Abstract: The perplexing problem of trinitarian unity can be logically resolved through the concept of
‘infinitistic relation regress.’ This offers an alternative understanding of unity, distinct from
traditional views that see unity either as parts sharing a common substance or as a function emerging from
cooperating parts.
Keywords: unity of God, unity of the proposition, problem of the fourth, Trinity, Holy Spirit, divine
essence, Bradley’s regress, St Augustine, Richard Gaskin, Georg Cantor.
How can three distinct persons constitute one God without generating a fourth entity or deriving from a prior
unity? The Axiom of Maria, attributed to the 3rd century alchemist Maria Prophetissa, captures this
dilemma:
One becomes two, two becomes three, and out of the third comes the One as the fourth. (Wiki, ‘Axiom of Maria’)
It makes sense, because it expresses what we all take for granted, namely that unity is something above and beyond the parts. Three distinct things can have unity in so far as they generate ‘a fourth,’ specifically some function. Augustine explains that, for anything to exist, it requires unity:
Now things which tend towards existence tend towards order, and, attaining order they attain existence, as far as that is possible to a creature. For order reduces to a certain uniformity that which it arranges; and existence is nothing else than being one. Thus, so far as anything acquires unity, so far it exists. For uniformity and harmony are the effects of unity, and by these compound things exist as far as they have existence. For simple things exist by themselves, for they are one. But things not simple imitate unity by the agreement of their parts; and so far as they attain this, so far they exist. (De morib. 6.8)
An automobile has unity because its parts contribute to its function of transport. That there can be a unity of three, without either generating a fourth or rising from a fourth, clashes with human understanding. That’s why some Christians think of ‘God’ as a universal and as the unity of the Trinity. But this is tritheistic ontology. It contradicts the Nicene-Constantinopolitan creed, according to which each person is God and the Son and Spirit are homoousion (same in essence) with the Father. Bernard Lonergan says:
If one objects that God subsists, we answer that we do not in the least deny this. For although God does subsist, God does not subsist as a fourth over and above the Father, the Son, and the Spirit, since God is not really distinct from these three. (Lonergan, 2009, p. 333)
The Trinity is understood as three personae in one essentia/substantia. However, Augustine clearly emphasizes that there is no essentia distinct from or additional to the three persons (cf. De Trin. 7.6.11). Substance, to Augustine is simply that which has Being: “God is a sort of substance: for that which is no substance, is nothing at all. To be a substance then is to be something” (en. Ps. 69.5 (68.5)). It implies that God is fullness of Being (ipsum esse) and it corresponds to the scholastic dictum that “God’s essence is God’s existence.” Thus, contrary to what is sometimes alleged (notably by Zizioulas and Gunton), Augustine did not promulgate a “substance ontology” that stipulates a prior essence equal to a divine universal. Augustine’s trinitarian ontology has divine personhood as the fundamental unit:
[W]e do not say three persons out of the same essence, as though therein essence were one thing, and person another… (De Trin. 7.6.11)
Maria Prophetissa formulated the ‘problem of the fourth’ — a theological
conundrum that persists today, often leading to contradictory interpretations. In the natural world, a unity of
three produces a fourth. For example, the proton consists of three quarks always in reciprocal communication
(reminiscent of the perichoresis, or mutual indwelling, of the divine persons). The quarks do not exist
independently but only in this very configuration. (They exist only in relation to each other, similar to the
Divine Three.) The quarks give rise to the proton as ‘the fourth.’ The proton is likely the only
composite thing in the universe that is everlasting. So the trinity of quarks is decidedly a vestigium
trinitatis. It would have been the perfect metaphor for the Trinity, if it weren’t for the fact that the
unity of the quarks is yet another thing; a proton that carries specific properties (cf. Wiki,
‘Proton’).
