Neo-platonic Infinity and Aristotelian Unity: a critique of W. Norris Clarke SJ’s reconstruction of Aquinas’ metaphysical development

W. Norris Clarke SJ has brought to our attention the Neo-platonic inspiration behind what has traditionally been called the Aristotelian-Thomistic thought of St. Thomas Aquinas. [1] The tendency has since been to say that the notion of infinity as imperfection properly befits Classical Greek thought whereas the Medieval, Scholastic and Thomistic paradigm which posits an “infinite perfection” is in contradiction to this, and to trace the proper antecedent of this anti-Grecian paradigm of infinity to the Neoplatonic participationists. Buttressing and built on this hermeneutic is the claim that the Aristotelian act and potency schema in Aquinas’ metaphysics of limitation was introduced later to preserve the unity of beings. This paper aims to critique the evidence for this reconstruction of Aquinas’ metaphysical development.

St. Thomas Aquinas expresses the metaphysical composition of beings in terms essence and of what he denotes as esse or (the act of) being. In the De Ente et essentia he writes,

From what has been said we can see how essence is found in different things. There are infact three ways in which substances have essence. There is a reality, God, whose essence is his very being [esse]. [2]
Essence is found in a second way in created intellectual substances. Their being [esse] is other than their essence, although their essence is without matter. Hence their being is not separate but received, and therefore it is limited and restricted to the capacity of the recipient nature. But their nature or quiddity is separate and not received in matter. That is why the Book of Causes [3] says that the intelligences are unlimited from below but limited from above. [4]

In a third way essence is found in substances composed of matter and form. In these, too, being [esse] is received and limited, because they have being from another. Their nature, or quiddity, moreover, is received in designated matter. They are thus limited from above and from below. [5]

It is recognized that St. Thomas’ metaphysics of esse limited by essence goes beyond Aristotle, for whom there is no more final act than form, and certainly no such a one which is the act of all the forms, as is esse in St. Thomas. [6] So Joseph Owens argues that “in a philosophy which is conditioned by this fundamental doctrine of Being, the absence of any treatment of existence is inevitable… What can be known and contemplated for the Stagirite is form, even though understood as act… The highest instance of Being is form; and it is that form that is studied by the Primary Philosophy in all the other instances. An act, like existence, which is irreducible to form has no place in the Primary Philosophy or in any other science.” [7] Norris Clarke explains,

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…St. Thomas takes over intact this perspective into his own system. But he adds to it another dimension, so to speak, in which the relations are reversed and matter also appears as limiting form. This new dimension, however, can have meaning only within the framework of some kind of participation doctrine, where form itself would be conceived either modo Platonico, as subsisting separately in its own right as a perfect plenitude or, for St. Thomas, a pre-existent idea in the mind of a Creator. There is no room for such a perspective in the universe of Aristotle. He has closed the door to it by his explicit rejection of all ontological logical participation or transcendence of material forms. [8]

Now, it need not be a simple extrapolation from the Aristotelian cosmos. But the other extreme is equally untenable, i.e., to suggest that St. Thomas mutates Aristotle’s intentions to make his own point. Indeed the ‘difficulty’ of the Aristotelian metaphysical intention as regards final actuality is that it points towards perfection as finite rather than infinite, whereas St. Thomas’ final perfection, esse, is infinite. As such, there is the possibility that the Aristotelian drift can be made out to look as if running counter the Thomistic one. Owens, whom Norris Clarke sees as confirming his ‘Aristotle as radically “finitist”’ position, [9] certainly does it:

Perfection is equated with finitude, act coincides with form. This philosophy of act does not lead in the direction of an omnipotent Christian God. Unlike the Christian…the Stargirite was under no obligation to posit unity as the all-embracing foundation of things. [10]

In the Christian teaching, the power of God is infinite; for the Greeks, it is finite. Perfect Being for Greeks meant limitation and finitude; for the Christians, the perfect Being is infinite. Limitation for the Christians denote imperfection; while for the Greeks, imperfection was implied by infinity. [11]

Or in Norris Clarke’s own words,

Act…is always identified with the fully complete, the actually present. Pure act, therefore, is simply a correlative of the immutable, i.e., of pure actualized form, complete in all that is proper to it and incorruptible. It is this immutability, self-sufficiency, and incorruptibility which for Aristotle is the primary characteristic of the “divine” and the perfect. In the notion of act so conceived there is no necessary implication of infinity, at least in the substantial order. In fact, Aristotle has no difficulty in admitting some fifty five of his prime movers, each one pure act or pure form but in virtue of its form distinct from all others. Substantial infinity would simply have no meaning in this Aristotelian universe… [12]

