At this point, I've written a number of pieces on the issue of the filioque, primarily with the intent of criticizing the arguments that perpetuate the East-West division and offering an irenic proposal that integrates theological, philosophical, and historical perspectives from both sides of the divide. Along the way, I've been openly critical of the false sort of irenicism that simply runs a rhetorical bulldozer over real obstacles without giving them serious considerations, which is the reason I considered Fr. Giulio Maspero's own proposal a dismal failure.
I am happy to recommend a work that is definitely not in the latter category. Scott Williams has contributed his work on the Trinity to the Cambridge Elements series on the Problems of God. The primary goal of the work is to defend the traditional account of the Trinity as articulated in the Nicene-Constantinopolitan Creed ("Conciliar Trinitarianism") against various philosophical challenges raised against it. Williams provides a survey of the strongest and most common philosophical objections to the doctrine of the Trinity along with plausible and effective responses to each of them based on Conciliar Trinitarianism. I had never read such a concise presentation on the current state of philosophy of religion, as most works in this area involve back-and-forth exchanges on one specific line of argument over the course of multiple journal articles. For those of us who are not professional academics, the value of a resource that collects and distills the literature in this way cannot be overstated.
Williams offers the following as the conciliar account of a divine hypostasis (DH) (p. 10):
[DH] x is a divine hypostasis if and only if x is the subject of (i) the singular indivisible divine being ("ousia"), nature ("phusis"), power ("dunamis"), and action ("energeia"), which are common to all divine hypostases, and (ii) an unshareable real relation to another divine hypostasis
With respect to the difference between the Latin and Greek views, I would classify the general objections raised by Williams as follows:
(1) The "relational" view of inner-Trinitarian relations (which I would assign primarily to Aquinas, Augustine, Boethius, and the Alexandrians) cannot coherently articulate the reality of the real relations in a way that meets requirement (DH)(ii) of the definition.
(2) Even Latins with an "emanational" view of inner-Trinitarian relations (e.g., Bonaventure, Scotus, Henry of Ghent) contradict the underlying Nicene-Constantinopolitan Creed by adopting the filioque.
With respect to (1), Williams does point out that "Conciliar Trinitarianism itself does not commit to any one explanation of these real relations" (p. 46), but he nonetheless concludes for ontological reasons that the relational view fails as an account of requirement (DH)(ii). With respect to (2), Williams describes the situation as follows:
If the Latins are right that [the filioque] is implicit in the Nicene-Constantinopolitan creed, then it is consistent with Conciliar Trinitarianism.... But, if the Greeks are right that the negation of the filioque is implicit in the Nicene-Constantinopolitan creed, then it would be inconsistent with Conciliar Trinitarianism.
Williams offers the following as a core philosophical argument for the filioque (CF) (p. 39):
[CF] P1: If (i) the Father's power to spirate the Holy Spirit is in the divine nature, (ii) the Father shares this divine nature with the Son, and (iii) the Son exists explanatorily prior to the Holy Spirit, then (iv) the Son has numerically the same power as the Father for spirating the Holy Spirit.
P2: If (iv) the Son has numerically the same power as the Father for spirating the Holy Spirit, then (v) the Father and the Son produce the Holy Spirit such that the Holy Spirit proceeds from the Father and the Son.
P3: (i)-(iii) obtain.
Therefore,
C1: (iv) obtains [MP from P1 and P3]
Therefore.
C2: (v) obtains [MP from P2 and C1]
I agree with Williams that, as between the Latin emanational account and the Greek monopatrist account, the argument really turns on (CF)(P1)(iii) -- whether the Son exists explanatorily prior to the Holy Spirit. Therefore, that seems to be the most productive line of discussion. Williams describes this as a "mediating position." But given that the sides are on opposite sides of a dichotomy, that would be in the sense of forming a conceptual bridge from one side to the other, rather than a compromise.
As a final observation, it doesn't appear to me that any of the arguments that Williams presents for Conciliar Trinitarianism as against other philosophical objections actually turn on which side is correct on the filioque. For example, in his use of the monarchy of the Father to defend Conciliar Trinitarianism as monotheistic, Williams defines monarchy as the conjunction of three premises (p. 30): (1) the Father is uncaused, (2) the Father alone (eternally) causes the Son and the Holy Spirit, and (3) the Son and the Holy Spirit share numerically the same divine nature as the Father's divine nature because the Father communicates it to them. But it isn't clear that the word "alone" is doing any conceptual work in the argument for the coherence of Christian monotheism. If there were an explanatory order between the Son and the Holy Spirit, for example, that account would still be consistent with (DH) and therefore with monotheism.
My response to the objections Williams raises to the Latin views will be as follows:
(R1) The Nicene-Constantinopolitan Creed cannot rule out the possibility of either the relational or the emanational account on ontological grounds due to the theological mystery around the divine nature
(R2) The Nicene-Constantinopolitan Creed either leaves open the possibility of both filioquism or monopatrism or rules out monopatrism, but definitely does not rule out filioquism.
I. R1. It's a mystery!
In articulating the relational and emanational models for inner-Trinitarian relations in my previous posts, I have more or less let the fact that the theological pluralism exists throughout history speak for itself. That is, the fact that Saints who are clearly accepted as orthodox by both East and West have held these views provides strong evidence that the different metaphysical explanations do not violate any underlying dogmatic requires, as contrasted with heretical explanations that do. But I also think that a stronger claim can be made: because the precise nature of inner-Trinitarian relations is a theological mystery, we cannot know certainly that either is an accurate description. Specifically, what counts as a "real relation" (as in requirement (DH)(ii)) is inscrutable in a way that prevents either account of relations being ruled out.
