«Thomas Aquinas and Aristotelian Metaphysics: Cause or Creator? The arguments of the seminal Greek thinker Aristotle and the 13th century medieval ...»
Andrew H. Waller
Sunoikisis Undergraduate Symposium
April 29, 2011
Thomas Aquinas and Aristotelian Metaphysics: Cause or Creator?
The arguments of the seminal Greek thinker Aristotle and the 13th century medieval
theologian St. Thomas Aquinas concerning cosmological origins and the concept of the Prime
Mover seem very similar at first glance, and, indeed, contain many of the same components.
However, upon closer examination, we see a few primary differences between the two thinkers.
St. Thomas’ masterwork, the Summa Theologiae, draws heavily on the work of Aristotle specifically in relation to Aquinas’ arguments concerning the existence of the Judeo-Christian God. However, although Aquinas makes use of the concept of Aristotle’s Prime Mover, an uncaused First Cause of all things, as described in book 12 of Aristotle’s Metaphysics, Aquinas takes Aristotle’s conceptions of the Prime Mover to a different level. Although much scholarship has equated Aquinas with Aristotle, or portrayed him in a highly Aristotelian light, Aquinas does not follow Aristotle in all areas of his theology. With regard to the scope of this particular paper, Aquinas and Aristotle differ significantly when it comes to the questions of cosmological origins and the agent of those origins. Aquinas’ God functions not only as the Aristotelian Prime Mover, but also serves as the Creator, as Aquinas lays out in Part I, Quaestio 44, 45, and 46 of the Summa Theologiae. This paper seeks to bring to light the ways in which these specific variances distinguish the Aristotelian Prime Mover from Aquinas’ conception of the Christian God.
But before directly addressing St. Thomas, let us briefly remind ourselves of Aristotle’s arguments concerning the Prime Mover. The Aristotelian works that are principally relevant to the discussion of the Prime Mover are Physics and Metaphysics, both of which treat concerning motion and movement. Aristotle’s case for the existence of a Prime Mover revolves around the concept of motion or change in the universe. The philosopher postulates in book 8 of Physics that everything in the universe changes and has motion.1 If this is true, and since motion as Aristotle conceives of it cannot be self-generated, there is therefore some original mover that initiated the motion that we see in the universe now, for Aristotle states that if we accept the statements of the cosmologists who generate everything from Night, or the doctrine of the physicists that “all things were together,” we have the same impossibility; for how can there be motion if there is no actual cause?
Wood will not move itself—carpentry must act upon it; nor will the menses or the earth move themselves—the seeds must act upon the earth, and the semen on the menses.2 This motion is, for Aristotle, embodied in the figure of the Prime Mover, the uncaused first cause of all things, as the philosopher describes in book twelve of Metaphysics, where he argues that, “There is something which is eternally moved with an unceasing motion, and that circular motion. This is evident not merely in theory, but in fact.”3 He expounds upon this idea later in book twelve, “The first principle and primary reality is immovable, both essentially and accidentally, but it excites the primary form of motion, which is one and eternal.”4 Thus, the Prime Mover, as Aristotle conceived of it, remained unmoved, but affected change upon the universe in such a way as to cause the eternal motion that Aristotle saw in the cosmos.
1 Aristotle, Physics, translated by R. P. Hardie and R. K. Gaye, (Oxford: The Clarendon Press, 1930).
2 Aristotle, Metaphysics, translated by Hugh Tredennick. Cambridge, MA: Harvard University Press, 1989), 12.1071b.
3 Ibid., 12.1072a.
4 Ibid., 12.1073a.
As we approach the formulations of St. Thomas, it is helpful to keep in mind three essential components of Aristotle’s arguments. First, that the motion of the Prime Mover, primary motion, is eternal. The Prime Mover, itself unmoved, began the processes of motion in the universe; those processes will continue indefinitely due to the infinite nature of primary motion.
Second, the Prime Mover is required for the continued motion of the universe. Philosophical scholar Istvan Bodnar puts forth that “Aristotle is describing here in the terminology of his physics a supra-physical entity without which the universe could not function or persist.”5 Third, as Aristotle has described things, it is not necessary for the Prime Mover to interact with the universe in any capacity other than that of the Mover.
