According to orthodox Christianity, the doctrine of the Trinity is the central doctrine of the Christian religion. At minimum, belief that the one God who created the universe is triune is what distinguishes Christianity from other forms of monotheism, such as Judaism, Islam, and Sikhism. Though orthodox Christians all agree that the one God, the God of Abraham, Isaac, and Jacob, is triune, they do not all agree on how to make sense of this claim. In this series of articles, I plan to provide readers with an overview of some of the most noteworthy models for making sense of the Trinity on offer.
Before getting started, though, it is important that we define some important terms. In particular, we need be clear on what we mean by “model,” since we are discussing models of the Trinity. But we also need to discuss some of the basic trinitarian lingo, or grammar, that governs our talk about the Trinity. Certain terms in this second category involve things such as “nature,” “substance,” “essence,” and “person.” Orthodox Christians all claim that there is numerically one God with one divine nature/substance/essence that exists as three persons who all relate to one another in such a way that there is exactly one God and not three Gods. In order to understand how the various models of the Trinity work, we need to have a basic understanding of these terms.
Let’s begin with the term “model.” When I use this term, I’m using it in a very specific way, the way that Oliver Crisp uses it in his essay on theological modeling in the T&T Clark Handbook of Analytic Theology. In that essay, Crisp defines a “model” as “simplified conceptual frameworks or descriptions by means of which complex sets of data, systems, and processes may be organized and understood” (Crisp 2021, 9). In other words, a “model” is just way of taking complex data and conceptualizing it in such a way that it is easier to understand and grasp.
Scientists use models all the time in their work, as well do engineers, architects, and so many other vocations. For example: We are all probably familiar with the typical double-helix picture of DNA in biology books. Actual DNA doesn’t look like this. These pictures, rather, are models to help us conceptualize DNA and better understand the concept.
When theologians make models of various doctrines, they are attempting to do the same thing. We don’t usually mean for a model to be an exact representation of the doctrine we are discussing. Rather, we just want to take all of the complex biblical, theological, and philosophical data that constitute these doctrines and present them in such a way that they are more easily ascertained.
Making doctrinal and theological models is important because biblical doctrine is meant to be understood. Doctrine is not simply the product of theological nerds pontificating upon pontifications of pontifications in some ivory tower completely segregated from everyday life. No, these doctrines are crucial for helping Christians understand God and all things in relation to God. These doctrines are intimately connected with the biblical story that fills out our Christian worldview, and so they give us direction and instruction for living out our Christian lives. But doctrines can’t perform these functions in our lives if we are unable to understand them. So, it’s important that theologians and clergy dedicate some of their time to modeling doctrines to help the laity better understand them and live them out. Such is part of the task of discipling believers and shepherding God’s flock.
The doctrine of the Trinity, as you might imagine, is one of the most frequently modeled Christian doctrines in academic theology. This has no less been the case sense the advent of analytic theology, which is something I will discuss in another post at another time. The purpose of model building when it comes to the Trinity is the same as doctrinal model building writ large. Theologians develop models of the Trinity so as to help other Christians better understand this fundamental doctrine so that they can better orient their lives to their Creator and Redeemer. So, it is important that Christian theologians and philosophers continue to work on such models, further clarifying elements of ambiguity and helping us better understand the God revealed to us in Scripture—though not every model offered by theologians on the Trinity succeed in their goal.
So, what exactly are theologians trying to model when they model the doctrine of the Trinity? What are the essential elements, or data, that need to be accounted for by a model of the Trinity? We can perhaps distill the doctrine of the Trinity into three minimum claims.
There is numerically one God.
There are precisely three persons properly called God.
There are not three Gods.[1]
There are many Christians who would disagree with this minimalist definition, arguing that there are other essential components of the doctrine of the Trinity that I am missing or ignoring. These components include the eternal generation of the Son and the eternal spiration of the Spirit. Recently, however, several Christian theologians and philosophers have raised considerable biblical and philosophical objections to these two teachings, and some of these critiques merit serious consideration and raise plausible problems for these aspects of classical trinitarianism. As a result, I will stick with this minimalist definition above.
So, at minimum, a successful model of the Trinity will make more understandable that there is numerically one God, there are precisely three persons properly called God, and that there are not three Gods. But again, there are some key terms that we need to define.