With respect to the two categories of divine nature (ousia) and divine person (hypostasis), theological mystery can apply to either. We cannot comprehend what it is like to be divine in aspects such as simplicity, eternity, omniscience, or omnipotence, nor can we comprehend how that nature is concretized in (necessary) existence. The Trinity and the Incarnation, both of which are dogmatically affirmed as theological mysteries, pertain to matters of divine personhood. How can multiple persons share possess the numerically same divine nature? How can a divine person with numerically the same divine nature as two other persons also assume an additional human nature? When we deal with theological mysteries, we offer a mental model -- a proposed explanation for how something could be -- based on what we experience as creatures and then attempt to identify whether there is an express logical contradiction, either internally or with respect to revelation. But outside of certain fixed dogmatic principles, which are mostly what can be known certainly based on the relationship of God to creation, the explanations are hypothetical and not certain.
(DH)(i) is a perfectly workable summary of those fixed dogmatic principles for the Nicene/neo-Nicene/pro-Nicene orthodoxy, in that every divine person is the subject of the singular indivisible divine being ("ousia"), nature ("phusis"), power ("dunamis"), and action ("energeia"), which are common to all divine hypostases. This is essentially saying that orthodox Christianity affirms monotheism, as opposed to, e.g., tritheism, persons-as-parts, or Sabellianism. So far, so good; this does not appear to be part of the East-West divide.
With respect to the inner-Trinitarian relations, the issue becomes more complicated. The revealed names "Father" and "Son" provide a sure dogmatic basis for concluding that there is a reason to apply the category of relation within the Trinity. The terms "begetting" and "proceeding" suggest some kind of productive activity, which is the basis for thinking that causality might be an applicable category. But none of these categories can apply in the same way to persons having a divine nature with a necessary and eternal existence as they would to anything within our experience. Even the term "person" here is inscrutable in terms of our experience, which is why the tripersonal Trinity and the Incarnation are theological mysteries in the formal sense. Likewise, with respect to divine simplicity, even created things that are metaphysically simple (e.g., angels, human souls) don't have such a degree of simplicity that potency within them is not converted to act. In a very real way, we don't even understand what it means for God to "act," although we refer to "powers" and "activities" based on the effects on created things that they produce.
We also know that, if we apply these terms too literally, the theological model can rapidly collapse in incoherence. Williams points out that modern concepts associated with "person," including "center of consciousness," "rational acts," or "self," can be dangerously inapt when applied to divine persons, which term has a relatively minimalist sense in context. The Nicene-Constantinopolitan Creed points to some of these restrictions when it says that the Son was "born of the Father before all ages," highlighting the divine eternity in the inner-Trinitarian relations. There is some degree of license to speculate theologically, and that speculation is subject to certain limits. While both the relational and emanational models have taken very different approaches on how to address those limits, both can fall within the realm of plausible speculation. We can look at a couple of specific situations that are asserted as being problematic in order to see whether the criticism holds.
A. Divine simplicity and identity
The relational model is fundamentally built on an apophatic denial based on divine simplicity: God includes no accidental being. From that premise, St. Augustine reasons through the Aristotelian categories to set limits on how we can think about God, ruling out every category but essence and relation (or, if we are thinking closer to what Augustine had in mind, relative properties). Augustine reasons that it is possible to have relative properties that are really true of a being without inhering in that being, viz., that something can have properties ad aliud without an inhering accidental esse ad aliud. A relation in Augustine's account can be described as a purely relative property, a property of a subsistence that is comprehensible only in relation to another subsistence.
Such a purely relative property is definitely a logical possibility for the Trinity. Thomas Ryba's chapter "Augustine's Trinitology and the Theory of Groups" in Augustine: Presbyter Factus Sum outlines a model using modern group theory that is consistent with Augustine's concept of relations. It also meets the definition for ENSWI (essential numerical sameness without identity) with the divine essence that Williams outlines (p. 23), because each divine person has an idiomatic, purely relative property. But is this purely a mathematical concept that is somehow unrealizable, or can it meet the definition of a real (ontological) relation?
Williams seems to think it cannot. Williams presents the argument by Henry of Ghent that a real relation cannot be founded on the end term of the relation itself (p. 46), so that the relation cannot be both the reason for the Son's existence and founded in the Son's existence:
Whereas Aquinas and Giles maintain that a real relation takes its reality from its end term, Henry denies this. (This is why Aquinas asserts that the Father is the Father only because of the Son; the Son is the end term for the Father's real relation.) For Henry, a real relation is real because it is founded on a real (nonrelative) foundation.... The being generative relation is founded on a real divine power, namely the power for generating (which is in the divine nature). So, the first hypostasis's relation of being generative is real because it is founded on a real power in the divine nature.
Williams later argues (p. 62) that Aquinas necessarily contradicts Conciliar Trinitarianism based on his view of divine simplicity in a way that Henry does not:
For Aquinas, if we compare each divine hypostasis and the one divine essence, then there is no real (mind-independent) difference whatsoever between them. They are identically the same being (see ... Summa Theologiae Part 1, Question 28, Article 2), "in God relation and essence do not differ in being from each other but are one and the same"). But, if we compare, for example, the Father and the Son, then they are different from each other. The problem is that if the Father is numerically identical to the one divine essence, and the Son is numerically identical to the one divine essence, then (by transitivity of identity) it follows that the Father is numerically identical to the Son. But that consequence is false, and it contradicts Conciliar Trinitarianism.
...
For on Aquinas's account of simplicity, there is no incommunicable (unshared) act or entity by which one divine hypostasis is not numerically identical to any other divine hypostasis, or to the one divine essence. If the Father is numerically identical to the divine essence, and the divine essence is numerically identical to the Son, then the Father is numerically identical to the Son. The fundamental problem with Aquinas's account is in saying that each divine hypostasis is numerically identical to the one divine essence. For Aquinas, there *is no* real ontological item that really distinguishes the divine hypostases. Moreover, this seems to contradict Conciliar Trinitarianism....
