Why It Is Not a Verbal Difference

The Latin tradition does not intend to posit two causes of the Holy Spirit, distinguishes processio from ἐκπόρευσις, and has officially conceded that the Father alone is the principle without principle. This file states that case in its own words and at its strongest — and then shows why the Orthodox objection stands anyway: because the interpolation was made into a creed no local church may alter, and because the doctrine relocates the ground of divine unity from the person of the Father to the shared essence.

Tradition: Pan-Orthodox

The Latin Case at Its Strongest

Nothing is gained by attacking a position no one holds. The Latin case has been refined for a thousand years and the best version of it must be on the table before anything is said against it.

1. The two verbs are not equivalent. Latin has one word, procedere, where Greek has several. The Greek ἐκπόρευσις, as the Cappadocians fixed it, names one thing only: the Holy Spirit’s coming-forth from the Father as to his very existence, his relation of origin to the sole principle. Latin processio is broader, covering any coming-forth. The 1995 Roman clarification states the distinction in these words: “The Greek ἐκπόρευσις signifies only the relationship of origin to the Father alone as the principle without principle of the Trinity. The Latin processio, on the contrary, is a more common term, signifying the communication of the consubstantial divinity from the Father to the Son and from the Father, through and with the Son, to the Holy Spirit” (Pontifical Council for Promoting Christian Unity, The Greek and Latin Traditions Regarding the Procession of the Holy Spirit, 1995). If Filioque qualifies processio and not ἐκπόρευσις, then it is not the proposition the Greeks deny.

2. Rome concedes the monarchy of the Father in terms. The same document states: “The Father alone is the principle without principle (ἀρχὴ ἄναρχος) of the two other persons of the Trinity, the sole source (πηγή) of the Son and of the Holy Spirit.” And: “the two traditions recognize that the ‘monarchy of the Father’ implies that the Father is the sole Trinitarian Cause (Αἰτία) or principle (principium) of the Son and of the Holy Spirit.” And: “the Father is the sole Cause of the Son and of the Spirit, of one by generation and of the other by ἐκπόρευσις.” These are not concessions extracted in debate; they are the official teaching document of the Pontifical Council, issued at the Pope’s request.

3. The conciliar definitions deny two principles. Lyons II (1274) defines that the Spirit proceeds “not as from two principles, but as from one principle”; Florence (1439) says “as from one principle and a single spiration.” Latin theology has never taught two causes and has explicitly condemned the proposition.

4. Augustine himself qualified it. He taught that the Spirit proceeds from the Father principaliter — principally, originally — because it is the Father who, in begetting the Son, gave the Son that the Spirit should proceed from him also; so that the Son’s role is itself the Father’s gift and the Father remains the ultimate source (Augustine, On the Trinity XV.17, 26–29; trans. NPNF I/3; see St. Augustine: Augustine and the Filioque).

5. An Orthodox saint defended the Latin usage. St. Maximus the Confessor, writing to the priest Marinus in Cyprus around 645 about Roman language that had scandalized the Greeks, explained that the Romans “showed the Father to be the one cause of the Son and the Spirit — of the one by generation and of the other by procession — but they showed the coming-forth through him, and thus the affinity and identity of the essence” (Maximus, Opusculum 10, Letter to Marinus [PG 91:136]). This is the single most important Greek patristic text the Latin side possesses, and it is not a forgery or a misreading. [Disputed: the scope of Maximus' defence. Siecienski reads the *Letter to Marinus* as a genuine and substantial defence of the Latin position, and makes it central to his irenic argument (*The Filioque*, Oxford, 2010, ch. 3); a more restrictive Orthodox reading holds that Maximus defends only a *per Filium* of manifestation and expressly grounds his defence in the Latins' confession of the Father as sole cause — that is, that he defends them precisely by showing they do not mean the *Filioque* as later defined. The text survives in fragmentary transmission, which sharpens the difficulty. This collection reports both readings; the second is the one that fits Maximus' own wording, but the question is genuinely open.]

6. The philosophical argument. Thomas Aquinas gives the strongest form: the divine persons are constituted and distinguished solely by relations of opposition. If the Spirit did not proceed from the Son, there would be no relation of opposition between them, and — since in God everything is one except where relative opposition obtains — the Son and the Spirit would not be really distinct (Summa Theologiae I, q. 36, a. 2). On this account the Filioque is not an extra claim but the condition of there being three at all.

