Commentary on actus essendiText no. 10

For a more extensive analysis of text no. 10 than what appears in this post, see my Actus essendi and the Habit of the First Principle in Thomas Aquinas (New York: Einsiedler Press, 2019), 134-136.

Commentary on 
Summa theologiae, part I, question 3, article 4, ad 2 

Aquinas uses the expression actus essendi in the Summa theologiae only once, in part I, question 3, article 4, ad 2.

In this article of the Summa, Aquinas explains that in God, essentia and esse are not two distinct metaphysical principles as is the case in creatures; in the Creator essentia and esse are one and the same reality. The expression actus essendi appears in the answer to the second of the only two objections addressed in the article. The body of the article is devoted to explaining why God is His own esse. And the answer to the first objection offers a brief explanation of the difference between the esse of God and esse commune. Here is a quick look at this context.

Aquinas had shown in the preceding article (article 3) that God is His own essence. He based his argumentation on the fact that in material things, the natura and the suppositum are distinct: In material things the suppositum includes not only the nature of the thing but also other elements that fall outside the scope of the nature such as accidents and individual matter. Even in Angels there are accidental perfections that fall outside the scope of the angel’s essence and so, to a certain extent, angels also possess a suppositum that cannot be said to be exactly the same as their natura. (For more on the distinction between suppositum and natura in the case of angels, see John F. Wippel, The Metaphysical Thought of Thomas Aquinas [Washington, D.C.: Catholic University of America Press, 2000], 238-253.)

In God, however, nothing can fall outside the scope of His own nature. God’s nature is itself per se a subsisting individual distinct from all other reality. God’s nature is such that it precludes any addition; therefore, in God nature and suppositum are the same. God is His own essence. Having established this, Aquinas now proceeds to show that God also is His own esse. Three reasons are offered in the present article (article 4) as follows:

(1) Anything inhering in a subsisting thing that does not belong per se to the essence of the thing is either caused by the constituent principles of the essence or caused by some exterior agent. (This is illustrated with two examples: (a) A property such as the human being’s ability for laughing—which if lacking would constitute a privation—is caused by the constituent principles of the essence of a human being; and (b) the quality of heat in hot water is caused by fire which is exterior to water.)

Now, regarding the inherent esse of things, Aquinas reasons as follows. If in a thing esse is distinct from essence, then this esse of the thing must be caused either by some exterior agent or by the thing’s essential principles.

It is impossible for a thing’s esse to be caused by its own essential constituent principles, for nothing can be the sufficient cause of its own esse, if its esse is caused. The guiding principle here is the impossibility of having an efficient cause that is capable of producing itself prior to its own existence. 

(See Summa theologiae, part I, question 2, article 3, corpus: "Nec tamen invenitur nec est possibile quod aliquid sit causa efficiens sui ipsius; quia sic esset prius seipso, quod est impossibile;" and De ente et essentia, chapter 3: "Non autem potest esse quod ipsum esse sit causatum ab ipsa forma vel quiditate rei—dico sicut a causa efficiente—quia sic aliqua res esset sui ipsius causa et aliqua res seipsam in esse produceret, quod est impossibile.")

Therefore that thing whose esse differs from its essence must have its esse caused by another.

But this cannot be true of God because God is the uncaused cause. Therefore it is impossible that God’s esse should differ from His essence. God is His own esse.

(Summa theologiae, part I, question 3, article 4, corpus: Primo quidem, quia quidquid est in aliquo quod est praeter essentiam eius, oportet esse causatum vel a principiis essentiae, sicut accidentia propria consequentia speciem, ut risibile consequitur hominem et causatur ex principiis essentialibus speciei; vel ab aliquo exteriori, sicut calor in aqua causatur ab igne. Si igitur ipsum esse rei sit aliud ab eius essentia, necesse est quod esse illius rei vel sit causatum ab aliquo exteriori, vel a principiis essentialibus eiusdem rei. Impossibile est autem quod esse sit causatum tantum ex principiis essentialibus rei, quia nulla res sufficit quod sit sibi causa essendi, si habeat esse causatum. Oportet ergo quod illud cuius esse est aliud ab essentia sua, habeat esse causatum ab alio. Hoc autem non potest dici de Deo, quia Deum dicimus esse primam causam efficientem. Impossibile est ergo quod in Deo sit aliud esse, et aliud eius essentia.)