Having repudiated substance ontology, Augustine approaches the problem from multiple angles — a
methodology that has proven valuable. As Lewis Ayres sees it, he delineates a number of different trinitarian
constellations that are brought into mutual illumination (cf. Ayres, 2010, p. 325). Augustine, no doubt
influenced by Cappadocian trinitarianism, perceived the persons, or hypostases, to be relative to one another. Each
person in the Trinity is predicated relatively. The distinguishing characteristics of the three are relation and
relationality, predicated on paternity (begetting), sonship (filiation) and sanctity (spiration) (cf. De
Trin. 5.5.6; 5.11.12). Importantly, divine unity is understood in terms of the communion of the Father and the
Son, where the spirit of communion is the Holy Spirit (cf. De Trin. 5.11.12). Communion emerges from the
relations among all three: Father, Son, and Spirit. Wolfhart Pannenberg expresses the same idea in modern
terms:
The divine persons, then, are concretions of the divine reality as Spirit. They are individual aspects of the dynamic field of the eternal Godhead. This means that they do not exist for themselves but in ec-static relation to the overarching field of deity which manifests itself in each of them and in their interrelations. But in this respect their reference to the divine essence that overarches each personality is mediated by the relations to the two other persons. (Pannenberg, 1992, p. 430)
In On Faith and the Creed, Augustine references the theological tradition that understands the godhead as the union of Father and Son, a union identified as the Holy Spirit (De Fide 9.19). Augustine would retain the concept of the Holy Spirit as the union of the godhead. The Trinity has unity of action in the world (De Trin. 1.5.8; 1.12.25; Io. ev. tr. 39.5; Letters 11.2). The Holy Spirit is the active agent of divine unity. Thus, Augustine comes to identify the unity of the godhead with the Holy Spirit. After all, it is proper to speak of the whole of God as Spirit. Says Augustine:
Neither can the Trinity in any wise be called the Son, but it can be called, in its entirety, the Holy Spirit, according to that which is written, God is a Spirit; because both the Father is a spirit and the Son is a spirit, and the Father is holy and the Son is holy. Therefore, since the Father, the Son and the Holy Spirit are one God, and certainly God is holy, and God is a spirit, the Trinity can be called also the Holy Spirit. But yet that Holy Spirit, who is not the Trinity, but is understood as in the Trinity, is spoken of in His proper name of the Holy Spirit relatively, since He is referred both to the Father and to the Son, because the Holy Spirit is the Spirit both of the Father and of the Son. (De Trin. 5.11.12)
For the same Spirit is, indeed, the Spirit of the Father and of the Son, making with them the trinity of Father, Son, and Spirit, not a creature, but the Creator. (De Civ. 13.24)
[T]he Holy Spirit is neither the Father nor the Son, but only the Spirit of the Father and of the Son, Himself also co-equal with the Father and the Son, and pertaining to the unity of the Trinity. (De Trin. 1.4.7)
Another name for the Trinity is the Holy Spirit. Yet, the name pertains also to the person “in the
Trinity.” This point has not received sufficient attention among theologians. We use to say that the Holy
Spirit is the Spirit of the Father and of the Son. By appeal to logic, if the Holy Spirit is the fount of love
between Father and Son and thus constitutes their communion, then he is the communion of Father, Son and Holy
Spirit, equal to the Spirit of the Divine Three. There is no antecedent ousia (divine essence), as this is
merely a word used for convenience. The Holy Spirit is the ousia, because the ousia is love.