7. Rome refuses the Greek interpolation. The 1995 document states that “the Catholic Church has refused the addition of καὶ τοῦ Υἱοῦ to the formula ἐκ τοῦ Πατρὸς ἐκπορευόμενον of the Symbol of Nicaea-Constantinople,” and affirms the “conciliar, ecumenical, normative and irrevocable value” of that Symbol as professed in Greek in 381. Rome does not claim that the Greek Creed is defective; she claims that the Latin Creed says something else in a different language.

That is the case. It is serious, it is made in good faith by people who mean what they say, and any Orthodox account that pretends otherwise is not worth reading.

Why the Objection Stands: The Canonical Ground

The first objection is independent of all the above, and would stand even if the theology were unobjectionable.

The Creed of 381 is not a private document or a local formulary. It is the confession of the whole Church, fixed by an Ecumenical Council, received at Chalcedon, recited at every baptism and every Liturgy. The Council of Ephesus (431) forbade the composing of any other faith beside that of the Fathers, on pain of deposition for clerics and anathema for laymen; the canon’s exact numbering varies among collections, and this collection follows the repository’s hub in noting that it is sometimes identified as part of the conciliar definition rather than as a separately numbered canon (Ephesus 431, Canon 7 or Definition; trans. NPNF II/14). The Council of 879–880 at Constantinople, with Roman legates subscribing, reaffirmed the Creed unaltered and anathematized addition or subtraction.

Against this, three points are decisive.

No part of the Church may alter the confession of the whole. Whatever the theological merits, a creed adopted by all cannot be amended by some. That is not a procedural nicety; it is the meaning of catholicity. The Latin reply — that the Filioque is not “another faith” but an explication of this one — is precisely the reasoning the canon was framed to exclude, since every innovator has held that his innovation was an explication.

Rome herself said so, for two hundred years. Pope Leo III accepted the doctrine of double procession and refused to insert it in the Creed, telling the Frankish legates that the Fathers had not put it there, and had the unaltered text engraved on silver shields in Greek and Latin at St. Peter’s. The canonical objection is not an Eastern invention; it was the position of the Roman See against the Frankish court (see What Was Added and When).

And nothing has changed. This is the point at which the 1995 clarification must be read carefully. It concedes a great deal about meaning; it did not remove the clause from the Latin Creed, and no Roman act has. As of this writing (2026), the Roman Catholic Church continues to recite qui ex Patre Filioque procedit in the Latin liturgy, and the definitions of Lyons and Florence remain dogmatic definitions of that communion. A clarification of what a text means is not the restoration of the text.

Why the Objection Stands: The Theological Ground

The canonical objection is sufficient by itself. The theological objection is what makes the difference more than procedural, and it must be stated with care, because the easy version of it — “the Filioque posits two causes” — is answered by the concessions above.

The precise claim is this: the Filioque relocates the ground of divine unity from the person of the Father to the common essence, and in doing so it makes the monarchy of the Father decorative rather than structural.

Three steps.

First: Florence defines more than a broad processio. If the Filioque concerned only the Spirit’s manifestation or his consubstantial communion with the Son, the Greek objection would indeed be verbal. But the Florentine definition is about origination of being: the Holy Spirit “has his essence and his subsistent being from the Father together with the Son, and proceeds from both eternally as from one principle and a single spiration” (Laetentur Caeli, 1439; trans. Tanner). Essence and subsistent being — essentiam suam suumque esse subsistens — is exactly what ἐκπόρευσις names: the Spirit’s coming to be what he is. Florence therefore says of the broader Latin processio what the Greeks reserve to ἐκπόρευσις, and the distinction of vocabulary does not, at the level of the definitions, hold the two apart.

Second: “one principle” locates the spirating in the essence. Suppose Father and Son spirate as a single principle, as Lyons and Florence require. Then what they spirate by cannot be what distinguishes them — for that would be two principles — and must be what they share, namely the divine nature. But then spirating is a property of the divine nature. And here the argument the Cappadocians made against Eunomius bites: since the Spirit possesses that same nature entirely, the Spirit too would spirate, which no one teaches. St. Photius put this reduction at the centre of the Mystagogy, and it has never been answered on its own terms (Photius, Mystagogy §§3, 8, 15; trans. Farrell, Brookline, MA: Holy Cross Orthodox Press, 1987; see St. Photius: The Mystagogy of the Holy Spirit).