We note here that this contrast as contrast cannot be brought too far, and perhaps cannot be made at all. To represent St. Thomas as running counter to the spirit of Aristotle is to make a straw man of either of them. Indeed, to make such a comparison for the sake of highlighting the supposed anti-thesis between the Thomistic Infinite Act and the Aristotelian finite act perhaps betrays a subtle perversion of the notion of Infinity as St. Thomas understands it. Note that the notion infinite can refer not merely to Pure Act in St. Thomas, but even matter, depending on the context, as when he says in the Summa Theologiæ, Ia, q. 7, a. 1:

A thing is called infinite because it is not finite. Matter is in a way made finite by form, and the form by matter. Matter, indeed, made finite by form, inasmuch as matter, before it receives form, is in potentiality to many forms; but on receiving a form, it is terminated by that one. Again, form is made finite by matter inasmuch as form, considered in itself, is common to many; but when received in matter, the form is determined to this particular one thing. Now matter is perfected by the form by which it is made finite; therefore, infinite as attributed to matter has the nature of something imperfect; for it is as it were formless matter. On the other hand, form is not made perfect by matter, but rather is contracted by matter, and hence the infinite, regarded in the part of the form not determined by matter, has the nature of something perfect.

If there be any point in Norris Clarke’s comment seeking to establish a contrast, it must at least presuppose that the Thomistic Act is somehow different from what is described in the Aristotelian act, apart from the fact that St. Thomas uses the term infinite, for to use terms as these are inconsequential, since they can mean different things in different contexts, as we saw above. It may be used to designate material infinity, which is related to potency and imperfection. Or, it may be used to designate formal infinity, which is related to act and perfection. Therefore, one cannot deduce from the use of the mere term “infinity, period” to the conclusion that for one it is act and for another it is potency and so they disagree. Rather, one must specify the kind of infinity. Now, “[t]he self-subsistent Being is…infinite, not as a corporeal or extended infinity, but as a spiritual infinity which surpasses not only all spatial and material limitations but even all limitations of essence” [13] We now see where the artful equivocation hides in this contrast. For they say, “For St. Thomas, act is infinite. For Aristotle, potency is infinite.” But following St. Thomas [14] we distinguish between material infinity and formal infinity:

There is a kind of imperfect infinity which can be attributed to matter in that it is not determined. Matter receives its perfection from the form by which it is determined, just as clay receives its perfection from the form of the statue. On the contrary, there is a formal infinity which consists in perfection in that perfection which is independent of all material limitations. Thus the ideal in the mind of the artist may be reproduced indefinitely, and, before it becomes a reality limited to a certain locality in space and to a certain portion of matter, it is in a certain sense infinite. [15]

Therefore, we explicate their statements as, “For St. Thomas, act is infinite of formal infinity. For Aristotle, potency is infinite of material infinity.” We reply, so also for St. Thomas, potency is infinite of material infinity, as we saw. So?

Precisely: unless one sees the Infinite Pure Act of Thomism as somehow antithetical to the Aristotelian Act, such that this Pure Act is, contra Aristotle, not immutable, not incorruptable and not self-sufficient, then what is the point of the comparison? Would one not rather say then that whilst St. Thomas surpasses Aristotle, he does not counter him, but rather continues in his spirit? But to do this, the considerations of Norris Clarke and Owens are irrelevant. Since these remarks have been made, they must intend to do otherwise, and this by presupposing that St. Thomas’s doctrine of an Infinite Act is anti-Aristotelian in the sense of denying the attributes of Aristotle’s Act. This, in turn, can only mean that St. Thomas’ doctrine of an Infinite Pure Act has been replaced with another such one as analogous with the Infinity of Matter, which we saw, could also be understood as infinite, but yet in the same would fulfill every criteria for satisfying the Anti-Aristotelian contrast. Now, to posit an infinity such as an infinity of matter as the final act would indeed be contrary to the spirit of the Philosopher. There is no doubt about that. The text of Norris Clarke, if taken to mean that the direction of St. Thomas’s Pure Act is somehow contrary to the Aristotelian one, would precisely insinuate such a conception of infinity for the Thomistic Pure Act: for there is no other way of seeing how the Thomistic Pure Act is not “complete in all that is proper to it and incorruptible” as is the Aristotelian.

By attempting to eliminate any Grecian or Aristotelian antecedent to the limitation structure in St. Thomas vis a vis the contrast of the two different “infinity-paradigms”, Norris Clarke wants to say that the metaphysics of the limitation of act by potency only derives from the Neo-platonic notion of participation.

