beings and phenomena, which are objects of experience, cannot explain themselves, but of necessity require the presence of a cause which renders them real and intelligible; if reason furthermore establishes the fact that this cause must be sought for beyond the limits of observation and experience—then we shall have a demonstration, not indeed scientific in the modern acceptation of the term, but philosophical or metaphysical. (See Zigliara, Summa Philosophica, Vol. I, p. 157). And if we also bear in mind, with Aristotle, that science does not really differ from ordinary knowledge, and that any branch of knowledge may be truly termed a science only when it gives the "why" or the necessary raison d'être of what is affirmed, then we shall see that metaphysics merits the name of science far more than any of the so-called positive sciences. "Scire simpliciter est cognoscere causam, propter quam res est et non potest aliter se habere," i.e., to know is simply to perceive the reason why a thing is actually so, and cannot be otherwise. (Post. Analyt., Bk. I; Commentary of St. Thomas, 4th lesson).

The positive sciences cannot give us this propter quid, this raison d'être, that would make intelligible the laws, which, after all, are but general facts. As Aristotle expresses it, they remain sciences of the quia, which means that they state the fact without being able to explain it, without giving the reason why it is so and not otherwise. The inductive method of reasoning, which can be traced back to the principle of causality, enables us to conclude with physical certainty that heat is the cause of the expansion of iron, but we do not see "why" this effect is to be assigned precisely to this cause and not to any other. We account for the antecedent phenomenon merely by empirical and extrinsic processes of reasoning, and this is because we do not know why heat and iron are specifically constituted as they are. When positive science proceeds from general facts or laws, to explain the reasons for these laws, it can only provide us with temporary working hypotheses, which are not so much explanations as convenient representations apt to classify the facts. Scientists state that the distance traversed by all falling bodies through space is proportionate to the square of the time taken. That is a general fact or law; but what is the nature of the force that causes bodies to fall in this way? Are they driven towards one another or mutually attracted? If there is mutual attraction, how are we to explain it? It is a mystery. The laws according to which light travels have been discovered; but what is light? Is it a vibration of a rarefied medium, the ether, or is it an extremely rapid current of impalpable matter? Neither hypothesis claims to be the true solution, excluding the other as false. The scientist's only concern is to give a more or less convenient classification of the phenomena.

The intelligible element found in the positive sciences is to be explained by the fact that they have recourse to the metaphysical principles of causality, induction, and finality. Since their objects, as Aristotle has pointed out, are essentially material and changeable, they reach but the fringe of being, and consequently of intelligibility. (Phys., Bk. II, ch. 1; Bk. VI, ch. 1). The objects accessible to our senses are hardly intelligible in themselves. They belong to the domain of the hypothetical and conjectural, to that which Plato termed δόξα (opinion). The intelligible world is the sole object of true science (ἐπιστᾓμη). In fact, the certitude properly called scientific grows in proportion as what one affirms approaches nearer to those first principles which are, as it were, the very structure of reason—the principle of identity implied in the idea of being, that most simple and universal of all ideas, the principles of contradiction, causality, and finality. If the principle of identity and non-contradiction is not only a law of thought, but also of being, if the other principles (in order to escape the charge of absurdity) must necessarily be referred to it, then every assertion necessarily connected with such principles will have metaphysical or absolute certainty, and its negation implies a contradiction. On the other hand, no assertion relying solely on the testimony of the senses can possess other than physical certainty, and, finally, every assertion based on human testimony cannot have other than moral certainty. That is why, according to the traditional philosophy, metaphysics—the science of pure being and of the first principles of being—deserves to be called "the first of all sciences," for it is more of a science than all the other sciences. The demonstration of the existence of God must, therefore, be in itself far more exacting than is usually the case nowadays with scientific demonstrations. It must not only establish, by reasons drawn from observation, that the world has need of an infinitely perfect cause, but also why it needs this cause and no other. Moreover, the reason given must not be a mere working hypothesis, but definitive; it must necessarily flow from the highest principle of our intelligence and from the very first of all our ideas, namely, that of being.