The Latin answer is Aquinas’: the Father and Son spirate not in virtue of the essence considered absolutely but in virtue of their relation of opposition to the Spirit. This is coherent — but it purchases coherence by making the persons constituted by mutual relations of opposition rather than by relation to the Father as sole cause. And that is the whole difference. On the Orthodox account, causality is a hypostatic property of the Father and of no one else, established as such in the 360s against Eunomius; the Son and the Spirit possess the entire divine nature and cause nothing, precisely because causing is not in the nature (see The Father as Sole Cause). On the Latin account, spirating is a property that the Father shares with the Son. Once it is shared, it is no longer the Father’s as Father; and once it is no longer the Father’s as Father, it is a property of what they have in common.

Third: what then makes God one? If the persons are constituted by relations of opposition among themselves rather than by derivation from a single source, then the Father’s monarchy is no longer what unifies the Trinity, and the unity must be sought where the persons converge — in the one essence. This is not an accusation about intent; the Latin tradition says explicitly that it does not intend two causes, and it is believed. It is a claim about what the definitions entail. The Orthodox Church confesses that God is one because the Father is one, and that the divine nature is one because it is the Father’s own, communicated wholly and without division to the Son by generation and to the Spirit by procession. A doctrine that makes the Father’s causality shareable has, whatever it intends, put the unity somewhere else.

Two consequences follow, and both are the Fathers’ own concerns.

The hypostatic properties are confused. If being the origin of the Spirit belongs to the Father and the Son alike, then it is not what distinguishes the Father, and the Father’s distinguishing property is diminished — Photius’ second horn: either two principles, or a blurring of Father and Son at the point where they are supposed to differ (Mystagogy §14).

And the relation is asymmetric without warrant. The Spirit contributes nothing to the Son’s generation; there is no Spirituque. The Latin structure makes the Spirit the terminus of a relation in which he alone does not participate actively, which is why so much Western theology has had to describe him functionally, as the bond of love between the other two, rather than by a relation of origin of his own.

What the Church Does Say: Per Filium

The Orthodox Church is not confined to a bare negation. She confesses, with St. John of Damascus, that the Spirit proceeds from the Father and rests in the Son; that he is the Spirit of the Son; that he is manifested and given to us through the Son; and that we do not say the Spirit is from the Son (John of Damascus, Exact Exposition I.8, 12; trans. NPNF II/9). Gregory II of Cyprus at the Council of Blachernae (1285) developed this into the doctrine of the Spirit’s eternal manifestation or shining-forth (ekphansis) through the Son — an eternal relation, not merely a temporal mission, and still not an origination of being. St. Gregory Palamas took up the same distinction.

The distinction between manifestation and origination is the whole of it, and it cannot be collapsed. That the Spirit eternally shines forth through the Son says something real about the Son’s relation to the Spirit without making the Son a source of the Spirit’s existence. Per Filium is therefore not a diplomatic softening of the Filioque; it is a different proposition, and it is the one the Church confesses.

Honest Concessions

Four, none of which the case requires to be suppressed.

The Greek patristic record is not uniform in phrasing. St. Cyril of Alexandria used expressions of the Spirit as “proceeding from the Father and the Son” and as the Son’s “own,” and Theodoret objected to the ninth of Cyril’s anathemas on exactly this ground. The Orthodox reading is that Cyril speaks of the Spirit’s consubstantiality with and manifestation through the Son and not of his origin — which is also how St. Maximus reads such language — but a reader should know that the sentences exist and that Latin theologians have quoted them for a thousand years.

Maximus defended the Latins. See the disposition above. Whatever its scope, the Letter to Marinus shows a Greek saint judging that Latin usage could be orthodox in intent, and it is why the Orthodox case has never rested on treating the West as simply obtuse.

