Thomas Aquinas: Limitation of Act by Potency

How do we make sense of reality? Of the stability within the change? Of the idea of being and becoming? Of the problem of the one and the many? Ancient philosophers have been wrestling with these inquiries ever since. When Aristotle came along, he made a great leap of progress and, in some sense, salvaged Western metaphysics when he articulated the distinction between act and potency. In Christian philosophy, this Aristotelian notion had been recovered in the medieval period and then refined and extended, especially by Thomas Aquinas. This critical distinction between actuality and potentiality aided the Dominican friar not only in understanding reality and creatures but, more importantly, in his arguments for the existence and being of God. By utilizing Aristotle, the keystone of the Thomistic metaphysical system which is the principle, "Actus non limitatur nisi per potentiam," i.e., no act or perfection can be found in a limited degree in any being unless it is conjoined with a really distinct limiting principle whose nature is to be a potency for that act"¹ was established.

At first glance, many would quickly argue that the Thomistic synthesis of act and potency is purely Aristotelian. However, upon closer inspection, this is not necessarily the case. In the book Exploration in Metaphysics, W. Norris Clarke, S.J., in Chapter 4, challenged his readers that the Thomistic act and potency doctrine should be properly traced in its historical origins. By doing so, Clarke first established that the act and potency notion of Aquinas contains two elements: First, the use of act and potency to explain the process and change, and second, the relationship between act and potency in terms of infinity and limitation.² The author would then argue that the former element came from Aristotle (Aristotelian) and the latter from Plato – or, more accurately, Plato transformed by Plotinus (Neoplatonist)³. By giving his readers a broad yet succinct sketch of the history of Western Philosophy, Clarke traced the roots of each of the elements of Aquinas' act and potency metaphysics, and consequently, showed the genius of the Angelic doctor's synthesis and even his original and significant contribution to Christian philosophy.

The notion of infinity-finitude and illimited-limited began early from the time of the Pre-Socratics. In trying to account for the first principle, the original material, the primal Monad, out of which all things are formed, they have articulated what they called the infinite. Being adherents to physicalism and unable to go beyond material categories, it became inevitable for them to conclude that the infinite, because it is above the sensible material world, must be identified with the formless, indeterminate, unintelligible, and therefore imperfect. On the other hand, the finite, because it represents the finished cosmos, must be identified with the fully formed, the determinate, intelligible to which the ancient philosophers attributed to the perfect.⁴ In other words, the infinite-illimited is associated with imperfection, while the finite-limited is equated to perfection. Incoherent as it was from the Thomistic standpoint, it must be pointed out that this metaphysical breakthrough by the Pre-Socratics became the foundation of the Greek philosophers that followed them.

As Plato tried to work around the metaphysical tradition that his predecessors handed down, he made considerable progress that elucidated some of the muddled lines in the infinite-finite distinction. His theory of Forms paved the way for a clearer understanding of the concept of the one and the many and, as a result, brought a new relationship between the illimited-limited notion. As Clarke explains, "According to the Platonic metaphysics, all realities below the supreme idea of the Good (or the One) are a 'mixture' of two opposing principles, the limit and the unlimited, which reappear with analogical similarity on all the levels of reality from the world of ideas to the half-real world of sensible things."⁵ By establishing differing degrees of realities, Plato can say that the sensible material world is composed of both infinity and finitude. Individually, since each Form can be truly known in the sensible world through the particulars, there is intelligibility therefore finitude. But since the natural world as a whole is composed of many forms and is a realm that is always changing, then it must also be infinite. Furthermore, by establishing the relation of particulars to Forms, Plato made considerable progress in the Classical Greek tradition. According to the philosopher, everything below the Ultimate Form, i.e., the supreme idea of the Good, relates via participation and imitation, thus explaining the finitude and limitation of the sensible world without annihilating its idea of infinity. As Clarke notes, "In the Platonic framework it is participation in the idea of being which makes a particular idea to be precisely it is, i.e., this well-defined essence. It is participation in non-being or otherness which, by negating the indeterminate or infinite multitude of all other ideas, preserves this particular essence distinct from all others and prevents it from melting into them in a blur of unintelligible confusion."⁶ Despite Plato's progress in metaphysics though, "we are still far, however, from any positive conception of infinity as linked with perfection as such." It can be noted that his idea of the perfect resides only in the realm of Forms, separate from the sensible world. With this, it can be seen that Plato followed the ancient Greek tradition in rejecting the notion of an actual and transcendent infinite.