The Holy Spirit could be called the “trinitarian person.” T. F. Torrance portrays him as the
invisible spokesperson of the Father and the Son. We cannot know him because he “hides himself from us”
(Torrance, 1991, p. 212). The Holy Spirit has an “ineffability of his own personal mode of being”
(ibid. p. 213) and a “transparent and translucent mode of being” (ibid. p. 212). This is a
questionable view. After all, to portray the Spirit as a “nonentity” that merely performs a function
does nothing to invigorate our faith. The Holy Spirit is special; he fulfils a function but is also the triune
person. His personhood is triune rather than invisible. Indeed, Jesus says that the Spirit “will speak only
what he hears” (John 16:13-14); but so did Jesus himself:
I tell you the truth, the Son can do nothing by himself; he can do only what he sees his Father doing, because whatever the Father does the Son also does. (John 5:19)
It must be so, or else John the Evangelist would have promulgated tritheism. The incarnate Son and the incarnate Spirit only speak the words of God and do nothing “of themselves,” because Christian faith is monotheistic. Jesus says: “He that has seen me has seen the Father” (John 14:9). Yet, we do not view the Son as “transparent.” As a person, he is more than a conduit of divine truth. He adds a personal quality to divine truth according to the Son. Since the Spirit mediates a human knowledge of the transcendent God, he paints with many colours. It does not mean that an act in the divine economy can be ascribed to the Father, the Son, or the Spirit alone. Accordingly, the Church Fathers understand the action of God as undivided ad extra. Says Augustine: “[T]he works of the Trinity are undivided” (De Trin. 1.5.8). Says Gregory Nazianzen: “When I contemplate the Three together, I see but one torch, and cannot divide or measure out the Undivided Light” (Orations, 40.XLI). Says Karl Barth:
What we can describe as personality is indeed the whole divine Trinity as such, in the unity of the Father, Son and Holy Spirit in God Himself and in His work — not the individual aspects by themselves in which God is and which He has. […] This one God as the Triune is — let us say it then — the personal God. (CD II/1, p. 297)
We may compare with three musicians, playing a serenade. They have unity of action and do nothing “of themselves,” because they follow the musical score. Together they create a wholeness, equal to the musical piece. What we hear is the tune of the triune person. This is a better picture of the Spirit. After all, faith cannot grasp an apophatic person that remains veiled behind the revelation of the Father and the Son. Accordingly, Pannenberg says:
The three persons of Father, Son, and Spirit are primarily the subject of the divine action. By their cooperation the action takes form as that of the one God. [My emphasis] (Pannenberg, 1992, p. 388)
The concept of the Spirit as vinculum amoris (or nexus amoris; ‘bond of love’) between Father and Son, commonly attributed to Augustine, actually originates with St Epiphanius — a historical misattribution that needs correction. To wit, Augustine uses other words and says that Spirit is ‘love,’ the Father is ‘he that loves’ and the Son ‘the beloved’ (De Trin. 15.19.37; 8.11.14). The Spirit is understood as the loving communion of Father and Son (De Trin. 5.11.12; 6.5.7; 15.17.27; 15.18.32; De Fide 9.20). Evidently, he belongs to the communion himself. But the communion of believers with God is also a gift of the Holy Spirit, a communion to which he himself belongs (2 Cor. 13.14). In Tractates on the Gospel of John Augustine represents the Holy Spirit as the unifying spirit of Father, Son, and Holy Spirit:
[if] many souls through love are one soul, and many hearts are one heart, what does the very fountain of love do in the Father and the Son? … If, therefore, ‘the love of God [which] has been poured forth in our hearts by the Holy Spirit who has been given to us’ [Rom. 5.5] makes many souls one soul and many hearts one heart, how much more does [the Spirit] make the Father and the Son and the Holy Spirit one God, one light, one principium? [si ergo caritas Dei … multa corda facit unum cor, quanto magis pater et filius et spiritus sanctus, Deus unus, lumen unum, unumque principium?] (Io. ev. tr. 39.5; Ayres, 2010, p. 257)
John Ayres comments on the above excerpt:
The same analogy also appears in a number of texts addressed directly to Homoians or Homoian converts to the Catholic faith, including his debate with the Homoian bishop Maximinus in 427. Thus, following a pattern we have already traced in a number of contexts, clear statement of the Spirit as active lover and active agent of unity within the Godhead appears most clearly c. 420, even if it seems to lie just beneath the surface of texts from around a decade earlier. (Ayres, 2010, p. 257)
We may conceive of the Spirit as breathed forth by Father, Son and Holy Spirit. Such a concept involving self-reference was not foreign to Augustine’s thought. In the same vein he understands the Son as being sent by the Father and the Son (De Trin. 2.5.9). Torrance talks in a similar manner about the Spirit:
[T]he procession of the Spirit is to be thought of not in any partitive way but only in a holistic way, as procession from the completely mutual relations within the one indivisible Being of the Lord God who is Trinity in Unity and Unity in Trinity. […] [The Trinity] is neither from the Three Persons to the One Being of God, nor from the One Being of God to the Three Persons. (Torrance, 1993)
The Holy Spirit, then, is none other than the living dynamic reality of God Almighty, the transcendent Lord of all being… (Torrance, 1991, p. 209)
In his own distinctive Person the Holy Spirit is whole God, God of God, of one and the same being with the Father and the Son, and in his own peculiar activity as the Holy Spirit, the one indivisible Trinity is fully and unreservedly participant (ibid. p. 221).
