There is a Christian doctrine that most theologians affirmed up until the 19thCentury. Recent proponents of this doctrine claim that if you deny this doctrine you are an idolater, or even an atheist. Some theologians make it sound as if Christianity lives or dies with this doctrine. What doctrine is this that elicits such strong rhetoric? Perhaps you think the answer has something to do with Jesus Christ, or a major biblical teaching. Surprisingly, the answer has nothing to do with either. The answer that I am referring to is the doctrine of divine simplicity.

This might sound bizarre to many readers because this is a doctrine that the average Christian believer has never heard of. In fact, the average theologian can barely understand the devilishly complicated doctrine of divine simplicity. There are contemporary Christian philosophers who wish to defend a traditional understanding of God as timeless and changeless, but reject the doctrine of divine simplicity because they cannot make heads nor tails of what the doctrine is even saying. Within contemporary biblical studies, attributes like divine simplicity do not receive much of a warm welcome either. Recently, a New Testament scholar said to me, “Why are you even bothering to research things like simplicity. In biblical studies, we think this stuff is just silly.”

I must admit that this comment gave me pause. Why would I bother researching and writing about a doctrine that has no explicit biblical support, that most people today have never heard of, and that many today can barely understand? Divine simplicity is important to study because it is a divine attribute that has captured the imagination of most Christian thinkers throughout history. It is a divine attribute that is assumed in a majority of the theological systems that we currently study and reflect upon regardless of whether or not we affirm or reject these different schools of thought. Moreover, divine simplicity is a doctrine that is making a strong comeback in recent years.

That being said, I wish to accomplish a few things in this brief essay. First, I want to explain what the doctrine of divine simplicity is. Then, I want to argue that divine simplicity is incompatible with God’s freedom and grace. Before getting to that, I will start by giving a broad overview of the Christian doctrine of God.

The Doctrine of God

Christian theists assume that God is absolutely perfect. As perfect, God is the greatest possible being. Yet, Christians differ over what properties they think a perfect being has. A property is a quality, characteristic, or power that a being has. For example, my shoes have the property of red. C.S. Lewis has various properties such as wisdomand being Irish. Christian theologians typically say that God has properties like necessary existence, omnipotence, omniscience, goodness, and freedom. What other properties would God have? It depends.

Some kinds of properties are essential to a being, whilst others are non-essential or accidental. An essential property is a property that a being cannot fail to have, whereas an accidental property is something that a being can gain or lose. A being’s essence or nature just is a set of essential properties. Today, many theologians will say that God has properties like omnipotence and freedom essentially. They will say that it is the nature of God to be all-powerful and free, and it is impossible for God to fail to be all-powerful and free. These theologians will say that things are different when it comes to God’s property of being the creator. They will say that this is an accidental property of God because God is not essentially the creator of this universe. The overwhelming majority of Christian theologians have traditionally said that God is free to create or not create. God did not have to create, and so did not have to be the creator.

Today, there are many different models or conceptions of God that a Christian theologian might adopt. Among the different available models, there is a disagreement over divine simplicity. Some models of God affirm that God has the property of simplicity essentially, whilst others deny that God has this property at all.

What is Divine Simplicity?

The doctrine of divine simplicity says that God essentially lacks parts. Theologians who affirm simplicity say that it is the very nature of God to be simple, and God cannot fail to be simple. It might sound rather trivial to say that God lacks parts, but the doctrine of divine simplicity assumes a fair bit of philosophical baggage in its understanding of what counts as a part. I shall begin to unpack this baggage by starting with a claim that all Christian theists are happy to say about God regardless of whether or not they accept divine simplicity.

Christian theists of various stripes will agree that God does not essentially have any physical parts. With embodied creatures like you and me, we have physical parts like arms and legs. My arms and legs are parts of my body that can be separated from me. I would prefer that you not separate my arms and legs from the rest of my body, but it is possible that they be separated from my body. Most Christian theists say that God does not essentially have any physical parts like this that one can separate from the rest of God. Of course, the idea of removing essential parts might be incoherent, but I digress. Most Christian theists will say that God accidentally has physical parts because God the Son freely became incarnate and acquired a human nature with a physical body. Yet, Christian theologians will say that God the Son is not essentially incarnate because God is free to become incarnate or refrain from becoming incarnate. On this point, proponents and critics of divine simplicity can agree.

Divine simplicity wishes to go further than denying that God essentially has physical parts. Divine simplicity says that God does not have metaphysical parts either. The notion of metaphysical parts is very tricky because just about anything counts as a metaphysical part. Theologians who affirm divine simplicity will say that all properties and actions count as metaphysical parts. Even a property like existenceis considered a part. This might sound strange because many today would not consider existenceto be a part. If I were to ask you, “What is your favourite part of the movie?” I would be surprised to hear you say, “My favourite part is its existence.” Furthermore, many contemporary theologians and philosophers will deny that all properties and actions count as parts, thus rejecting what proponents of divine simplicity affirm.

