At William Lane Craig’s Reasonable Faith website, Dr. Craig answers a complex question about the Trinity and prior causation. Although most of the article is dedicated to explaining the “First Cause” argument for God’s existence, there are a few interesting quotes about the eternal generation of the Son from the Father. He says,
Theologically, it seems to me, the doctrine of the generation of the Logos from the Father cannot, despite assurances to the contrary, but diminish the status of the Son because He becomes an effect contingent upon the Father. Even if this eternal procession takes place necessarily and apart from the Father’s will, the Son is less than the Father because the Father alone exists in Himself, whereas the Son exists through another. Such derivative being is the same way in which created things exist. Despite protestations to the contrary, Nicene orthodoxy does not seem to have completely exorcised the spirit of subordinationism introduced into Christology by the Greek Apologists.
For these reasons evangelical theologians have tended to treat the doctrine of the eternal generation of the Son from the Father with benign neglect. If we do decide to drop from our doctrine of the Trinity the eternal generation and procession of the Son and Spirit from the Father, how should we construe the intra-Trinitarian relations? Here I find it useful to distinguish between the ontological Trinity and the economic Trinity. The ontological Trinity is the Trinity as it exists of itself apart from God’s relation to the world. The economic Trinity has reference to the different roles played by the persons of the Trinity in relation to the world and especially in the plan of salvation. In this economic Trinity there is subordination (or, perhaps better, submission) of one person to another, as the incarnate Son does the Father’s will and the Spirit speaks, not on His own account, but on behalf of the Son. The economic Trinity does not reflect ontological differences between the persons but rather is an expression of God’s loving condescension for the sake of our salvation. The error of Logos Christology lay in conflating the economic Trinity with the ontological Trinity, introducing subordination into the nature of the Godhead itself.
So I regard God the Father as neither ontologically nor causally prior to God the Son, and I view Augustine and the Damascene’s views as extra-biblical and unfortunate.
From this it is not clear whether there is an eternal subordination of the Son; only an eternal generation is denied. But many complementarian scholars seem to conflate the two thinking that the Son’s eternal generation is evidence (or perhaps better said, the explanation) of His eternal subordination. Still, Craig does not see the economic Trinity as reflecting the ontological Trinity, which is fundamental to the complementarian scheme.