John Macquarrie (1966) develops a threefold understanding: the Spirit as ‘unitive Being,’ the Father
as ‘primordial Being,’ and the Son as ‘expressive Being.’ Through the Spirit, a new and
higher unity emerges between divine Being and created beings (Macquarrie, 1966, pp. 184-85). The Spirit
is God, and he is God at his closest to us (p. 295). The initiative in incarnation is to unitive Being
(p. 259). By building unity in diversity he grants the beings their own initiative, because he is the Spirit
of freedom. We must recognize his initiative while not destroying “that measure of freedom and responsibility
that is indispensable to the conception of personal existence in man.” Christianity must offer salvation
(making whole) of human existence and not “an escape from existence, whereby we shed its responsibility and
become marionettes” (pp. 296-97).
The natural world appears appears universally composite. There are even theories suggesting that the electron,
which is generally regarded as elementary, might be a composite particle. This suggests that all existence
manifests as composite unity. In fact, the word ‘unity’ means synthetic
wholeness — only pluralities can be unities. Aristotle maintains that every sensible substance
exists as a functional unity with structural complexity. A thing’s essence, identical with its telos,
must be understood through its process of becoming (cf. Cao, 2015). It is in accordance with Aristotelian thought
to say that the essence of the Trinity is synonymous with the unity of the divine persons.
The Neoplatonic One, by contrast, is ‘simple’ and transcends being itself (cf. Wiki,
‘Plotinus’). While monadic, it transcends both plurality and unity, existing beyond these categories.
The conclusion is that the monad transcends the world and exists only as a content of mind. It is simple, but it is
not a unity. In Parmenides, Plato proves that the naive concept of unity, that is, as a simple, cannot exist
in the world. So it must be a universal. The conclusion is that unity is necessary for anything to
‘be’ — unity is ‘being.’ Divine unity is not prior to the godhead, but
eternally generated. The Holy Spirit is the unity of the Trinity.
In our natural way of thinking, we expect the unity of the Trinity to be more than the three persons, like a
trichord harmony, which is more than the three notes. By Augustine’s suggestion, while the third person is a
member of the triad, he also operates as the Spirit of the Trinity. The C major triad, composed of the notes
C–E–G, is a suitable metaphor. We could reinterpret “out of the third comes the One
as the fourth” as “out of the third comes the One as the triunity.” The mathematician
Georg Cantor (1845 – 1918) developed set theory as a mathematical framework for
understanding multiplicity as unity. A set represents unicity by constituting an abstract object that transcends
yet contains its members. In Cantorian set theory, a set can be a member of itself (since there are no axiomatic
rules to prevent this). Thus, we may represent the Holy Spirit as a set that contains itself as a member. Sets are
denoted by any number of members embraced by curly brackets. I use the Latin names for the persons; pater,
filius, and spiritus sanctus, and place spiritus in the middle.