Since there is numerically one God, there is going to be only one divine nature in a successful Trinity model. But what in the world is a nature? I, for example, have a human nature. Dogs have a dog nature. And trees have a tree nature. A nature is the fundamental whatness of a thing. A thing’s nature makes that thing the kind of thing that it is. What makes a dog a dog and not a tree is that it has a dog nature and not a tree nature.
Many philosophers—and I tend to think they are correct—prefer to describe natures as essences. A thing’s essence is constituted by its essential properties. An essential property is a feature that a thing has that is necessary to make that thing the thing that it is. For example: An essential property of being a human being is the property of being a mammal. There are no human beings that are not mammals. If you come across a person that is a reptile, that is not a human being; that is a lizard people, and you should probably make tracks.
Essential properties are often contrasted with what philosophers call accidental properties. An accidental property is a feature that a thing has that is not necessary to make that thing the kind of thing that it is. Here’s an example. It is a common feature, or property, for human beings to have two legs and two arms. Suppose some person—we can call him Jeff—has two arms and two legs. So far so typical. But suppose someone comes along and cuts off both of his arms and both of his legs. Is Jeff still a human being? Of course he is! His nature hasn’t changed just because his limbs have been removed. Though having two arms and two legs is a common property of human beings, it is not an essential property for human beings. These are the differences between essential and accidental properties.
So, when we talk about the divine nature, we are talking about the divine essence. There is numerically one divine essence. That is to say, there is only one such nature that has all of the essential properties for being God. These essential properties include, but are not limited to, metaphysical necessity, aseity, omnipotence, omniscience, omnipresence, moral perfection, and perfect rationality.
So, to say that there is numerically one God is to say that there is numerically one being that has the divine nature, or divine essence. So far so good. This is the basic claim for all versions of monotheism. But the doctrine of the Trinity claims more. According to the doctrine of the Trinity, there are precisely three persons properly called God. This is to say that there are precisely three persons that have the numerically one divine nature. This is where the Trinity gets hard to understand.
How can three distinct persons have the numerically one divine nature? This is the question that all models of the Trinity attempt to answer. But before we can start answering this question, we need to understand what we mean by the term person. Unfortunately, defining this term isn’t as straightforward as defining nature and essence, both of which are terms that have a pretty high level of consensus amongst philosophers. Philosophers and theologians are not as agreed upon what a person is.
The classical definition of person was proposed by Boethius, an early medieval Christian philosopher. According to Boethius, a person is a concrete substance of a rational nature. Notice that Boethius doesn’t limit this definition to human substances of a rational nature. By the way: substance, in this context, is used to describe a concrete object, like you or me, or a table, or a tree. Concrete objects are distinguished from abstract objects, the latter which being kind of like ideas or conceptual forms that we abstract from concrete objects we encounter in everyday life.[2] So, when we say that God is three persons, what we mean is that there are three concrete instances of a single divine rational nature. As we will see in later articles in this series, how Christian thinkers cash this idea out varies greatly.
So, to bring everything together: When we talk about making or building models of the Trinity, what we are doing is trying to develop a way of understanding the Trinity that makes sense of the claims that 1) there is numerically one God, i.e., there is numerically one being that has the divine nature, and 2) that there are precisely three persons, i.e., three concrete instances of a rational nature, that are properly called God, i.e., that have the one divine nature.
In the next article in this series, I will discuss the classical, or traditional, way that the church has modeled the doctrine of the Trinity. This model is often referred to as classical trinitarianism or Latin trinitarianism. This is the view of the Trinity that is the majority view during the patristic, medieval, and reformation periods of church history. Indeed, it is called the classical model for a reason.
Bibliography
“A Discussion of the Trinity and Unitarianism.” The Analytic Christian. YouTube Podcast.
Crisp, Oliver D. 2021. “The Importance of Model Building in Theology.” In T&T Clark Handbook of Analytic Theology, edited by James M. Arcadi and James T. Turner Jr., 9–19. New York: Bloomsbury.
[1] I get this minimal definition of the Trinity from William Lane Craig. He provides this definition in an exchange with Dale Tuggy on The Analytic Christian.
[2] For example, tableness is a feature possessed by every concrete table we experience. Though there are all kinds of different tables in the world, they all have something in common, namely tableness.
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