“We Believe in One God”

Christianity is a philosophically difficult religion. Not only are we asked to believe that God has taken on a human nature such that one Person is both God and man, but we are also to believe that God is three Persons in one substance. We must avoid polytheism – there is only one God, not three. And that one God is the same one and unique God Who, the first commandment tells us, alone is to be worshipped. A difficult doctrine indeed. You might just throw up your hands and cry, “It’s a mystery!” And probably everyone who has encountered these doctrines does, and should, allow that the human mind is not going to plumb the depths of the divine being. But, as St. Augustine points out, you cannot love what you do not know. And we are commanded to love God.  How, then, can we approach the unity of the triune God?

Many of the great theologians and philosophers who meditated on what the “oneness” of God might mean, thinkers like St. Augustine and St. Anselm and St. Thomas Aquinas, took the oneness of God so seriously that they subscribed to the Doctrine of Divine Simplicity (DDS) – a view standard among Christian philosophers throughout the Middle Ages, but subject to lively debate among philosophers of religion today. The DDS holds that God is absolutely simple. He is not composed of any parts at all. All of His attributes – for example His omnipotence, omniscience, and perfect goodness – are ultimately the same and identical to His divine nature. All of His activities and knowledge are ultimately the same and identical to His divine nature. And that entails that God is immutable. It cannot be the case that there is God in his perfect nature, but then, as something added on and changing, his activities and knowledge. Difficulties piled on top of difficulties! Yet, at least according to St. Augustine, St. Anselm, and St. Thomas Aquinas, there is powerful reason to accept the DDS and human knowers can have some grasp of the simple nature of God. All of his attributes – for example His omnipotence, omniscience, and perfect goodness – are ultimately the same and identical to his divine nature. Click To Tweet

Before offering the briefest sketch of why one might want to accept the DDS and how one might try to make some sense of it, three preliminary remarks are in order. The first has to do with philosophy in general. Anyone who has studied philosophy knows that a big part of the job is to take something ordinary, something everybody is familiar with and encounters in everyday life, and then to think hard about it. And as soon as you start to think hard about anything it ceases to be ordinary and gets bizarre very fast. St. Augustine in his ground-breaking meditation on time in his Confessions 11 says that as long as you don’t ask him what time is he thinks he knows, but when you ask him to explain what it is he finds that time is deeply puzzling. And the same goes for the other issues that philosophers find interesting.

Some Preliminary Remarks

One such issue, relevant to the present discussion, is the issue of “mereology”: What does it mean for something to be a part or a whole? How do we determine what counts as a single, discreet, unified object? But we all deal successfully with parts and wholes and unified objects every day, don’t we, so how hard can those questions be? Well, a glance at contemporary mereology proves that they are very hard indeed. Some philosophers hold that there are no unique objects, some that only a living thing can be a unique object, and some that any assortment of things – your laptop, the moons of Jupiter, and the Taj Mahal all combined – is a unique object. And those are just a few of the long list of theories. It is true that common sense – the vague, unexamined assumptions we operate with as we go about our daily business – finds the Trinity and the DDS hard to accept. But upon closer consideration, there is no philosophical consensus on parts and wholes and objects even regarding the things we find around us every day, so the threeness and oneness of the Trinity and the DDS are not unique in being difficult to grasp.

The next preliminary point is that God is the absolute source of all. Of course. Who doesn’t say that? But what that means is that He transcends the limitations of his creation. He is not to be categorized by the categories of nature. He is not like a human being only much larger and smarter and more powerful. Were one to insist that no claim regarding God should be accepted unless we – little human beings – can imagine how it works, make a picture of it in our minds, we would be circumscribing God and envisioning a diminutive divinity. But we do not want to fall into the opposite error and propose that God cannot be spoken of or thought of meaningfully. As the source of all God has created a vast and grand mirror of His nature in which we can observe, as innumerable reflected sparks, the wonder of his being. Humans especially are made in the image of God, and in considering our own natures we can get a glimpse of the simple Trinity.

The last preliminary is this: In the words of St. Anselm, “God is that than which no greater can be conceived” (Proslogion 2 – Which is not to say that we can “comprehend”, wrap our minds around, God). Too obvious! If you and I, suffering the radical cognitive limitations that are inevitable in a human life, were able to think about a better, a more impressive, a more worthy of worship being than some being X, then surely X is not God. But it is this non-negotiable claim that produces the DDS.

Divine Simplicity

St. Anselm explains (and St. Augustine before him and St. Thomas Aquinas after him agree) that God must be absolutely simple for at least two reasons.

