Entry 0394: Commentary on
De potentia, question 7, article 2, ad 1
Aquinas uses the expression actus essendi once in Quaestiones disputatae de potentiae, in question 7, article 2, ad 1. The expression is used again to explain the reasoning process whereby the human intellect establishes the truth of the proposition Deus est (“God is,” “God exists”). This truth, Aquinas insists, is not grounded on the knowledge of God’s actus essendi as such. The issue being addressed in this article of the De potentia is the same issue we saw in the context surrounding the text from Summa theologiae, part I, question 3, article 4, ad 2, namely, Aquinas’s identity thesis holding that in God, God’s essentia and God’s actus essendi are one and the same reality.
In conclusion, then, just as Aquinas did in Summa theologiae (part I, question 3, article 4, ad 2), now in De potentia (question 7, article 2, ad 1), he again explicitly uses the res significata of the expression actus essendi to define the essence of God as actus essendi.
In De potentia, question 7, article 2, Aquinas presents only one argument in the body of the article to show that God’s esse is the same as God’s essence. This argument is different from the three arguments given in the Summa. In the argument in De potentia Aquinas first observes (a) that the proper effect of any cause proceeds from it according to the likeness of its nature; (b) that where different agents produce an effect in common, there must be a higher cause to which this effect properly belongs; and (c) that the higher cause must possess this common caused perfection per essentiam.
Then Aquinas reasons that all created causes, while having their own proper effects which distinguish them one from another, also share in a single common effect which is esse. Two examples are given here: (a) fire which makes things to be hot and (b) builders who make something be a house. These particular causes have this in common that they cause esse, but they differ in that fire causes ignition and a builder causes a house. Therefore, Aquinas contends, there must be some higher cause of all in virtue of which all cause esse, and whose proper effect is esse, and this we call God. And since the proper effect of any cause proceeds from it as a similitude of its nature, there follows that this which is esse is the substance or nature of God. Thus Aquinas writes:
“Ad cuius evidentiam considerandum est quod cum aliquae causae effectus diversos producentes communicant in uno effectu, praeter diversos effectus, oportet quod illud commune producant ex virtute alicuius superioris causae cuius illud est proprius effectus. Et hoc ideo quia, cum proprius effectus producatur ab aliqua causa secundum suam propriam naturam vel formam, diversae causae habentes diversas naturas et formas oportet quod habeant proprios effectus diversos. Unde si in aliquo uno effectu conveniunt, ille non est proprius alicuius earum, sed alicuius superioris, in cuius virtute agunt. … Omnes autem causae creatae communicant in uno effectu qui est esse, licet singulae proprios effectus habeant, in quibus distinguuntur. Calor enim facit calidum esse, et aedificator facit domum esse. Conveniunt ergo in hoc quod causant esse, sed differunt in hoc quod ignis causat ignem, et aedificator causat domum. Oportet ergo esse aliquam causam superiorem omnibus cuius virtute omnia causent esse, et eius esse sit proprius effectus. Et haec causa est Deus. Proprius autem effectus cuiuslibet causae procedit ab ipsa secundum similitudinem suae naturae. Oportet ergo quod hoc quod est esse, sit substantia vel natura Dei” (De potentia, question 7, article 2, corpus).
This argument does not appear either in the parallel text of the Summa contra gentiles (book I, chapter 22), or in the parallel text of the Compendium theologiae (chapter 11). The argument, however, is used in other contexts. See, for example, In VI Metaphysicorum, lecture 3, nos. 17-19; In II Sententiarum, distinction 1, question 1, article 4, corpus; and In I Sententiarum, distinction 2, question 1, article 2, corpus.
After presenting his response in the corpus, Aquinas then proceeds to answer objections against the identity of God’s essentia and God’s actus essendi. It is in the answer to the first objection that Aquinas uses the expression actus essendi.
The first objection invokes the authority of Saint John Damascene to argue as follows: God is known to us because the affirmation Deus est is evident to us. But God is also unknown to us because what God is in substance and nature is utterly incomprehensible and unknown. A thing, however, cannot be both known and unknown. Therefore the esse of God is not the same as the substantia or essentia of God. (We have already seen this objection in the previous text where it was formulated in terms of the answers to the questions an sit and quid sit about God.)
To this objection Aquinas answers again with an explanation of the meaning of the terms ens and esse. Here is Aquinas in his own words:
“Dicit enim Damascenus in I lib. De orthodoxa fide: quoniam quidem Deus est, manifestum est nobis; quid vero sit secundum substantiam et naturam, incomprehensibile est omnino et ignotum. Non autem potest esse idem notum et ignotum. Ergo non est idem esse Dei et substantia vel essentia eius” (De potentia, question 7, article 2, objection 1).
