Divine simplicity and the Trinity

If “all that is in God, is God,” then God cannot subsist in three really distinct persons.

The doctrine of divine simplicity asserts that God is without parts. One way of understanding this is according to the formula: all that is in God, is God.

This formula must be understood carefully. In a sense, the parts of a thing “are” that thing. My arms, my legs, my ears, and so on “are” me. At the same time, they are not individually the whole of me. At best, they are collectively the whole of me. That’s what it means to call them “parts” of me.

If God is without parts, then whatever is in God, is not only collectively but also individually the whole of God. Put another way, whatever is in God is the whole of God and not simply a part of him.

For example, a proponent of divine simplicity would reason like this. If God is good, just, and merciful, then goodness, justice, and mercy are not only collectively but individually the whole of God. Goodness is the whole of what God is, as also justice, as also mercy. These things are “in” God in such a way as each to be the whole of God and not simply a part.

At the same time, notice how “parts” may be defined. My arms and legs are in me, but they are really different from each other. They have different properties and powers that really distinguish them. This is to say that they are in me without individually being the whole of me. That’s what it means for something to be a part of something else: to be in it without being the whole of it.

Thus, we have a simple principle. If x and y are in A, but they are really different from each other, then x and y are not individually the whole of A but only parts of it.

Now, notice what follows for the doctrine of the Trinity. On the one hand, the persons of the Father, Son, and Holy Spirit are supposed to be in God. If the persons were not in God, they would be outside of God. And if the persons were outside of God, then God would not subsist in three persons or be tri-personal.

At the same time, according to the orthodox doctrine of the Trinity, the persons of the Father, Son, and Holy Spirit are supposed to be really different from each other. The Father is unbegotten and unspirated while begetting and spirating, while the Son is begotten without begetting and the Spirit is spirated without spirating. If they were not really different from each other, then the three “persons” would be no more than three names for the one thing that God is.

Thus, it can be seen that the doctrine of the Trinity is incompatible with the doctrine of divine simplicity. If x and y are in A, yet are really different from each other, then x and y are not individually the whole of A but only parts. If the Father, Son, and Holy Spirit are in God, yet are really different from each other, then Father, Son, and Holy Spirit are not individually the whole of God but only parts of him. But if God is simple, then he has no parts. All that is in God is individually the whole of God and not a part. Therefore, the doctrine of the Trinity is incompatible with the doctrine of divine simplicity.

My friend Gavin Ortlund has recently appealed to the long-standing tradition of appealing to the doctrine of divine simplicity in defense of the doctrine of the Trinity. He writes, “If God is not simple, then each individual member of the godhead is less than fully God.” But in light of the argument given above, I think the argument can be reversed. If the three persons of the Trinity are in God but really different from each other, as the orthodox doctrine of the Trinity demands, then each is individually less than the whole of God. At best, they are collectively the whole of God.

I suppose someone might respond to this argument as follows. The Father, Son, and Holy Spirit are all identical to the one divine nature. At the same time, the Father is that one divine nature as begetting, the Son is that nature as begotten, and the Spirit is that one divine nature as [insert some other participle].

By way of response, I would argue that this approach simply confuses things through unnecessarily obscure language. Once the intention of the language is clarified, it can be seen to subject to the same problem as earlier.

When we speak of the divine nature-as-begetting or -as-begotten, are we speaking of something in or outside of God?

Presumably we are not speaking of something outside of God. If the divine nature-as-begetting were something outside of God, e.g. a conceptualization of the divine nature in someone else’s mind, then it would not be a characterization of the real being of God himself. In that case, God would not really be triune. He would simply be thought to be triune by some people.

Suppose instead that we are speaking of something in God. Presumably begetting and being-begotten are really different. One is active and the other passive. One is doing and the other is being-done-to. In that case, that in God to which we refer as the divine nature-as-begetting is really different from that in God to which we refer as the divine nature-as-begotten. But if these two things are in God while being really different from each other, then they are parts of God and not individually the whole of him. So the same problem remains as earlier.