The search for such a framework forces us to leap five centuries down to Plotinus and Neoplatonism…This basic Platonian intuition of participation in terms of an infinite source and a limiting participated subject is organized into a rigid systemization by Proclus, the “Scholastic” of Neoplatonism, in his famous textbook of Neoplatonic participation metaphysics, entitled The Elements of Theology. [16]

Indeed he says that participation is the source of the doctrine of limitation: “The point we wish to make here is that the general structure of the limitation principle…is by no means original with St. Thomas;…is clearly Neoplatonic in origin and is so recognized by St. Thomas himself;” [17] The fitting application of Norris Clarke’s thesis for the Neoplatonic source is his transposition thesis, i.e., that Aquinas transposed the Neoplatonic structure into the Aristotelian schema. Norris Clarke argues that there is a gradual realization of the possibility of the synthetic principle “act is limited by potency”: that St. Thomas realized philosophically the synthesis only at the point of the Summa Contra Gentes, and this for the ‘per se unum reason’. Thus Norris Clarke,

[i]t is only from the Summa Contra Gentes on that he appears to realize the possibility of fusing both the limitation principle and act and potency into a single synthetic principle…Here too we find explicitly stated the reason for the transposition of the compositions resulting from participation into act and potency: because only in terms of act and potency can the intrinsic unity of any composite being be maintained. Over and over again St. Thomas now tells us: from two entities in act it is impossible to make an unum per se (an intrinsic unity). [18]

If we already presuppose that Aquinas was transposing the participation schema into Aristotelian act and potency, then it would be fitting to suggest that the participatory schema contributes that limitation aspect, whereas Aristotelian act and potency contributes the unity aspect. But this is to put the cart before the horse, since precisely we are here to judge this hermeneutic. Hence one must look, bracketing this hermeneutic, to see if the unum per se of creatures yields the synthetic principle “act is limited by potency”. On close scrutiny, one notes that this particular unum per se reason itself does not explain why, if at all, act is limited by potency. It would be well to quote what he says along similar lines in another paper, The Meaning of Participation in St. Thomas, in order to show that this justification, even for Norris Clarke, is mainly to explain the composition aspect, and not the limitation aspect.

The next and last step in the analysis, however, represents a peculiarly original stroke of genius on his part. This is the transposition of the whole structure of participation, especially of the metaphysical structure within the participant subject, into the technical Aristotelian framework of metaphysical composition in terms of act and potency. “Every subject,” he tells us, “which participates something is compared to that which it participates as potency to act: for by that which it participates it becomes in act such a participant…Therefore every created substance is compared to its act of existence as potency to act.” What is the reason for operating this transposition? St. Thomas tells us again with all desired explicitness: “In every composite there must be act and potency. For a plurality (plura) cannot become simply one unless there be there something which is act and something else which is potency”. [19]

There seems no way which this explanation justifies how act limits potency. It justifies a composition, but not a limitation. Even if limitation follows from this composition, there is nothing here which explains how this limitation results from the composition. The preservation of the per se unum of created beings, while necessarily requiring the composition of act and potency, does not in itself require the limitation of act by potency (which for Norris Clarke expresses the participation structure), although, in addition with other premises, it leads to limitation. Now, the wording of St. Thomas is this, as Norris Clarke says: “In every composite there must be act and potency. For a plurality (plura) cannot become simply one unless there be something which is act and something else which is potency.” That is, if there is no act and potency in the being, then there cannot be unum per se in the plurality. To put it another way, if there is unum per se in the plurality, then there must be act and potency in it, period. What then of limitation and participation? It does not come into the picture. Therefore, in affirming the unity of beings one need not go so far as to say that act is limited by potency. As we have pointed out, to say that in a being (ens) act and potency are composed is not quite the same as to suggest that these principles being composed are further specifically related as one limiting the other. That is, philosophically, there is no real synthesis here on account of the unum per se of creatures, because this motive does not yield the synthetic principle.

Instead, the text rather shows that after acknowledging the composition, we are further from there impelled to affirm the limitation, after proving further the real distinction between essence and existence. It is from the real composition of act and potency that we affirm the consequent limitation of one by the other; the fact that a being is composed does not always imply a priori that therefore these two principles are really distinct and hence are related as one limiting the other. So, in the De Ente, [20] St. Thomas has to argue for the real distinction between esse and essence. [21] He first distinguishes ‘existence’ from ‘essence’ to ensure that we are not confounding concepts, so that we have different meanings by these notions as ‘existence’ and ‘essence’. This is a conceptual distinction [22] and John Wippel correctly points out [23] that this does not as yet establish the real distinction. St. Thomas does not stop there; he argues that there can only be one being whose essence is identical with its existence since if there were another such one, it would be the same one without distinction. Hence the minimal condition for multiplication for a plurality, is that its essence must be distinct from its existence, or else it would not be multiplied and would be simple. Granted that there are pluralities, we must thus admit that these pluralities have in them a real distinction between essence and existence, since as was said above, there can only be one in which essence and existence are identical. Hence in creatures, essence and existence are really distinct. [24] And only after having established that can it be stated that such a creature’s being is not from itself but given by another, and hence received from another, since