At this point, there are two questions that I want to address. First, if properties count as parts, what does it mean to say that the simple God lacks properties? On the classical understanding of God, theologians will say that all of God’s essential properties are identical to each other, and identical to the divine nature, which is identical to God’s existence. The identity claim here is very strong, and can be easily missed. This is because we use the word “identity” in rather loose ways in contemporary English. There is a sense in which I can talk about my identity as an American Christian living in Scotland. This is what is called my narrative identity. This is not what the doctrine of divine simplicity is referring to. There is a strict, philosophical notion of identity that is being used in the doctrine of divine simplicity. On strict identity, one can say that Superman is Clark Kent. This is because Superman and Clark Kent are the same thing. The strict notion of identity is what is in mind when proponents of divine simplicity say that God’s property of omniscience is identical to God’s omnipotence, and these in turn are identical to God’s existence. It is a way of capturing the claim that the simple God does not possess any properties, forms, immanent universals, or tropes. Instead, there is the simple, undivided substance that we call God. This simple substance does not have any intrinsic or extrinsic properties because it does not possess any properties at all. There is just God, end of story.

Now consider a second question. If actions count as parts, what does it mean to say that the simple God lacks actions? On the classical understanding of God, the simple God’s actions are identical to one another such that there is only one divine act. For example, God’s act of creating the universe is identical to God’s act of predestining to save the elect. Proponents of divine simplicity go further and say that this one divine act is identical to God’s essence and existence. In other words, God is the one divine act. This is a rather odd claim, but proponents of divine simplicity do not shy away from it. They will say the oddness should be emphasized because this is what distinguishes God from creatures. With creatures like you and me, we are not identical to our actions. We perform actions; we are not actions. Yet, with the simple God, things are different. God is His one divine act.

Divine Freedom

Now that I have articulated the doctrine of divine simplicity, I wish to raise a particular problem from divine freedom. It is my contention that divine simplicity is incompatible with divine freedom. Allow me to explain by starting with some basic claims about divine freedom that will be affirmed by most critics and opponents of divine simplicity.

The overwhelming majority of Christian theologians believe that God is free in the following sense: for any transitive action that God can perform (a) God is the source of His own action, and (b) God has the ability to do otherwise. A transitive action is a divine action that has an external object as its end (e.g. creation). Theologians often distinguish this from God’s immanent actions which have God as its own end (e.g. the eternal generation of God the Son). Immanent actions are necessarily performed, and thus cannot satisfy condition (b), whereas transitive actions are not necessarily performed in accordance with condition (b).

Divine freedom plays a major role within Christian theology, and it would be absolutely devastating to Christian thought if God’s freedom were incoherent. Most Christian theologians believe that God is free to create the universe or refrain from creating the universe. They believe that the contingency of the universe is grounded in God’s freedom to create or refrain from creating. Also, Christian theologians often claim that God’s grace towards sinners is unmerited and undeserved. God’s grace is not something that God had to give. Grace is a free gift from God. One of the most amazing gracious acts of God is the incarnation. God did not have to become incarnate, but He freely became incarnate.

In order to get my argument up and running, I shall focus on God’s act of giving grace to sinners. I shall assume a broad doctrine of grace at the moment, but the argument can be amended to fit different, particular theological systems. On this broad doctrine of grace, God has in fact eternally chosen whom to give grace to. Prior to the act of creating, God decides whom He will give saving grace to and whom He will refrain from giving saving grace to. This decision by God is eternally made, and is now being temporally enacted by God. On this doctrine of grace, God did not have to give grace to anyone because grace is a free gift from God. Yet, God has in fact freely given grace to the elect. The idea can be stated like this.

1) If God is free, then God can refrain from acting to give grace.

2) God is free.

3) Therefore, God can refrain from acting to give grace.

Most proponents and critics of divine simplicity will affirm premises (1) through (3). But there is more agreement to be found over God’s freedom.

Another way to look at God’s freedom is to focus on the contingency of God’s action. God’s freedom in the act of grace is said to be contingent, and not absolutely necessary. Something is contingent if it does not have to be that way. Something is absolutely necessary if it has to be that way. For example, God’s act of giving grace is contingent because God does not have to give grace to anyone. If God’s act of giving grace were absolutely necessary, then God could not do anything else. Most theologians will complain that it is difficult to understand how God’s act is gracious in any sense if it is absolutely necessary. This idea can be stated as follows.

4) If God’s act to give grace is absolutely necessary, then God cannot refrain from acting to give grace.

5) God can refrain from acting to give grace.

6) Thus, God’s act to give grace is not absolutely necessary.