With these three points in mind, we now turn to Saint Thomas Aquinas, the thirteenth century medieval theologian and scholastic. He is considered one of the greatest Catholic theologians and is one of the Four Doctors of the Catholic Church. Aquinas’ most extensive work is the Summa Theologiae, a systematic theology. Aquinas began work on the Summa in 1265 and continued writing until the year he died in 1274. When it comes to the question of the Prime Mover and cosmological origins, Aquinas does utilize almost the exact same line of reasoning that we find in Aristotle; a simple summation of his argument is as follows: One, there is motion in the universe, Two, this motion is not self-generated, Three, there is a regressive chain of movement, Four, therefore there must be an unmoved Prime Mover, which Aquinas identifies as the Christian God.6 5“Aristotle’s Natural Philosophy,” last modified Dec. 31, 2009, http://plato.stanford.edu/entries/ aristotle-natphil.
6 Alister E. McGrath, Christian Theology: An Introduction, (John Wiley and Sons, 2010), 183.
However, it is important that we recognize one key difference between the Christian God and Aristotle’s Prime Mover. Aquinas’ God functions not only as the Aristotelian Prime Mover, but also serves as the Creator of the Universe, as Aquinas argues in Part 1, Quaestio 44 of the Summa: “We must consider not only the emanation of some particular being from some particular agent, but also the emanation of all being from the universal cause, which is God, and to this emanation we designate the name of creation.”7 Aquinas’ Creator-God actually brings things into existence, rather than merely setting them into motion. In the Aristotelian view it is not necessary for the Prime Mover to have a role into the initial existence of the universe, since the Mover is only responsible for its motion.
When Aquinas uses the term “creation” he is referring to something very specific, creatio ex nihilo, creation out of nothing. In Part 1, Quaestio 45, Thomas explicitly points to the phrase ex nihilo as an integral part of his definition of creation. This is part of the traditional orthodox Christian interpretation of the Biblical account of creation as portrayed in the book of Genesis 8 and this is the principle which Aquinas holds to as he wrestles with the question of cosmological origins. Unlike Aristotle’s eternal universe, the Christian God existed before the creation of a temporal universe, as St. Thomas argues in Part 1, Quaestio 46: “Nothing except God has existed from eternity.... for it has been shown above that the will of God is the cause of things.”9 And again, “We affirm that there had existed no place or space before the world was.”10 Thus, it is 7 St. Thomas Aquinas, Summa Theologiae, translated by A.H. Waller, I, q. 46, a. 1.
8 Alister E. McGrath, Christian Theology: An Introduction, (John Wiley and Sons, 2011), 219-221.
9 St. Thomas Aquinas, Summa Theologiae, translated by A.H. Waller, I, q. 46, a. 1.
10 Ibid., I, q. 46, a. 1.
very clear that Aquinas views the universe as a temporal place, that is, there was a time before the universe existed. This stands in sharp contrast with Aristotle’s conception of the universe as eternal.
Furthermore, the Creator-God is necessary for the continued existence, or esse, of the created order. In Part 1, Quaestio 3, Aquinas states that “Since the esse of God is his essentia, as has been shown, if God would be in some genus, it is necessary that his genus would be ens, because genus signifies the essence of a thing, since it is predicated by that which it is.”11 Thus, Aquinas argues that if we were to place the Christian God into a genus or a category, it would be the category of ens, or of pure being. Aquinas’ God is a being who retains esse as an essential part of his own nature, meaning that he holds within himself the very fabric of esse rerum, the existence of all things. A Creator-God who interacts with his creation and upon whom all things depend for their existence is decidedly different from the impersonal Aristotelian Mover, whose purpose is solely motion, and not creation.
Let’s recap. The Christian God is, according to Aquinas, the Prime Mover, but Aquinas takes this concept a few steps further. Aquinas’ God is also the Creator ex nihilo of the universe, not merely a force that provided it with motion. God existed before the universe was created and continues to provide the cosmos and its contents with their esse, or existence. This stands in contrast to Aristotle’s view of the universe as eternal and his conception of the Prime Mover as an impersonal being who caused the universe’s motion, but does not sustain the existence of the created order. Aquinas’ fundamental conception of the Christian God as the source of all motion, creation, and being is what separates his formulation of deity from the Aristotelian Prime Mover.