S = { p, {s}, f }
Now insert S into the middle set and we get an eternal regress. I shall argue that this is how trinitarian unity is generated from eternity. Cantor proved that this kind of infinity is an ‘actual infinity,’ i.e., something completed and definite (cf. Wiki, ‘Actual infinity’). Before Cantor, ever since Aristotle, infinity was seen as a way of speaking about a limit that could never be reached. Cantor’s radical shift meant that an infinity can be regarded as a unity, and thus there can also be different sizes of infinities. Actual infinity is today commonly accepted among logicians and mathematicians, so this revolutionary insight ought to influence theology. The Trinity can also be represented in the form of a proposition (from John 3:35 and 5:20):
(1) The Father loves the Son
This formulation offers the simplest definition of the Trinity, with the copula representing the Holy Spirit. The philosophical problem of propositional unity emerges here: what transforms a list of words into a meaningful declarative sentence? Many philosophers, among them Frege, Russell and Wittgenstein, have attempted to solve the problem. Richard Gaskin (2008) shows that neither of them is successful, as all attempts to avoid “Bradley’s regress” lead to contradictions. British idealist philosopher F. H. Bradley (1846 – 1924) pointed out, as many had done before him, that if relations are conceived as independent from their relata, then any relation would require further relations between itself and its relata, and these relations would again need further relations, and so on ad infinitum. Or in Bradley’s words:
The links are united by a link, and this bond of union is a link which also has two ends; and these require each a fresh link to connect them with the old. (Gaskin, 2008, p. 315)
Of course, relations cannot connect their relata if they are not themselves connected to their relata. Bradley saw this regress as vicious and concluded that a relational unity of properties is unattainable. To the contrary, Gaskin argues that Bradley’s regress is a harmless and constituting regress. It is the solution to the unity problem. In terms of proposition (1), it can be described as follows:
- Father and Son are One through participation in the Spirit of Love
- Father, Son, and Spirit are One through participation in the Spirit of Love1
- Father, Son, Spirit and Spirit1 are One through participation in the Spirit of Love2 , continuing ad infinitum
Augustine realized the first implication of the regress; that from Love as the bond between Father and Son follows that Love is the unity of the Trinity. The unity of the proposition consist in the generation of an infinite set of propositions. So it is the regress itself which is ultimately constitutive of unity. The unity of the original proposition is only preserved by producing another unity, and so on indefinitely. At each stage of the regress is a unified proposition that has no unconnected elements. Thus, it is an innocent and constituting regress. Bradley, however, saw it as a ‘practical’ regress, as if it required the practical task of connecting an eternal number of links. Gaskin comments:
I claim that a regress that arises in the analysis of meaning will be vicious just if it is a ‘practical’ regress, in the sense that it presents an infinite series of discrete epistemic tasks to be completed by the would-be understander. By contrast, a regress that arises in the analysis of meaning will be innocent just if it is a ‘metaphysical’ regress, in the sense that it places an infinitistic structural condition on what it is to understand; its stages are not epistemically discrete moments, requiring to be processed seriatim by the understander, but are rather acquired all at once and in their entirety as an epistemological package. (pp. 350-51)
For the understander, the regress infinitism is not an unperformable, infinitistic task. Rather, it has a holistic explanatory status, like the mythological image of an infinite series of turtles that upholds the earth. But if the first proposition cannot be unified, how can an infinity fare any better? The point is that “[e]ach stage guarantees the unity of the previous stage, and tells us what that unity consists in” (p. 367). It might be that the earth is too heavy for one, or a great many, turtles to support. But it does not follow that an infinite series of turtles cannot support the earth, for it is a condition on a turtle supporting the earth that it be supported by a next turtle, and so forth, ad infinitum. Thus, the condition for supporting the earth is fulfilled: it is turtles all the way down (cf. Gaskin, 2008, p. 368). In propositional terms:
[I]t is a condition on one instantiation relation’s unifying a proposition that a second instantiation relation unify the first instantiation relation with its relata, and so on. (ibid.)
The mythological idea that there are turtles all the way down (or “elephants all the way down,” as
the Indians say) is really a sublime truth. Gaskin argues that Bradley’s regress “sustains the very
existence of the world in the philosophically hygienic sense of that word — the totality of
(true and false) propositions at the level of reference” (ibid. p. 420). The conclusion is that unity
need neither rely on a prior substance nor an external function. The ‘problem of the fourth’ is solved.
Nothing exists beyond the persons and their relationships, since unity inherently requires distinct elements in relation to each other. There is no contradiction in saying that God is a oneness of Three. The reason why God is One is
because he is Three. The ongoing controversy in theology between (historical) proponents of God’s
unity and modern proponents of diversity in the godhead, is meaningless.