[w]hatever belongs to a thing is either caused by the principles of its nature…or comes to it from an extrinsic principle…Now being cannot itself be caused by the form or quiddity of a thing…, because that thing would then bring itself into being, which is being, which is impossible. It follows everything whose being is distinct from its nature must have being from another [25]

and then finally restricted. [26] Or again, in chapter 5,

Essence is found in a second way in created intellectual substances. Their being is other than their essence, though their essence is without matter. Hence their being is not separate but received, and therefore it is limited and restricted to the capacity of the recipient nature. [27]

Hence, this real distinction is for Aquinas the philosophical antecedent to the doctrine of limitation. It makes possible the talk of limitation by way of reception. Conversely, given the “gap” between the composition and the limitation without the real distinction, there is no good reason to say that for Aquinas the per se unity of beings is preserved via limitation as well as composition, when already the latter is sufficient; indeed the aspect of limitation is irrelevant to the preservation of the unity of beings, as was said above; if Aquinas simply wanted to preserve the unity of beings, limitation and participation do not at all enter into the picture. And this is precisely what we see. In the whole of chapter 4 of the De Ente, no mention is made of limitation at all. On the contrary, after saying that angels have no matter, he merely brings on the composition of potentiality in these beings to account for their distinction from God and their individual unity in plurality. That for Aquinas composition suffices without limitation as regards the unity of creatures is evident in these words: “[s]ince there is potency and act in the intelligences, it will not be difficult to find a multitude of them, which would be impossible if they had no potentiality.” [28] Hence the per se unum of creatures does not seem to be a motive for the synthetic principle “act is limited by potency”. Rather, the synthesis seems to be a consequent of the real distinction, from the De Ente, written way before the Contra Gentes.

Thus I submit that the evidence for the thesis that St. Thomas’s doctrine of limitation is a transposition of the Neo-platonic participation motif into the Aristotelian schema after the Summa Contra Gentes to preserve the unity of beings is weak on two counts: firstly, that the Thomistic Act fails to reduce only to Neo-Platonic Infinity, and two, that the motive for the limitation of act by potency fails to reduce to the Aristotelian unity of beings. And here I end my paper.


[1] W. Norris Clarke SJ, “The Limitation of Act by Potency in St. Thomas Aquinas: Aristotelianism or Neoplatonism?”; “The Meaning of Participation in St. Thomas”, in Explorations in Metaphysics, 1994: UNDP (USA)

[2] St. Thomas Aquinas, On Being and essence (De Ente et essentia)., Armand Maurer CSB (transl.), 1968: Pontifical Institute of Medieval Studies (Cananda) p. 60

[3] Liber de Causis, 4.

[4] St. Thomas Aquinas, op. cit., p. 62

[5] Ibid., p. 65

[6] C.f. W. Norris Clarke SJ, op. cit., p. 74

[7] Joseph Owens CSsR, The Doctrine of Being in the Aristotelian Metaphysics. 1951: Pont. Inst, of Medieval Studies (Toronto, Canada)., p. 296

[8] W. Norris Clarke SJ, op. cit., p. 73-74

[9] Ibid., p. 75 n. 31

[10] Ibid., p. 297

[11] Ibid., p. 306 n. 19

[12] W. Norris Clarke SJ, op. cit., p. 74

[13] Reginal Garrigou-Lagrange OP, God: His Existence and His Nature, Vol II, 1946: Herder (USA), p. 47

[14] see his Compendium of Theology, op. cit., chapter 18, p. 21; Summa Theologia Ia q. 7 a. 1

[15] Reginald Garrigou-Lagrange OP, op. cit., p. 47; also, Cajetan, In De Ente, op. cit., pg. 257

[16] W. Norris Clarke SJ, op. cit., pp. 75-79

[17] Ibid.., p. 79

[18] Ibid., p. 81

[19] Ibid., pp. 95-96

[20] Also see John F. Wippel, “Essence and Existence in the De Ente, ch.4”, in Metaphysical Themes in Thomas Aquinas. 1984:CUA Press (USA), esp. pp 109-110, where he also notes St. Thomas’ explicit intention to argue for a Real Distinction.

[21] St. Thomas Aquinas, De Ente, chapter. IV, op. cit., pg 55-6.

[22] Francis A. Cunningham SJ commits this very error. See his Essence and Existence in Thomism: A Mental vs. the “Real” Distinction?, 1988:University Press of America (USA). Pp. 244-5

[23] John Wippel, op. cit., pg 110

[24] See John Wippel, op. cit.

[25] St. Thomas Aquinas, De ente, op. cit., pg. 56

[26] See Ibid., pg 56.

[27] Ibid., chapter V, pg. 62. Italics mine.

[28] Ibid., chapter IV, pg. 58

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