Trinity and Simplicity

One of the most difficult objections against classical theism is this: How can God be triune if he is perfectly simple? Divine simplicity implies that God is not composed of parts. It is captured in the maxim that all that is in God is God. But if that is the case, the critic insists, then it must follow that “All that is the Father is whatever else in in God—including the Son and the Holy Spirit, and vice versa.” At the very least, the likes of Augustine and Thomas Aquinas are accused by modern theologians of being functional modalists. It is assumed that we cannot take the personal distinctions seriously if we try to maintain this “static” oneness that admits of no complexity.

However, this is not the case. In order to see this, we will have to put a few puzzle pieces together which are both philosophical and theological in nature.

Real and Logical Distinctions

Simplicity implies that there is no real distinction between God’s existence and his essence. However the meaning of the phrase “real distinction” is often misunderstood and requires a bit of background understanding of Scholastic metaphysics. Here one would speak of a (1) real distinction and a (2) logical distinction. The difference between these is that a real distinction is one that is both extra-mental and between two separable entities, whereas a logical distinction is one that is intellectual between predicates or properties, or between senses in which one subject can be predicated in two or more ways. Here I only introduce this concept. Do not hastily jump to the punchline that the divine Persons are merely logical relations. That is not the takeaway. But we will still need to have this category firmly fixed in our minds. 

Actus Purus, Substance, and Simplicity

That God is simple follows from the impossibility of there being any potentiality in God, and the equal impossibility of there being any accidents in God. These are two Aristotelian distinctions to which Thomas appeals in the early going of the Summa Theologica. What it amounts to is this: If God is the First Cause, then nothing superior to him (no act before him) could have activated something in him. Nothing in God could be merely potential. All that He is must be the ultimate Substance in act. In addition to this notion of “pure actuality,” it must also be the case that God’s “substance” (that which He is) cannot be like other beings which have what is substantial and what is accidental. What is accidental is what may be added or taken away. Accidents “inhere in” the substance. They are predicates or properties of a thing, but they could be removed from that thing. But if God is the First Cause, then all that He is He must be eternally and immutably. Hence all of the other attributes of God really depend upon the truth of this attribute that we are calling simplicity. Composition implies both accidents and potentiality. 

How Then are the Persons Different from the Attributes? 

In the first place, we have to understand that “personhood” in the Godhead, does not have a univocal meaning with the conception we would have with respect to human personhood. We are not speaking of separable “centers of consciousness,” as the terminology goes. That represents the view known as Social Trinitarianism. In classical Trinitarian theology we deny that there are three minds and three wills.

Consequently, the way that we will distinguish the Persons will already have this difference from the way that we distinguish the attributes. Although, just as with the attributes, the Father, Son, and Holy Spirit are not accidents in relation to the one substance, just as they are not composite parts of a greater whole.

In concise language, the maxim “All that is in God is God,” clearly means that all that is of the divine essence is God. Here the referent is treated abstractly from what is proper to the Persons. The Persons are not composite parts of the divine essence, but as Giles Emery put it, there is “the identity of substance of the three persons.”1  

We might be able to see how one can treat the Persons abstractly from the essence at one moment, and then the essence from the Persons abstractly at another moment. In other words, we can understand easily enough how to make two equal and opposite kinds of logical distinctions without concluding that the triune God has come apart at the seams. But our question is not how to “keep it all together,” but rather how to prevent “it all” from collapsing into a monotony. How can we make a merely logical distinction between the Persons, when to do that same thing with the attributes still implies their identity? We do not want to say that the Father is “identical” to the Son, and so forth, in the same way that we want to say that the Father and the Son have identical substance to infinity, spirituality, holiness, and so forth. 

Real Relations

Here is where Aquinas proves his unparalleled sophistication. The distinction to be made between the Persons are real relations. The first thing to note is that “a relation” does not imply what is accidental. Thomas builds this up in a way that would be rather cumbersome to anyone without a background in the metaphysical language. 

“Relations exist in God really; in proof whereof we may consider that in relations alone is found something which is only in the apprehension and not in reality. This is not found in any other genus; forasmuch as other genera, as quantity and quality, in their strict and proper meaning, signify something inherent in a subject. But relation in its own proper meaning signifies only what refers to another” (ST I, q. 28, 1).

With the other of Aristotle’s categories, such as quantity or quality, the predicate exists in another. They describe the subject. But to put it in Plato’s terminology, the substance (the particular thing) is “participating in” the form of that quantity or quality.

