This is an excerpt from a larger article. See Here. This discussion picks up right after I talk about Bruce Ware’s claim that the orthodox notion of eternal generation is no less threatening to the doctrine of the Trinity than Ware’s own Eternal Relational Authority Subordinationism (ERAS).
The issue that Ware points out here has already been dealt with, primarily in the work of Francis Cheynell, a seventeenth century Puritan who exposited the doctrine of the Trinity perhaps more comprehensively than any other during his time. Cheynell, in response to the Socinians—who thought that eternal generation implied division of essence—writes:
The Father did beget his Son without change or motion after a most glorious and wonderful manner; there can be no change, motion, or succession in this eternal and most perfect generation. The essence of God is spiritual, John 4:24. And therefore the Son is not begotten of the Father’s seed, or any material substance, because God is a single and pure Act, who doth beget a Son within himself Essentially one with himself and therefore his Son doth not subsist out of himself, John 14:10, John 10:30. For an infinite nature cannot be poured forth beyond itself. There can be no essential change in the Son by this generation, because the generation is eternal, and the nature which is communicated by generation unchangeable; the Father did unchangeably beget his Son, and his Son is unchangeably begotten (Cheynell, 195).
Cheynell points out that the Son is eternally generated. Yet, just as the Son is generated, the Father generates only by virtue of the Son’s generation. In other words, the Father wouldn’t be who He is, as generator, without the Son’s being generated, and visa versa. Joel Beeke and Mark Jones writes:
Therefore, the Son “depends” on the Father to be Son in the same way the Father“depends” on the Son to be Father. The Father’s act of begetting the Son is necessary, not voluntary. Besides the fact that the three persons are all essentially God, the act of the Father’s begetting and the begottenness of the Son are necessary relations because of their distinctive personality (A Puritan Theology, 95).
What Beeke and Jones are referring to is the ineffable fact that if the personal distinctions are actual within the Godhead (i.e. Father, Son, Spirit), then the acts of generation, being generated, and spiration are ontologically necessary. However, the same cannot be said for Eternal Relational Authority Subordination (henceforth ERAS). ERAS is not needed in order to maintain anything fundamental to the doctrine of the Trinity. It’s not necessary that the Son willfully submits to the Father’s primal authority eternally like it’s necessary that the Father eternally begets, that the Son is eternally begotten, and that both the Father and Son eternally spirate the Spirit. These eternal necessary “acts” obtain simply by virtue of Scriptural data (cf. G. Vos, Reformed Dogmatics: Theology Proper), and the fact that there are real distinctions of persons in the Godhead, contra the old Socinian heresy.