This demonstration, though far excelling the empirical demonstrations in point of rigor and certainty, will, however, not be so readily understood by us, at least when presented in scientific form. As Aristotle remarked (Met., Bk. I; Commentary of St. Thomas, Lect. 2; Met., Bk. II, Lect. 5; Bk. VI, Lect. 1), the realities of sense perception are in themselves not so readily knowable, because they are material and changeable (the mind must abstract from material conditions, since they are a hindrance to intelligibility), but are more readily knowable by us, since they constitute the direct object of sensible intuition, and we acquire our ideas through the senses. Metaphysical truths and realities of the purely intelligible order, though they are more easily knowable in themselves, are not so easily known by us, because sensible intuition cannot reach them. The image accompanying the idea is extremely deficient, and the idea which we obtain through the medium of the senses, is but an analogical expression of the purely intelligible reality.

Between the physical sciences (which abstract only from individual matter and consider matter in common, such as, for instance, the sensible qualities, not of any particular molecule of water, but of water in general), and metaphysics (which abstracts from all matter), is the science of mathematics (which abstracts from sensible qualities and considers quantity as either continuous or discrete). It is, to a certain extent, a combination of the rigorous exactitude of metaphysics and the facility of the physical sciences, because its proper object, quantity, on the one hand, may in itself be defined by terms that are intellectual and fixed, and, on the other hand, it may be adequately expressed by the ideas we derive from the senses, and made clear by appropriate illustrations. In this way a superficial aspect of being is presented to us, evidently very different from pure being, which is the object of metaphysics. We cannot claim to prove the existence of God by a mathematical demonstration; the nominal definition of God assures us that, if He exists, He does not belong to the order of quantity, because He is the first cause and final end, two aspects of causality with which mathematics is not concerned.

Our demonstration will, therefore, be more exact in itself than any empirical demonstration could be, but it will not be as easy to understand as is a mathematical demonstration; to grasp its full force, a certain philosophical training is required, and conflicting moral dispositions can prevent a man from perceiving its efficacy. "Some there are who do not grasp what is said to them, unless it is presented in a mathematical form. Others refuse to accept anything that does not appeal to the senses. That which is more according to general custom is better known to us, for habit becomes second nature. Aristotle observes that we must not expect the same degree of certitude from physics, mathematics, and metaphysics." (St. Thomas, Comment. in II Met., Lect. 5).

This difficulty, for the rest, applies only to the scientific form of the demonstration. Reason spontaneously rises to a certain knowledge of God's existence by a very simple inference derived from the principle of causality. The sensus communis need not bother itself with the difficulties presented by objectivity and the transcendental and analogical value of the principle of causality, but quite naturally arrives at a knowledge of the first cause, one and unchangeable, of multiple and changeable beings. The orderly arrangement of things in this world and the existence of intelligent beings prove that the first cause is intelligent; the moral obligation made known by conscience necessarily calls for a legislator; lastly, the principle of finality demands that there should be a supreme, sovereignly good end, for which we are made, and which, therefore, is superior to us. The manner in which we shall present the traditional proofs for the existence of God, from the point of view of the philosophy of being, (which in reality is but an explanation and vindication of the sensus communis), makes it unnecessary for us to treat ex professo of the problems arising from spontaneous knowledge. The teaching of Catholic theology on this point will be found in the Dictionnaire de Théol. Cath., art. "Dieu," cols. 874-923.


8) This will not be an "a priori" demonstration. Insufficiency of the ontological proof.


How shall we proceed in the philosophical demonstration of the existence of God? The Vatican Council tells us that it is from created things that God can be known with certainty (e rebus creatis certo cognosci potest). We do not, therefore, as the Ontologists contended, come to know of God's existence and His attributes by a direct intuition of His essence. This vision is the ultimate crowning of the supernatural order. The created intellect, by its unaided natural powers, can by no means rise to such a knowledge; created and finite as it is, the intellect has for its proportionate object created and finite being, and possesses direct knowledge only of creatures. (St. Thomas, Summa Theol., Ia, q. 12, a. 4). By means of created things it can come to know God, not indeed as He is in Himself, in that which essentially constitutes Him what He is (quidditative; see infra, no. 32), not in the eminent simplicity of His Godhead, as if the intellect had an intuitive perception of this, but only in so far as there is an analogical similarity between Him and His works. The great number of analogical concepts derived from created things, to which we must have recourse in order to form an idea of God, is sufficient proof that we have not that immediate intuition of which the Ontologists speak.