Thus far, the overwhelming majority of Christian theologians will affirm premises (4) through (6) as well as (1) through (3). These premises will be affirmed by proponents and critics of divine simplicity.

Here is another premise that both groups of theologians will affirm. Most theologians say that God’s existence is absolutely necessary. God has to exist, and cannot fail to exist. Nothing, not even God Himself, can make Him fail to exist. This idea can be stated as follows.

7) God’s existence is absolutely necessary.

I wish to focus on one more premise that proponents and critics of divine simplicity can agree upon.

8) Anything that is identical to God’s existence must be absolutely necessary.

Critics and opponents must agree to premise (8) on pain of violating the strict philosophical notion of identity. Proponents of divine simplicity need strict identity in order to maintain the various identity claims that they make in the doctrine of divine simplicity. Moreover, defences of divine simplicity will often assume (8) by saying that divine simplicity guarantees that God’s essential attributes are absolutely necessary. For example, a proponent of divine simplicity might say that God’s omnipotence is absolutely necessary because it is identical to God’s existence. They will then go on to say that anyone who rejects divine simplicity has no way to guarantee that God’s omnipotence is absolutely necessary.

Now that I have established a set of premises that proponents and critics of simplicity can agree on, it will be helpful to focus on premises that only proponents of divine simplicity can affirm. Here is a set of premises that must be affirmed by anyone who holds to divine simplicity.

9) All of God’s actions are identical to each other such that there is only one divine act.

10) God’s act to give grace is identical to God’s one divine act.

11) God’s one divine act is identical to God’s existence.

Thus far, all of this is explicitly endorsed by proponents of divine simplicity. Yet, here is where the conflict between divine freedom and divine simplicity starts to show. In what follows, I will show how the addition of divine simplicity contradicts premises (2), (5), and (6). In other words, divine simplicity contradicts the claims that God is free, that God can refrain from acting to give grace, and that God’s grace is not absolutely necessary.

Premise (8) tells us that anything that is identical to God’s existence is absolutely necessary. Premises (9) through (11) tell us that God’s act to give grace is identical to God’s one divine act, which in turn is identical to God’s existence. This entails the following conclusion.

12) Therefore, God’s one divine act is absolutely necessary.

This is not a desirable entailment for Christian theology. In order to show why this is undesirable, allow me to unpack the entailments from (12).

13) If God’s one divine act is absolutely necessary, then God’s act to give grace is absolutely necessary.

From premise (12) and (13) we get this conclusion.

14) Therefore, God’s act to give grace is absolutely necessary.

(14) puts the proponent of divine simplicity in a very tight spot because (14) contradicts premise (6). Again, premise (6) says that God’s act to give grace is not absolutely necessary. To make matters worse, with premise (4) and (14) we get the following.

15) Therefore, God cannot refrain from acting to give grace.

Premise (15) contradicts premise (5). Recall that premise (5) says that God can refrain from acting to give grace. That is a problem. But the contradictions run even deeper. From premise (15) and premise (1), we get the following conclusion.

16) Therefore, God is not free.

Premise (16) contradicts premise (2), which says that God is free. That is a serious problem for Christian theology.

Let me clarify what has just happened. I started by pointing out eight different premises that proponents and critics of divine simplicity can agree on. These are premises about God’s freedom, grace, and necessary existence. Then I pointed out three different premises that only divine simplicity can affirm. What I have just shown is that one can derive three contradictions from God’s freedom, grace, and necessary existence when they are combined with divine simplicity. In order to avoid these three contradictions, a Christian theologian will need to deny several premises in the argument. But which ones should a Christian theologian deny? In the remaining sections, I will try to anticipate different strategies for removing these contradictions.

Deny Divine Simplicity

The easiest way to avoid the three contradictions is to deny premises (9) through (11). You will recall that those premises contain the explicit teachings of divine simplicity. On this strategy, one removes the contradictions by denying the doctrine of divine simplicity. This is the strategy that I endorse. It is my contention that denying divine simplicity is the only way to avoid the three contradictions.

However, proponents of divine simplicity are very clever, and they might find a hole in my argument somewhere. So I shall consider some common strategies from proponents of divine simplicity to avoid the contradictions.

The Cheap Mystery Strategy

By far, the most common response to arguments like mine is to invoke the mystery card. The mystery card can take several forms. On the first version of the mystery card, the proponent of divine simplicity might say that it is just a mystery as to how God can be free and simple. Call this the cheap mystery card. This mystery card is cheap because it fails to specify which premise in the argument that it rejects. Thus, the contradiction stands. If one has a contradiction derived from her own beliefs, appeals to cheap mystery do not remove the contradiction. Instead, they leave the incoherence intact.