Let me illustrate. In the case of relation, I just am the father of Joshua, and Joshua is the son of Matt, in a way that is not the case for any other particular substance called “father” or “son.” The relation in these cases is not accidental in itself. Each is real, “opposite” to the object so related.

James Dolezal explains why this helps us make the basic jump in seeing the coherence of the doctrine:

“For all the other accidents inherence in a subject is entailed in their specific character and thus their act of existence is that of 'existence in' (inesse) a subject. They depend upon the existence of the substance in which they inhere and they also determine the subject to exist in some way not proper to its substance as such. Accordingly, they are really distinct from the essences of the subjects they describe. Of course, if this were true of God he would most certainly not be simple”2

But remember, the claim of Trinity and simplicity is that the divine personal relations are not “in” the subject “God” in that way. For example, someone may object that this still makes “Father” and “Son” and “Holy Spirit” accidents to the substance of God, since God is Father and God is Son and God is Spirit. They are still real predicates. But the first mistake that this makes is that it is not true on the face of it. The orthodox say this in reverse for a reason: the Father is God, and the Son is God, and the Spirit is God. This is because the shared essence is the predicate identically. Unlike the division between real and logical distinction we started with, these divine relations are in neither category, strictly speaking. They are not confined to a concept in the mind, and they are not real qua accidens. They are real relations, subsisting as all that is in God.

What are called “paternity,” “filiation,” and “spiration” in the three are each said in relation “to the opposite term” (ST I, q. 28, 2), not at all in relation to the one essence. This real opposition is the basic reason why this can be a sui generis case of a real distinction, one that does not imply separability of entities. Consider the following logic:

1. All that is in God is God.

2. The Father (... the Son, the Spirit) is God. 

3. Each Person is not the other two Persons as relations. 

4. Each Person is all that is in the one God as essence. 

5. Relations are to the opposite relation, not accidental of the essence.

6. Therefore, it follows that each Person can subsist, as distinct relation and one in essence, as do the other two Persons.  

To demonstrate this is not to explain all that it entails. That is not our burden of proof. On the contrary, it belongs to the critic to prove how relation, much less divine relation, must imply what is accidental in relation to substance. 

Note also that the critic of simplicity agrees with premises 2 and 3. He must, lest he descend to either Subordinationism or Tritheism. Our attention is so intent on premise 1 and the burden of the defender of simplicity that we neglect the implications of the critic’s position. If he accepts 2 and 3, then he already makes the logical distinctions concerning what is shared in essence versus what is proper to the Persons.

In short, he too believes that “All that is in the Son is God” and “All that is in the Spirit is God,” in such a way that (simplicity or not), the whole of what is divine is predicated to the Son and to the Spirit, and yet they are distinct. This will either imply that there is some shared essence of divine attributes that is distinct, yet again, from any of the three Persons (a sort of fourth “something” in which the three participate); or else, he must mean that the three Persons have all that is divine separately, without remainder, and yet not in the sense of a real shared essence.  

We ought to consider the awkwardness of the critic. What does he offer us in between divine simplicity and Tritheism? How precisely are the three Persons separable and yet not also three beings: in fact, three Gods? Whatever the answers are, it is not clear how it would not be an appeal to a logical distinction that requires explanation every bit as much as the classical notion of these relations. One difference, then, is that the classical theologian has articulated such a defense, and it is tacitly assumed that the critic has no such burden of his own. In fact, no explanation is ever given for why ditching simplicity does not result in tritheism. 

Interestingly, those who want to charge the classical view of Modalism at least have to grant that the modes are logical distinctions, even if they are not of persons. So it would be more consistent of the critic to charge that he who holds to divine simplicity must conclude in a simple Unitarianism. Most critics see this and collapse the whole object of their critique into a deity with no intelligible attributes at all. 

There are many implications of this which open up other horizons of Trinitarian controversy and always have. But our only burden at this point is to demonstrate a base level logical coherence between Trinity and simplicity.

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1. Giles Emery, The Trinity: An Introduction to Catholic Doctrine on the Triune God (Washington DC: Catholic University of America Press, 2011), 91

2. James E. Dolezal, “Trinity, Simplicity and the Status of God’s Personal Relations,” International Journal of Systematic Theology, Volume 16, Number 1 (January 2014), 84.