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



General modes


Affirmative: Essence, expressed by the word "thing" (res)

Negative: indivision, expressed by the word "one" (unum)

Special modes.


to another thing distinct from it is:—"something" (aliquid)

to the intellect—"true" (verum)

to the appetitive faculty -"good" (bonum)

The Categories.


The order in which these primary notions are arranged shows us the order of the formulas, more and more explicit, expressing the principle of identity. The simplest formula, as we have seen, is this: "Being is being, not-being is not-being," and it may be condensed into the negative formula of the principle of contradiction: "Being is not not-being." The identity of being, and of every being with itself, is expressed by the following formulas: "Every being is a thing," or, "Every being has an essence or nature." Or we may say: "Every being is one," and if we wish to emphasize the perfection of its unity, which means more than similarity or equality, we may add: "Every being is one and the same," or identical with itself. "It is one and the same thing," is an expression frequently heard. Further, in relation to some other thing distinct from itself, we say that "Every being is something"— which means that it is some definite thing, some determinate nature, constituted as such by some property of its own, that it is one thing and not another.

All these formulas are more or less explicit expressions of the principle of identity, of which the principle of contradiction is but the negative formula. Clearly all these formulas are implied in the notion of being, and in that of not-being. Being is being, not-being is not-being, flesh is flesh, spirit is spirit, good is good, evil is evil (est est, non non); a square is a square, a circle is a circle; that a square is a figure with four equal sides is of its very nature and cannot be otherwise. Peter is a human individual and cannot, while remaining Peter, cease to be a human individual. Every being has a definite nature; it is its own self and cannot at the same time be and not be what it actually is.

This is the first principle of our reason. It forms the basis of all direct demonstrations, which presuppose the identity of the terms employed, and rest on the real identity of the extremes with the middle term, to conclude that the extremes themselves are really identical. Indirect demonstrations, or those by the method of reduction to absurdity, are also based on this principle.

In conclusion, we may say that if, as we have shown, the principle of sufficient reason has ontological validity, then this must also be true of the principle of contradiction; it is not only a logical law of thought, but also the metaphysical law of reality. In other words, the absurd is not only unthinkable, but it is also absolutely impossible of realization.


21) The anti-intellectualistic objection raised against the principle of non-contradiction. Solution of the same by means of the concept of potency, which enters into all the proofs for the existence of God.


This first principle—whether the formula by which it is expressed be affirmative or negative—is not tautological; in fact, there is a certain school of philosophers which denies its truth, and consequently rejects all the proofs which reason offers for the existence of God. The philosophy of this school is based on the theory of "becoming"; it denies the existence of "things," admitting only "actions"; it defines the real, not as that which is (a certain determined nature), but as that which becomes and changes incessantly. Bergson writes in his book on Creative Evolution, p. 270: "There are no things, there are only acts; things and states are merely modes of thinking, which our mind derives from the idea of becoming." Accordingly, this philosopher refuses to see a real distinction between "a glass of water, water, sugar, and the process by which sugar is dissolved in water." (Ibid., pp. 10 and 366). This amounts to saying that everything is what it is, and what it is not; hence the square is a square and no square, since it constantly changes and, therefore, has no proper nature. Likewise, man is rational and irrational, and not having any proper nature of his own, it was possible for him to have evolved from pure animality by the process of creative evolution. Everything is in everything.

Le Roy reduces all his objections to the traditional proofs for the existence of God to this: that they all depend upon the postulate of morcellation. "The distinctions between mover and moved," he says, "between movement and the object moved, between the affirmation of the primacy of the act over the potency, rest on the same postulate of common thought. . . . But of what value are these idols of the practical imagination? Why not simply identify being with becoming? Since all things are movement, there is need to ask ourselves what causes them to be in movement."

"Comment se pose le Problème de Dieu," in the Revue de Métaphysique et de Morale, March, 1907.


Such a view leads one to conclude that God, far from being "He who is," in every respect identical with Himself, is but "a reality in the making, . . . a continuous projection,"

Bergson, Evolution Créatrice, p. 270.


that He is "an infinite in becoming."

Le Roy, Rev. de Mét. et de Morale, July, 1907, p. 512.


He is no longer conceived as apart from the world which is projected from Him, but He is the process of becoming, is always becoming, yet will never be.

Those who profess this Pantheistic philosophy are fully aware that the stand which they take is the result of denying the objective validity of the principle of identity or non-contradiction. According to Le Roy, "the principle of non-contradiction is not as universal and necessary as has been believed; its application is limited; it is restricted and circumscribed in meaning. Being the supreme law of speech, but not of thought in general, its influence extends merely to what is static, morcellated, immobile, in a word, to the things endowed with identity. But just as there is identity in the world, so also there is contradiction. Such are those fugitive fluxes, as becoming, duration, life, which of themselves are not of the rational order, and which speech transforms so as to incorporate them into contradictory schemata."

Revue do Métaphysique et de Morale, 1905, pp. 200-204.


Our intellect reifies (objectivates) the universal flux for the needs of speech and of practical Life, and in that way pretends to submit all that is real to the principle of identity.

The moral consequences of this doctrine have been stated by Jean Weber of the Bergsonian school. It ends in unmorality of conduct; there is no more a distinction between good and evil than there is between being and not-being. "Morality, in planting itself on a terrain from which invention grows in all its vigour, immediately and full of life; in manifesting itself as the most insolent encroachment of the realm of the intellect upon spontaneity, was fated to encounter the continual contradictions of that undeniable reality of dynamism and creation which is our activity. . . . Confronted with these morals of ideas, we outline morality, or, more correctly, the unmorality of the act. . . . We call ‘good' whatever has triumphed. Success, provided it is fierce and implacable, provided the vanquished are completely defeated, destroyed, abolished beyond hope—success justifies everything. . . . The man of genius is profoundly immoral, but for anyone to be immoral is not the proper thing. . . . ‘Duty' is nowhere in particular, and yet it is everywhere, for all actions possess absolute value. The repentant sinner deserves all the anguish of his contrite soul, because he was not strong enough to transgress the law, and unworthy to be a sinner."

Revue de Mét. et Morale, 1894, pp. 549-560.


Hence there is no longer any difference between Ravachol and a Christian martyr. This conclusion of "the philosophy of becoming" was clearly condemned in the first proposition of the Syllabus of Pius IX.

"God is the same as nature, and therefore subject to change. God actually becomes in man and in the world; all things are God and have the same divine substance; God is absolutely identical with the world, and hence there is no difference between spirit and matter, necessity and liberty, truth and falsehood, good and evil, justice and injustice." (Denz., n. 1701).


This denial of the objective validity of the principle of identity is of Sensualist origin; it originated in the theory of the perpetual movement of sensible appearances, and especially in the facts of consciousness.

Bergson, Evolution Créative, pp. 2 ff.


Heraclitus said: "No one goes twice into the same river, . . . where everything is flowing, proceeding on its course, without ever stopping." We can never say of anything which changes that "it is such and such a thing," because at the very moment when we say so, it is something else. In matter of fact, nothing is, everything is becoming. This argument has been thrown into logical form by saying that "Ex ente non fit ens, quia jam est ens," i.e., nothing can come from being, since whatever is, already exists, and what is becoming, before becoming does not exist; on the other hand, "Ex nihilo nihil fit" (nothing can came from nothing); if at any given moment nothing exists, then nothing ever will come into existence. From these two principles Parmenides concluded that becoming is an illusion, and the only thing he was willing to affirm was the principle of identity that: "Being is, non-being is not, and we can never escape from this thought." From these same principles Heraclitus concluded that being and non-being are mere abstractions of the mind, and "becoming" is the only reality, a mobile identity of contraries. This explains the universal "contradiction" which is found in all things.

See Aristotle, Phys., Bk. I, c. 8; Commentary of St. Thomas, Lect. 16, and Metaphys., Bk. IV (III), cc. 3, 4, and 5.


Aristotle devotes to the defence of the principle of contradiction Book IV of his Metaphysics, from the third chapter to the end of the fourth. "It is not possible," he writes, "for anyone ever to think that the same thing exists and does not exist. Heraclitus, according to some, is of a different opinion, but a man need not believe all that he says. This would be an affirmation which would deny itself. . . . (c. 3). It would mean to deny language and then to admit that we can speak (c. 4); all words would be synonymous, and all beings would be reduced to one single being; a galley, a wall, a man would all be one and the same thing (c. 4). The admission of a becoming without a something which is becoming, completely destroys substance and forces one to assert that everything is accident, to admit a process of becoming without a subject which becomes (c. 4). The reason why these philosophers [of the school of Heraclitus] held such an opinion is, that they regarded only objects of sense perception as constituting being, . . . and seeing that all sensible nature is in perpetual flux, . . . certain ones amongst them, such as Cratylus, believed that we must affirm nothing. Cratylus deemed a movement of the finger to be a sufficient answer (c. 5)."

