Entry 0385: Commentary on
In I Sententiarum, distinction 8, question 1, article 1, corpus
In this article Aquinas addresses the issue of whether or not the name “Qui est” is—among other names—the most proper name of God. He answers in the affirmative and provides four reasons to justify his answer.
For the first three reasons Aquinas invokes the authorities of Saint Jerome, Saint John Damascene and Pseudo-Dionysius, and makes no use of the term “actus essendi.” It is for the fourth reason, which Aquinas takes from the authority of Avicenna, that Aquinas introduces the term “actus essendi.”
Commenting on the reference to Avicenna in this text, Rollen Edward Houser remarks that in this passage Aquinas uses the expression “actus essendi” twice and, more importantly, Houser affirms here that the term “actus essendi” was invented by Aquinas to substitute “the more familiar term actus for the Latin Avicenna’s vehementia.” (1)
It is with this modification that Aquinas highlights in his explanation the contrast between the metaphysical principle of actus essendi and the metaphysical principle of essence. Thus Aquinas explains his fourth reason:
“Cum in omni quod est sit considerare quidditatem suam per quam subsistit in natura determinata, et esse suum per quod dicitur de eo quod est in actu, hoc nomen ‘res’ imponitur rei a quidditate sua, secundum Avicennam, hoc nomen ‘qui est’ vel ‘ens’ imponitur ab ipso actu essendi. Cum autem ita sit quod in qualibet re creata essentia sua differat a suo esse, res illa proprie denominatur a quidditate sua, et non ab actu essendi, sicut homo ab humanitate. In Deo autem ipsum esse suum est sua quidditas: et ideo nomen quod sumitur ab esse, proprie nominat ipsum, et est proprium nomen ejus: sicut proprium nomen hominis quod sumitur a quidditate sua” (In I Sententiarum, distinction 8, question 1, article 1, corpus).
This is the radical difference between creatures and Creator. In creatures, actus essendi and essence are inseparable metaphysical principles, but they are principles really distinct from each other.
It is not on the basis of the actus essendi that we properly call the things of nature “res.” It is the metaphysical principle of essence what allows us to call the things of nature by their proper name. The name “man,” for example, is the proper term to refer to certain living beings because this name is taken from their quiddity or essence, which in this case is humanity.
In God, however, there is no real distinction between the metaphysical principle of actus essendi and the metaphysical principle of essence. Aquinas explicitly states in the text that in God, “ipsum esse suum est sua quidditas,” and later he shows that in God, esse actu “est de ratione quidditatis suae” (In I Sententiarum, distinction 19, question 2, article 1, corpus).
Now, if to name a thing properly one must refer to its essence, one should conclude that the name “Qui est” does not properly name God because the name “qui est” or “ens” in the case of creatures does not refer to essence, it refers to actus essendi. And we certainly name God from what we can know of Him through creatures. But no, Aquinas says. In the case of God, one can say that the name “Qui est” is His proper name because, given the identity of His actus essendi with His essence, to say that the name “Qui est” comes from His actus essendi is equivalent to saying that the name “Qui est” comes from His essence. Aquinas states this explicitly in De potentia, question 2, article 1: “Sed ipsum esse Dei est eius natura et quidditas, et inde est quod proprium nomen ipsius est: ‘Qui est,’ ut patet Exod., cap. III, 14, quia sic denominatur quasi a propria sua forma.”
“Qui est” is the proper term to refer to God because in Him and only in Him essence puts no limit to the actus essendi.
In other words, the three terms “esse,” “ens,” and “actus essendi” have the same res significata. And the term “ens” is to be distinguished from the terms “esse” and “actus essendi” only in this, that it expresses a different modus intelligendi.
To be observed in this text also is the use of the term “subsistit.” According to Aquinas, “subsistere vero dicitur aliquid inquantum est sub esse suo, non quod habeat esse in alio sicut in subjecto” (In I Sententiarum, distinction 23, article 1, ad 3). The term “subsistit” therefore indicates clearly that in this article the term “quidditas” is being used to refer to the quidditas of the substance and not to the quidditas of accidents. It is only with the metaphysical principle of substantial quidditas that Aquinas finds the presence of the other metaphysical principle of actus essendi.
To be noted as well is the appearance of the three interrelated terms: “esse,” “ens,” and “actus essendi.” Now, concerning the res significata of these terms, the article expresses clearly that the res significata of the term “esse” is the metaphysical principle of actus essendi. And since the terms “esse” and “actus essendi” are being used indistinguishably as synonyms they both have not only the same res significata but also the same ratio significata, the latter being the intellectual conception of the metaphysical principle of actus essendi.
The res significata of the term “ens” is clear also. Just as the concrete term “homo” is taken from the substantial quidditas “humanitas,” the concrete term “ens” is taken from the metaphysical principle of “actus essendi.” And because the ratio significata of terms is the intellectual conception or modus intelligendi which the term expresses, it follows that just as the term “homo” responds to the intellectual conception of “humanitas” as existing in a suppositum, so also the term “ens” responds to the intellectual conception of the metaphysical principle of actus essendi as it is possessed by that which is a subsisting extramental thing.
(1) Rollen Edward Houser, “Introducing the Principles of Avicennian Metaphysics into Sacra Doctrina: Thomas Aquinas, Scriptum super Sententiarum, Bk. 1, d. 8,” American Catholic Philosophical Quarterly 88 (2014): 195-212. On p. 204 of this article, Houser writes: “In order to move from a whole ‘being’ (ens) to the principle that underlies it, namely, existence (esse), Thomas turns to yet another Avicennian technique, defining one fundamental notion in terms of another. We have seen Avicenna define the ‘necessary’ as the ‘assuredness of existing’ (ta’akkud al-wujūd; vehementiam essendi). This definition gave Br. Thomas warrant to restate Avicennian claims about necessity in terms of existence. Not only that, but ‘vehemence’ signifies ‘force,’ ‘vigor,’ ‘strength,’ notions that, in Br. Thomas’s philosophical vocabulary, are expressed by words like perfectio or actus. The Thomistic description of esse as the ‘act of existing’ (actus essendi), then, which is used twice in this very text, was invented, I would submit, when Thomas substituted the more familiar term actus for the Latin Avicenna’s vehementia.” The same paragraph appears on p. 41 of Rollen Edward Houser’s “Why the Christian Magistri Turned to Arabic and Jewish Falāsifa: Aquinas and Avicenna” (Proceedings of the American Catholic Philosophical Association 86 : 33-51).