...
One way to resolve Aquinas's fundamental problem is to deny that each divine hypostasis is numerically identical to the one divine essence, and to affirm that what distinguishes each divine hypostasis from the one divine essence is a real act or entity that is not the same real act or entity that is the real divine essence. But this affirmation would require Aquinas to give up his theory of real relations according to which a real relation is numerically identical to its absolute foundation....
Some of the suspicion here relates to Andrew Radde-Galwitz's critique of divine simplicitly in the West, but I am persuaded by Richard Cross's response that what Augustine and what Gregory of Nyssa mean by divine simplicitly is fundamentally the same, despite certain metaphysical disagreements. I do not see any real difference between Aquinas's position here and Augustine's assertion that "in [the divine persons] to be is the same as to be great, as to be good, as to be wise, and whatever else is said of each person individually therein, or of the Trinity itself, in respect of themselves."
Augustine's position on relation as a non-accidental property would likewise put being-in-relation as existing in the divine essence. But the formality of relation itself, which pertains to the existence of another distinct existent, is not in the divine essence, either in Augustine or in Aquinas. As Gilles Emery explains in the same section of The Trinitarian Theology of St. Thomas Aquinas quoted by Williams (p. 96, emphasis added), "this [formal] character *does not pertain to the divine essence* but to the correlative term ('relation does not bear upon essence, but on its opposed term')." This formal existence of the relative properties can and does distinguish the divine persons, even though the being-in-relation to which that relative property attaches is the divine essence, just as the divine persons themselves are identical with the divine essence but not with the divine persons to whom they relate.
Regardless of whether this idea of purely relative properties is considered plausible or not, it strains credibility to think that Augustine and Aquinas simply didn't realize that they were committing themselves to a fundamentally Sabellian account of the Trinity. (In fact, as noted below, Aquinas specifically responds to the accusation of Sabellianism.) If nothing else, both theologians clearly believed that they were giving a logical and metaphysical account of their shared faith. Their proposals have never been condemned as anti-Trinitarian by any ecclesial authority. But rather than simply excusing them, I would argue that the account of relative properties has only become more plausible given the numerous relative properties that have emerged for fundamental particles, such as charge or magnetic polarity.
We could consider as an example the most basic building block of all matter: the proton. In the proton are three quarks: two up quarks and one down quark. These quarks each have two relative properties: electric charge and color charge. The two up quarks each have electric charges of +(2/3), while the down quark has an electric charge of -(1/3). Each of the quarks will have one of the color charges red, green, and blue. Within all of the matter that we see, there are protons with three quarks distinguished solely by relative properties. If we take one of the up quarks as the "origin" or reference point, then the other up quark is distinguished from the origin by exactly one relative property (color charge), while the down quark is distinguished from both up quarks by two relative properties (color charge and electric charge). These relative properties are essential for the existence of the proton; indeed, they define the existence of the proton.
The existence of quarks was theorized not even a century ago, so it is understandable why the idea of purely relative properties as constitutive was not realistically possible in the pre-modern or even the modern era. It would have required following the axioms of a model consistently to the point of reaching a conclusion that did not have a corresponding real example, much as theoretical physicists have done with particle theory. But just as Augustine's view of relations as a Trinitarian category has subsequently been shown to be feasible in mathematical group theory, the idea of purely relative properties as constitutive have subsequently been shown to be feasible.
With regard to the relational account, we might still question how exactly the state of affairs came to be, which I will address below. But the claims about implicit Sabellianism in the account of relative properties seem overstated. That is why I must conclude that the relational model remains within the scope of permissible speculation on how we can give a coherent account of the divine nature.
B. Different uses of the psychological model
[N.B., although it isn't intended as a direct response, this section can be usefully read in comparison with Williams's 2010 article "Augustine, Thomas Aquinas, Henry of Ghent, and John Duns Scotus: On the Theology of the Father's Intellectual Generation of the Word, Recherches de Theologie et Philosophie medievales 77.1:38-81.]
In terms of the explanations provided for the relations, the relational and emanational models are each associated with "weak" and "strong" versions of the psychological model of the Trinity. This is not historical accident; the reason that the emanational model relies so heavily on the psychological model is that it has more to explain. The relations themselves need to be founded on something else. The relations are not themselves asserted as "real," but they draw their reality from another foundation. By contrast, given its definition of how "relations" are constituted, the relational model considers explanations of relations as a cognitive concession to our fallibility as opposed to an ontologically necessary foundation.
Aquinas explains this as follows (ST I, Q. 41 "The persons in reference to the notional acts," RO 2):
The notional acts differ from the relations of the persons only in their mode of signification; and in reality are the same. The Master says that "generation and nativity in other words are paternity and filiation" (Sent. i, D, xxvi). To see this, we must consider that the origin of one thing from another is firstly inferred from movement: for that anything be changed from its disposition by movement evidently arises from some cause. Hence action, in its primary sense, means origin of movement; for as movement derived from another into a mobile object, is called "passion," so the origin of movement itself as beginning from another and terminating in what is moved, is called "action." Hence, if we take away movement, action implies nothing more than order of origin, in so far as action proceeds from some cause or principle to what is from that principle. Consequently, since in God no movement exists, the personal action of the one producing a person is only the habitude of the principle to the person who is from the principle; which habitudes are the relations, or the notions. Nevertheless we cannot speak of divine and intelligible things except after the manner of sensible things, whence we derive our knowledge and wherein actions and passions, so far as these imply movement, differ from the relations which result from action and passion, and therefore it was necessary to signify the habitudes of the persons separately after the manner of act, and separately after the manner of relations. Thus it is evident that they are really the same, differing only in their mode of signification.