(2) The second reason comes from the observation that esse is the actuality of every form or nature. Goodness and humanity, for example, are said to be real on account of the esse of the subsisting thing that instantiates goodness and humanity. Therefore, in things whose essence is distinct from esse, esse must compare to essence as act to potency. But in article 1, Aquinas had already shown that in God there is no potency. It follows then that in God essence does not differ from esse. God’s essence and God’s esse are identical.

(Summa theologiae, part I, question 3, article 4, corpus: Secundo, quia esse est actualitas omnis formae vel naturae, non enim bonitas vel humanitas significatur in actu, nisi prout significamus eam esse. Oportet igitur quod ipsum esse comparetur ad essentiam quae est aliud ab ipso, sicut actus ad potentiam. Cum igitur in Deo nihil sit potentiale, ut ostensum est supra, sequitur quod non sit aliud in eo essentia quam suum esse. Sua igitur essentia est suum esse.)

And (3) just as something on fire that is not the fire itself is said to be on fire by participation, so also that which has esse but is not esse itself is said to be an ens by participation. But since it was shown above that God is His own essence, if God were not also His own esse, it would follow that He would then be ens per participationem, and not the ens per essentiam. And this would in turn show that God is not the first ens which is absurd. Therefore God is His own esse, and not merely His own essence.

(Summa theologiae, part I, question 3, article 4, corpus: Tertio, quia sicut illud quod habet ignem et non est ignis, est ignitum per participationem, ita illud quod habet esse et non est esse, est ens per participationem. Deus autem est sua essentia, ut ostensum est. Si igitur non sit suum esse, erit ens per participationem, et non per essentiam. Non ergo erit primum ens, quod absurdum est dicere. Est igitur Deus suum esse, et non solum sua essentia.)

With this background Aquinas proceeds to answer the two objections.

In the first objection it is argued that God’s essence is not identical to God’s esse because if this were the case then nothing should be added to God’s esse. But the esse to which no addition is made is esse commune which is predicated of all things. God would therefore be esse commune. But this is false, for revelation tells us that men have wrongly attributed the name of God to stones and wood thinking that there was something divine in them. (See Wis. 14:21.) Therefore God’s esse is not God’s essence.

(Summa theologiae, part I, question 3, article 4, obj. 1: Videtur quod in Deo non sit idem essentia et esse. Si enim hoc sit, tunc ad esse divinum nihil additur. Sed esse cui nulla fit additio, est esse commune quod de omnibus praedicatur, sequitur ergo quod Deus sit ens commune praedicabile de omnibus. Hoc autem est falsum, secundum illud Sap. XIV: Incommunicabile nomen lignis et lapidibus imposuerunt. Ergo esse Dei non est eius essentia.)

In answer to this objection Aquinas explains that esse sine additione can be understood in two ways. In one way, he says, esse sine additione is that esse that precludes addition, and he illustrates this with the example of irrational animals whose essence precludes the addition of reason. 

But in another way, Aquinas continues, esse sine additione can be understood to be that esse which does not preclude addition. The addition of reason for example, he says, is not precluded in the scale of animal beings as such. 

God’s esse can be said to be esse sine additione in the first sense because God’s esse precludes addition; esse commune, on the other hand, is esse sine additione in the second sense, that is to say, esse commune is that esse that does not preclude addition.

(Summa theologiae, part I, question 3, article 4, ad 1: Ad primum ergo dicendum quod aliquid cui non fit additio potest intelligi dupliciter. Uno modo ut de ratione eius sit quod non fiat ei additio, sicut de ratione animalis irrationalis est, ut sit sine ratione. Alio modo intelligitur aliquid cui non fit additio quia non est de ratione eius quod sibi fiat additio, sicut animal commune est sine ratione, quia non est de ratione animalis communis ut habeat rationem, sed nec de ratione eius est ut careat ratione. Primo igitur modo, esse sine additione, est esse divinum; secundo modo, esse sine additione, est esse commune.)