Aristotle gives eight principal reasons for defending the necessity and real validity of the principle of contradiction. They are briefly: (1) to deny this necessity and this validity would be to deprive words of their fixed meaning and to render speech useless; (2) all idea of the reality of an essence, or thing or substance as such, would have to be abandoned; there would be only a becoming without anything which is on the way of becoming; it would be like saying that there can be a flux without a fluid, a flight without a bird, a dream without a dreamer; (3) there would no longer be any distinction between things, between a galley, a wall, and a man; (4) it would mean the destruction of all truth, for truth follows being; (5) it would destroy all thought, even all opinion; for its very affirmation would be a negation. It would not be an opinion which Heraclitus had when he affirmed that contradictories are true at the same time; (6) it would mean the destruction of all desire and all hatred; there would be only absolute indifference, for there would be no distinction between good and evil; there would be no reason why we should act; (7) it would no longer be possible to distinguish degrees of error; everything would be equally false and true at the same time; (8) it would put an end to the very notion of becoming; for there would be no distinction between the beginning and the end of a movement; the first would already be the second, and any transition from one state to another would be impossible. Moreover "becoming" could not be explained by any of the four causes. There would be no subject of becoming; the process would be without any efficient or final cause, and without specification, and it would be both attraction and repulsion, concretion as well as fusion.


We cannot deny, therefore, as Heraclitus did, the principle of non-contradiction. It remains for us to refute the objection derived from the idea of movement. Aristotle met this objection by introducing the notion of potency, as an intermediary between actual being and pure nothingness. (Phys., Bk. I, c. viii; Met., Bk. IX).

See F. Ravaisson, Essai sur la Métaphysique d'Aristote, Vol. I, pp. 391-394.


He says that it must be conceded that whatever becomes, does not come from actual being (ex ente non fit ens), and that nothing cannot come from nothing (ex nihilo nihil fit). And yet, whatever Parmenides may say, there is such a thing as becoming. To admit this, must we, like Heraclitus, deny being, the principle of all intelligibility, and say that becoming has its reason within itself? By no means; for becoming marks the transition from undetermined being to determined being. We have examples of this in the difference between one's capacity for acquiring knowledge and the knowledge acquired, between the embryo and the fully constituted being, between the seed and the plant, etc. Undetermined being is susceptible of receiving a determination, and this susceptibility we call potency. This potency, which is not being, cannot pass into actuality, but demands to be reduced to actuality by an active power, which itself must be aroused to action by some previous power, and, in the final analysis, by an active supreme power, which is its own activity, and hence unmoved, pure actuality, always absolutely the same. In that way becoming is explained, and the principle of contradiction remains intact.

Aristotle even goes so far as to claim that his position alone entitles us to affirm the process of becoming, just as it permits us to affirm identity. "This system [of Heraclitus], in which being and not-being are alleged to exist simultaneously, must lead to the admission of perpetual repose rather than of perpetual movement. In fact, there is nothing left which beings may become, since everything is in everything else." (IV Met., c. v). A becoming without a "subject" which remains unaltered throughout the process of change, would no longer be a becoming, for at each instant there would be both annihilation and creation. Later on we shall see that a causeless and purposeless process of becoming is no less an impossibility. (See nos. 26 and 27).

Bergson presents the argument of Heraclitus in a new form. "There is more," he says, "in a movement than in the successive positions attributed to the moving object, more in a becoming than in the forms passed through in turn, more in the evolution of form than in the forms realized one after another. Philosophy can, therefore, derive terms of the second kind from those of the first, but not vice versa; for it is from the first terms that speculation must take its start. But the intellect reverses the order of the two terms, and on this point ancient philosophy proceeds as the intellect does. It installs itself in the immutable, it posits ideas, and passes to becoming by way of attenuation and diminution."

Evolution Créatrice, pp. 341 f.


"A perpetual mobility is possible only if it is backed by an eternity of immutability, which it unwinds in a chain that has neither beginning nor end. Such is the last word of Greek philosophy. It has its roots deep down in the soul of pagan antiquity. It would, therefore, be useless to try to deduce it from a simple principle. But if every element derived from poetry, religion, social life, and a rudimentary system of physics and biology be removed from it, if we take away all the light materials that may have been used in the construction of the stately building, a solid framework remains, and this framework marks the main lines of a metaphysic which is, we believe, the natural metaphysic of the human intellect."

Ibid., p. 354.


Bergson's philosophy is of the dynamic order, which is the very opposite of the natural metaphysic of the ancients, for the reason that such a metaphysic is merely the systematization of dissociated objects, and of the morcellation to which the universal flux has been submitted by common opinion, or, in other words, by the practical imagination and by speech. In Bergson's opinion the intellect is made only for considering "inert objects, more especially solids, where our action finds its fulcrum and our industry obtains its tools; our concepts have been formed on the model of solids, our logic is pre-eminently a logic of solids," incapable of representing the real, which is essentially becoming and life.

Ibid., p. 1.


This argument has remained almost unchanged since the time of Heraclitus, and its Sensualist origin becomes more and more evident as we go along. If solid bodies constitute the sole object of the intellect, how are we to explain the verb "to be," which is the soul of every judgment, and in what way does man differ from the animal? If the object of the intellect is not the solid body, but being and all which has a raison d'être, the Bergsonian proposition that "there is more in the movement than in the immobile," is true only of immobilities viewed by the senses as actual becoming. But it is false, if interpreted in the sense of an absolute principle, because in that case it would imply that "what is as yet merely a becoming, is more of a reality than what actually is." The senses see in the immobile object something which is at rest; the intellect, something which is, in opposition to something which is becoming, just as the immutable is that which it is and cannot be other than what it is. Bergsonian Sensualism confuses immutability, which transcends all movement, with something which is inferior to it; namely, the terminus ad quem with the terminus a quo, actuality with potency. In this way it lowers the immobile life of the intellect, which contemplates the highest eternal laws, to the level of the inertia of inanimate solids. From this point of view, the vegetative life of the stomach is superior to the immobile life of the intellect; time is superior to eternity, for it is life, whereas eternity is death.

Boutroux answers Spencer by remarking that "evolutionism is the truth envisaged from the point of view of the senses, but as the intellect considers things, it remains true that the imperfect does not exist and does not determine itself except by reason of the more perfect. . . . Moreover, the intellect persistently proclaims with Aristotle that everything has a reason, and the first principle must be the ultimate reason of things. Now, to explain means to determine, and the ultimate reason for the existence of things must be sought in the completely determined being."

See Etudes d'Histoire de la Philosophie, p. 202.


"This is the last word of Greek philosophy," but it is not, as Bergson says, "connected by invisible threads with all the fibres of the ancient soul" and with what constitutes the basis of the human intellect. It is not true to say that we cannot "deduce it from a simple principle." It is connected with the intellect by the supreme law of thought and of reality—the principle of identity, implied in the very first of all ideas, which is that of being. It is connected with the intellect, not by a utilitarian division of the sensible content, imposed by the conventional modes of practical life and speech; but, if we wish to avoid an absurd conclusion, it rests of necessity upon the principle of the morcellation of intelligible being.


22) Hegel's objection (absolute intellectualism) to the principle of identity.


The anti-intellectualism of Heraclitus, repeated at the present day by Bergson, is at the opposite pole of the absolute intellectualism of Hegel, which also denies the objective validity of the principle of identity. While the Sensualist philosophy of becoming reduces the rational to experimental reality, to the fact of consciousness, what must be to what actually is, right to the fait accompli, morality to success, necessity to a meaningless and lawless liberty, to a sort of blind spontaneity resembling the "unconscious" of Schopenhauer; the intellectualist philosophy of becoming, on the contrary, restores experimental reality to the rational order, that which is to that which ought to be, the fait accompli to right, success to morality, liberty to necessity. Thus Bergsonism appears like a reversed Hegelianism.

Hegel's Pantheism was the result of his denial, from an intellectualist point of view, of the principle of non-contradiction, in the very name of the idea of being.