This leads to what can only be called a drastically different understanding of intellectual procession between the relational and emanational models. The link between the begetting of the Son and the intellectual power results from the title Word of God, which has always had significant philosophical associations. The motivation for the psychological model is this connection to the intellect along with the older philosophical idea, primarily from Stoic philosophy rather than Aristotle, of the word as an internal production of the mind, which seems to have influenced especially Tertullian and Augustine. The theological conclusion of the models is the same, i.e., that the result of the intellectual production (begetting) is a Word that is a perfect Image of the Father. But the explanation of exactly how this analogy to intellectual production is used varies wildly:
Latin relational (LR) model: The revealed reality is the existence of the relations (notions), and the notional acts of intellect and will are merely conceptual tools to better grasp the fundamentally inscrutable way in which these relations exist (weak psychological analogy)
Latin emanational (LE) model: The revealed reality is the existence of the relations, but these relations can be further explained by reference to formally distinct intellectual and volitional powers (strong psychological analogy)
Greek emanational (GE) model: The revealed reality is the existence of eternal productive acts (begetting and proceeding), which produce relations that can in turn be described analogically, including by analogy to the soul (non-productive psychological analogy)
At least as I see it, each model is offering an answer to the question "how does the Father produce an internal Word that is a perfect Image of the Father?" The LR model asserts that the internal act of existence in the divine essence is inscrutable and can only be (1) known (virtually) with regard powers corresponding to created effects and (2) described by reference to created qualities that do not involve any attribution of imperfection to God. In particular, Aquinas rejects that the act by which God knows Himself, an essential act, can be an adequate notional act to describe the intellectual procession, rejecting what he sees as an erroneous position taken by St. Anselm. Emery (p. 186) explains this as follows:
One cannot disclose the personal character of the Word simply by looking at knowledge or by reflecting on the 'Supreme Mind' [ST I, q. 34, a. 1, RO 2 and RO 3; cf. De potentia, q. 9, a. 9, ad 8]. Doing that ultimately rebounds into a Sabellian conception of the Word, because it cannot show a real relation within God between the Word and the One from whom he proceeds. In other words, Thomas rules out understanding the Word as if it were a derivate of the divine essence. One of the fundamental features of his Trinitarian epistemology is brought out again here. Faith in the Trinity cannot be adequately set forth by beginning from God's essential attributes (which are the matter for appropriations). Their personal distinctions do not arise within the order of essence, but in the order of relative properties. To avoid confusing these two orders, one must distinguish carefully between the following notions:
* To know (intelligere): this is an essential act, commong to the whole Trinity; each person knows himself and knows the others. God knows himself through himself and, in this way, knows other things.
* To be known (intelligi): God is known through himself; each person is known by the others.
* To speak (dicere): this is the action proper to the Father who 'speaks' or 'pronounces' his Word; this 'notional action,' which is identical to generation, is done by the Father alone; neither the Son nor the Holy Spirit 'speak the Word' any more than they 'engender the Son.'
* To be spoken (dici): each person in the whole Trinity and even creatures are 'spoken' by the Father in his Word: 'In knowing himself, in knowing the Son and the Holy Spirit, and in knowing everything which is contained in his science, the Father conceives the Word: and thus the Trinity is spoken in the Word, and creatures in addition' [ST I, q. 34, a. 1, RO 3].
The psychological model is thus being applied in a very narrow sense; it is not the ordinary operation of the intellectual power (pace Scotus) but the specific mental act of producing a concept for communication, speaking an internal word, which is a specific personal exercise of the intellectual power. It is not the act of the Father knowing Himself, which is common to all divine persons, but speaking Himself with the perfect concept, the perfect Image of Himself, that Aquinas considers the proper notional act. (To use a contemporary concept, the Word could be though of as the production of the Father's inner monologue.) And because the Word is, in fact, the perfection of this power -- the perfect concept -- there is no further opportunity (or, perhaps more pointedly, no further reason) to exercise this notional act.
To show consistency, a similar argument can be made for the Holy Spirit in that spiration is the specific personal expression (imprint) of love by the Father and the Son in view of one another, not the very love by which God loves, which would be an essential act and not a notional act. The Spirit is thus the perfection of this act of expression, which is why there is no further opportunity (or reason) to exercise this notional act. In contrast, the view that the Spirit is the very love of the Trinity, espoused by Richard of St. Victor, is called inept by Aquinas. Yet, as Fr. Christiaan Kappes has pointed out, it was still used in Western catechesis in the East, which contibuted to the confusion at Florence.
In contrast with Aquinas, the LE advocates, like Bonaventure and Scotus, will say that the relations cannot be taken as a given but must have an underlying metaphysical foundation. This they find in the formal distinction of the powers, and in particular, infinite intellectual and volitional powers. Because the Father by nature has both an intelligible object (in the divine nature) and an intellectual power capable of producing concepts from the object, the Father by the perfect exercise of this power (not the act of self-knowing itself but self-conceiving, as it were) produces the Word. Note that it is not the exercise of the intellectual power itself but the personal possession of the intellectual power by the Father who is likewise capable of knowing His own essence that underlies the productive act. Thus, both Scotus and Aquinas distinguish the essential act of self-knowing from the personal act of conceiving the Word, and both assert that the personal (notional) act of conceiving the Word would produce a perfect Image of the Father. Based on their respective metaphysical positions, they differ significantly on the question of "in what does this personal act of conceiving consist?" Given that the subject matter directly pertains to the mystery of the divine essence and how causality is even possible for an eternal being, it is again difficult for me to say how both attempts, each of which achieves the required dogmatic conclusion, can be condemned as erroneous. (I reserve judgment on whether Scotus's criticism of Henry of Ghent, viz., that he seems to be taking the act of intellectual production in God too literally to be acceptable, is valid; I defer that discussion to Williams's 2010 article.)