In the Summa contra gentiles, book I, chapter 26, Aquinas offers a more complete explanation of why God cannot be said to be esse commune. That which is common, he affirms, is specified or individuated through addition. 

Through addition to esse commune one can reach down to the esse proprium. What is common or universal cannot exist without addition, but can intellectually be considered without addition. 

The concept of animal, he now explains, is not instantiated in reality without the difference rational or the difference irrational, although the concept animal can be understood without these differences. 

What is more, although a universal concept may be considered without addition, it cannot be understood without the receptibility of addition; for, if no difference could be added to the concept animal, it would not be a genus. 

But God’s esse is without addition not only in the consideration of reason but also in reality; and not only is the esse of God, esse without addition, the esse of God is also esse without the receptibility of addition. 

Thus, since God’s esse neither receives nor can receive addition one can rather conclude that God is not esse commune but esse proprium, for God’s esse is distinguished from all the rest by the fact that nothing can be added to it.

(Summa contra gentiles, book I, chapter 26: Quia enim id quod commune est per additionem specificatur vel individuatur, [aliqui] aestimaverunt divinum esse, cui nulla fit additio, non esse aliquod esse proprium, sed esse commune omnium; non considerantes quod id quod commune est vel universale sine additione esse non potest, sed sine additione consideratur: non enim animal potest esse absque rationali differentia, quamvis absque his differentiis cogitetur. Licet etiam cogitetur universale absque additione, non tamen absque receptibilitate additionis: nam si animali nulla differentia addi posset, genus non esset; et similiter est de omnibus aliis nominibus. Divinum autem esse est absque additione non solum in cogitatione, sed etiam in rerum natura: nec solum absque additione, sed etiam absque receptibilitate additionis. Unde ex hoc ipso quod additionem, non recipit nec recipere potest, magis concludi potest quod Deus non sit esse commune, sed proprium: etiam ex hoc ipso suum esse ab omnibus aliis distinguitur quod nihil ei addi potest. Unde Commentator in libro De Causis dicit quod causa prima ex ipsa puritate suae bonitatis ab aliis distinguitur et quodammodo individuatur.)

Finally Aquinas addresses a second objection against the identity of God’s essence and God’s esse. The objection is an argument based on the fact that about God one can only answer the question an sit and not the question quid sit. It is in answer to this objection that Aquinas uses the expression actus essendi. 

In his answer Aquinas explains that the verb esse has two meanings. In its primary signification, esse means the actus essendi, and in its extended meaning esse connotes the composition of a proposition effected by the mind in joining a predicate to a subject.

While granting that about God one cannot answer the question quid sit, Aquinas appeals to the primary meaning of esse to hold also that it is not by knowing God’s actus essendi that one can answer the an sit question about God. 

One can indeed answer the an sit question about God, but by appealing to the extended meaning of esse.

Aquinas explains that one can establish the truth of the proposition “God is” through a sequence of judgments whose connection is established through reasoning from God’s effects. But the esse thus known by the human intellect is not God’s actus essendi. Hence, the argument of the second objection does not follow.

Regarding this use of the expression actus essendi, here is Aquinas in his own words:

Objection 2:

Praeterea, de Deo scire possumus an sit, ut supra (qu. 2, art. 2) dictum est. Non autem possumus scire quid sit. Ergo non est idem esse Dei, et quod quid est eius, sive quidditas vel natura (Summa theologiae, part I, question 3, article 4, obj. 2, Rome: Leonine edition, 1888, vol. 4, p. 42, column A).

Answer to objection 2:

Ad secundum dicendum quod esse dupliciter dicitur: uno modo, significat actum essendi; alio modo, significat compositionem propositionis, quam anima adinvenit coniungens praedicatum subiecto. Primo igitur modo accipiendo esse, non possumus scire esse Dei, sicut nec eius essentiam: sed solum secundo modo. Scimus enim quod haec propositio quam formamus de Deo, cum dicimus Deus est, vera est. Et hoc scimus ex eius effectibus, ut supra (qu. 2, art. 2) dictum est (Summa theologiae, part I, question 3, article 4, ad 2, Rome: Leonine edition, 1888, vol. 4, p. 42, column B).