Hegel proposes to refute the Pantheism of Schelling, in which the relatively transcendental absolute becomes the world by a sort of evolution in the descending order, which reminds one of the emanation theory of the Alexandrian school. According to Hegel, the transition from this unique Absolute to the multiplicity of things cannot be logically explained. If this Absolute is perfect in itself, and incapable of further perfection, how could the world proceed from it? The transition from the one to many would be irrational, without reason. Knowledge, on the contrary, presupposes that everything which is real is rational and logical. In fact, the real is nothing else but the rational. Hegel is thus led to admit the real idea of being as the principle of all knowledge and of all reality. This idea, by an internal necessity, and in accordance with a logic superior to that of the principle of contradiction, gradually determines itself into genera, species, and individuals, and by this ascending scale of evolution establishes the mineral, vegetable, and animal kingdoms, until finally, on the appearance of man, it takes cognizance of its own self. With the evolution of human thought, both individual and collective, this consciousness of the absolute passes from a confused to a distinct knowledge, until there appears idealistic evolutionism, the philosophy of the creative idea, superior to all forms of art, religion, and philosophy. The point of departure of this philosophy is the identification of the idea of being with the reality of being in general—an identification which is contrary to the testimony of conscience and to the principle of contradiction. In the course of its evolution, it is a constant violation of the principle of contradiction and of the principle of causality, since the less is the cause of the greater; it also runs contrary to the principle of mutation, for the change is without a subject which changes, and to the principle of finality, for there is no orderly connection between the evolution of the lower forms of life and the higher; this passive ordination presupposes an active ordination. But, according to this doctrine, there is no original and intelligent designer.


His argumentation, as set forth in his Logik (French translation by A. Véra, 2nd ed., § 85, Bk. 1, pp. 393-412), is correctly summed up by the historian Weber in the following words: "Being is the most universal of all notions, but for this very reason it is also the poorest and the most negative of notions. To be white or black, to have extension, to be good, means to be something; but to be without any determination, is to be nothing, is simply not to be. Pure and simple being is, therefore, equivalent to not-being. It is at one and the same time itself and its contrary. If it were merely itself, it would remain immobile and sterile; if it were mere nothingness, it would be synonymous with zero, and in this case also completely powerless and infecund. It is because it is the one and the other that it becomes something, another thing, everything. The contradiction contained in the notion of being resolves itself into becoming, development. To become is at the same time to be and not to be (that which will be). The two contraries which engender it, namely, being and non-being, are rediscovered, blended and reconciled in becoming. The result is a new contradiction, which will resolve itself into a new synthesis, and thus the process will continue until the absolute idea is reached."

Cfr, also G. Noel, La Logique de Hegel, Paris, 1897, pp. 23-52 and 135—159.


To perceive the sophism contained in this argument, we need only cast it into syllogistic form: Pure being is pure indetermination. But pure indetermination is pure non-being. Therefore, pure being is pure non-being. The middle term, "pure indetermination," is used in two different senses, In the major it means the negation of all determination, generic, specific, or individual, but not the negation of (ideal or real) being, which transcends the generic determinations of which it is susceptible. In the minor, on the other hand, pure indetermination is not only the negation of all generic, specific, and individual determination, but also implies the negation of any further determination of which being is capable. Therefore, the argument amounts to this: that pure being is undetermined being; but undetermined being is pure non-being. The minor is evidently false.

See Zigliara, Summa Philosophica, Vol. I, Critica, pp. 247-252.


Besides, there is no apparent reason why becoming should emerge from this realized contradiction, this identification of contradictories. On the contrary, we must hold with Aristotle that "to maintain that being and non-being are identical, is to admit permanent repose rather than perpetual motion. There is in fact nothing into which beings can transform themselves, because "everything includes everything." (IV Met., c. v).

Finally, this absolute intellectualism of Hegel is no less destructive of all knowledge than is the anti-intellectualism of Heraclitus and Bergson. All reasoning presupposes that every idea employed in the process represents a reality, the nature of which remains the same; but for Hegel, the principle of identity is merely a law of inferior logic, of the mind working with abstractions, and not a law of superior logic, of reason and reality. "From this it follows," as Aristotle remarked (IV Met., c. iv), "that one can with equal right affirm or deny everything of all things, that all men tell the truth and that all lie, and that each one admits that he is a liar."

For the rest, Hegel himself acknowledges "that if it is true to say that being and non-being are one and the same, it is also true to say that they differ, and that the one is not the other." (Logik, Bk. I, p. 404). It follows from this that, according to Hegel, nothing can be affirmed and everything can be affirmed. If this attitude does not destroy all science, it cannot at least be said to have more than a relative value, and hence to possess nothing more than the name of science.

We may rightly conclude, therefore, that the objections raised against the principle of contradiction in no way affect its validity. Those of Hegel as well as those of Heraclitus and of Bergson are mere paralogisms. These philosophers admit that the principle of contradiction is a law of the reasoning mind and of speech, and it must also be accepted as the law of being. In other words, the absurd is not only unthinkable, but also impossible of realization, because no power, however great, can make it real. For the mind, this principle is the first of all evident certainties; its ontological validity is based on that of the notion of being, which has occupied us through so many pages. The objections just examined are powerless to weaken or depreciate the soundness of this principle in any way.

Renouvier, as various philosophers before him, in his Dilemmes de la Métaphysique Pure, p. 2, casts doubt upon the objectivity of the principle of contradiction. In reference to this it suffices to say, with Evellin (Congrès de Métaphysique, Paris, 1900, p. 175), that "if the law of non-contradiction were merely a law of thought, but not of reality, being would lose precisely that which constitutes it what it is—its identity with itself, and consequently, being as such would be non-existent. Everything would disappear in an intangible flux. . . . The principle of identity is not only an essential requisite of thought, but it also constitutes nature, having thoroughly emancipated it from the tyranny of the phenomenon." In fact, as we shall see further on, the principle of substance is merely a determination of the principle of identity. The principles of sufficient reason and of causality can also be traced back to this principle of identity, by showing the absurdity of the opposite contention; which means that they, too, have ontological value, i.e., are laws of being.

From the preceding discussion it is evident that, if the principle of identity and of non-contradiction had no objective value, evolutionistic Pantheism would be victorious and "becoming" would be the fundamental reality. If, on the contrary, the absolute universality and objectivity of this principle are established, the fundamental reality is necessarily pure identity, or self-subsistent Being (ipsum esse subsistens), pure being, pure actuality, pure perfection, a transcendent reality essentially distinct from the world, which is composite and subject to change.

Hegelianism, Heraclitism, and Bergsonism thus, by their avowed contradiction, which is an essential feature of their systems, furnish a proof per absurdum for the existence and transcendental nature of God.


23) Substance is the determining principle of identity. What place it holds in the demonstration of the existence of God.


It is easy to see that the principle of substance, denied by the philosophy of becoming, is nothing but a determination of the principle of identity. It is important to recall this truth here, because the proofs for the existence of God presuppose the existence of substances, and of substances distinct from one another. In an article entitled "La Dernière Idole," which appeared in the Revue de Métaphysique et de Morale, of July, 1902, M. Hébert wrote: "The principle of causality, bringing us back to a first extrinsic cause in accordance with the axiom that ‘quidquid movetur, ab alio movetur' [whatever is in motion, is set in motion by another], derives its apparent lucidity from a spatial image which has been illicitly introduced into a metaphysical problem. It is based on the supposition that the movers and those moved are distinct substances, which Pantheism denies." We have already had occasion to note that this same objection was developed by Le Roy in discussing the postulate of morcellation. In his view, as in Bergson's, substance is "a position in space," resulting from the advantageous morcellation of the continuous in sense perception. From the empirical point of view, or as far as the senses are concerned, it is difficult to see how it could be defined otherwise. But from the intellectual point of view, substance is conceived as a fundamental reality belonging to a different order than quantity and sensible qualities. Being present entirely in the whole and in every part of it, it gives to the object its unity. It cannot be perceived as such by the senses, but only by the intellect. (St. Thomas, IIIa, q. 76, a. 7). Nevertheless, it is called a sensibile per accidens (an accidentally sensible object) because the senses recognize it accidentally as the subject of phenomena concerning which they have a direct knowledge. As a matter of fact, the sense of sight perceives, not color in general, but that which is colored, a colored object perceived precisely as colored, whereas the intellect, upon the simple presentation of a sensible object, perceives it as a substance without any investigation. "What is immediately apprehended by the intellect, when confronted with the object of sense perception, is called sensibile per accidens (accidentally sensible)." (Aristotle, De Anima, Bk. II; Comment. of St. Thomas, Lect. 13). As soon as the dominant one of the internal sense faculties has reunited the data presented by each of the external senses, therefore, the substance is thus grasped by the intellect.