That leaves open the possibility that we cannot even effectively speculate in this area because of that mystery: the GE view. We could simply say that begetting literally conveys only that the Son is a being of the same nature caused by the Father and that the even-more-mysterious "procession" is intended to convey the production of another being with the same nature in a manner other than begetting. One can use the human mind as a certain kind of analogy to the threefold existence of Trinity in dependence on the Father, just as one might use numerous other created examples (a body of water with a source, a tree, the emission of rays from the Sun, the fragrance of a flower, etc., etc.). But they are just creaturely analogies without the univocal quality necessary to demonstrate, even notionally, what begetting or proceeding actually means in the divine context. This likewise does not seem like an account that violates any dogmatic requirements. It does not explain the monarchy of the Father, but it certainly affirms it, even while refusing to give a metaphysical account. If it is somewhat less satisfying than the more ambitious accounts offered by the Schoolmen, there is nonetheless no requirement to explain (or to even try to explain) divine mysteries. I would only say that what speculation has been offered also does not seem to violate any dogmatic boundaries.
But there is still the question of whether dogmatic boundaries have been violated. For the answer, we must assess whether we have sufficient reason in revelation to rule out the filioque as permissible speculation. Thus, we turn to the next response.
II. R2. The Nicene-Constantinopolitan Creed definitely does not exclude the filioque
Recall that Williams takes what I call the GE view above and that the debated premise as between that model and either LR or LE is (CF)(P1)(iii) -- whether the Son exists explanatorily prior to the Holy Spirit. The purpose of the Nicene-Constantinopolitan Creed was simply to affirm the full consubstantial divinity of the Holy Spirit. As the North American Orthodox-Catholic Theological Commission put it in 2003, "it was not a concern of the Council to specify the manner of the Spirit's origin, or to elaborate on the Spirit's particular relationships of the Father and the Son." It is historically implausible to believe that the creed was intended to rule out the filioque in any sense, much less to prohibit any sense of explanatory priority between the Son and the Spirit, which would have contradicted the contemporaneous writings of all of the relevant theologians at the time.
A. Why is John 15:26 paraphrased in the creed?
Williams asserts that "the Scriptural basis for the non-filioque account is John 15:26. All other Scriptural passages are interpreted as consistent with the Father, Son, and Holy Spirit's numerical unity of action." But the use of John 15:26 is actually an example of the opposite exegetical rule: that appropriations relating to sending of the Spirit in the economy are always understood to correspond to inner-Trinitarian relations in eternity. John 15:26 is set in the clearly economic situation of the Helper (Paraclete) being sent by the Father after the Ascension, but it is taken to stand for an eternal relation of origin, which was common to several Scriptural passages.
John 15:26 is likely used as a kind of core passage because it uses two personal titles, Paraclete and Spirit of Truth, so that the passage can't be interpreted as if the Spirit were some sort of impersonal force. However, John 15:26 doesn't explicitly show divine origin. Instead, it reads para tou Patros ekporeuetai, which means something more like "goes forth from beside the Father," as if the Spirit were descending from the Father in Heaven. The creedal phrase ek tou Patros ekporeuomenon ("goes forth out of the Father") seems to be an allusion to John 15:26, which establishes the Spirit as a divine Person, but the language appears intended to articulate a theological concept of origination that goes beyond what that passage states.
David Coffey ("The Roman 'Clarification' of the Doctrine of the Filioque, Int'l Journal of Systematic Theology, v. 5, no. 1, March 2003) argues that the change from the Scriptural language reflects a change to a "technical" usage of the ekporeuomai:
[The use of ek] shows that by the time of Constantinople ekporeueomai (with its cognate ekporeusis) had acquired a technical meaning. It was no longer a general word able to be used for any and every kind of coming-out, but was restricted to a single meaning in a single context: it now designated only the coming-forth of the Holy Spirit 'out of' the depths of the Father, and in this sense it served to distinguish the Spirit's coming forth from that of the Son.
What seems unique about John 15:26 is not the concept of divine production. On the contrary, the language in the creed seems to have been specifically modified to add the concept of divine production that is missing from that passage. The source of that addition is ambiguous. It could have been a parallel construction to the description of the Son's begetting. In terms of potential Scriptural sources, the closest Scriptural reference to the creed is Rev. 22:1, which reads ekporeuomenon ek tou Thronou tou Theou kai tou Arniou ("proceeds from the Throne of God and of the Lamb"). There is also 1 Cor. 2:12 stating simply that the Spirit is ek tou Theou ("out of the Father"). It could also have come from the first formula in St. Epiphanius's Ancoratus, which uses exactly the same phrase, although the prevailing opintion is that this formula was a later addition to the text. In any case, it is clear that the eternal causal sense was something added to John 15:26 by the drafters of the creed. For that reason, it wouldn't make sense to use the silence of John 15:26 to limit the sense of procession from the Father, as the monopatrist account seeks to do.
With regard to that additional causal sense, this is interpreted by monopatrists to assert that only the Father can take this causal action. But that is an unwarranted inference even from the Father's being named the only cause (aitia). In describing the causality of creation, St. Basil the Great (On the Holy Spirit 21) says "The expression 'through whom' [all things were made] contains a confession of an antecedent cause [prokatarktikes aitias], and is not adopted in objection to the efficient cause [ouk epi kategoria tou poietikou aitiou paralambanetai]." We need to take into account that Basil's Origenist background that categorizes divine causality into creation into three types: the Father is the original (willing) cause, the Word is the creative (efficient) cause, and the Spirit is the perfecting cause (On the Holy Spirit 16.38). But the point is still sound; the fact that there are multiple Persons acting as cause does not diminish the Father's causal property. The fact that another divine Person executes the act of spiration, for example, would not diminish the Father's being the cause (aitia) of that act.