In this text it is clear that Aquinas does not connect God’s actus essendi with the knowledge of the esse of God that the human intellect is capable of reaching through God’s effects. The esse of God known though God’s effects is the esse that answers the question an Deus sit, that is to say, the question of God’s existence. But esse in its meaning of God’s actus essendi answers rather the question of God’s essence, the quid est of God.

Therefore, in the present context something that may seem obvious needs to be emphasized. The issue of how to reason and conclude correctly about God’s actus essendi is not to be confused with the issue of how to reason and conclude correctly about God’s existence. 

Two different paths can be easily traced about the historical development of these two issues. In his understanding of esse, Aquinas distinguishes clearly between the esse that answers the question of existence (an sit) and the esse that connotes the metaphysical principle of actus essendi.

Commenting on the meanings of esse, J. F. Wippel remarks that “Aquinas is only too aware that the term esse (literally: ‘to be’) can be used with different meanings. For instance, in an early texts from his Commentary in I Sentences (d. 33, q. 1, a. 1, ad 1), he distinguishes three different meanings for it. As he puts it there, the term esse may be taken to signify the very quiddity or nature of a thing, as when we refer to a definition as signifying what a thing’s esse is; for, as Thomas remarks, a definition signifies the quiddity of a thing” (Wippel, The Metaphysical Thought of Thomas Aquinas, 24-25).

In the footnote to this sentence Wippel writes: “Here Thomas is discussing the nature of relations in the Trinity. In responding to an objection he comments: ‘Sed sciendum, quod esse dicitur tripliciter. Uno modo dicitur esse ipsa quidditas vel natura rei, sicut dicitur quod definitio est oratio significans quid est esse; definitio enim quidditatem rei significat’ (Mandonnet ed., Vol. 1, pp. 756-66).”

“Secondly,” Wippel continues, “esse may signify the very act of an essence, meaning thereby not its second act or operation but its first act, i.e., its actual existence.”

“Taken in a third way,” proceeds Wippel, “esse signifies the truth of composition, that is, of judgment, as this is expressed in propositions. In this sense, continues Thomas, the verb ‘is’ is referred to as copula. When used in this way esse is realized in the full sense in the intellect which composes or divides. Nonetheless, when so used this esse itself is grounded in the esse of the thing, that is, in the act of its essence (its existence) just as truth is.”

The footnote for this line reads as follows: “‘Alio modo dicitur esse ipse actus essentiae; sicut vivere, quod est esse viventibus, est animae actus; non actus secundus, qui est operatio, sed actus primus. Tertio modo dicitur esse quod significat veritatem compositionis in propositionibus, secundum quod ‘est’ dicitur copula: et secundum hoc est in intellectu componente et dividente quantum ad sui complementum; sed fundatur in esse rei, quod est actus essentiae, sicut supra de veritate dictum est’ (p. 766). Concerning truth cf. In I Sent., d. 19, q. 5, a. 1 (cited below in n. 16).”

“Of these three usages,” Wippel remarks, “the first may strike the reader as somewhat surprising. In many other context Thomas is content simply to distinguish between esse insofar as it signifies the composition of a proposition which the intellect effects through judgment, and esse that is actual existence or, as Thomas often expresses it, as the actus essendi (act of being). In other words, he often limits himself to the second and third meanings he has singled out in the present text. For instance, he appeals to this twofold distinction in Summa Theologiae I, q. 3, a. 4 in order to meet an objection against his claim that in God essence and esse (act of being) are identical.”

As footnote to this passage, one reads: “Leon. 4.42. Note: ‘Ad secundum dicendum quod esse dupliciter dicitur: uno modo, significat actum essendi; alio modo, significat compositionem propositionis, quam anima adinvenit coniungens praedicatum subiecto.’ Also see Quodlibet XII, q. 1, a. 1, ad 1: ‘…esse dupliciter dicitur: quandoque enim esse idem est quod actus entis; quandoque autem significat compositionem enuntiationis et sic significat actum intellectus’ (Leon. 25.2.399:34-38). Cf., however, Thomas remark on De potentia, q. 7, a. 2, ad 1: ‘Ad primum ergo dicendum, quod ens et esse dicitur dupliciter, ut patet V Metaph. Quandoque enim significat essentiam rei, sive actum essendi; quandoque vero significat veritatem propositionis …’ See Quaestiones disputatae, vol. 2, M. Pession ed. (Turin-Rome, 1953), p. 191. Also see In V Met., lect. 9, pp. 238-40, nn. 889-896” (Wippel, The Metaphysical Thought of Thomas Aquinas, 24-25).

