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I’ve been thinking a lot about Thomas Aquinas’s relationship to Platonic philosophy and his incorporation of it into his system. The saying goes, as I have often heard, that Thomas basically (and even, simply) appropriates Aristotle in his stance on, say, the passive and active intellect. On this reading, the active intellect is a capacity of the soul and not in any way something transcendent to it; thus, following the logic of Aristotle, there is no “universal” form of intellect but rather only particular forms in matter. (I realize that there are competing interpretations of Aristotle at this juncture.)

The objection often raised against Aristotle at this stage is the following: if there is no universal form apart from instantiated form, then universals could not exist (which of course contradicts Aristotle’s program). It is not the purpose of this blogpost to solve all these problems. Rather, I want to show how Thomas employs Platonic ideas via Augustine in order to solve Aristotle’s problem. The post thus accentuates a Platonic Thomas as much as an Aristotelian one. This research is now new, but is rather a personal response and rumination that was spurned by a discussion with a friend. (Bear in mind that I am no Thomas Aquinas scholar.)

Thomas shows his cards early in the Summa as he discusses the divine intelligence.[1] Indeed, the divine intelligence, as Thomas says, must be attached to the perfections of God, which are the logical assumption of the rest of theology.[2] He thereafter continues to elaborate the idea of the good in general, God’s goodness, infinity, existence, immutability, and eternity.[3] His philosophy/theology thus must be traced back to God himself, or more specifically, the divine intelligence.[4]

God created the world intelligently, that is, not by chance but according to God’s exemplary idea. In other words, the “ideas” (cf. Plato, Augustine) are in the divine mind. Thomas writes, “As then the world was not made by chance, but by God acting by his intellect . . . there must exist in the divine mind a form of the likeness of which the world was made.”[5] Or, as he more succinctly suggests earlier: necesse est ponere in mente divina ideas (“It is necessary to posit ideas in the divine mind”).[6] He continues, “Hence by ideas are understood the forms of things, existing apart from the things themselves.”[7] In this way, Thomas is able to incorporate the thoughts of both Plato and Augustine—a noticeable feat, indeed—by suggesting that the universal ideas are in the mind of God. (Of course, he also rightly criticizes Plato for postulating the existence of ideas apart from a [divine] mind.[8] By the way, this is where Plotinus picks up Plato by suggesting that the latter’s conception of the Good [or Beauty] is the abstract form that is contained within the Nous of the One, thus completing and perfecting Plato’s own unfinished system. This is another story….)

Importantly, Thomas avers that the exemplary idea is Christ himself. While it is true that Thomas does not explicitly say that the ideas are in the Son, the implication of his theology leads to this reality in two ways. First, just as Thomas before argues that the ideas are in the intellect of God (see above), so also by calling Christ, among other things, the emanation of the intellect, he suggests that the ideas are in Christ by extension. As he writes, using Aristotle and Augustine, the Word corresponds to the “concept of the intellect” within God; or, Christ is the “emanation of the intellect,” and, by way of this emanation, he “is called the Son”.[9] Second, Thomas often associates the Son with the mind of God. Namely, just as the “exterior vocal sound is called a word from the fact that it signifies the interior concept of the mind,” so also “first and chiefly, the interior concept of the mind is called a word.”[10] In other words, as the Son is called the Word, the biblical witness means to point us to the reality that he is himself the intellect of God. Therefore, again by extension, Thomas suggests that the ideas are in the Son. While at the beginning of his theology, he may be faulted for being less that Christocrentric,[11] he later overturns this problem.

The above argument grounds his later (more prominent) argument that a person, using an a posteriori method, can discern the existence and (basic) nature of God in the natural world. Thomas is attempting to clarify how general revelation in the natural world discloses God’s “power” and “nature” (Rom 1:20). The world reveals God, as the ideas of God found in the world are comprehended by the intellect of a person.[12] Furthermore, in a similar manner to God’s revelation in the natural world, Scripture reveals God through words.[13] As in the natural world, there must be correspondence between the ideas in Scripture and the ideas in the knowing person. In other words, in the natural world, God’s revelation is through “things,” that is, events; whereas in Scripture, revelation is through “words.”[14]

The manner in which Thomas argues for this revelation in the natural world and Scripture is both technical and dense. While this post cannot comprehensively elaborate his arguments here, it shall explain, first, the knowledge that may be gleaned from sensible objects and, second and more pertinently, the revelation-knowledge that may be gleaned from immaterial or spiritual objects, i.e., God’s revelation in creation or Scripture. While the argument that Thomas Aquinas uses a Platonic conception—via Augustine—to justify the reality of ideas in the divine mind should already be clear, the following discussion should explain it further.