In its relation to the intellect, substance is but a primary determination of being, necessary for the purpose of rendering intelligible, in the role of being, a group of phenomena which presents itself as autonomous. On the first presentation of any sensible object whatever, such as, e. g., the swaddling-clothes in which an infant is wrapped, whilst the sense of sight perceives the color of this object, that of touch its shape and resistance, the intellect acquires a confused knowledge of its being—that the object is "something which is." This first known object of the intellect becomes more clearly defined as something which is one and permanent (a substance), after the intellect has noted the multiplicity of its phenomena and the changes which they undergo. In fact, it is only by reason of this oneness that the multiple becomes intelligible, just as the permanent or the identical explain the transitory; for one of the formulas of the principle of identity is that "every being is one and the same with itself." To say of a being that it is a substance, is to assert that it remains one and the same under its multiple and changing phenomena. The principle of substance, therefore, is simply a determination of the principle of identity, and the idea of substance a determination of the idea of being. In the acquisition of its knowledge the intellect proceeds from the idea of being—in which that of substance is de facto implicitly included—to the somewhat confused ideas of the manner of being implied in phenomena, multiplicity, and change. It seeks to render these new ideas intelligible in the light of the idea of being, and comes to recognize the "something which is" as one and a permanent subject, as a being in the full sense of the word, as something which exists in itself or subsists (a substance). The intellect is now in a position to narrow down the concept of the manner of being implied in the phenomenon, which cannot be defined except in terms of what exists in itself, for it is ens entis, "an entity of an entity." Thus, the confused concept of the phenomenon adds to the definiteness of the concept of substance, and is in turn more clearly defined by it. (St. Thomas, Summa Theol., Ia, q. 85, a. 5). Therefore, the morcellation which separates being from the phenomenon is not a utilitarian division of the continuous in sense perception, but a division of the intelligible, which, by reason of the principle of identity, is a metaphysical or a priori requisite.

From this point of view, the second Kantian antinomy, which concerns corporeal substance, presents no difficulty. The continuous is divisible, but not divided indefinitely;

Aristotle, Phys., Bk. VI.


the corporeal and extended substance is not a contradictory collection of unextended indivisible parts, but its unity is assured by a principle superior to that of the spatial order, namely, the substantial form, which exists as a whole in the object as a whole and in each part of the object, and which demands such extension—the least possible—as a condition for the subsistence of the composite.

As for the numerical distinction of individual substances of the sensible order (a distinction presupposed by certain proofs for the existence of God, but not essential to these proofs), we often have only physical certitude, derived from experience and the laws which experimental science has discovered. But the criterion of the substantial unity of a being is not merely, as Le Roy would have it,

Rev. de Mét. et Mor., July, 1899, p. 383.


its quantitative unity in space, a unity perceptible to the sense of touch, for this sort of unity often presupposes only an accidental union, namely, that of an aggregation of molecules. The true criterion of the substantial unity of a being is activity, and "the action which reveals the unity of the whole must be produced by a single part, and not by the association of parts; but the influence of the other parts must also be revealed in this action. A frequently quoted example is that of a mare with a broken cannon bone, having a colt whose cannon bone looks as if it were broken but grown together again." It is by means of this principle that the individuality of the higher animals is established.

De Munnynck, "L’individualité des animaux supérieurs," in the Revue Thomiste, 1901, p. 664.


When, in reality, we distinguish between two animals, or between an animal and its environment, this is not merely "an arrangement, a simplification convenient to the word and the action." Bergson in his Creative Evolution admits that the living body is isolated by nature itself, even though its individuality is not perfect.

As for the substantial distinction between human souls, it is the object of metaphysical certitude and can be scientifically demonstrated. The intellect, which is the basis of freedom, is intrinsically independent of the organism when in operation, and its object is universal being. It presupposes, therefore, a subsistent and simple principle, intrinsically independent of matter and of the world of corporeal beings (operari sequitur esse, et modus operandi modum essendi). This subsistent and simple principle, which is conscious and master of itself, must be distinct from similar subsistent principles. St. Thomas proves this in his Summa Theologica, Ia, q. 76, a. 2, saying that "it is absolutely impossible for one intellect to belong to all men; if there were one intellect for all men, it would not be possible to distinguish my intellectual action from yours on the basis of one intelligible object; there would be only one intellectual act." Finally, it follows as an evident conclusion that human souls are distinct from the Absolute, if it is proved that the Absolute cannot harbor within itself either multiplicity or becoming.

The principle of sufficient reason, which we are about to consider, will show us clearly that whatever is multiple (composite) and changing, cannot have a sufficient reason for its existence in itself, but in the final analysis this reason must be sought in a being which is pure identity, pure being, pure act, pure perfection. From this point of view, it matters not whether the world from which we start to prove the existence of God is one single substance, or a number of substances. It is sufficient for our purpose if there be found in it (at least accidental) multiplicity and becoming. God cannot be conceived as the substance of the world, for that would mean that He is determined and consequently perfected by the multiple and transitory phenomena superadded to Him. He would no longer be identified with His being as A is A, be pure being or pure act.


24) The principle of sufficient reason is the immediate basis of the proofs for the existence of God. By the appeal to the impossible it resolves itself into the principle of identity. In this sense, it is an analytical principle.


The principle of sufficient reason, on which the proofs for the existence of God are based, is not, like the principle of substance, a simple determination of the principle of identity, but resolves itself into this principle by an appeal to the impossible. The principle of sufficient reason may be expressed by the following formula: "Everything which is, has a sufficient reason for existing," or, "Every being has a sufficient reason;" consequently, "everything is intelligible." This principle is self-evident, and though it cannot be directly demonstrated, it can be indirectly demonstrated by the indirect method of proof known as reductio ad absurdum. The direct demonstration furnishes, by means of a middle term, intrinsic evidence of a proposition not immediately evident, or not self-evident. The demonstration by the method of reductio ad absurdum of an immediately evident principle cannot make this principle intrinsically evident for us, but merely proves that he who denies this principle must also deny the principle of contradiction, and that he who doubts it must also doubt the principle of contradiction. It is a unanimously accepted doctrine in Scholastic philosophy, that metaphysics explains and defends the first principles by the method of reductio ad impossibile, referring them to the principle of identity, which is immediately implied in the first of all ideas, that of being.

Cfr. Book IV of Aristotle's Metaphysics, and the Commentary of St. Thomas, Lect. 6. Also the Summa Theol., Ia, IIae, q. 94, a. 2; Suarez, Disp. Met., disp. III, sect. 3, no. 9; John of St. Thomas, Cursus Phil., q. 25, a. 2; Goudin, ed. 1860, IV, p. 255; Kleutgen, Phil. Schol., nos. 293, 294; Zigliara, Ontol., p. 235; De la Lumière Intellectuelle, t. III, p. 255; Delmas, Ontol., p. 642. This point has been fully discussed by the present writer in the Revue Thomiste, Sept., 1918, in an article entitled, "Comment le principe de raison d'être se rattache au principe d'identité, d'après St. Thomas," reproduced in Le Sens Commun, la Philosophie de l'Être et les Formules Dogmatiques (p. 208).


"In principles which are knowable in themselves," writes St. Thomas, "there is found a certain order, so that some of them are plainly included in others; just as all principles are reduced to this one as to their first: that it is impossible to affirm and deny at the same time, as is evident from what the Philosopher says in the Fourth Book of his Metaphysics, text. 9." (IIa IIae, q. I, a. 7).

Let us explain in what this reductio ad absurdum consists. First of all, we must show what is the exact meaning of the formula as an expression of the principle: "Everything which is, has its reason for being." The reason for being is twofold: intrinsic or extrinsic. When we speak of the intrinsic sufficient reason of anything we mean that which constitutes it to be of such and such a nature, endowed with certain properties and none other. Thus, there must be something in a square which makes it to be what it is, a square with certain properties, rather than a circle with certain other properties. If it were only a question of the intrinsic sufficient reason, this principle would merely be a determination of the principle of identity, and from this point of view, envisage substance as essence. To deny that every being has in itself that by which it is as it is, when it is such of itself and by what properly constitutes it as such, would evidently be tantamount to denying the principle of identity, to deny that red is red in itself and that a square has in it something which constitutes it as such with certain properties, rather than a circle with certain other properties.