11 St. Thomas Aquinas, Summa Theologiae, translated by A.H. Waller, I, q. 3, a. 5.
Having said all of this, what is the point? Here we have two thinkers, Aristotle and Aquinas, and they happen to be different. It is certainly not uncommon for two intellectuals to arrive at different conclusions concerning such a weighty topic as the origins of motion in the cosmos, so why is this gap between the Philosopher and the Saint so noteworthy? The issue at stake here is how we as scholars view these two men and their work. It has been the habit of much scholarship to make some very general assumptions about St. Thomas and his relationship with Aristotle. Many scholars have placed far too much emphasis on what some have called Aquinas’ “Aristotelian-Thomistic” philosophy,12 and have tied Aquinas to Aristotle in such a way that one might think that St. Thomas was some kind of medieval bird dog, devotedly following his Greek master through the fields of philosophical inquiry. This sort of mindset does an incredible disservice to the contributions that Thomas made to medieval thought and greatly discounts the vast legacy that he left behind.
Still others have banned Thomas from the realm of philosophy altogether, kicking him up into the attic and dismissing his work as mere theology, rather than true philosophy.13 Until the 1960’s it was quite uncommon for Aquinas to be mentioned or addressed in the wider world of philosophical scholarship, and any use of his work would more often than not be limited to discussions of natural law or natural theology, topics which only breach a miniscule fraction of Thomas’ body of work.14 Although Aquinas does address quite a wide variety of theological topics in the Summa Theologiae, as well as in his other works, I would put forth that his religious 12Norman Kretzmann and Eleonore Stump, eds., The Cambridge Companion to Aquinas, (Cambridge: Cambridge University Press, 1993), 11.
13 Ibid., 10.
14John Haldane and Patrick Lee, “Aquinas on Human Ensoulment, Abortion and the Value of Life,” Philosophy, Vol. 78, No. 304 (Apr., 2003): 255.
belief does not compromise the validity of his thought any more than Aristotle’s does. Aristotle does not seem to be totally immune to the effects of the ancient Greek worldview, so why should we allow him to speak in the congress of true philosophers while at the same time giving Aquinas a seat at the intellectual children’s table?
When it comes to addressing the question of cosmological origins, Aristotle and Aquinas approach the topic in much the same way, however, as has been discussed, their final arguments have decidedly different implications. As we have seen in both Physics and Metaphysics, Aristotle’s Prime Mover, the uncaused First Cause, set an eternal, yet motionless universe into motion, and continually sustains that motion. Beyond the role of the Mover, however, this being does not interact with the cosmos or its content. However, Aquinas’ God, as he is portrayed in the Summa Theologiae, is the Creator ex nihilo of all things. He brought the universe into being and continues to provide the cosmos with its very existence, providing all things with their esse. As I hope my limited comparison on the topic of the Prime Mover has shown, I would argue that Aquinas was not a lock-step Aristotelian, nor was he a religious fanatic; he was a legitimate thinker and a first-rate philosopher, and, as many contemporary scholars are realizing, he deserves to be examined afresh in his own right.
Adler, Mortimer J. Aristotle for Everybody. New York: Simon and Schuster, Inc., 1978.
Aquinas, St. Thomas. Summa Theologiae. Translated by A.H. Waller.
Aristotle. Metaphysics. Translated by Hugh Tredennick. Cambridge, MA: Harvard University Press, 1989.
Aristotle. Physics. Translated by R. P. Hardie and R. K. Gaye. Oxford: The Clarendon Press, 1930.
Ford, Lewis S. “Contrasting Conceptions of Creation.” The Review of Metaphysics. Vol. 45, No.
1 (Sep., 1991): 89-109.
Gamwell, Franklin I. “Speaking of God After Aquinas.” The Journal of Religion. Vol. 81, No. 2 (Apr., 2001): 185-210.
Haldane, John and Patrick Lee. “Aquinas on Human Ensoulment, Abortion and the Value of Life.” Philosophy. Vol. 78, No. 304 (Apr., 2003): 255-278.
Kreeft, Peter. Summa of the Summa. San Francisco: Ignatius Press, 1990.
Kretzmann, Norman and Eleonore Stump, eds. The Cambridge Companion to Aquinas.
Cambridge, UK: Cambridge University Press, 1993.
McGrath, Alister E. Christian Theology: An Introduction. Wiley-Blackwell, 2010.
Morris, Thomas V. and Christopher Menzel. “Absolute Creation.” American Philosophical Quarterly. Vol. 23, No. 4 (Oct., 1986): 353-362.
Piper, Josef. Guide to Thomas Aquinas. Translated by Richard and Clara Winston. San Francisco:
Ignatius Press, 1991.
Stanford Encyclopedia of Philosophy. “Aristotle’s Natural Philosophy.” Last modified Dec. 31,