The eternal procession of the Holy Spirit follows naturally from the model of relation regress. It also has
implications for the question of God’s attributes. Theologians use to say, with Augustine, that in God
“quality and substance are identical” (De Civ. 11.10). In other words, the being of God is
identical to the properties (or ‘attributes’) of God. This follows from God’s simplicity. But the
fact that God has the property of Love means that he is Love. Love is what unites Father and Son. But what is the
property that holds between Father and Love, and between Son and Love? It is the property of “having the
property of Love.” But what is the property that holds between Father and “having the property of
Love,” and between Son and “having the property of Love”? It is the property of “having the
property of having the property of Love,” and so on ad infinitum.
God’s identity with Love stems from the unity of God being Love itself, manifested as Holy Spirit. Unity in
the godhead presupposes distinction within it — unity necessarily emerges from relations between
distinct elements. Since there is separation, the persons have the relation of Love. From this follows a relation
regress, which constitutes the unity of Love. The reason why God is Love is because the persons have the
property of Love. In God there’s no contradiction between having the property and being the property. Nor is
there a way of telling whether a sugar cube has whiteness or is whiteness. The property of whiteness
cannot be separated from the sugar. The fact that it has whiteness means that it is whiteness.
Modern thought distinguishes between a person and his or her properties — an angry person has anger.
Archaic thought, by contrast, saw the person as possessed by anger itself, becoming anger incarnate. This state of
identity precludes relation. If God is Love and is Wisdom, he cannot relate, either. Divine
completeness necessitates both having and being love, requiring otherness within the godhead. Only triunity can
reconcile complete divine nature with genuine unity. The problem with relying on the doctrine of God’s
simpleness is that it collapses the Trinity. But, as I’ve shown, God’s simpleness and oneness follow
from his diversity, and so we needn’t oppose the two ostensibly contradictory doctrines.
Lonergan posits that divine relations “are really identical with the divine essence” (Lonergan, 2009,
p. 261). This raises a logical challenge: if these relations are identical with the same divine substance,
their distinct nature becomes problematic. Lonergan addresses this difficulty properly. However, such philosophical
theory is not appealing to faith, because faith needs images. An explanation in terms of relation regress is easier
to understand and much more appealing. As has been shown above, ‘substance’ is equal to
‘being,’ which comes from ‘unity.’ The Divine Three have their being from their relation
whose unifying capacity is embodied in a regress. Thus, distinction and unity go together, like the two sides of
the same coin.
Regress infinitism provides an ontology of relational unity instead of personhood (pace Zizioulas). This
understanding of divine unity as communal unity aligns with both modern and Augustinian theological perspectives.
That each person is predicated relatively implies trinity. Unfortunately, if their relation is
‘substance,’ this tends to be understood as ‘the fourth.’ Luckily, the alternative to this
is relation regress, which gives unity. Especially since it is validated by Cantor’s ‘actual
infinite,’ we can forget about ‘the fourth.’
The apparent challenge to divine aseity (self-sufficiency) arising from God’s composite nature can be
addressed through regress infinitism. Rather than depending on self-subsistent components, God’s
self-sufficiency manifests through eternal self-repetition in an infinite series. Without resorting to an argument
from God’s simplicity we can argue that there can be no subordinationist, modalist, or tritheist
understanding of God’s being and action. The unity of the Trinity is maintained regardless of the economic
activity of God in creation and in revelation. Furthermore, it allows that the Holy Spirit proceeds from the Father
and the Son without thinking in terms of another reality which gives the Father and the Son their underlying
unity.
Unity requires multiplicity. A human being is one because of the harmonious coordination of many organs. The
notion that unity and multiplicity are opposites depends on a category error. Unity is a higher level category than
multiplicity, and this is the reason why they do not conflict. It was William of Ockham
(c. 1287 – 1347) who poisoned the Western mind with his nominalism, according to
which only particulars have real being. When we think of a wholeness, it is just the act of thinking about
several objects at once (cf. Spade & Panaccio, 2019). Thus, an automobile is nothing more than a concept,
since it is merely a mental aggregation of discrete objects. In point of fact, in our act of thinking we see the
automobile as a means of transport. It is the unity of its parts that generates this function, and unity has
being. Is this transport capacity not real? Common perception naturally grasps wholes rather than mere
aggregates — we apprehend a town as an integrated unity rather than merely a collection of
buildings.