When Aristotle introduced his act and potency metaphysics, it is important to note that the Philosopher still followed the Greek tradition of attributing the infinite to imperfection (potency) and the finite to perfection (act). As Clarke notes, "In what is the type par excellence of act and potency for Aristotle, namely, the composition of form and matter, he tells us explicitly that the role of form or act is to impose a limit on the formless infinity of matter in itself and thus confer upon it determination and intelligibility…"⁷ This is crucial information. While Thomas Aquinas, in some measure, adopts Aristotle's act and potency, this is not identical to that of the Philosopher. Aquinas moves further by positing that matter also limits the form, which is only possible if some participation framework is granted to which Clarke argued, "there is no room for such a perspective in the universe of Aristotle."⁸ So, if Aristotle's act and potency scheme do not necessarily mean that matter limits the form, what is it all about? Upon closer inspection, it could be deduced that the Philosopher's distinction between actuality and potentiality is only suited as a function of the problem of change. Potency, then, is not necessarily a limiting principle to act but an essential principle that must be added to act to account for everything capable of change. Being in potency is having the capacity of becoming what it is that is not yet. Act, on the other hand, is identified as the thing actualized, completed and that which is "actually present." In Aristotle's metaphysics, Pure act is the absence of change, which also implies incorruptibility and self-sufficiency. Because the Philosopher did not accommodate any doctrine of participation and considered the forms as ultimate and absolute, there is no room for him to attribute infinity to the perfect.

It was in the time of Plotinus and Neoplatonism that "a doctrine of participation linked with a wholly new concept of infinite and finite, correlated now with the perfect and the imperfect respectively in a complete reversal of the age-old classical Greek tradition."⁹ By fighting against the religious and philosophical challenges of his day, Plotinus posits a concept of emanation to the One while maintaining the old Platonic view of infinity to imperfection and finitude to perfection. As Clarke states, "In this perspective, all the intelligible essences below the One now appear as limited and hence imperfect participations of this supremely perfect and absolutely simple first principle, which somehow embraces within itself the perfection of all the lower determinate essences but is none of them particular."¹⁰ This framework allowed Plotinus to use the word infinite in a reverse manner, describing the first principle as separate and above all, the unparticipated source, infinite with the plenitude of perfection and the supreme indetermination or infinity, not of defect but of excess. Consequently, everything below the infinite is the finite, limited, intelligible, and imperfect participants. With this original synthesis, Plotinus paved the way for what would be coined later on as the Neoplatonic participation-limitation theory, to which the Christian thinkers of the medieval ages, especially Thomas Aquinas, would explicitly appeal in synthesis with Aristotle's act and potency doctrine to advance Christian philosophy and thereby formulate his own metaphysical formula.

The Angelic doctor acknowledged that Aristotle and Plotinus' metaphysics have strengths and weaknesses that must be carefully studied. Nevertheless, as the great synthesist, St. Thomas fused "into one the best elements of the two main streams of Western philosophical thought"¹¹ and "to recognize that the strength of each doctrine remedied precisely the weakness of the other…"¹² In doing so, Aquinas not only modified both doctrines but also put forward his original contribution to Christian metaphysics. Concerning Neoplatonism, Thomas revised the hierarchy of the universal concepts of beings by removing at the top anything that over-emphasized forms and hard-realism ideas. As a Christian moderate-realist, the Dominican friar "substituted as the fundamental ontological perfection of the universe the supra-formal act of existence, participated first directly by essential form, as limited potency in pure spirits, then dispersed, so to speak, in material beings, by being communicated through specific forms to their multiple participations in matter."¹³ The distinction between esse and essence is Aquinas' original and genius work. It is very helpful in differentiating and categorizing creatures, especially angelic spirits, which are pure forms but inferior to God as their existence is determined by Him, Whose Essence and Existence are identical. Secondly, Thomas modified the act and potency principle of Aristotle by detaching its sole function to the idea of change. He added a vertical dimension to it, "the static 'vertical' function of receiving subject limiting a higher plenitude in a participation framework."¹⁴ With these modifications and synthesis, the Thomistic principle "Actus non limitatur nisi per potentiam" was seen to be established in Aquinas' later systematic works.

Thomas Aquinas' work on the act and potency principle is rich and complex. Furthermore, his synthesis regarding the limitation of act by potency should not be labeled as purely Aristotelian, but as Clarke tried to prove, should be "Aristotelianism specified by Neoplatonism." In all of these, it was also demonstrated that Thomas Aquinas is worthy of careful study and inquiry. Above all, one should remember that he is a devout Christian; as such, his love and passion for the truth should be admired and emulated.

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Note: This is an Engagement Paper submitted to Dr. James Dolezal AP 501 Foundations of Philosophical Theology International Reformed Baptist Seminary Neiko Guil-An Paje — November 11, 2024

Footnotes

1. W. Norris Clarke, Explorations In Metaphysics: Being-God-Person (Notre Dame, Indiana: University of Notre Dame Press, 1995), 67. ↩

2. Clarke, 69. ↩

3. Clarke, 82. ↩

4. Clarke, 70. ↩

5. Clarke, 71. ↩

6. Clarke, 71. ↩

7. Clarke, 73. ↩

8. Clarke, 74. ↩

9. Clarke, 75. ↩

10. Clarke, 77. ↩

11. Clarke, 82. ↩

12. Clarke, 79. ↩

13. Clarke, 80. ↩

14. Clarke, 80. ↩