Might not the existence of God be a self-evident truth (veritas per se nota), which needs not to be proved, as, for instance, is the principle of identity: "That which is, is," or the principle of contradiction: "What is, cannot at the same time and in the same sense be and not be"? Or at least, might it not be possible to give an a priori demonstration of the existence of God, abstracting from contingent realities? St. Anselm and the defenders of the ontological argument thought so. St. Anselm points out that existence is implied in the notion conveyed to the mind of every man by the word "God." When one fully realizes what is meant by that word, he says, one conceives of a being greater than which none can be conceived. But if such a being does not exist, then it is possible to conceive of another being, which has all the qualifications of the former, and which, in addition, really exists, and so it would be greater than the being considered to be the greatest that can be conceived. Therefore, if we wish to retain the meaning that the word "God" conveys to the mind, we must affirm that God exists.

The proposition, "God exists" or "the most perfect being that can be thought of, really exists," is, according to St. Anselm, evident in itself and also for us (per se nota quoad nos); and in this respect it does not differ from those other two principles, "That which is, is," and, "What is, cannot at the same time and in the same sense be and not be."

St. Thomas and many other theologians reject St. Anselm's view on this point. Without doubt, they say, in itself (quoad se), the essence of God implies His existence, since God is the necessary being and cannot but exist; but the proposition, "God exists," is not in itself evident for us (quoad nos). In fact, we do not know the divine essence such as it is in itself (quidditative); we can reach it only by means of positive analogical concepts which reveal to us the traits it has in common with created things; but what it possesses as peculiarly its own, this we know only in a negative way (non finite being) or relatively (supreme being) It follows that we know the Deity just as we know all other essences, in an abstract way. This abstract idea which the mention of the word "God" awakens in us, though it differs from all other ideas in that it implies aseity or essential existence (existentiam signatam), abstracts, like all other ideas, from actual or de facto existence (ab existentia exercita).

To the a priori argument of St. Anselm we reply by distinguishing the minor. St. Anselm says: If the most perfect being that can be conceived did not exist, it would be possible to conceive of a being which has all the qualifications of the former, plus existence, so that this latter being would then be more perfect than the most perfect being that can be conceived. I admit that if this being did not exist, and was not conceived as self-existing, it would be possible to conceive one more perfect. But I deny the assertion that if it did not exist, though it was at the same time conceived as self-existing, then it would be possible to conceive of a more perfect being. Hence it is not logical to conclude: "Therefore, God exists"; all that can be logically concluded is: Therefore, God must be conceived as self-existing, and in truth does so exist, and is entirely independent of any other being, if He exists. (St. Thomas, Summa Theol., Ia, q. 2, a. 1).

Descartes (Méd., V, rép. aux object.) and Leibniz (Méd. sur les Idées, ed. Janet, p. 516; Monadologie, § 45) vainly endeavored to give to this argument, generally known as ontological, that logical exactness which it tacked. To regard it as conclusive in the form given it by Leibniz, two propositions would have to be established a priori: (1) that God is possible, and (2) that if He is possible, He exists. Now, whatever one may think of the second of these propositions (that it is possible to argue from logical possibility to a real intrinsic possibility, in virtue of the principle that the operations of the intellect have objective validity, and then from this real possibility to actual existence) the first proposition of Leibniz is certainly not self-evident for us, nor can it be demonstrated a priori. The only thing that Leibniz, like Descartes, can demonstrate is, that we cannot perceive the impossibility of the existence of God. So long as we have not a direct knowledge of the divine essence, we cannot give an intrinsic reason for this possibility, and never shall be able to do so. We must recall to mind what St. Thomas wrote against St. Anselm, and say: "Because we do not know of God what He is, we cannot know whether it is possible for Him to exist." Moreover, the idea of a being, the most perfect that can be conceived, necessarily demands certain absolute perfections, such as immutability and liberty, which seem incompatible. Herbert Spencer developed this objection, which is also one of the standard objections among theologians, at considerable length. Later on we shall see that the a posteriori proof is not affected by it. Leibniz claims to have proved that the infinite being is possible, because the negative element, being excluded from that idea, removes from it the presence of contradiction. It was pointed out to him in reply, that there is nothing negative about the idea of the swiftest possible movement, which yet involves a contradiction.

See Revue Thomiste, July, 1904, "Note sur la preuve de Dieu par les degrés des êtres," by R. Garrigou-Lagrange.


We cannot affirm the possibility of God a priori. We only know that our ideas of being, goodness, intelligence, liberty, acquired from finite things, can be applied by way of analogy to a reality of another order, and that if a reality of another order is required to account as cause for the finite beings from which we derived these ideas, that cause must necessarily have a similarity, at least analogical, to its effects. (St. Thomas, Summa Theol., Ia, q. 4, a. 3; q. 88, a. 3; see infra, no. 29).