But the sufficient reason can also be extrinsic. Thus we say that the properties of a thing have their sufficient reason in the nature from which they are derived, and in the specific difference from which they can be deduced, and which gives them their intelligibility. The investigation of the nature of a triangle, for instance, reveals its properties, and in the deliberative capacity of the reason we detect the presence of freedom. Again, we say that the sufficient reason for the existence of a being which does not exist of itself, must be found in another being which exists of itself. This extrinsic sufficient reason of a contingent being is called its efficient cause; it is its realizing or actualizing raison d'être, i.e., that which makes it a reality or an actuality. Finally, we say that a means which is not willed for its own sake, but in view of an end, has its extrinsic sufficient reason in that end. Thus we see that the extrinsic sufficient reason may be either the efficient or the final cause. Without going into details, we shall apply the term cause in its generic sense to this principle, not considering, for the present, the question of efficiency.

If, therefore, we wish to express concisely the formula of the intrinsic and extrinsic elements in the principle of sufficient reason, we may say that "Every being has a sufficient reason, either in itself or in some other being, for being what it is; in itself, if what constitutes it as such belongs to it by its very nature; in another, if what is attributed to it does not belong to it by its very nature."

As we have already seen, the first part of this formula, which concerns the intrinsic sufficient reason, is simply a determination of the principle of identity. It is the second part which, by the method of reductio ad impossibile, can be referred back to the supreme principle. In other words, it is not only unintelligible, as the followers of Kant claim, but also contradictory, to say that a being which has not in itself a sufficient reason for what it is, cannot be said to have its raison d'être in another. That such is the case can easily be proved. A. Spir's Pensée et Réalité

Translated from the German by M. Penjon, Paris, 1896, pp. 146 and 203.


will help us to present this argument in a convincing form.

The principle of identity may be stated as follows: "Every being is by itself constituted in its own specific nature." Thus A is A; what is red, is red by its very nature; the square is by its very nature a square. From this we derive the negative formula, which is the principle of non-contradiction: "One and the same being cannot be and not be what it is;" it cannot, for instance, be round and not-round. A third formula resulting from this, which may be called the principle of contraries or disparities, is: "One and the same being cannot be at the same time and in the same sense determined in two different ways;" it cannot, for instance, be round and square, for what is square, as such, is the opposite of what is round, and by its very nature is not-round. This prepares us for a fourth formula: If it is a contradiction to say that "the square is round," it is no contradiction to say that "the square is red," since the attribute in this case is of a different order. In a square it is the form that we are considering, but in a red object it is the color. The square can be red without ceasing to be a square. But there is a contradiction in terms if we say that "the square of itself, and as such, that is to say, by what determines it in its own nature, is red;" for what determines a square to be a square is something different than what determines an object to be red. It cannot be said that it belongs to the essence of a square to be red. Hence the fourth formula may also be stated as follows: "That which is predicated of a being, without properly belonging to it, as constituting it in its species, does not have its raison d'être in itself." This formula, a direct deduction from the principle of identity, may also be expressed in this way: "Elements which are different in themselves, do not of themselves coalesce to form some sort of unity, and cannot of themselves be united or mutually predicated."

Finally, the extrinsic principle of sufficient reason in addition to this affirms that "what is predicated of a being, though not belonging to it as properly constituting it in its species, has of necessity its sufficient reason in something external to it." St. Thomas puts it thus: "Omne quod alicui convenit non secundum quad ipsum est,

This "secundum quod ipsum est" is the equivalent of Aristotle's καθ҆ αὑτὸ καὶ ᾐ αὑτὸ, which occurs in his Analytica Post., Bk. I, c. 4.


per aliquam causam ei convenit, nam quod causam non habet primum et immediatum est" "whatever a thing may fittingly have, according to its nature, accrues to this thing from an extrinsic cause, for what has no cause, is primary and immediate." (C. G., II, ch. 15 c. 2). In another of his works he expresses the same thought more briefly by remarking that "things in themselves different cannot unite, unless something causes them to unite" (Ia, q. 3, a. 7).

This principle enunciates a new truth, not included in the fourth formula, for it affirms a relation of dependence, the presence of an external cause, which cannot be deduced from the principle of identity by a direct demonstration, but is in itself immediately evident; however, it can be referred to the principle of identity by an indirect demonstration, or, in other words, by the method of reductio ad absurdum.

It has often been disputed whether it is possible to invoke this particular method of proof against one who would deny the extrinsic principle of sufficient reason.

M. J. Laminne, in the Revue Néo-scolastique de Philosophie (Louvain, Nov., 1912) examines this reductio ad absurdum method, which has been fully explained by the present author in another of his works, entitled: Le Sens Commun et la Philosophie de l’être, p. 230. The conclusion that Laminne came to was this: "To deny that the contingent being is conditioned or relative, is to affirm that it is non-conditioned, non-relative, in a word, that it is absolute, and that we should have to say that what is, though not self-caused, is self-caused." "Again it must be observed," remarks Laminne, "that this reasoning holds good only on the supposition that there must be a sufficient reason for everything which exists; otherwise, to deny that a contingent being is conditioned, would be to affirm its absolute existence, in the sense that it does not depend upon another, but not in this sense that it has the reason for its existence in itself, in other words, that it exists per se."


All reductions so far proposed would seem to imply a begging of the question. Hence it is contended that the negation of the principle of sufficient reason is unintelligible, but not absurd. In other words, it is unintelligible, but it is not absurd, that the contingent should be uncaused. If it were uncaused, it would exist without a sufficient reason; for it could not be explained by anything intrinsic or extrinsic to it.

Those who reason in this manner depart from the principles of traditional philosophy and can be refuted by the very fact that several of their own number admit the absolute necessity of the principle of sufficient reason or causality. That something should be absolutely necessary and yet not exist, is an absolute impossibility. Now, the metaphysical principle of sufficient reason is not simply a necessity of the hypothetical order, such as the laws of physics, but it is also an absolute necessity. Therefore, its denial involves an absolute impossibility, or an absurdity, for the absurd is that which is absolutely impossible. In other words, all those who are at variance with us on this point must concede, as Hume and radical Empiricism do, that, absolutely speaking, a contingent being can be uncaused, which is the same as denying the absolute necessity of the principles of sufficient reason and of causality, which in this case are nothing more than empirical laws endowed with a purely hypothetical necessity. And just as God can miraculously raise the dead to life and conserve an accident in existence apart from its substance, so also He could by His absolute power have created a world in which there would have been effects without causes, an absolute beginning of things, uncaused beings springing from nothing. These absolute beginnings would be incomprehensible mysteries, but they would no more involve a contradiction than the Divine Trinity and the Incarnation. These stringent deductions will not be accepted by any one who wishes to conform to the general principles of traditional philosophy.

In the second place our answer to those who deny the absolute necessity of the principle of sufficient reason must be that the reductio ad absurdum method of proof, rejected by them, can be established without begging the question, in the following manner:

To deny the principle of sufficient reason is to affirm that a contingent being which exists, though not by itself, can be uncaused or unconditioned. Now, what is uncaused or unconditioned exists by itself. Therefore, an uncaused contingent being would at the same time exist by itself and not by itself—which is absurd. This is precisely what St. Thomas means when he says: "Whatever it is proper for a thing to have, but not from its nature, accrues to it from an extrinsic cause; for what has no cause, is first and immediate." (C. Gentes, Bk. II, ch. 15, § 2). What is uncaused must by itself and immediately be existence itself. If the unconditioned were not existence itself, there could be no possible connection between it and existence, and it could not be distinguished from nothing. An absolute beginning, a being originating from nothing without any cause, is, therefore, an absurdity, since it would be both contingent, that is to say, not caused by itself, and at the same time uncaused, unconditioned, non-relative, that is to say, absolute or caused by itself. Its existence would be its own a se and not a se. Therefore, between unconditioned or uncaused contingency there is a contradiction.

Against this argument Hume objected that an uncaused contingent being is only negatively a se, that is to say, not caused by another, but not positively, because it has neither within nor outside itself a sufficient reason for its existence.

This same objection was proposed by Laminne; see footnote to pp. 185 f.


In answer to this objection we say that what is neither positively its own reason for existence nor derives this reason from something else, is not only unintelligible, but also absurd and impossible, and cannot be distinguished from nothingness. In fact, intelligibility, like possibility, cannot be conceived except in relation to being. That is possible which is capable of existing, and that is intelligible which has reference to being, the primary object of the intellect. Consequently, what can in no way refer to being is absolutely unintelligible; likewise, what in itself excludes the idea of existence as something repugnant to its nature, what is not susceptible of existence, is absolutely impossible. Hence it follows, with regard to actual existence, that a thing cannot actually exist unless it has an actual relation to existence. Now, an uncaused contingent being could in no way be said actually to be related to existence. In fact, according to the previous hypothesis, it is not caused either by itself or by something else, and consequently cannot be said either of itself or by reason of something else to be actually related to existence. But a relation without any foundation is an impossibility.