Not every Orthodox theologian has held it church-dividing. The Russian church historian V. V. Bolotov, in the Theses on the Filioque prepared for the Old Catholic discussions and published posthumously in 1898, argued that the Filioque as a private theological opinion is a theologoumenon rather than a heresy, and that the real impedimentum dirimens to reunion is the interpolation into the Creed rather than the doctrine (Bolotov, “Thesen über das Filioque,” Revue internationale de théologie 24 [1898]). Bolotov’s theses have never been received as the Church’s position, and they stand against the Encyclicals of 1848 and 1895, which name the clause a heresy. But they are the work of a serious Orthodox scholar and are part of the record.

The 1995 clarification is a real movement. It is not a rhetorical exercise. It concedes the monarchy of the Father in Greek terms, distinguishes the two verbs, refuses the interpolation into the Greek text, and affirms the irrevocable normative value of the Symbol of 381. An Orthodox reader should register how much that is, and then register what it leaves: the clause still in the Latin Creed, and Lyons and Florence still dogmatic.

What Is Not Claimed Here

This file argues a dogmatic point and does not argue a historical one. It does not claim that the Filioque is the root cause of Western ecclesiology, of Western spirituality, of scholasticism, of the Reformation, or of the modern condition. Vladimir Lossky and the tradition following him made claims of that order, and those claims are contested among Orthodox scholars and are reported without adjudication in Section 09 (see The Modern Personalist Reading; The De Régnon Paradigm Critique). The argument made here rests on the Cappadocians, Photius, and the Damascene, and on the texts of Lyons, Florence, and 1995; it stands or falls on those, and it does not need the grand narrative.

The Position, Stated

The Creed of 381 confesses that the Holy Spirit proceeds from the Father. That confession is the Church’s, and no part of the Church has authority to add to it. The addition was made without a council, against Rome’s own two-hundred-year resistance, and has never been withdrawn. The doctrine it carries, as defined at Lyons and Florence, makes the origination of the Spirit’s subsistent being proceed from Father and Son as one principle, and therefore locates it in what they share rather than in the Father as Father — displacing the monarchy of the Father, which is what grounds the unity of God.

The Orthodox Church has examined this doctrine and has not received it. That is the state of the matter, and it is not a quarrel about a word.

References

Council of Florence. Laetentur Caeli (6 July 1439). In Norman P. Tanner, ed., Decrees of the Ecumenical Councils, vol. 1. Washington, DC: Georgetown University Press, 1990.
Second Council of Lyons (1274). Constitution On the Supreme Trinity and the Catholic Faith. In Tanner, Decrees, vol. 1.
Council of Ephesus (431). Canon 7 / Definition. Trans. NPNF, Second Series, vol. 14.
Pontifical Council for Promoting Christian Unity. The Greek and Latin Traditions Regarding the Procession of the Holy Spirit. 29 June 1995; published in L’Osservatore Romano, 20 September 1995.
Photius. The Mystagogy of the Holy Spirit §§3, 8, 11, 14–15. Trans. Joseph P. Farrell. Brookline, MA: Holy Cross Orthodox Press, 1987. ISBN 0-916586-88-X. Greek in Patrologia Graeca 102:279–401.
John of Damascus. An Exact Exposition of the Orthodox Faith I.8, 12. Trans. NPNF, Second Series, vol. 9.
Maximus the Confessor. Opusculum 10 (Letter to Marinus) [PG 91:136].
Augustine of Hippo. On the Trinity V.14; XV.17, 26–29. Trans. NPNF, First Series, vol. 3.
Thomas Aquinas. Summa Theologiae I, q. 36, a. 2.
Siecienski, A. Edward. The Filioque: History of a Doctrinal Controversy. Oxford: Oxford University Press, 2010.
Papadakis, Aristeides. Crisis in Byzantium: The Filioque Controversy in the Patriarchate of Gregory II of Cyprus (1283–1289). Rev. ed. Crestwood, NY: SVS Press, 1997.
Bolotov, V. V. “Thesen über das Filioque: Von einem russischen Theologen.” Revue internationale de théologie 24 (1898): 681–712.
Encyclical of the Eastern Patriarchs (1848); Patriarchal and Synodical Encyclical of the Church of Constantinople (1895).
Meyendorff, John. Byzantine Theology. New York: Fordham University Press, 1974.