Fr. Lepidi (Revue de Philosophie, Dec. 1, 1909) presented the ontological argument in a new way, which we are sorry we cannot give in full here. Notwithstanding the skill and profound learning displayed in this new method, it fails to answer satisfactorily the objections raised against Leibniz, and merely transforms the ontological argument into an argument based upon the contingency of finite being. Later on we shall show (nos. 20 and 38 d) that a trained metaphysician could interpret such a proof in a sort of intuitive sense: in that the intellect, fully understanding both the sense and the import of the principle of identity, the supreme law of thought and of the reality directly implied in the idea of being, would see "quasi a simultaneo" (almost simultaneously) that the fundamental reality, the Absolute, is not this composite and changing universe, but a reality in every way identical with itself, ipsum esse subsistens, the self-subsisting being, and, therefore, essentially distinct from all that is by nature composite and subject to change.


9) The demonstration will have to be a posteriori. For it to be rigorously exact, it must start with a particular effect, and trace this effect back to its proper (i.e., to its necessary and immediate) cause.


We cannot, therefore, demonstrate a priori that the essence of God is possible, and even less, that it exists; but there is another kind of demonstration, known as a posteriori. These two demonstrations, like every process of reasoning, proceed from the better known to the less known; but when we demonstrate anything a priori, the better known is at the same time not only the source, but also the raison d'être of our knowledge. To demonstrate a priori means to give the reason why (propter quid) the predicate of the conclusion necessarily belongs to the subject. This demonstration presupposes that one knows the essence of the subject, which is the, reason for what has been demonstrated as belonging to that subject. Thus, it is demonstrated a priori that man is free, because he is a rational being and knows, not only this or that particular good, but good in general.

The a posteriori demonstration, like the preceding, is a syllogism that results in a necessary conclusion; but here the better known is not the raison d'être of what we know by it; only in the order of things known by us does it come first; in the order of reality it is not dependent upon our knowledge. The knowledge of the effect necessarily leads us to conclude to the existence of the cause. This a posteriori demonstration does not tell us why (propter quid) the predicate of the conclusion necessarily belongs to the subject; it merely establishes that (quia) the predicate refers to the subject, that the cause exists. It does not give us the reason for what is affirmed by the conclusion, but only the raison d'être of the affirmation of the object. Without knowing God as He is in Himself, as the ontological argument demands, we nevertheless can know by such a demonstration that He is. "To be can mean either of two things. It may mean the act of being, or it may mean the composition of a proposition effected by the mind in joining a predicate to a subject. Taking to be in the former sense, we cannot understand the being of God, nor His essence; but only in the second sense. For we know that this proposition which we form about God when we say God is, is true, and we know this from His effects." (St. Thomas, Summa Theol., Ia, q. 3, a. 4, ad 2um). This a posteriori demonstration proving that God exists, in itself is superior to any empirical demonstration; for, as we have already remarked, it will have to explain just why the world demands a cause corresponding to the nominal definition of God, and which cannot be attributed to any other cause. (See supra, no. 7).

This a posteriori demonstration, or demonstration from the effect, cannot be considered a strictly metaphysical process, unless it argues from the proper effect to the proper cause, which means to the necessary and immediate cause of the effect. "From every effect," says St. Thomas, "the existence of its proper cause can be demonstrated; because, since every effect depends upon its cause, if the effect exists, the cause must pre-exist." (Ia, q. 2, a. 2). "Every effect depends upon its cause, in so far as it is its cause." (Ia, q. 104, a. 1).

The proper cause in metaphysics is that which the Scholastics, following Aristotle, call causa per se primo, i.e., the absolutely first cause. (See Aristotle, II Phys., c. iii; V Met., c. ii; St. Thomas, Summa Theol., Ia, q. 45, a. 5; Commentary of Cajetan, q. 104, a. 1; John of St. Thomas, In Iam, q. 44, De Creatione, disp. XVIII, a. 1 and 4).

These articles of St. Thomas, taken from his treatise on creation and the divine government of the world (conservation in being and divine movement), are the veritable and indispensable commentary on the proofs for the existence of God as given in the first part of the Summa Theologica, q. 2, a. 2. Theological speculation follows the reverse order of philosophical speculation; it argues from God to created things, and discusses the great metaphysical problems concerning God and the world, not with reference to the existence of God, but as presented by creation, conservation, and divine movement.