Yet this answer does not fully solve the difficulty, for we may say that this actual relation to existence would be indeed without a foundation, that is to say, without any raison d'être, and therefore unintelligible, but not absurd. The answer to the preceding objection is simply a begging of the question, because it presupposes the principle of sufficient reason, which it claims to defend by a reductio ad absurdum.

In reply we may say that this relation without a foundation is unintelligible only for the reason that it is in no possible way related to being; it is beyond the sphere of being and of intelligibility, just like mere nothing, and consequently, is not only unintelligible, but also absurd and impossible. To make this point still clearer, we must consider that this relation without a foundation would be a relation denoting an agreement between actual existence and uncaused contingent being. Now, a relation which denotes an agreement necessarily presupposes two terms which have some element in common, by which the one refers to the other; but in this case actual existence and uncaused contingent being have nothing in common by which they could be referred to each other, since the very definition of uncaused contingent being implies that which exists neither by itself nor by reason of anything else, and has, therefore, nothing by reason of which it could be said to exist. This relation of agreement consequently is not only unintelligible, but also absurd, since it would be a relation of agreement between terms which are in no way related to each other, and have nothing in common which might constitute a basis of agreement.

Hegel perceived this truth clearly when he admitted that a becoming which is its own sufficient reason involves a contradiction.

In a word, the uncaused contingent being either is without any sufficient reason for its existence, in which case it is and is not distinguished from nothing; or else it is its own sufficient reason, and then it is and is not distinct from self-existent Being.

Of course, this indirect demonstration does not pretend to give the intrinsic evidence of the principle of sufficient reason —which principle is immediately self-evident and therefore needs no proof. But it does show that the denial of the necessity of this principle is not only unintelligible and disastrous, as Kant maintains, but also contradictory. To deny this principle means to deny the principle of contradiction; and to doubt it means to doubt the principle of contradiction. In this sense we say that the principle of sufficient reason is analytical. For a judgment to be analytical, it is not necessary that there should be logical identity between the subject and the predicate, for in that case the judgment would be purely tautological and convey no knowledge whatever to the mind. In every affirmative judgment, even in the principle of identity, there is real identity between subject and predicate, though they differ logically. A judgment is analytical and a priori or synthetical and a posteriori, according as this real identity appears from a mere analysis of the notions implied in the subject and the predicate, or is acquired by observation of existing things. In the present case the analysis of the terms reveals to us that a real identity underlies the logical difference between subject and predicate, which cannot be denied without absurdity.

However, the principle of sufficient reason is not analytical on the same grounds as the principle of identity. In fact, the predicate of this latter principle is included in the notion of the subject, as the elements of a definition are included in the defined subject; whereas in the case of the (extrinsic) principle of sufficient reason, the predicate agrees with the subject merely as an immediate property agrees with the essence from which it derives. Aristotle distinguishes these two different modes of necessary attribution. (Analytica Post., Bk. I, ch. iv; Comment. of St. Thomas, Lect. 10). In the principle of identity we affirm that "every being has its own proper essence," by which it is defined; thus a man is a man, a lion is a lion, what is necessary is necessary, and cannot as well not be, the contingent is the contingent, and can as well not be. We are here concerned with definitions which, as the Scholastics say, belong to the first mode of per se predication (in primo modo dicendi per se) as explained by Aristotle in the above-quoted passage. The principle of sufficient reason, on the contrary, affirms of a contingent being not that which defines it, but a property which immediately follows from its nature, and this is known as the second mode of per se predication (in secundo modo dicendi per se). "Though the relation to its cause," says St. Thomas (Ia, q. 44, ad 1), "is not part of the definition of the thing caused, it follows from its nature; from the fact that a thing has being by participation, it follows that it is caused by another being. Hence such a being cannot exist without being caused, just as a man cannot be a man without having the faculty of laughing," which is one of the properties of human nature. The contingent being can and must be defined without reference to its relation of dependence upon some other being. Contingent being is in fact defined as that which can be and just as well not be. But we cannot deny that a contingent being is related to some other being upon which it depends, without at the same time denying its very contingency. This point has been established by our method of proof showing that such a view leads to an absurdity or impossibility. To deny to such a being this relation of dependence is to identify it either with self-existent Being or with nothing.

The chief difficulty presented by the principle of sufficient reason is, how to reconcile it with (divine or human) liberty. For either there is a sufficient reason which determines the free act as such, and then it is no longer free, or else it has no determining cause, and then its beginning is absolute, which implies a contradiction. We shall discuss this problem later.


25) The principle of efficient causality is the immediate basis of the proofs for the existence of God. The idea of efficient cause and its ontological validity. Efficient causality, defined in terms of actual being, transcends the order of phenomena and is an accidentally sensible, but essentially intelligible, entity.


From the principle of sufficient reason are derived the principle of efficient causality, properly so called, of finality, and of induction. The sufficient reason of a thing is more general in scope than its cause. The cause is that upon which something depends for its existence;

All reality and becoming depend for their existence upon various principles: the formal cause, which intrinsically specifies them; the material cause, which individualizes them; the efficient cause, which brings them into being, and the final cause, which denotes the end to which they are ordained. The exemplary idea is an extrinsic formal cause.


in other words, it is the sufficient reason for the existence of its effect, and especially is this the case with the efficient cause, in that it realizes, or, more correctly, actualizes the effect; but not every sufficient reason is a cause; thus, the specific difference is the reason for the properties of a being, but not their cause.

We shall not investigate, in order to refute the Empirics, whether this idea of the efficient cause comes to us from external experience (resistance offered by material things with which we come in contact), or whether it is the result of internal experience (a consciousness of the effort which we exert upon these external objects). It would also be futile to inquire, concerning the knowledge acquired by sense perception, such as found in animals, whether the effort is merely followed by a displacement of an external mobile, or whether it produces or realizes this displacement. Hume and all his followers affirm that the senses tell us nothing about the effects of causality, but merely that there is a succession of events. It is certain that causality cannot be perceived by the senses in the same way as color or sound; not being directly sensible (sensibile per se) it is, like substance, a reality of the intelligible order per se (a noumenon) ; but it can truly be said to be accidentally sensible (sensibile per accidens) "because the intellect immediately perceives it when confronted with the object of sense perception." (De Anima, Bk. II; Comment. of St. Thomas, Lect. 13). The sensitive faculty perceives the object which is the cause, but not precisely qua cause. In like manner the intellect perceives being as such, just as it alone perceives substance as such, underneath the sensible qualities of color, sound, and smell, which are direct objects of sense perception; in the same way the intellect alone can perceive directly (per se) the realization, or production, or actualization of that which comes in addition to existence. In fact, this realization can have no meaning except in so far as it refers to being, and cannot, therefore, be perceived as such except by that faculty which has for its formal object being, and not color, or sound, or the internal act. As soon as the senses show that a change has taken place, reason seeks to explain the why and wherefore. Hence it is of little consequence, by what experience, or by what sensible image we arrive at the idea of cause. This idea does not derive its absolute, universal, and supra-phenomenal entity from sense perception (for it could be an innate idea and still have these same traits), but from its relation to being, which is the formal object of the intellect. We are absolutely certain that every being which is indifferent to existence requires an efficient cause, that is to say, has to be realized (whether in time or from eternity, makes no difference), because the intellect knows intuitively that this being does not exist as something which has existence intrinsically and primarily as its own (per se primo), but as something which gets this existence from another (ab alio or per aliud).

Having proved the absolute necessity of the extrinsic principle of sufficient reason, it is unnecessary to stress the point any further. So far we have referred only to the principle of efficiency in support of this principle, but later on we shall see that it receives additional confirmation from the principle of finality.

This concept of causality, therefore, is by no means anthropomorphic; universal causality is not an externally exerted influence of an internal experience, of an occurrence in human life. Causality is not, like universal attraction, a generalized experience; it is the object of a primary idea of the human intellect, considered not as human, but as intellect. In so far as it is human, our intellect has for its object the essence of sensible things; in so far as it is intellect, like all intellects, its formal and adequate object is being. (St. Thomas, Summa Theol., Ia, q. 12, a. 4, c and ad 3um). Now, we have just defined causality as immediately referring to being, and have thus established its ontological validity and laid the remote foundation of its transcendental and analogical validity—in other words of the possibility of attributing it to God. Further on (nos. 29 and 30) we shall see that being can be attributed to God, because the notion of being, unlike that of genus, is not univocal, but transcends all genera. The same must be said of causality and of certain other notions (such as those of intellect and will) which are defined by reason of their immediate reference to being, and not to some particular mode of being.


26) All "becoming," and every composite, necessarily demands a cause.