First, as that than which no greater can be conceived, God cannot be conceived to be destructible, to cease to exist. But anything with parts, whether or not it actually ceases to exist, can be conceived  to cease to exist, since, at least conceptually, the parts can be separated from one another, causing the destruction of the whole. Thus it must be understood that God is simple (Proslogion 18).Were one to insist that no claim regarding God should be accepted unless we – little human beings – can imagine how it works we would be circumscribing God and envisioning a diminutive divinity. Click To Tweet

Secondly, Anselm insists that God exists in perfect independence, that is, he does not depend upon anything not himself for his existence. He is absolutely uncaused. Now consider something composite. The classic example in the Middle Ages is the human being, defined as a rational animal. But being rational and being an animal are two different attributes. And a person’s rationality is not just the same thing as himself, nor is his animality.

Thus the human person depends upon these qualities for his existence. (If you don’t like “rational animal”, you can make the same case with atoms and sub-atomic particles, all conforming to the laws of nature, behaving in ways describable by mathematical equations – without all of which you could not have a human being.) Things with parts depend for their existence upon those parts, and so cannot be independent the way God is. God, then, must be simple (Monologion 17).

The Simple Trinity

But how can God possibly be simple, if he is three Persons? First of all, “Persons” should not be understood as we might analyze the term in common usage today where in order to be a person you must be a unique and discreet individual separated from other persons. Assuming that the Church Councils are guided by the Holy Spirit, we know at least this – “Persons” in the conciliar statements allows for three “Persons” to be united in one substance. (Where “substance”, too, is a tricky term.) Unimaginable? Certainly we cannot picture this to ourselves.

And yet St. Augustine in his On the Trinity provides an analogy to help us understand. Consider, he says, the closest reflection of the divine that you are likely to run into here in the natural world. It is something immediately present to you – your own mind! In order to think anything at all, three aspects or facets of your mind must be operating. There is your intellect, actively entertaining a concept. But that would be impossible if your memory were not actively supplying that concept to your intellect. And further, there must be will, since if you did not actively desire to be entertaining the concept, you would not be doing so and memory would not be supplying it. Memory is analogous to the Father, intellect to the Son who proceeds from the Father, and will to the Spirit who proceeds from both and connects them. Consider carefully this dynamic interplay involved in the thinking of a thought and you see that there is a relationship between intellect, memory, and will, such that they can be distinguished as three, and yet here is just your one mind, thinking. 'Persons' should not be understood as we might analyze the term in common usage today where in order to be a person you must be a unique and discreet individual separated from other persons. Click To Tweet

St. Anselm, embracing the Augustinian approach, goes perhaps even a step further. In his Monologion he tries to prove that God must be a simple Trinity. In offering this “proof” Anselm is much more ambitious than most of the Medieval Philosophers who, like Thomas Aquinas, hold that one must believe that God is a Trinity as a matter of faith. But even if Anselm has not proven that God must be a Trinity (as an Anselm fan, I do not say he hasn’t), his spelling out the case can help us to grasp, however dimly, the mystery of the Trinity.

Anselm starts by noting that creation cries out that it comes from an ultimate source, the Highest Being. This Highest must produce His creation through reason, a “Word” which is the pouring forth of the ideas in the mind of the maker. But this Word is simply the expression of the Highest, and hence is not separate from or different from the Highest. The Word is the Highest as creating. And this Word is connected to the Highest through Love. And this Love, as manifested between the Highest and the Word, is identical with them. The Highest, Anselm goes on to argue, can properly be called “Father”, the Word can be called “Son”, and the Love can be called “Spirit”.  Anselm concludes the Monologion by reminding us of Augustine’s point that we can appreciate this dynamic, simple Trinity through the mirror of our own minds.

Both Augustine’s analogy and Anselm’s “proof” portray the Trinity not so much as a thing – an object like a cat or a car – but as a “doing”; the mind thinking, God expressing and loving himself. And an action – like thinking a thought – can contain discernible elements which are nonetheless aspects of the one action, not parts like the tail of a cat or the engine in the car. St. Thomas Aquinas in his Summa Theologiae (Part 1, Question 3) insists on divine simplicity, and argues that God must be pure act. In order for a mere thing to do something – the cat yawns, the car moves – it must contain some element of potentiality, some quality or ability not yet fully realized. But God is perfect. There are no unfulfilled corners in the divine being. His very nature is to be his act of existing. And within that act, distinguished by their relations to one another (Summa Theologiae, Part 1, Question 29) are three Persons. Still extremely difficult. Still impossible to picture. But that is to be expected from the source of all. Click To Tweet

St. Augustine, St. Anselm, St. Thomas Aquinas, and many of the other great theologians and philosophers of Christendom defend the unity of the triune God by invoking the DDS. Were one comfortable with the thought that God is composed of parts, those parts might quickly devolve into three gods – a conclusion that orthodoxy must avoid. But if the divine unity is the unity of a single, perfect action, it can involve internal dynamic relations allowing for a distinction of Persons in the unity of Substance. Still extremely difficult. Still impossible to picture. But that is to be expected from the source of all.