Answer to objection 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, etiam in his quae esse non habent: sicut dicimus quod caecitas est, quia verum est hominem esse caecum. Cum ergo dicat Damascenus, quod esse Dei est nobis manifestum, accipitur esse Dei secundo modo, et non primo. Primo enim modo est idem esse Dei quod est substantia: et sicut eius substantia est ignota, ita et esse. Secundo autem modo scimus quoniam Deus est, quoniam hanc propositionem in intellectu nostro concipimus ex effectibus ipsius” (De potentia, question 7, article 2, ad 1).
To be noted in this response is the fact that Aquinas uses the terms ens and esse indifferently. The text makes clear once again that the res significata of both terms, ens and esse, is the metaphysical principle of actus essendi. This is their primary signification. But it is clear also that the terms ens and esse have an extended meaning whereby they denote the truth of a proposition.
What Aquinas meant with the statement, “ens et esse significat essentiam rei,” can be gathered from other contexts. Ens means “quod habet essentiam in rerum natura,” that is to say, “ens significat essentiam rei extra animam existentis.” (See In II Sententiarum, distinction 37, article 2, ad 3; and Summa contra gentiles, book III, chapter 8, no. 13. See also De veritate, question 1, article 1, corpus: “Quaelibet natura est essentialiter ens;” and De potentia, question 7, article 2, ad 5: “Ipsum esse Dei distinguitur et individuatur a quolibet alio esse. … Omne autem aliud esse quod non est subsistens, oportet quod individuetur per naturam et substantiam quae in tali esse subsistit.”)
In his The Metaphysical Thought of Thomas Aquinas ([Washington, D.C.: Catholic University of America Press, 2000], 522-523), John F. Wippel commented on De potentia, question 7, article 2, as follows: “In a. 2 Thomas argues that in God essence (substantia) and act of being (esse) are identical, i.e., not diverse. Even though this conclusion rests on the negation of distinction of essence and esse in God, it also raises a question. In affirming that in God essence and act of being are identical, is Thomas not allowing for some positive and perhaps even some quidditative knowledge of God? The first objection makes this point. According to John Damascene, that ‘God is’ is manifest to us. But what he is in terms of his substance and nature is altogether incomprehensible and unknown to us. But, continues the objection, the same thing cannot be known and unknown at the same time. Therefore God’s esse and his substance or essence cannot be identical.” (In the footnote to this line Wippel refers to De Potentia, Pession ed., p.190; and adds “For the text from John Damascene see De fide orthodoxa, c. 4 [ed. cit. p. 19]”.)
Wippel then continues: “To this Thomas replies by introducing a distinction we have previously seen concerning the ways in which the terms ens and esse may be used. Sometimes they are taken as referring to the essence of a thing or to its act of being; but on other occasions these terms simply signify the truth of a propsosition, and can even be applied to things which do not actually exist (as when we say blindness is because it is true that a particular person is blind). Accordingly when Damascene says that God’s esse is manifest to us, he is using esse in the second way as expressing the truth of the proposition ‘God is,’ not in the first way (as the act of being). But it is only when esse is taken in the first way that we can say that God’s essence and esse are the same. Hence just as His substance or essence remains unknown to us, so too does His esse when this is taken in the first way as act of being. Nonetheless, we can know that God is when ‘is’ is taken in the second way, for this merely means that we know that the statement ‘God is’ is true.”
In the footnote here Wippel reports: “‘…dicendum, quod ens et esse dicitur dupliciter, ut patet V Metaph. Quandoque enim significat essentiam rei, sive actum essendi; quandoque vero significat veritatem propositionis, etiam in his quae esse non habent: sicut dicimus quod caecitas est, quia verum est hominem esse caecum. Cum ergo dicat Damascenus, quod esse Dei est nobis manifestum, accipitur esse Dei secundo modo, et non primo. Primo enim modo est idem esse Dei quod est substantia: et sicut eius substantia est ignota, ita et esse. Secundo autem modo scimus quoniam Deus est, quoniam hanc propositionem in intellectu nostro concipimus ex effectibus ipsius’ (pp. 191-192). Cf. my Ch. II above, n. 7 for other references to this.”
The references given by Wippel in n. 7 of chapter II are as follows: “[Summa Theologiae I, q. 3, a. 4, ad 2],
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.