The metaphysical principle of causality, so closely connected with being, applies to everything which does not exist by itself. It includes within its scope all becoming, and, on a closer consideration of the question in its more general aspect, everything composite comes under its influence.

First of all, becoming demands an extrinsic and sufficient reason, because it is a successive union of diverse elements (for instance, when what is violet becomes red). Now, the unconditional union of diverse elements is impossible, for elements that are different in themselves cannot be united (principle of identity). This extrinsic reason is an efficient cause. Becoming, which is a gradual process of realization, must be realized by some other thing than itself. In fact, as Aristotle points out in his reply to the arguments of Parmenides and Heraclitus (Phys., Bk. I, c. 8; Met., Bk. IX), the origin of becoming presupposes an intermediate state between being, which is determined, and mere nothing; this intermediate state is being as yet undetermined or in potency, for what is already determined, since it is actually being, cannot be the cause of being as such; from nothing, nothing comes; and yet being becomes. (See no. 21). Hence becoming is a transition from potency to act; what becomes hot had a capacity for becoming hot, though it was not actually hot; the pupil who was capable of becoming a philosopher (a potency which no dog possesses), but who was not a philosopher, becomes one. Potency, which of itself is not an act, or is not actualized, cannot by itself pass from potentiality to act. To deny this would be to deny the principle of identity. It cannot, therefore, be actualized, except by something which is in act. But it is impossible for the same thing in the same sense to be both in potentiality and in act, and, therefore, the transition from potentiality to actuality must be accomplished by something else; and this actualizing or realizing principle is precisely what we call the efficient cause. "Nothing can be reduced from potentiality to actuality, except by some being already in a state of actuality. But it is not possible that the same thing should be at once actual and potential in the same respect." (Ia, q. 2, a. 3).

Becoming is thus rendered intelligible, not by interpreting it in terms of rest (as did Descartes, who considered it to be a mechanical and not a metaphysical problem), but by considering it from the standpoint of being, in accordance with the theory of potentiality and actuality into which being is divided. As we have already observed (no. 21), this division of being must needs be admitted if we wish to defend against Parmenides the existence of becoming, and against Heraclitus the objective validity of the principle of identity. The proofs derived from the theories of movement, efficient causes, and contingency are grounded on this division of being.

From this point of view we not only arrive at a satisfactory explanation of becoming, but also, in the static order and in accordance with the ultimate profundities of being, which are beyond the scope of becoming, we get an explanation of multiplicity or diversity. In the first place, whether we consider multiplicity as a plurality of beings having a common element which establishes their claim to a unity consisting in a certain similarity, which is either specific, generic, or only analogical; or whether we view it as a plurality of parts in one and the same being, by reason of which it claims for them a unity of composition—all multiplicity demands an extrinsic sufficient reason. In fact, such a multiplicity is a union of diverse elements. Now, an unconditional union of diverse elements is impossible. Elements which are in themselves diverse cannot of themselves and as such be united, nor even be similar (principle of identity). "Multitudo non reddit rationem unitatis" (multitude does not explain the notion of unity). See further on, in no. 39, the proof for the existence of God from the degrees of perfection in being.

This extrinsic raison d'être must be an efficient cause, or, in other words, a principle of actualization. In fact, multiplicity, like becoming, is always a composition of potentiality and act, and not pure actuality. Aristotle showed how Parmenides was mistaken on this point when he declared all multiplicity, like all movement, to be an illusion. "Everything external to being (other than being itself) is non-being," said the Eleatic philosopher; "and what is non-being is non-existent. Therefore, being is one, and there is only one being; we can conceive of nothing that could be added to being as a differentiating element, for anything thus added would also be being. In other words, if there were two beings, they would have to be distinguished the one from the other by something other than being, and what is other than being is non-being. Now, being exists, whereas non-being does not exist; and we cannot think otherwise." (Aristotle, I Met., Bk. I, c. 5; Comment, of St. Thomas, Lect. 9). This was practically a denial of the world as something external to us and its absorption in God, who alone is absolutely one and immutable. Yet we must be grateful to Parmenides for so resolutely affirming the supreme law of thought and reality, i.e., the principle of identity, which is the basis of every proof for the existence of God. After all, it is a fact attested by experience that the world exists, and in it we observe that there is multiplicity. This same multiplicity is noticeable also in the conceptual order. It must be explained, without, however, abandoning the first principle of reason.

Plato in his Sophist (241 D, 257 A, 259 E), in order to explain the notion of multiplicity, does not fear to "incur the risk of being considered a parricide, by attacking the formula of Parmenides and affirming the existence of non-being," which is the intermediate state between being and mere nothing, the limit with regard to being. In virtue of this very principle of identity, since the objects of our knowledge all have being as their common element, it is only by this common element that they can differ from one another. We are, therefore, compelled to say that they differ by something other than being; and what is other than being, is non-being. We must consequently admit that non-being is the intermediate state between being and mere nothing, the limit of being.

Aristotle says that the distinction between various individuals of the same species cannot be explained except by admitting the reality of non-being, or matter, as the subject and limit of the form common to these individuals. Thus matter—inasmuch as it postulates this particular quantity and not some other—is the principle of individuation and suffices to distinguish two individuals which, if we were to consider merely their form and qualities, would be as indistinguishable as two drops of water. St. Thomas states still more precisely that multiplicity or distinction between beings in general can be explained only by assuming the reality of non-being in each of them, or, in other words, a potency, which is the subject and limit of the existential act common to all these beings. Hence we say that "actus multiplicatur et limitatur per potentiam" (act in its recurrence and restriction depends upon potentiality. (Ia, q. 7, a. 1; C. Gentes, Bk. II, c. 52). Minerals, vegetables, animals, men, and angels all have one element in common, namely, existence; one principle which differentiates them, namely, an essence susceptible of existence and which in the scale of beings ranging from stone to pure spirit receives existence according to its more or less limited capacity for it. We see that this composite of essence and existence, which results from a union of diverse elements, demands an extrinsic raison d'être, since an unconditioned union of diverse elements is impossible. This raison d'être must be the cause of actualization, since this composite does not actualize itself and is not, as such, self-existent. "Every composite has a cause, for things which are different in themselves cannot unite into one, unless something causes them to unite." (Ia, q. 3, a. 7).

Multiplicity is thus made intelligible by means of being, by the division of being into potency and act. This division imposes itself if we wish to maintain that the multiple exists, without denying the objective validity of the principle of identity. It is this principle which compels us to distinguish in everything that is, and can as well not be, non-being (real or potency) and actual being, essence and existence. This same principle, together with that of sufficient reason, constrains us to refer all beings to a self-subsistent Being, "Ipsum esse subsistens," namely, God, who alone is His own sufficient reason for existing, because He alone is pure identity. The supreme principle of thought will then appear as the supreme principle of reality. (Ia, q. 3, a. 4 and 7).


27) The principle of finality, derived from the principle of sufficient reason. The knowledge of its absolute validity, far from presupposing the knowledge of God's existence, must be the means by which it becomes known to us.


All becoming and every composite, therefore, demands an efficient cause, and likewise a final cause, and two external raisons d'être. We shall stress this second point, that of finality, when we come to discuss the proof for God's existence derived from the order observable in the universe. For the present it is sufficient if we show how the principle of finality is connected with that of sufficient reason, in order to complete the general metaphysical notions upon which the proofs for the existence of God ultimately rest.

The idea of an end or purpose is derived from our activity as reasonable beings; we propose to ourselves certain ends, and act for the purpose of reaching them. As for the senses, these, if left to themselves, are no more capable of acquiring the notion of finality than they are of arriving at the notion of causality, or that of substance, or that of being. The animal, remarks St. Thomas, tends by instinct both toward the means and toward the end of its action, without perceiving the reason why there is a connection between means and end. Thus the bird picks up wisps of straw for building its nest, without adverting to the fact that the nest is the end or reason of its action. (Ia IIae, q. 1, a. 2). Man, on the other hand, endowed with intelligence, which is a faculty of being, discovers in his own actions the idea of finality, and when he wishes to give an intelligent explanation of any action as a faculty of being, no matter whether the one performing the action be intelligent or non-intelligent, animate or inanimate, perceives that this action just as necessarily postulates a final as it does an efficient cause. And so he formulates the principle of finality by affirming that "Omne agens agit propter finem" (every agent acts for an end). (Aristotle, Phys., Bk. II, ch. 3; St. Thomas, Summa Th., Ia, q. 44, a. 4; Ia IIae, q. 1, a. 2; C. Gentes, Bk. III, ch. 2).