Why does St. Thomas say: "Ex quolibet effectu potest demonstrari propriam causam ejus esse (from every effect the existence of its proper cause can be demonstrated)"? It is because, if any other than the proper cause is assigned, the demonstration is not conclusive. For instance, it would be false to argue: "This man exists; therefore his father exists also"; and yet the father is in a certain sense the cause of the existence of his son, who often survives him. In like manner, every phenomenon presupposes an antecedent phenomenon; but frequently all trace of the latter is gone, whereas the former endures. The agnostics also refuse to acknowledge the principle of St. Thomas just mentioned, but say that from every effect it can be demonstrated, not that its cause exists, but that it has existed. Thus, they would argue that local movement presupposes a certain form of caloric energy which has disappeared; that another phenomenon preceded this one, and so on, ad infinitum.

The answer which St. Thomas would give to this would be that in the principle just mentioned the proper cause means that cause from which the effect necessarily and immediately proceeds. Now, if the proper causes of effects, however particular and momentary they may be, are also particular and transient, then the proper causes of universal and permanent effects are likewise universal and permanent, and hence belong to a higher order. For instance, to say that this particular animal is the direct cause of this other animal, does not suffice to explain the presence of animal life on the surface of the earth, which compels us to have recourse to more important and general principles, such as the sun, which is the permanent source of the heat required for the generation of plants and animals, and for their continuance in life. In like manner, this particular motor, which was itself set in motion by something else, truly accounts for the presence of this movement, but it does not explain the movement in itself; and if this movement (wherever it may be found) does not contain in itself a sufficient reason for its existence, it demands a universal cause, constantly in action and of a higher order, a source of energy which does not stand in need of actuation or conservation, but which produces and conserves all movement in the universe.

This argumentation is based on Aristotle's profound analysis of the notion of the proper cause, which we were able to give only in a brief note, but which must be studied for a complete understanding of the demonstrability of God's existence.

See Appendix I at the end of this book.


The principle here invoked, "that the proper effect demonstrates the existence of the proper cause," may in the last analysis be reduced to the principle of causality, which gives us the metaphysical aspect of being, and may be formulated thus: "That which exists, but not by itself, exists in virtue of some other being, which is self-sufficient." A contingent existence cannot have its completely sufficient cause in another contingent existence as dependent as itself; but both equally demand a necessary existence of a higher order.

The permanent causality which a being of a higher order exerts upon one of a lower order is called by the Scholastics equivocal or non-univocal causality, because it produces an effect which is not of the same nature as the cause. Thus heat is the proper cause, not only productive, but also preservative, of the expansion of bodies, of the fusion of solids, and of the vaporization of liquids; electricity also has its own proper effects, which are, as it were, its properties ad extra.

This causality of the superior over the inferior is, of course, particularly manifest when in the hierarchy of being we consider the influence which one order exerts upon another, lower order, for instance, the influence of a living being upon nutritive minerals, which it transforms into organic substances; in the animal, the influence of sensation and desire upon the action aroused by this desire; in man, the influence of the intellect upon all the activities under its direction, and that of the will upon the other faculties under its control; in the sciences, the influence of principles upon conclusions. In all these cases the superior cause not only produces, but also conserves the effect. The evidence of principles not only engenders, but also preserves in us the evidence of conclusions; if the first disappears, then the second vanishes, just as light ceases at the setting of the sun. In the same way the attraction of the good which we perceive, stirs up and foments within us a desire for the same; especially is this the case concerning that good which we propose to ourselves as the ultimate end. When this idea of good ceases to be for us a source of attraction, then our desire itself and our activity are at an end; as long as the attraction lasts, it may buoy us up for years in our daily labors.

On the contrary, a succession of univocal or specifically similar causes, as, for instance, the temporal succession of human lives or of physical movements in the past, are at bottom but a series of effects coming from a higher cause; if the movement as such cannot be explained sufficiently in itself, it demands a prime mover, who in his turn does not have to be set in motion.

This is the deeper sense of the principle: universal and permanent effects have for their proper cause a cause that is universal, permanent, and consequently of a higher order. This cause may truly be called the first principle or highest foundation. Thus we speak of the fundamental truth of philosophy, of the fundamental principles of the sciences, of the foundations of morality. If there is a first cause, it must evidently be a cause in this profound sense. Empiricism, which accepts only univocal causes, material or accidental, which denies the superior validity of the principles of reasoning, which rejects all foundations (the foundation of induction, that of the syllogism, that of morality, and that of society), must end by denying, or at least not affirming, the existence of God. For the Empiric, who is necessarily a Nominalist, as for the ordinary grammarian, the two propositions, "God is" and "Peter is," have about the same meaning; just as the world has no need of Peter, so it can get along without God.