First, Thomas holds that, while the concrete particular is always in view in knowledge,[15] the direct object of such knowledge is the form or universal within the concrete body: “So, then, our intellect understands the universal itself directly through the intelligible species, whereas it indirectly understands the singulars that the phantasms are phantasms of.”[16] The point of knowledge for him, therefore, is for the mind to abstract the universal form from the individualizing matter. In this manner, following Aristotle, he is able to say simultaneously that the mind has knowledge of the particular and the universal. Namely, “the sensory power has direct cognition of them [contingent things] and the intellect has indirect cognition of them, whereas the intellect has cognition of the universal and necessary aspects of contingent things” so that “some scientific knowledge has to do with necessary things and some has to do with contingent things.”[17] Notice, therefore, that Thomas’ epistemology leads him to implicate a sort of tabula rasa of the mind as sense-perception is the only source of knowledge. Reminiscent of Aristotle, he writes that “our natural knowledge begins from sense [i.e., perception]. Hence our natural knowledge can go as far as it can be led by sensible things.”[18] (Neither, of course, falls into the Humeian trap.)

Second, because all knowledge necessarily stems from sensible particulars (see above), he continues to define just how a person knows invisible or immaterial objects (which include God’s revelation through the natural world and Scripture). His basic argument is this: a person’s idea (from the natural world or Scripture) is true insomuch as it correlated with the divine idea (in the natural world or Scripture). Namely, while we cannot sense immaterial objects, we have an “active intellect” that allows us to see God in natural objects.[19] Indeed, as he suggests, the primary object of the intellect is being.[20] Incorporating some insights from Plato, Aristotle, and Augustine, he continues to explain, however, that there is a difference between our sensory and intellectual capacities: the former roughly correspond to material objects, whereas the latter correspond to spiritual objects.[21] In this manner, he answers his original question—how then does a person know the immaterial, spiritual, or divine?—by turning to intellectual cognition. As he states, “It seems that intellectual cognition is not taken from sensible things.”[22] In other words, part of the rational faculty of people includes the ability to induce God through analogy from the natural world and Scripture. Therefore, as sensible cognition is not the sum of a person’s mental capacity, “it is nothing to be astonished at if intellectual cognition extends further than sensible cognition” so that we may have a sort of “knowledge of invisible things.”[23] While the mind cannot apprehend the being of God directly, it can do so indirectly through the world because “sensible objects, as finite and contingent, reveal their relation to God, so that the intellect can know that God exists” and something about his nature.[24] He applies this same principle to Scripture because, as he argues, “It is appropriate for spiritual things to be proposed by means of likeness drawn from corporeal objects.”[25] In the end, he explains that, in the natural world, we can know God through nature “by cause, by way of excess, and by removal of” (lit. ut causam, et per excessum, et per remotionem [1:84.7, 3]); and, in Scripture, God can be known through the fourfold senses of his Word.[26]

In the end, the fondness of Thomas for Aristotle is usually overblown. This post has been long and technical, but it has sought to show that Thomas appeals to divine ideas as a ground for his understanding of the intellect. While he was a hylomorphist—conceiving of being as a compound of body and soul—he also avers that being is ultimately exemplified in the divine ideas (within the mind of God). Such a conclusion is hardly a blind following of Aristotelianism. He is rather following the logic of Augustine, whose incorporation of Plotinus perfected the incomplete system of Plato before him. Ideas are ultimately grounded in the divine mind. (How he connects his hylomorphism to his understanding of the divine ideas is unclear to me at this juncture.)