Jan A. Aertsen for his part commented briefly on the text from Summa Theologiae, part I, question 3, article 4, ad 2, in his discussion on the relationship between the “if” question (the question an sit) and the “what is” question. Here is a lengthy quotation from Aertsen’s reflections on this subject found in his Nature and Creature: Thomas Aquinas’s Way of Thought, (Leiden, The Netherlands: E. J. Brill, 1988), 20-23.

On the issue of whether or not the question an est is the most fundamental question Aertsen comments first that “In the second book of the Posteriora Analytica (89 b 38-90 a 1: 90 a 8 ff.) Aristotle says only this: ‘Whenever we know if something is, we ask what it is.’ The ‘if’ question is twice dismissed in this manner in passing. Thomas speaks more extensively of it in various loci in his writings and places the answer to the question an est within a dichotomy of being, namely, extra-mental and intra-mental being.”

In the footnote to these remarks Aertsen writes: “See S.Th. I, 3, 4, ad 2 and 48, 2, ad 2; S. c. G. III, 9; De pot. 7, 2, ad 1; De malo 1, 1, ad 19; Quodl. IX, 2, 2; De ente, c. 1; In I Sent. 19, 5, 1; In II Sent. 34, 1, 1; In V Metaph., lect. 9.”

Aertsen then specifies, “Ens or esse (in this context Thomas uses the terms indifferently) is said in two ways. In the first way it signifies ‘the entity of the thing according to its division by the ten categories’ (S.Th. I, 48, 2, ad 2); ‘the essence of the thing or the act of being’ (De pot. 7, 2, ad 1); ‘the nature of the ten genera’ (De malo 1, 1, ad 19); ‘what is divided by the ten genera, and so being signifies something existing in nature, whether a substance, such as man, or an accident, such as color’ (In II Sent. 34, 1, 1); and ‘what is outside the soul (extra animam), divided by the ten categories’ (In V Metaph., Lect. 9, 889). In a second way ‘being’ signifies what is ‘only in the mind’ (ibid.); means ‘the truth of a proposition that exists in a composition the mark of which is the verb “is”’ (S.Th. I, 48, 2, ad 2). And this text continues: ‘In this sense being is what answers the question “if something is”’ (hoc est ens quo respondetur ad quaestionem ‘an est?’). Similarly, in De malo 1, 1, ad 19: ‘being’ is said in a second way, ‘according as it answers the “if” question.’”

“The reasons for this distinction [extra-mental being versus intra-mental being],” Aertsen emphasizes, “become clear especially when attention is given to the problems it means to resolve.”

“What ‘is’ according to the first way,” Aertsen reports, “is also ‘being’ according to the second mode; for an affirmative proposition—e.g., ‘man is’—can be formed about whatever has natural being. Yet the reverse is not the case. Whatever is in itself a non-being, such as a privation, can be regarded as a being by the intellect and affirmed in a statement—e.g., ‘evil is.’ This does not imply, however, that evil is something in reality, that is, is according to the first mode of ‘being.’”

The reference here is to In I Sent. 34, 1, 1; In V Metaph., lect.9, 896; De ente, c. 1.

“The possibility of affirming privations and negations,” Aertsen continues, “is therefore a first reason to regard the answer to the question ‘if it is’ as purely logical, predicative synthesis.”

