Simplicity and Trinity

Gregory of Nazianzus has this clever little argument for the equality of Father and Son in the Third Theological Oration. He responds to the Arian argument that Augustine also deals with: a) God is simple, and has no accidents; b) therefore, every statement about God speaks of substance; c) since the Father is “unbegotten,” He is substantively unbegotten, and since the Son is begotten, He is substantively begotten; d) thus, the Father and Son are not the same substance, since ungenerate and generate substances are different. God’s simplicity supports Arianism.

In his answer, Gregory assumes that it is proper to speak of the Father as “ungenerate” and the Son as “generate,” the Father as “unbegotten” and the Son as “begotten.” He would, I think, defend these terms from Scripture. With this in view, He argues that the doctrine of simplicity actually supports Nicene orthodoxy. “Begetter and begotten . . . must be the same,” he argues, because “it is in the nature of an offspring to have a nature identical with its parent’s.” Like intelligence and lack of intelligence, begetter and begotten are properties that inhere in beings of the same substance.

Then this: “Do immortality, innocence, and immutability each constitute God’s being? No, if that were so, there would be a plurality of ‘beings’ in God, not a single being. Or is Deity a composite resulting from these? – if these are ‘beings’ or substances, there would have to be composition.” If the Son is begotten of the Father, then He must be of the same substance. And, the doctrine of simplicity demands that “ungenerate” and “generate” not be component parts of God, but properties (persons) within the single substance. The Ungenerate, or the Father, is no more a “part” of God than “immortality” is one component of God’s essence.