Shall we fall into the other extreme, and return to the "ideas" of Plato, those supreme types, those "mothers" (see the Timaeus), which Goethe, following his natural mysticism, resuscitated in the second part of Faust? Shall we admit the self-sufficiency of man? By no means. All the material elements implied in any definition (such as that of man) cannot exist apart from matter, which is their principle of individuation. (See no. 39). But it is not so with being, truth, goodness, intellect, and will; there is nothing material or even imperfect involved in their formal notions. This will naturally lead us to conclude that the proper cause of pure being and of all contingent realities, is a self-subsistent Being, which, for that very reason, is the Supreme Truth, the foundation of all truth, the First Intellect, which conceives the eternal types of things, the Sovereign Good and Supreme Love, and the pre-eminent Source of every good desire.

This idea of the proper cause of universal effects will assume concrete shape and thus become clearer in the general proof for the existence of God, derived from the contingency of existing things, and which may be summed up by saying that the greater does not come from the less, nor the higher from the lower. (Cfr. no. 35).


10) Therefore, it is not in a series of accidentally connected past causes that we must seek for the original cause, but in one in which there is an essential connection between the causes.


From what was said above we see that the proofs for the existence of God, if they are to refer the effect back to its absolutely necessary cause, must not get hopelessly involved in a series of accidental causes. This mistake is frequently made by those who argue that the hen is the cause of the egg, and the egg the cause of another hen, and so on, indefinitely. St. Thomas can see no reason why there should be an end to such a series of causes. "It is not regarded as impossible to proceed to accidental infinity in efficient causes." (Ia, q. 46, a. 2, ad 7um). It is only in the order of necessarily and actually connected causes, the holy Doctor continues, that we must of necessity arrive at a final cause. If a clock consisted of an infinite number of wheels, each one depending on another in ascending order, there would be in fact no principle of movement, and it would make little or no difference whether this clock were wound up a hundred times, a thousand times, or ever so many times; for the one who winds it up is only per accidens the cause of its movement. So also, in the example which St. Thomas gives, for the sound of the anvil we ascend first to the movement of the hammer, then to the movement of the blacksmith's hand, and, finally, to some first principle of this local movement. But it does not matter much whether the blacksmith makes use of an indefinite number of hammers: "An artificer acts by means of many hammers accidentally, because one after the other is broken. It is accidental, therefore, that one particular hammer acts after the action of another. In like manner it is accidental to this particular man, in so far as he generates, to be generated by another; for he generates as a man, and not as the son of another man. . . . Hence it is not impossible for a man to be generated by man in infinitum." (Ia, q. 46, a. 2, ad 7um). If the blacksmith takes up a different hammer each time he strikes the anvil, the causal action of each hammer is not necessary in order that the following one should be able in its turn to strike the anvil. Similarly, there is no need that the son in his turn should have children, for him to be dependent on his father, grandfather, great-grandfather, and others as efficient causes. Neither does it seem to be metaphysically impossible for the world always to have been revolving on its axis; in this case there would have been no commencement of rotation; for, as St. Thomas remarks, "Quaelibet circulatio praecedentium transiri potuit, quia finita fuit; in omnibus autem simul, si mundus semper fuisset, nonesset accipere primum, et ita nec transitum, qui semper exigit duo extrema," that is, "any of the previous revolutions could be completed, because it was of finite duration; but in all things that happen simultaneously, if the world had always existed, there would have been no beginning, and hence no transition, since this always demands the presence of the two extremes." (C. Gentes, 1. II, c. 38). That there should be an actually infinite series of phenomena is not in itself an impossibility; for the series would be infinite "a parte ante" only, and finite "a parte post."

Aristotle, who held that the world and movement are eternal, said that this was an additional reason for assuming that there must be an eternal and infinite principle of all movement, capable alone of producing perpetual motion. As for St. Thomas, he taught that we know for certain only from revelation that the world had a beginning and is, therefore, not created ab aeterno. This depends entirely upon the divine will.