Sometimes the cheap mystery card looks more plausible than it really is because it appears to have a rational basis. A proponent of divine simplicity might say that she has good arguments in favour of affirming God’s freedom, and she has good arguments in favour of God’s simplicity. She might say something like, ‘Look, reason pushes me to affirm that God has both of the attributes of simplicity and freedom. It is just a mystery as to how the two are reconciled to one another.’

Despite whatever arguments one may have in favour of affirming that God has both of these attributes, one has still not removed the contradiction. The contradiction is derived from a combination of freedom and simplicity. The contradiction demonstrates that it is impossible for any being to have both of those attributes. One cannot have evidence or arguments in favour of an impossible model of God.

Moreover, appeals to cheap mystery can be used by absolutely anyone in the face of any theological objection. Thus, they prevent any progress within theology. No advances in our understanding of God are made by appeals to cheap mystery.

The Mysterious Language Strategy

There are other versions of the mystery card. Other versions of the mystery card focus on the inability of our language to accurately describe God. To be sure, I think it is plausible that there are limits on the ability of our language to accurately describe God, but I must confess that I don’t know what those limits are. What is worrying is that theologians can sometimes point out the limitations of human language at suspiciously curious moments, such as in the face of an objection that they cannot answer. Call this the mysterious language card. On some versions of this strategy, one will see theologians exhibiting a great deal of confidence in the ability of human language to accurately describe their preferred model of God, only to take this confidence back when objections and contradictions rear their ugly head.

On this strategy, one might say God’s freedom is mysterious, and that it is nothing like ours. Perhaps a proponent of divine simplicity will play this card and reject premise (1) in the argument, and the definition of divine freedom that (1) is presupposing. Perhaps she will say that God’s freedom doesn’t have to involve the ability to do otherwise, and thus God need not be able to refrain from giving grace in order to be free. This strategy is saying that God cannot refrain from giving grace, but somehow, mysteriously, this grace is a free act of God’s.

This strategy has the advantage of actually specifying which premise in the argument that it is rejecting. However, this strategy has the distinct disadvantage of gutting the doctrine of divine freedom and grace of its content. The very notion of grace is a gift that God does not have to give. I must confess that if God cannot refrain from giving grace, then I have lost my grasp on the meaning of grace. Perhaps this is a personal problem of mine that I cannot grasp this mysterious meaning of grace. However, I suspect that entire systems of theology will need to be revised if grace is going to be understood as something that God cannot refrain from giving. What will those revised theological doctrines look like? It is a mystery to me.

The Modal Mystery Strategy

There is another way that one can play the mystery card. A proponent of divine simplicity could reject premise (8) by saying that there is mystery in our understanding of necessity. Call this the modal mystery card. On this strategy, one admits that God’s act is identical to God’s existence, but denies that they have the same kind of necessity. The proponent of this strategy says that it is a mystery as to how God’s act and existence do not share the same kind of necessity. The proponent of this strategy will try to say that God’s existence is absolutely necessary whereas God’s act is only hypothetically necessary, all while somehow being identical to each other.

In reply, I say that this is not a mystery. Rather, this is straightforwardly incoherent. Two things cannot be strictly identical and fail to have the same kind of necessity. Allow me to explain.

In many traditional theological systems, and within contemporary modal logic, theologians will distinguish between absolute necessity and hypothetical necessity. Earlier, I noted that a thing is absolutely necessary if it has to be that way. Something is absolutely necessary if it cannot be any other way. This is the kind of necessity that most theologians predicate of God’s existence.

Hypothetical necessity is different. Something is hypothetically necessary if it must follow from some prior conditions. Those prior conditions do not have to be necessary themselves. Most theologians wish to say that God’s act of creating the universe is an example of hypothetical necessity. They will say that God does not have to create the universe because God is free. Yet, they will say that if God does freely chose to create the universe, then the universe must come into existence. The universe could not fail to come into existence if an omnipotent being wills it to exist.

I think that the distinction between absolute and hypothetical necessity is an important one for theology. However, the distinction presupposes non-identity. Nothing that is absolutely necessary can be identical to something that is hypothetically necessary. Thus, the modal mystery card is a non-starter.

Conclusion

I have argued that divine simplicity is incompatible with divine freedom and grace. In order to avoid this argument, one will need to identify which premise in the argument she rejects, and explain why she rejects it. I look forward to the responses from my dialogue partners as we explore the doctrine of God together.

R.T. Mullins (PhD, University of St Andrews) specializes in philosophical theology. He has published on topics such as God and time, the Trinity, the Incarnation, disability theology, and the problem of evil. His book, The End of the Timeless God was released in 2016 by Oxford University Press. He has previously held research and teaching fellowships at the University of Notre Dame and the University of Cambridge. Currently, he is a research fellow at the University of St Andrews. His forthcoming book, God and Emotion is due for publication in 2020. He is the host of The Reluctant Theologian podcast. When not engaging in philosophical theology, he is often found at a metal show. Checkout more at rtmullins.com.