What Monogenēs Meant as Applied to the Son—According to the Church Fathers
Giles claims that when the church fathers applied the term μονογενής to the Son, they only intended “to speak of the uniqueness of Jesus Christ” and not to affirm that he is “only begotten.” Giles would grant that what makes the Son unique is that he is eternally begotten, but I take him to be saying this was something the fathers stated synthetically and theologically, that is, not analytically inferring “begottenness” as a predicate contained in the word μονογενής itself. I think this is demonstrably untrue. Here is some evidence showing that the church fathers did indeed apply the term to the Son with the understanding that it positively affirms the Son is “only begotten.”
The church fathers often used μονογενής substantivally (or absolutely as they would say) as a name or title of the Son lifted from John 1:14 (“glory as of the Only Begotten from the Father”) but without quoting the verse. This usage suggests they interpreted the word to mean “only begotten.” Otherwise, we would have to translate the substantival use as “the Only One,” which hardly has any significance, or “the Unique One.” This translation problem was noted by the modern translators of Basil’s work, Against Eunomius, Mark DelCogliano and Andrew Radde-Gallwitz (The Fathers of the Church [FoC], vol. 122). Giles himself says he wrote to Mark DelCogliano asking him about their decision to render μονογενής as “only begotten.” This was Dr. DelCogliano’s reply:
“I remember when beginning the project we toyed with translating the term as ‘only’ or ‘unique,’ in line with modern biblical translations. This led to what seemed to us odd substantive usages such as ‘Only One,’ but at least it was accurate, we thought. But the more we thought about it, we thought that Basil (as well as others) really understood the term in the sense of ‘only offspring of the Father’—what we here in the states would call an ‘only child’ (see Contra Eunomius 2.20-21). And we thought that this understanding of the term accorded well with the traditional translation ‘Only-Begotten’” (quoted by Giles, The Eternal Generation of the Son, p. 145 n124).
This absolute, substantival use occurs about 95 times in Basil’s Against Eunomius. I literally counted each occurrence of “the Only-Begotten” by hand in the recent (2011) English translation by DelCogliano and Radde-Gallwitz. I say “about 95” because I may have missed a few, and a couple of times it was Eunomius who used the term. (Basil quotes Eunomius throughout and refutes him point by point.) I would even go so far as to say “the Only-Begotten” seems to be Basil’s preferred way of referring to the second person of the Trinity. As Basil’s translators pointed out, it would result in a rather odd translation to render all 95 of these as “the Only One.” It seemed to the translators that Basil took the word in the sense “only offspring” or “only child,” and that therefore the best translation was the traditional one, “the Only-Begotten.”
Not only do we have the frequent substantival use, ὁ Μονογενής (“the Only-Begotten”), but the church fathers explicitly asked why the Son is called μονογενής and gave a clear answer.
Athanasius says the Son is called μονογενής “because of his generation from the Father” (μονογενὴς μὲν διὰ τὴν ἐκ πατρὸς γέννησιν). And he immediately adds: “One should say that the attribute of being only-begotten has justly the preference in the instance of the Word, in that there is no other Word, or other Wisdom, but He alone is very Son of the Father .... The Son is the Father’s ‘Only begotten,’ because He alone is from Him” (Against the Arians 2.62, 64; NPNF2 4.382-83).
Basil said the Son is called μονογενής because he is “the only one begotten” (τὸ μόνος γεγεννῆσθαι) (Against Eunomius 2.21; PG 29.617; FoC 122, p. 161), and repeatedly speaks of “the begetting (or generation) of the Only-Begotten” (Against Eunomius 2.3, 14, 15, 17).
Cyril of Jerusalem said: “This is the reason why He is called μονογενής, because in the dignity of the Godhead, and His generation from the Father, He has no brother” (Catechetical Lectures 11.2; NPNF2 7.64).
Gregory Nazianzen argued that “He is called Only-Begotten, not only because He is the only Son and of the Father alone, and only a Son; but also because the manner of His Sonship is peculiar to Himself and not shared by bodies ... on account of His passionless generation” (Fourth Theological Oration §20; NPNF2 7.316 modified).
The church fathers explicitly ask why the Son is called μονογενής. The answer they gave was not because he is “unique” or “the only one of his kind,” but because he alone is begotten of the Father. They agree that the term μονογενής tells us something about his “generation” or “begetting” (his γέννησις).
Additionally, if the church fathers thought μονογενής meant “unique” without any notion of begetting, they could not have used the term as a peculiar name for the Son when they wanted to identify the Son as a particular person within the Trinity distinct from the other two persons. But they did use the term this way. For the church fathers, the term μονογενής is a descriptor applicable only to the Son and not to any other person of the Trinity, because only the Son is begotten. But it would be applicable to all three persons of the Trinity if they thought the term only meant “unique.” The title “unique,” paradoxically, says nothing unique to distinguish the Son from the Father or the Spirit. But the descriptor “only begotten” does. They made this argument in particular when they discussed the Holy Spirit, the third person of the Trinity. They repeatedly said the Holy Spirit, though derived from the Father, is not “only begotten,” because that is the distinguishing property of the Son. Here are some quotes to that effect:
Gregory Nazianzen: “Nor is the Spirit Son because He is of God, for the Only-begotten is one” (οὔτε τὸ πνεῦμα υἱὸς ὅτι ἐκ τοῦ θεοῦ, εἷς γὰρ ὁ μονογενής) (Fifth Theological Oration §9; NPNF2 7.320). In other words, just because the Spirit is “of God” doesn’t make him God’s Son, for there is only one who is “the Only-Begotten.”
Gregory of Nyssa said the Holy Spirit’s “most peculiar characteristic is that He is neither of those things which we contemplate in the Father and the Son respectively. He exists simply, neither as ungenerate (μήτε ἀγεννήτως), nor as only-begotten (μήτε μονογενῶς): this it is that constitutes His chief peculiarity. Joined to the Father by His uncreatedness, He is disjoined from Him again by not being ‘Father.’ United to the Son by the bond of uncreatedness, and of deriving His existence from the Supreme, He is parted again from Him by the characteristic of not subsisting as only-begotten from the Father (μήτε μονογενῶς ἐκ τοῦ πατρὸς ὑποστῆναι)” (Against Eunomius 1.22; NPNF2 5.61 modified).
Basil of Caesarea is succinct and direct: “Nor do we speak of the Holy Ghost as begotten (γεννητόν), for by the tradition of faith we have been taught one Only-Begotten (ἕνα Μονογενῆ)” (Letter 125; NPNF2 8.195).
Try rendering μονογενής as “only” or “unique” in any of these statements, and the argument would fall apart. Consider especially the last quote, the one by Basil: “Nor do we speak of the Holy Ghost as begotten, for by the tradition of faith we have been taught one Only One (or one Unique One).” Such a translation makes nonsense of Basil’s argument and would in fact be heretical, because the Son is not the only one or the only unique one (the Father and the Spirit are unique as well). But if we render Μονογενής as “Only Begotten,” it makes perfect sense. Basil is saying we do not speak of the Holy Spirit as “begotten” because there is only one “Only Begotten,” the Son. Neither the Father nor the Spirit is begotten. Only the Son is begotten.