In any case, the addition of a causal sense to John 15:26 in the creed seems entirely incompatible with then making John 15:26 the only passage defining the procession of the Spirit in eternity. Perhaps the best evidence that this is the wrong interpretation is that it wasn't contemporaneously interpreted to rule out the filioque, much less to exclude any possibility of explanatory order between the Son and the Spirit.
B. The Nicene-Constaninopolitan Creed in East and West
Constantinople I is interesting in that it was an ecumenical council in the older sense of the term (a council gathered from the entire world), but unlike its predecessor Nicaea, it did not involve the active participation of papal legates or other Western bishops. Instead, the Council reported back on its conclusions in the "Letter to Western Bishops." Among those Western bishops was listed St. Ascholius of Thessalonica, who had been appointed to his see by Pope St. Damasus and who was a close ally and correspondent of both St. Ambrose of Milan and St. Basil the Great.
At Constantinople I, Ascholius was uniquely positioned to understand both East and West, including the dispute between Damasus and Basil on the term hypostasis. This resulted from the East and the West using different language to articulate the pro-Nicene theology (the exercise of one divine power showing the divinity of the three divine persons). The Latin view is best described as a subject-power theology, in that the focus is not on the philosophical categories of nature and person but rather on three entities exercising power (personae) and a singular divine power (potestas, virtus, maiestatis), glory, and splendor. Basil instead wanted to normalize Origen's terminology of ousia and hypostasis, an essence-person theology. This terminology was more typical in the East, but it could be confusing for the Latins, who used the literal translation substantia to indicate essence or nature and used subsistentia as the term for an individual substance. Ascholius's role as mediator of the Western position at the Council likely explains why he was specifically addressed in the Council's letter.
The Letter to the Western Bishops confirms that the intent was to harmonize with the Latin view (I've inserted the Greek cognate theological terms in their more familiar forms into the translation) :
This is the faith which ought to be sufficient for you, for us, and for all who do not distort the word of the true fatih; for it is the most ancient faith, and it is the faith of our baptism; it is the faith that teaches us to believe in the name of the Father, and of the Son, and of the Holy Spirit.
According to this faith there is one Godhead, power, and ousia of the Father and of the Son and of the Holy Spirit; their dignity being equal, and their majesty being equal in three perfect hypostases and three perfect prosopa. Thus there is not room to prevail for the heresy of Sabellius by the confusion of the hypostases or destruction of the idiomata, nor for the blasphemy of the Eunomians, of the Arians, and of the Pneumatomachi, which divides the ousia, the physis, and the Godhead, and introduces in the uncreated, consubstantial, and co-eternal Trinity a later nature, one created or of a different physis.
...
Let this suffice for a summary of the doctrine which is fearlessly and openly preached by us, and concerning which you will be able to be still further satisfied if you decide to read the report of the synod of Antioch, which was issued last year by the ecumenical council held at Constantinople, in which we set forth our confession of the faith at greater length and included a written anathema against the heresies which innovators have recently introduced.
There is nothing in the letter to indicate that the phrase concerning the procession of the Holy Spirit is critical for the faith, apart from the uncontroversial assertion that the Spirit was produced by the Father. The argument that the creed was intentionally binding belief on the origin of the Holy Spirit by silence in a specific phrase that was not even indicated as being essential is untenable. More importantly, this was a letter written from a council that was held at the urging of both Pope Damasus and the bishop who had personally baptized the Emperor and who was present at the Council. It is inconceivable that the Council intended (or that Ascholius would have endorsed) some kind of Cappadocian corrective to Latin theology. Again, Ascholius was fully aware that there was a divergence of opinion between Damasus and Basil on exactly how the faith should be articulated, and Constantinople I was intended to respond to those who denied the divinity of the Holy Spirit, not to arbitrate between those disputes.
As one might expect then, all of the Latin theologians continued their belief that the Holy Spirit proceeded from the Father and the Son, which had already been espoused to a significant degree by Tertullian and St. Hilary of Poitiers. Damasus commissioned St. Jerome to make a Latin translation of Didymus's On the Holy Spirit, which expressly stated that the Spirit proceeded from the Father and the Son. St. Ambrose wrote his own treatise on the Holy Spirit, which followed Didymus so closely that Jerome sarcastically charged him with plagiarism. In that work, Ambrose said that the Spirit proceeded from the Father and the Son, explicitly citing Rev. 22:1 as the Scriptural basis for the belief in Book III.
Further, the Letter to the Western Bishops was specifically addressed to Pope Damasus in advance of his own Council of Rome (382), which was essentially the Western ratification of Constantinople I. One of the decrees was as follows:
For the Holy Spirit is not only the Spirit of the Father or not only the Spirit of the Son, but the Spirit of the Father and of the Son. For it is written: "If anyone love the world, the Spirit of the Father is not in him" [1 John 2:15; Rom. 8:9]. Likewise it is written: "Now if any man have not the Spirit of Christ, he is none of his" [Rom. 8:9]. When the Father and the Son are mentioned in this way, the Holy Spirit is understood, of whom the Son himself says in the Gospel, that the Holy Spirit proceedeth from the Father [John 15:26], and "he shall receive of mine and shall announce it to you" [ John 16:14.]