Fredrick Copleston is right to suggest that, while Thomas incorporated Aristotelian vocabulary and concepts, the theologian “was no blind worshiper of the Philosopher.”[27] Frederick Christian Bauerschmidt argues similarly.[28] Thomas often either attempts to explore and explain Augustine through the Aristotelian categories, or he interprets Aristotle in a manner that is consonant with Augustine. Lydia Schumacher concludes, “In affirming all of this, I implicitly challenge the longstanding assumption that Aquinas’ philosophy is essentially Aristotelian, at the expense of being Augustinian.”[29]

[1]Norman Kretzmann explicitly argues for this logic. Cf. Norman Kretzmann, The Metaphysics of Creation: Aquinas’ Natural Theology in Summa Contra Gentiles II (Oxford: Clarendon, 1998), 33-35.

[2]Thomas of Aquinas, The Summa Theologica, trans. Fathers of the English Dominican Province, rev. ed. (New York: Benziger Brothers, 1920), 1:4.

[3]Ibid., 1:5-10.

[4]For a comprehensive logical or topical overview of the Summa Theologica itself, see Martin Grabmann, Introduction to the Theological Summa of Thomas Aquinas (St. Louis: B. Herder, 1930). For a more chronological approach, see Edward J. Gratsch, Aquinas’ Summa: An Introduction and Interpretation (New York: Alba House, 1985).

[5]Ibid., 1:15.1.



[8]Ibid.; see also Thomas, Truth, trans. Robert W. Mulligan (Indianapolis: Hackett, 1954), 2.1, 3.1; cf. Copleston, A History of Philosophy, 2:359-360. For his defense of the (plural) ideas in the mind of God along with God’s own simplicity, see 1:15.1-3; idem, Contra Gentiles, 1:53-54. Therefore, while finite minds and their language compel us to speak in terms of subject and predicate, and while we apprehend the divine intellect in piecemeal, no such distinction exists in the simple mind/nature of God (idem, Summa Contra Gentiles: On the Truth of the Catholic Faith, trans. Anton C. Pegis (Garden City, NY: Doubleday and Company, 1955), 1:31).

[9]Summa, 1:34.1, 2; cf. idem, Truth, 4.1, cf. 3.1.

[10]Ibid., 1:34.1.

[11]Cf. Ibid., 1:1-26, 44-119.

[12]He fundamentally argues this notion by appealing to his doctrine of analogy for knowledge (Summa Theologica, 1:13.5; cf. Bauerschmidt, Holy Teaching, 68). Regarding the existence of God, he induces the necessity of God’s existence via the five ways: from (1) motion, (2) efficient cause, (3) possibility and necessity, (4) gradation, and (5) governance (Ibid., 1:2.1-3; cf. 1:12-15; idem, Summa Contra Gentiles, 1:13.1-35). Regarding the nature of God, he suggests that God’s perfections may be induced from the natural world “by cause, by way of excess, and by removal of” (lit. ut causam, et per excessum, et per remotionem [1:84.7, 3]). He thereafter posits the nature of God in terms of his perfections, goodness, infinity, existence, immutability, eternity, oneness, knowledge, truth, life, will, love, justice, mercy, providence, predestination, power, and beatitude (cf. 1:4-26). To bring Thomas’ thought together, it seems that the world reveals to us (1) the kind of relationship that God has with the world, (2) that God is not part (but rather cause) of the world, and (3) that God’s not being in the world is a result of his transcendence and not imperfection (Ibid., 1:12.12; cf. Bauerschmidt, Holy Teaching, 62, fn. 5). For an excellent discussion of the natural theology inherent within Thomas’ discussions here, see Bruce D. Marshall, “Quod Scit Una Uetula: Aquinas on the Nature of Theology,” in The Theology of Thomas Aquinas, ed. Rik Van Nieuwenhove and Joseph Wawrykow (Notre Dame, IN: University of Notre Dame Press, 2005), 1-35.