To say that it is no sufficient reason why the divine will should create at this particular moment, rather than at any other, is to doubt whether there is such a thing as freedom. (See infra, Vol. II, ch. IV).


(Ia, q. 46, a. 2).

That in a series of accidentally connected causes we must finally arrive at the first of these causes, is not because we understand what is implied by the term causality, but simply for the reason that an actually infinite multitude is an impossibility. But, as St. Thomas remarks (Ia, q. 7, a. 3, ad 4um; q. 46, a. 2, ad 6um and ad 7um), there can be an actually infinite multitude only if all the units comprising it coexist simultaneously; but this is not the case with an infinite series in the past; because that which is past no longer exists. Moreover, while it is evident that an infinite number involves a contradiction in terms, it is very difficult to prove the impossibility of an actually infinite and innumerable multitude. In his opusculum, "De aeternitate mundi," St. Thomas about the year 1264 wrote: "Adhuc non est demonstratum quod Deus non possit facere ut sint infinita in actu," that is, "it has not as yet been proved that God cannot bring it about that there be infinite beings in actu." In the "Quodlibeta," which he wrote towards the end of his life, he recapitulates (No. 12, q. 2) with greater exactness what he had said on this point in the Summa Theologica (see Ia, q. 7, a. 4). The passage reads as follows: "To make something infinite in actu, or to bring it about that infinites should exist simultaneously in acau, is not contrary to the absolute power of God, because it implies no contradiction; but if we consider the way in which God acts, it is not possible. For God acts through the intellect and through the word, which assigns to all things their forms, and hence it must be that all things are formally made (that is, determined) by Him."

Finally, in his Commentary on the Physics of Aristotle (Book III, Lect. 8), St. Thomas, discussing the Aristotelian proofs for the impossibility of an actually infinite multitude (proofs which he himself had reproduced in his Summa

See Ia, q. 7, a. 4.


), emphatically says: "It must be observed that these arguments are probable, expressing the commonly accepted view; they are not, however, rigorously conclusive: because . . . if anyone were to assert that any multitude is infinite, this would not mean that it is a number, or that it belongs to the species of number: for by number a multitude becomes measurable, as is stated in the tenth book of the Metaphysics, and, therefore, number is said to be a species of discrete quantity; but this is not the case with multitude, which is of the nature of a transcendental."

Among those who admit that an actually infinite multitude is not an intrinsic impossibility, we must include Scotus, the Nominalists, Vasquez, Descartes, Spinoza, and Leibniz. The Jesuits of Coimbra, and Toletus (in the first part of his Summa, q. 7) defend as probable the opinion that the actually infinite is a possibility. Just recently Renouvier's argument for the finite has been refuted by Milhaud (Essai sur les Conditions de la Certitude Logique, p. 177). In our day mathematicians versed in the theory of transfinite ensembles are increasingly less disposed to accept as valid any of the arguments by which the notion of an actually infinite multitude is proved to involve an intrinsic contradiction.

It is important to note, therefore, that in any of the classical proofs for the existence of God, this disputed point must be taken into consideration. Just why we cannot proceed to infinity, is because there must be a sufficient reason, a cause. Even if we could go back to infinity in a series of past accidental causes, as, for instance, transformations of energy, or of generations of living beings, or of human beings: movement, life, the human soul would still have to be explained. These accidental causes are in themselves insufficient, and demand a further explanation. To carry the series to infinity would not change their nature. As Aristotle remarked: If the world is eternal, it is eternally insufficient and incomplete; it eternally demands a sufficient reason for its reality and intelligibility. (Met., 1. XII, c. 6. See also Sertillanges, "Les preuves de l'existence de Dieu et l'éternité du monde," four articles in La Revue Thomiste of 1897 and 1898).

This remark makes it unnecessary for us to discuss at length the first Kantian antinomy concerning the eternity of the world.


11) In this series of essentially connected causes, we eventually arrive at one which must be the proper cause, without any further affirmation.