This principle, which is self-evident to all who correctly understand the terms, is by no means an anthropomorphic extension of our internal experience, but can easily be referred back to the principle of sufficient reason.

As soon as we understand what is meant by the word end, this principle is self-evident. End is not only the terminus or result of an action, but the reason why the action has taken place; it is the τὸ οὗ ἕνεκα, id cujus gratia aliquid fit—that for the sake of which an agent acts. It is a definite perfection, which directly refers to the agent as its own good, and for the sake of which the agent acts. It will not do to say that the agent has acquired this end accidentally, by some fortunate chance; it must be the result of a pre-ordained action on his part.

Now every agent, aside from the accidental effects which result from its contact with other agents, produces a definite effect according to its own natural law, and this effect directly accrues to it as its own perfection, its own good. It cannot produce this definite and appropriate effect rather than any other, except on condition that it has a tendency to produce this particular effect rather than any other. It is not necessary for the agent to know the cause of this tendency, but at least that it is by its nature ordained towards this object. Thus the sense of sight produces an act which is not indifferent, but determined, and this act constitutes for it a good, a perfection, which it is natural for it to have. The reason why the sense of sight perceives colors instead of hearing sounds is because it is naturally ordained to seeing and not to hearing, because seeing is its very raison d'être. This is a self-evident truth, which certainly transcends the range of sense perception, but is perceived at once by the intellect, a faculty of being, when it considers such an organ as the eye or ear. Finality is sensibile per accidens and intelligibile per se. No process of reasoning is required to satisfy ourselves that the eye is made for seeing or that the wings of a bird are made for flying. Natural reason sees at once that the bird does not fly because it has wings, but it has wings in order that it may fly. Flying is of its very nature. The mind has intuitive knowledge of this fact, which is practically an answer to the objection that it may have happened by some fortunate chance; for chance is accidental and the fortuitous effect is an accidental result of the contact of two agencies, whereas vision, on the contrary, is not an accidental effect of the eye, but the natural exercise of this organic faculty.

This principle of finality ("every agent acts for an end") is not only self-evident as soon as the terms of the proposition are understood, but it can also be proved indirectly by showing that to deny it leads to the absurdity of denying the principle of sufficient reason, which latter cannot be rejected without necessarily rejecting the principle of contradiction.

If every agent produces, not an indifferent effect whatsoever, but a determined effect which belongs to it by right, though it does not tend towards this effect, and is not ordained for it; if, e. g., the acorn produces the oak rather than the poplar, though it is not ordained for the one rather than for the other; if the eye sees rather than hears, though it is not naturally predisposed for the former act instead of the latter—it follows that there is no way of explaining by the principle of sufficient reason how it is that the effect is definitely established and essentially refers to a definite cause. Unless these qualities were somehow present in the efficient cause, they could not be produced in the effect. Now, they are there merely in a virtual manner, inasmuch as the efficient cause tended to produce this particular effect rather than any other, and inasmuch as it was ordained for this effect. Thus, nutrition is virtually contained in the vegetative faculty and in the food, whereas this nutritive element is not contained in the faculty of sight and the object seen. A fine play at the theatre is not food for the body, nor is the process of digestion accomplished with the eyes. The stomach is ordained for that purpose, just as the eye is ordained for seeing. To deny this order is to deny the raison d'être of the determination and inherent goodness or essential appropriateness of the effect produced. As St. Thomas remarks (Ia, q. 44, a. 4), "Every agent acts for an end, otherwise one thing would not follow from the action of the agent more than another, unless it were by chance." If the agent did not tend towards its effect, if it did not have at least a natural intention for it, if it were not naturally ordained to produce it, it would no more produce this particular effect than any other, except by accident or chance—which would mean that it had no natural effect. In other words, action is essentially intentional, i.e., ordained towards some end. Without this tendency not only the effect, but the activity itself, would be without a sufficient cause, i.e., without determination or congruity, or, to put it differently, it could no more be said to be an attraction than a repulsion, vision than audition, digestion than respiration. There must be some special reason why the efficient cause begins to operate, instead of remaining inactive, and why it produces this particular effect rather than another. Finally, the principle of activity itself, i.e., potency (active or passive) cannot be conceived except as something essentially ordained towards its act. "Potentia dicitur ad actum,"

In God, active potency does not differ from activity; but the transitive influence of this activity must be directed to some end, not indeed, to that of the acquisition of the Sovereign Good, which God possesses in Himself, but to the manifestation of this good or His glory.


is one of the formulas expressing the principle of finality. As the imperfect is to the perfect, the relative to the absolute, so is potency to actuality. Only the absolute has its own sufficient reason in itself. That is why the final is the noblest of the four causes.

To say that finality operates after the manner of fortuitous chance, does not explain this principle. Chance is, indeed, an accidental cause (Aristotle, Phys., Bk. II, ch. 8; Lect. 7 to 10 of the Commentary of St. Thomas); but it explains only accidental effects and congruities. In digging a grave, one may accidentally find a treasure. But it cannot be maintained that all the effects produced in nature are accidental, for it is a philosophical truth that the accidental presupposes the essential ("quod est per accidens, accidit ei quod est per se"). It is an accident if a doctor happens to be a musician, says Aristotle, but that he is a physician and can cure diseases, is no more accidental than it is for a musician to be a musician and to possess a knowledge of his particular art. To relegate the essential to the accidental would mean the complete destruction not only of all nature, but of all being. We should then have simply a series of fortuitous events with nothing to bring them about, which is absurd.

Nor will it do to reject the final and have recourse solely to the efficient cause; for in that case there would be no raison d'être for the action produced by the agent. If there is not in it some good corresponding to the agent's natural inclination, the action itself, and the fact that it is directed towards some certain end rather than another, would both be inexplicable.

The principle of induction that: "Every natural cause in the same circumstances always produces the same effect," is also derived from the principle of sufficient reason; for a change in the effect without a previous change in the cause or in the circumstances, would be without a raison d'être.


Therefore, every agent acts for an end. The word for has a meaning, not only when applied to human activity, in which the end is known and intended, but also when applied to any other kind of activity. Whereas the efficient cause is the sufficient reason as a realizing principle (or that by which a thing is accomplished), the final cause is the sufficient reason for the thing which is accomplished. The eyes are made for seeing, and not for hearing. Therefore, the principle of finality, like that of causality, is an analytical one in the Aristotelian sense.

Two agents may come in contact by chance, but the proper action of each must necessarily have an end in view. Some

P. Janet, for instance, in his work, Les Causes Finales.


have thought that the knowledge of the absolute validity of the principle of finality presupposes absolute certainty of the existence of God as the intelligent cause of the world. They retain the argument based on the order to be found in the world as a popular proof, but they reject every proof for the existence of God based upon intrinsic finality, as begging the question. This finality rests upon the principle that a natural desire cannot remain unfulfilled. We have just seen that the principle of finality, on the contrary, is an analytical principle.

See further on (no. 40) the quotations from the writings of P. Gardeil, O.P., Hartmann, Jouffroy, Ravaisson, and Lachelier.


Not only is it self-evident, anteriorly to any knowledge whatever of the existence of God, that every agent acts for an end, but, as we shall see, it can be shown that this end must be known precisely as an end (sub ratione finis) by this or some other agent. A means cannot be ordained to an end, except by an intelligent agent, for only an intelligent being can perceive this reason for being ("the object of the intellect is being"), and unite both means and end in one concept. And if intelligence can be referred as a transcendental relation to being, and does not imply an imperfection, any more than this is implied in being, then intelligence can and must be attributed analogically to the first cause.

This idea of an intelligent designer will be the basic principle in the proof of the existence of God from the order that exists in the world (see infra, no. 40).

These are the metaphysical principles

To these principles may be added that of mutation or change. "Every change presupposes a subject." What is actually subject to change, cannot be absolutely simple; it is not simply what it acquires, but it receives what it acquires. Or, if this change is a loss, the loss is to be attributed to a subject. This principle is related to the material cause (the subject of change), just as the principle of finality is related to the final cause, that of efficient causality to the cause of the same order, and those of identity and intrinsic sufficient reason to the formal and specifying cause.


of the proofs for the existence of God. They are connected with each other in the following manner: First of all we have the proper object of sensible intuition, which is the phenomenon; then the intellect, by means of abstractive intuition, acquires a knowledge of being and its first principles, which it connects one and all with the principle of identity, which declares what belongs primarily to being.

Thus we have established the ontological validity of first ideas and first principles. All that now remains is to defend their transcendental validity, or their aptitude to enable us to acquire a certain knowledge of God as the first and transcendental cause.


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