The Shema Yisrael’s declaration “Hear, O Israel: The Lord our God, the Lord is one” (Deut. 6:4)
should not be interpreted through the Greek philosophical concept of divine simplicity, which was foreign to Hebrew
thought. God is a oneness of multiplicity throughout the bible. Already in Genesis 18 it is revealed that God is
Three:
The Lord appeared to Abraham near the great trees of Mamre while he was sitting at the entrance to his tent in the heat of the day. Abraham looked up and saw three men standing nearby. When he saw them, he hurried from the entrance of his tent to meet them and bowed low to the ground. (Gen. 18:1-2)
However, verse 22’s statement that “[t]he men turned away and went towards Sodom, but Abraham remained standing before the Lord” suggests a distinction: rather than the Lord being three men, the text indicates the Lord appeared accompanied by two angels. Hans Urs von Balthasar suggests that it is a “clarifying redaction” (Balthasar, 1992, ch. IV.B). The scribe likely reinterpreted the revelation to accommodate it to our naive view that the cardinal number 1 stands for unity. As a matter of fact, all cardinal numbers stand for unity. It is time that theologians and philosophers get a clear grip on what unity means. Philosopher Paul Thom understands Augustine like this:
The only substance is God (who is identical with divinity and with the divine perfections). The Persons exist, but only as relative and not as substantial beings: their being reduces substantially to that of God. (Thom, 2012, p. 39)
Thom’s interpretation exemplifies the confusion surrounding the ‘problem of the fourth.’ His
attribution to Augustine of a fourth element — ‘God’ equated with
‘substance’ — lacks textual support in Augustine’s writings. Augustine’s
cerebrations about essence and substance can be misleading, if we forget that he sees substance as synonymous with
being. The three persons are the same divine being by the fact that their personhood as well as their
triunity are predicated relatively. Thom misrepresents Augustine because he knows of no other way to achieve unity
than to postulate a prior substance. But since unity is achieved through relation regress, it turns out that
Augustine was right, after all.
Thom claims that Augustine’s model “does not show what it is about the Persons that makes them distinct
from one another” (ibid. p. 40); and since their being reduces substantially to that of God, the model
must fail. But, as I’ve already shown, the persons aren’t reducible to a common ontological substance.
Rather, divine personhood is the fundamental unit. It is the relation of love that creates an ontology of divine
being. Or in Karl Barth’s words: “And this loving is God’s being in time and eternity.
‘God is’ means ‘God loves.’ ” (Barth, CD II/1, p. 283).
It could be that infinitistic regress is a hard pill to swallow for logicians; but it might find appeal among
theologians, who already speak in similar terms. Barth sees the being of God as “event” or
“act” (ibid. p. 263). He says:
Inasmuch as God’s being consists in God’s act, it reveals itself as being which is self-moved. (ibid. p. 268)
Barth envisions divine life as “eternal self-repetition and self-affirmation” (ibid. p. 492).
God must “constantly become real” and this becoming “rules out every need of this being for
completion” (CD I/1, p. 427). In terms of relation regress the procession of the Holy Spirit is really
what constitutes and reconstitutes the being of God. It seems to fit with Barth’s notion that God’s
being is constituted in procession or self-movement.
On the other hand, Barth also wrestles with ‘the problem of the fourth’ in that he introduces something
called “the natura divina, the one undifferentiated divine essence” (ibid. p. 361). This,
he argues, does not entail “an extinction of the independence of the three modes of being in a neutral,
undifferentiated fourth” (ibid. p. 396). Ugh! The fourth is like a spectre that keeps reappearing. I
have presented a theory that once and for all exorcizes the spectre.
© Mats Winther, 2021. (2025: minor emendations.)
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