[13]Theology or sacred doctrine, Thomas writes, “properly uses citations from the canonical Scriptures when arguing from necessity, whereas it uses citations from other doctors of the Church as if arguing from what is properly its own, though with probability. For our Faith is based on the revelation made to the Apostles and Prophets who wrote the canonical books and not on any revelation that might have been made to the other doctors” (idem, Summa Theologica, 1:1.8; cf. Dulles, Revelation Theology, 41). As he continues, “Holy Scripture” reveals God through words so that “spiritual truths are fittingly conveyed with bodily metaphors” (Ibid., 1:1.9). As Bauerschmidt summarizes, the point of the Scriptures is “for God to teach us” and “like any good teacher, God adapts his methods to the requirements of his students” (idem, Holy Teaching, 40, fn. 34; cf. Thomas, Summa Theologica, 1:1.8-10; 1:13.5). While Thomas’ understanding of Scripture and relation to theology is notoriously difficult and complex, it is important to note that, for Thomas, Scripture, tradition, and theology are overlapping and interdependent concepts. As Valkenberg notes, “my modern question ‘how do you use Scripture in your theology?’ would have been redundant in his [Thomas’] view” (Valkenberg, Words of the Living God, 11; cf. Christopher T. Baglow, “Sacred Scripture and Sacred Doctrine in Saint Thomas Aquinas,” in Aquinas on Doctrine: A Critical Introduction, ed. Thomas G. Weinandy, Daniel A. Keating, and John P. Yocum [London: T & T Clark, 2004], 1-25; cf. Bauerschmidt, Holy Teaching, 37, fn. 24). For an excellent treatment of Thomas’ relationship between faith and reason, see Frederick Christian Bauerschmidt, Thomas Aquinas: Faith, Reason, and Following Christ, in Christian Theology in Context, ed. Timothy Gorringe, Serene Jones, and Graham Ward (Oxford: Oxford University Press, 2013). For Thomas’ own “biblical theology,” or at least the closest he comes to laying out one, see Thomas, Summa Theologica, 3:27-59; cf. Valkenberg, Words of the Living God, 20. Especially within Protestant circles, Thomas’ commentaries have been overlooked in favor of his philosophical theology in his two Summas. For a helpful introduction to his exegesis, see Thomas G. Weinandy, Daniel A. Keating, and John P. Yocum, eds., Aquinas on Scripture: An Introduction to his Biblical Commentaries (London: T & T Clark, 2005); Thomas Prügel, Thomas Aquinas as Interpreter of Scripture, in The Theology of Thomas Aquinas, ed. Rik Van Nieuwenhove and Joseph Wawrykow (Notre Dame, IN: University of Notre Dame Press, 2005), 386-415.

[14]Ibid., 1:1.10; cf. Bauerschmidt, Holy Teaching, 43, fn. 41.

[15]Cf. his contrast between the concrete/particular of something and its concept/idea (Ibid., 1:5.2).

[16]Aquinas, Treatise on Human Nature: The Complete Text (Summa Theologiae I, Questions 75-102), trans. Alfred Freddoso (South Bend, IN: St. Augustine, 2010), 1:86.1.

[17]Ibid., 1:86.3.

[18]Ibid., 1:12.12; cf. 1:84.7; 1:88.1; Bauerschmidt, Holy Teaching, 40, fn. 33; Copleston, A History of Philosophy, 2:392, cf. 388-393.

[19]Ibid., 1:88.1.

[20]Ibid., 1:79.7; 1:5.2.

[21]Ibid., 1:84.6.

[22]Ibid., 1:84.6.

[23]Ibid., 1:84.6.

[24]Copleston, A History of Philosophy, 2:393-394.

[25]Ibid., 1:1.9.

[26]Ibid., 1:1.10; cf. Bauerschmidt, Holy Teaching, 43, fns. 41-44.

[27]Copleston, A History of Philosophy, 2:323.

[28]idem, Holy Teaching: Introducing the ‘Summa Theologiae’ of St. Thomas Aquinas [Grand Rapids: Brazos, 2005], 14, 21-22.

[29]Schumacher, Divine Illumination, 155. For an excellent translation and survey of biographical documents surrounding Thomas’s life, see Kenelm Foster, trans. and ed., The Life of Saint Thomas Aquinas: Biographical Documents (London: Longmans, Green, and Co., 1959).