#866 The Case for Unitarianism and the Logical Relation of Identity

Dr. craig’s response

Thank you for your question, Agustin!

By way of review, I have argued that the New Testament (NT) teaches that (i) there is exactly one God and (ii) there are exactly three persons who are properly called God. By “properly,” I mean something like “in truth,” where truth is intended to be literal truth. Christ, in particular, is not called God merely hyperbolically or figuratively in the way in which intermediate figures in Judaism, such as exalted patriarchs and principal angels, are only improperly called God. He is called God in the same sense that the Father is called God. This is what I refer to as “the biblical doctrine of the Trinity.” I think that I have shown that the NT does teach this doctrine (see the forthcoming book). If I am right about this, it follows that Unitarianism is false, since Unitarianism denies (ii).

Christian philosophers Jeff Brower and Michael Rea observe that there is nothing particularly philosophically problematic about what I’ve called the biblical doctrine of the Trinity.

The central claim of the doctrine of the Trinity is that God exists in three persons – Father, Son, and Holy Spirit. This claim is not problematic because of any superficial incoherence or inconsistency with well-entrenched intuitions. Rather, it is problematic because of a tension that results from constraints imposed on its interpretation by other aspects of orthodox Christian theology. . . neatly summarized in . . . the so-called Athanasian creed.[1]

It is these accreted constraints that occasion philosophical problems for the biblical doctrine of the Trinity. So one finds that philosophical articles on the subject of the Trinity very typically begin with quotations from later conciliar formulations of the doctrine, particularly the apparently incoherent Athanasian creed.

The biblical doctrine of the Trinity, by contrast, becomes logically problematic only when statements such as the following:

are construed as identity statements. This assumption lies at the heart of Tuggy’s case for Unitarianism.

But, as I explained, trying to generate logical problems from NT affirmations like (1) and (2) requires a modern grasp of the logical relation of identity that the ancients in general and the NT writers in particular did not have. This fact illuminates Arthur Wainwright’s provocative suggestion that most of the authors of the NT were not even aware of “a Trinitarian problem,” much less interested in a solution to it.[2] That is to say, the mutual relationship of Father, Son, and Holy Spirit just did not appear problematic to them. Wainwright thinks that Paul, the author of Hebrews, and John were aware of a problem, though John alone clearly conceived it and sought to provide a solution to it (presumably, in his doctrine of the immanent Logos).

Now, as you note, my claim might seem at first implausible. What, after all, could be more obvious than that a = a, that everything is identical to itself? Doubtless, NT writers were intuitively aware, for example, that the Father is the Father and not the Son. But the identity relation is far more subtle and difficult than that, and a fairly sophisticated understanding of identity is necessary in order to discern a problem of the Trinity.

The relation of identity is today understood to be the strongest equivalence relation, holding between an object and itself and nothing else, an irreducible relation characterized by reflexivity (a =a), symmetry (if a =b, then b =a), and transitivity (if a =b and b =c, then a =c). As such, it is also a Euclidean relation (if a = c and b = c, then a = b). It thus entails what has come to be known as Leibniz’s Law of the Indiscernibility of Identicals, which may be simply stated as

In the ancient world, philosophers had scant understanding of the identity relation. A prescient Aristotle wrote briefly in his Topics,

Again look and see if, supposing the one to be the same as something, the other also is the same as it; for if they be not the same as the same thing, clearly neither are they the same as one another. Moreover, examine them in the light of their accidents and the things of which they are accidents; for any accident belonging to the one must belong also to the other, and if the one belong to anything as an accident, so must the other also. If in any of these respects there is a discrepancy clearly they are not the same (Topica vii.1 (152^a30).

Here Aristotle not only grasps the relation of identity as a reflexive, symmetric, and transitive relation, but, incredibly, anticipates Leibniz’s Law of the Indiscernibility of Identicals.  The historians of logic William and Martha Kneale observe, however, that these isolated comments of Aristotle went largely unnoticed, his insights being rediscovered only centuries later, and so it is “not surprising that he does not generally get any credit for them.”[3]

If ancient philosophers were largely ignorant of the relation of identity, how much more the missionary-pastors who authored the NT! For example, while they believed that the Son is God, they would have balked at the assertion that God is the Son, as required by the symmetry of the identity relation, which suggests that we misinterpret them if we construe their initial belief as an identity statement. Similarly, the same author who affirms that the Father is “the only true God” (Jn 17.3) also affirms that Jesus Christ “is the true God and eternal life” (I Jn 5.20), but he did not therefore think that the Father is Jesus Christ, which again suggests that we misconstrue these affirmations if we interpret them as statements of identity. Or again, the fact that the NT authors affirm that the Father is God and that Jesus Christ is God does not lead them to infer that Jesus Christ is the Father, in accordance with the symmetry and transitivity of identity, showing once more that it is an anachronistic hermeneutical error to import a modern grasp of the identity relation into these authors’ statements.

As if this were not enough, add to the mix the ambiguity of the word “is” in ordinary language, whether Greek or English. Philosophers have distinguished multiple meanings of the word, including not only the “is” of identity (“Mark Twain is Samuel Clemens”), but also the “is” of predication (“Jones is the tallest man in North Dakota”), and the “is” of constitution (“The statue is the block of marble”).

This inherent ambiguity of ordinary language can make it very difficult to discern just when an author, especially one utterly unacquainted with the modern relation of identity, intends to make an identity statement. Philip Bricker rightly warns, “Surface grammar often misrepresents the underlying logic: one must beware inferring logical from grammatical form.”[4] He cautions in particular that “We should not confuse identity with the relation of co-designation, the relation that holds between singular terms whenever those terms designate the same object.” This fallacy is committed by those who, like Tuggy, assume too readily that every NT use of the proper name “God” is intended to assert an identity statement between God and the Father.

I think you can see that what “the unitarian needs to make his case” is a whole lot more than “a basic, intuitive logical relation of identity” as simply a = a. Obviously the NT authors might have wondered why there are not three Gods. But God’s unicity was already given by Jewish monotheism, which they presupposed. In order to find it problematic that the one God is Father, Son, and Holy Spirit one would have to have a modern understanding of the identity relation, which NT authors did not have. Given NT authors’ lack of a modern grasp of the identity relation, we must beware of overreading them. It is hardly surprising that they did not find their own trinitarian statements about the Father, Son, and Holy Spirit problematic.

So when one says that the Father is God, one is not making an identity statement. When one says that the Son is God, one is not making an identity statement. Rather this “is” is an “is” of predication, not of identity. For example, if I say, “Elizabeth is Queen,” I'm not saying that Elizabeth is identical to the Queen. I am saying she holds the office or the role or the title of being Queen. But it would be possible for there to be co-regents. Sometimes that happens. There's more than one king or more than one queen. So when we say, “Elizabeth is Queen,” we're not making an identity statement; we're making a predication. You're predicating being Queen of Elizabeth. You're making a statement like this: “Elizabeth is regal.” You're not making an identity statement; rather you're assigning a predicate.

So when NT authors say that the Father is God or the Son is God, those are not identity statements; rather they are predications. They are predicating properties of the Father and the Son, namely the property of being fully divine.