The combination of John 15:26 and 16:14 in eternity breaks the exegetical rule that Williams asserted concerning John 15:26. It is also an unquestionably filioquist position. It is notable that Epiphanius, who might have even been the source of the language in the creed, used John 15:26 and John 16:14 in tandem in the Ancoratus and also affirmed that the Spirit was "breathed by the Father and the Son." If the Nicene-Constantinopolitan Creed were intended to rule out this exegetical combination, it certainly would have come as news to Pope Damasus and Epiphanius. They certainly wouldn't have agreed with St. Gregory Palamas that "it is implied [by the creed] that the Holy Spirit proceeds only from the Father" (Williams, p. 43).
Lastly, the Letter to the Western Bishops commends St. Cyril of Jerusalem, who appears to have had a significant hand in authoring the Nicene-Constantinopolitan Creed. In commenting on his own use of "the Holy Spirit, the Paraclete, who spake through the prophets" in the baptismal creed, Cyril explains in his Catechetical Lectures, citing John 16:14-15:
And the Father indeed gives to the Son; and the Son shares with the Holy Spirit. For it is Jesus Himself, not I, who says: "All things are delivered unto Me of my Father;" and of the Holy Spirit He says, "When he, the Spirit of Truth, shall come," and the rest -- "He shall glorify Me; for He shall receive of Mine, and shall show it unto you." The Father through the Son, with the Holy Spirit is the giver of all grace; the gifts of the Father are none other than those of the Son, and those of the Holy Spirit; for there is one Salvation, one Power, one Faith; One God, the Father; One Lord, His only-begotten Son; One Holy Spirit, the Paraclete.
For in the Divine Trinity nothing is unlike or unequal, and all that can be thought concerning its substance admits of no diversity either in power or glory or eternity. And while in the property of each Person the Father is one, the Son is another, and the Holy Spirit is another, yet the Godhead is not distinct and different; for whilst the Son is the Only begotten of the Father, the Holy Spirit is the Spirit of the Father and the Son, not in the way that every creature is the creature of the Father and the Son, but as living and having power with Both, and eternally subsisting of That Which is the Father and the Son.
Given that Leo affirmed the doctrine of Constantinople I in his support of Chalcedon, it is clear that the Latin side never understood (and likely would not have accepted) the Nicene-Constantinopolitan Creed as a rebuke of the filioque.
I would say that there is more than sufficient evidence to conclude that Constantinople I was never intended to dogmatically preclude the filioque. But Williams made the stronger claim that it was intended to rule out explanatory priority between the Son and the Spirit. Even the Cappadocian contributors to the Council would not have gone that far.
St. Gregory of Nyssa, the inheritor and developer of the work of his late brother Basil, is one candidate for the source of this monopatrist doctrine. There is certainly a live debate about whether Gregory explicitly taught the filioque, and I find it difficult to see how he would have disagreed with St. Bonaventure in any relevant respect. But if we grant that he did not explicitly teach the filioque, then it seems impossible not to at least accept the proposition that he gave the Son explanatory priority in his Trinitarian account. Notably, he called the Holy Spirit the syndetikon (bond) between the Father and the Son, and a bond logically presupposes the things that are bound. He likewise emphasized the irreversible taxis (order) in a way that strongly suggests that this is a feature of the eternal Trinitarian relations.
In terms of theologians of major influence at the Council, that leaves only St. Gregory the Theologian. In his Oration 41 on the Holy Spirit, he certainly seems to accept the concept that the Spirit comes after the Son, and he appears to use John 16:14-15 to say that the Spirit has what the Father has from the Son (my emphasis added).
The Holy Spirit, then, always existed, and exists, and always will exist. He neither had a beginning, nor will He have an end; but he was everlastingly ranged with and numbered with the Father and the Son. For it was not ever fitting that either the Son should be wanting to the Father, or the Spirit to the Son. For then Deity would be short of Its glory in its greatest respect, for It would seem to have arrived at the consummation of perfection as if by an afterthought.... All that the Father has the Son has also, except the being Unbegotten, and all that the Son has the Spirit has also, except the Generation. And these two matters do not divide the Substance, as I understand it, bur rather are divisions within the Substance.
Given that Gregory was the first to introduce explicitly the concept of personal properties as relations, it is worth turning back to his Fifth Theological Oration (Oration 31) for comparison (my emphasis added):
VIII. But since we do not admit your first division, which declares that there is no mean between Begotten and Unbegotten, at once, along with your magnificent division, away go your Brothers and your Grandsons, as when the first link of an intricate chain is broken they are broken with it, and disappear from your system of divinity. For, tell me, what position will you assign to that which Proceeds, which has started up between the two terms of your division, and is introduced by a better Theologian than you, our Saviour Himself? Or perhaps you have taken that word out of your Gospels for the sake of your Third Testament, The Holy Ghost, which proceeds from the Father; Who, inasmuch as He proceeds from That Source, is no Creature; and inasmuch as He is not Begotten is no Son; and inasmuch as He is between the Unbegotten and the Begotten is God. And thus escaping the toils of your syllogisms, He has manifested himself as God, stronger than your divisions. What then is Procession? Do you tell me what is the Unbegottenness of the Father, and I will explain to you the physiology of the Generation of the Son and the Procession of the Spirit, and we shall both of us be frenzy-stricken for prying into the mystery of God. And who are we to do these things, we who cannot even see what lies at our feet, or number the sand of the sea, or the drops of rain, or the days of Eternity, much less enter into the Depths of God, and supply an account of that Nature which is so unspeakable and transcending all words?