“A still more important motive,” Aertsen underlines, “becomes apparent at the beginning of the Summa theologiae. After Thomas in q. 1 has shown that sacred doctrine is a science, he asks and affirms in the very first place (q. 2), in conformity with the order of questioning: ‘if God exists’ (an sit Deus). When it is subsequently inquired in q. 3, art. 4 whether ‘essentia’ and ‘esse’ are identical in God, then the objection arises (obj. 2): ‘We can know ‘if God is,’ as has been explained above. ‘What He is,’ however, we cannot know. Therefore there is a nonidentity between God’s being (esse) and his essence (quod quid est eius).’ To this objection Thomas responds with the dichotomy of ‘being’ just mentioned. 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 ‘being’ in the first sense, we cannot understand God’s being; but only in the second sense.”

In the footnote Aertsen reports, “Esse dupliciter dicitur, uno modo, significat actum essendi; alio modo, significat compositionem propositionis, quam anima adinvenit coniungens praedicatum subiecto. Primo igitur modo accipiendo esse, non possumus scire esse Dei, sicut nec eius essentiam, sed solum secundo modo. Scimus enim quod haec propositio quam formamus de Deo, cum dicimus Deus est, vera est.”

And then Aertsen continues, “This reply raises, however, various questions. Let us have a closer look at it.”

“In the first place,” Aertsen reasons, “the objection suggests that the ‘if’ and ‘what’ questions imply a composition of ‘being’ (esse) and ‘essence’ in that which can be questioned. In 1.3.2., [of Aertsen’s book], however, we saw that this questioning was, indeed, restricted to composed things, but then to a thing that is characterized by the composition of form and matter. What would have to be explained first, therefore, is how the order of the questions is related to the composition of ‘esse’ and ‘essentia’ (cf. 1.9., [of Aertsen’s book]).”

“From this remark,” Aertsen contends, “there follows directly a second point that is usually given too little consideration. The preliminary question must be whether this mode of questioning is at all possible with respect to God. Are the limits of this questioning not overstepped in the question ‘if God exists?’ For with regard to a simple being, there is no room for any question (1.3.2., [of Aertsen’s book]).”

Aertsen then affirms that “After drawing this corollary in his commentary on the Metaph. (VII, lect. 17, 1671), Thomas adds that what is required here is another mode of questioning (alter modus quaestionis). For we come to knowledge of simple substances only from the sensible ones, of which the first are in a certain sense the causes. ‘Therefore we make use of sensible substances as that which is known, and through them we inquire concerning the simple substances.’ That is precisely the method that Thomas follows in his ‘ways’ to the existence of God. It must, however, be realized that this mode of questioning is not the ‘analysis’ of an inner composition but the reduction to the extrinsic cause of sensible things. In Thomas’s reply the important structural difference between the two modes of questioning is by-passed, so that the necessity arises to regard the answer to the ‘if’ question as, simply, propositional truth.”

“Two considerations,” argues Aertsen, “evidently lead Thomas to reduce the answer to ‘if’ question to something purely mental (Quodl. IX, 2, 2: tantum in actu animae componentis et dividentis), namely, the affirmation of privations, which are not ‘something;’ and the affirmation of immaterial substances, of which the being-something is unknown to us. With regard to both, it is accordingly impossible to ask: ‘What is it?’”

“From this negative conclusion,” Aertsen contends, “there results an important positive insight: as question, the ‘if’ cannot be separated from the ‘what’ ontologically. But this implies that in both the cases mentioned, the ‘if’ question fails to reach its end. The affirmation of negations and of immaterial substances would therefore have to be distinguished expressly from an affirmation in which the sense of the ‘if’ question is really fulfilled. Such is the case whenever what is affirmed is not merely an accidental predicate, but means ‘being’ in the first way, which is already connected with the ‘what’ question. One can affirm that ‘evil is’—insofar as answer is given to the ‘if’ question—but this does not mean that evil is ‘something,’ because ‘being something signifies not only what answers to the ‘if’ question but also what answers to the ‘what’ question’ (De malo 1, 1, ad 19). The sense of the ‘if’ question (an est) is to manifest the subject as ‘ens,’ as ‘that which is,’ a substantial predicate, a ‘being something’ that has its sequel in the ‘what’ question” (J. A. Aertsen, Nature and Creature, 20-23).

We conclude by saying that in the Summa theologiae, part I, question 3, article 4, ad 2, Aquinas once again makes use of the res significata of the expression actus essendi (a metaphysical principle) to explain his understanding of the several meanings of the verb esse.