The proper cause is that which is necessarily (per se) and immediately (primo) required. Of course, there are necessary causes which are not immediate causes (per se non primo). We can more readily understand the reason why of anything than we can discern its true cause. Aristotle says that the essence of the triangle contains the necessary though not immediate reason for the properties of the scalene triangle. These properties, in fact, necessarily presuppose that the scalene is a triangle, but they cannot be said to follow as an immediate deduction from the definition of a triangle; if such were the case, they would belong to every kind of triangle and not to the scalene per se primo καθ' αὐτό καὶ ᾗ αὐτό (of itself and from its nature). (Post. Anal., I; Commentary of St. Thomas, Lect. II). The same holds good for metaphysical causality: for the proper effect of a cause is, as it were, one of its properties ad extra, existing by reason of something else, which is its principle of inherence. The proper effect bears the same relation to its proper cause, as property does to the essence upon which it necessarily and immediately depends. It is of this proper cause that Aristotle writes (Post. Anal., I; Commentary of St. Thomas, Lect. 10: "Quartus modus dicendi per se": immediate necessity in the order of causality). He gives as examples: "the murderer is the cause of death;" "the doctor cures one," "the chanter sings." If one were to say, "the man sings," this would not be an example of an immediate cause. To say, "the doctor sings," would be an example of an accidental cause, since it is purely an accident that he who sings happens to be a doctor.

Other more appropriate examples of the proper cause could easily be given. St. Thomas frequently refers to the fire which generates heat; to the light which dispels the darkness; to color which is the immediately predisposing cause (formal object) of sight, as sound is of hearing; to being, which is the direct object of the intellect as goodness is of the will. In matter of fact, it is by color that we see things, it is by sound that we hear, and things become intelligible to us according to the degree in which they participate in being, desirable in so far as they are good. Thus we may say that the ens realissimum, the absolutely Real Being, makes all things real, just as fire creates heat, and light, illumination, in the sense that the self-existing Being is the proper cause not of this or that mode of being, but of being in general. (See Ia, q. 45, a. 5). In like manner, the primary intelligent Being is the proper cause of our intelligence and of whatsoever intelligibility there may be in material things. The sovereign Good is the cause of all goodness, of all attraction to the same, and of all obligation founded on the idea of good.

Many authors, in presenting the proof for the existence of God, argue from a cause which is not immediate, and as a result, their demonstration is not conclusive. If, for instance, it is a question of explaining the order in the world, we do not have to affirm the existence of an absolutely perfect being, but it is enough if we prove the existence of a primary intelligence disposing all things, one that is the proper cause of this order. In explaining local movement it is not necessary to arrive forthwith at the "Actus Purus," but it is sufficient to show that there is a mover which itself is not moved locally, as would be a world-soul (see Cajetan, In Iam, q. 2, a. 2). If this soul is itself moved by some spiritual force, we must explain the difference in movement (which is movement in general and no longer a particular kind, such as local movement), by recourse to a prime mover of a higher order, which does not have to be started in its activity. But even this would not immediately prove the existence of an infinitely perfect being. To explain the existence of contingent beings, all that is required is to show the existence of a necessary being, but it is not necessary to prove immediately the existence of a personal, intelligent, and free God.

The five classical proofs given by St. Thomas (Ia, q. 2, a. 3) ascend per se primo, necessarily and immediately, to five divine predicates, to wit, (1) that there is a first unmoved mover of all things; (2) a first efficient cause; (3) a necessary and self-existent being; (4) the maximum in being; (5) the first of intelligent beings who directs all things to their predestined end. He then proceeds to show that these five predicates cannot be affirmed of anything corporeal (q. 3, a. 1), not even of a being composed merely of essence and existence, such as we find to be the case with spiritual beings of the finite order; but that they belong exclusively to the one who is Being itself (ipsum esse subsistens, q. 3, a. 5). In the fourth article of question 3 of the Summa St. Thomas finally proves that essence and existence are the same in God. This truth is the keystone of the two theological treatises in which God and Creation are discussed. Without it, the proofs for the existence of God cannot be said to be complete. The divine attributes—absolute simplicity, perfection and infinite goodness, immutability, eternity, uniqueness, omniscience, absolute freedom in regard to creation, omnipotence, universal providence, infinite beatitude—are all deduced from the single truth that God is the self-subsistent Being. From this it is also concluded that between God and the world there is this difference: He is essentially simple, immutable, and incapable of further perfection, and therefore necessarily distinct from the world, which is essentially composite, changeable, and imperfect.

Such, then, is metaphysical causality (causality necessarily and immediately required), and it is only upon this solid basis that we can construct the a posteriori proofs for the existence of God: for, "the proper cause of anything can be demonstrated from any of its effects." The foundation of all these proofs is, therefore, the principle of causality, which may be expressed metaphysically by saying that "what is not per se or self-existing, necessarily depends upon some other being which is self-existing" ("quod est non per se, est ab alio, quod est per se").


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