IX. What then, say they, is there lacking to the Spirit which prevents His being a Son, for if there were not something lacking He would be a Son? We assert that there is nothing lacking—for God has no deficiency. But the difference of manifestation, if I may so express myself, or rather of their mutual relations one to another, has caused the difference of their Names. For indeed it is not some deficiency in the Son which prevents His being Father (for Sonship is not a deficiency), and yet He is not Father. According to this line of argument there must be some deficiency in the Father, in respect of His not being Son. For the Father is not Son, and yet this is not due to either deficiency or subjection of Essence; but the very fact of being Unbegotten or Begotten, or Proceeding has given the name of Father to the First, of the Son to the Second, and of the Third, Him of Whom we are speaking, of the Holy Ghost that the distinction of the Three Persons may be preserved in the one nature and dignity of the Godhead. For neither is the Son Father, for the Father is One, but He is what the Father is; nor is the Spirit Son because He is of God, for the Only-begotten is One, but He is what the Son is. The Three are One in Godhead, and the One Three in properties; so that neither is the Unity a Sabellian one, nor does the Trinity countenance the present evil distinction.
Let's situate the argument. The Eunomians maintain that, just as there can be no mean between Creator and created (the divine nature and created natures), there can be no mean between Unbegotten and Begotten, which in their view name natures. Gregory's response is that there is a mean (meson), not between unbegottenness and begottenness as properties but between the Persons Who are Unbegotten and Begotten. That meson is the relation of the Holy Spirit to the Father and the Son. And like Gregory Nyssen's syndetikon, it is a relation that makes no logical sense without the priority of the Son; a mean is incoherent without the extremes.
It is that relational structure that situates Gregory Nazianzen's account of deficiency, and in Oration 41, he introduces the concept of relational deficiency to the account of natural deficiency from Oration 31. This parallels his account of the necessity of the Trinitarian relations; Gregory does not believe that they are necessary in the sense of any kind of external necessity. But to the extent that relations are revealed, it would not be fitting for those relations to end in a Dyad, which would produce an eternal asymmetry. The Spirit's relation as meson closes the pleroma of the Trinity. Again, for Gregory's argument to work, the Son's existence must be presupposed. That is the reason that Gregory specifically says that the Son would be lacking the Spirit, even as the Father would be lacking the Son.
This is likewise why even Gregory's account of natural deficiency follows the Trinitarian order. The Son does not lack what the Father has on account of His relational distinction from the Father. Likewise, the Spirit does not lack what the Son has on account of His relational distinction from the Father and the Son. The Spirit "is what the Son is" and "has all that the Son has, except for Generation." (N.B., Basil makes a similar argument concerning nature from the Son against the Eunomians, but since this article is about Constantinople I specifically, I will direct to Fr. Thomas Crean's explanation in Vindicating the Filioque rather than reproducing it here.) Gregory's account of relational distinction does not function without this sequence: the Son is relationally distinguished from the Father, and the Spirit is relationally distinguished from the Father and the Son. Thus, even if the Son and the Spirit are distinguished by their modes of divine production (begetting and proceeding), Gregory's account requires a logically sequential order between begetting and proceeding.
This belief doesn't go away in later Byzantine theology. St. John Damascene, who was the last great systematizer of the patristic age, certainly kept the idea of explanatory priority. Crean (p. 239 et seq.) surveys On the Orthodox Faith (OF) as well as some lesser known Trinitarian works. In De Sancta Trinitate, John parallels Gregory's argument from Oration 41: "Neither was the Son ever lacking to the Father, nor was the Holy Spirit ever lacking to the Son" (cf. OF 1.7, arguing that the Word could not be spoken without the breath of the Holy Spirit). John likewise describes the Spirit as "between the unbegotten and the begotten" (OF 1.13). John calls the Spirit the image of the Son (OF 1.13), which presumes the logical priority of the Son. Lastly, John says that the Spirit proceeds "through the Son" (e.g., OF 1.12), which likewise presumes the logical priority of the Son if applied in the eternal context. For further context, Crean cites a fascinating passage from Dialogous contra Manichaeos:
I do not say that having previously not been Father, he later became Father, for he always was such, having his own Word from himself, and through his Word having his Spirit proceeding from himself [dia tou Logou ... ekporeumenon].
The significance here is that "through his Word" is unquestionably applied in the eternal context, although (as Crean admits) it's an open question whether this language does or can imply any kind of causal role. For example, "through his Word" could mean something like "throughout his Word," as in that the procession of the Holy Spirit thoroughly permeates the Word. But from the perspective of logical priority, the sequence of the assertions strongly implies that the Word's existence in the first phrase is a precondition for the Spirit's procession in the second.
We can even go further based on what we see in Gregory's and John's arguments. Explanatory priority seems to have been an inevitable consequences of reading John 16:14-15 in the eternal context, which likewise seems to have been the unanimous consensus of every Father who wrote about it around the time of Constantinople I. For example, Hilary particularly comments (De Trin., Book VIII) that while John 16 uses the future tense "will receive," this is just the working-out of the eternal Trinitarian relations in the temporal context, and there does not appear to be even one dissenting voice from that view. The belief that John 15:26 somehow uniquely signified the divine relations in eternity is completely absent; rather, that belief is performatively contradicted by the exegesis of John 16:14-15.
If we are open to metaphysical plurality in these various schools, then what I have written would not amount to a refutation of the GE view, so much as a truce based on the admission that we cannot know for certain which of these descriptions of the theological mystery is most accurate. What such openness would not allow is the assertion that the filioque is definitely wrong, because that would be confusing a particular metaphysical explanation of the Trinitarian mystery with the Trinitarian dogma itself. We might quibble over the right way to express the explanatory priority of the Son to the Spirit, what the philosophical questions associated with it are, or even what the term ekporeuomenon actually means in the creed (is it solely emergence from an original source or not?). But even if those disputes cannot be settled, Williams has nonetheless demonstrated that the unquestionably agreed requirements (three relationally distinct subjects having a numerically identical essence, power, and activity) suffice to mount a formidable defense against the philosophical opponents to creedal Christianity.
