Trinity Sunday

And now, dear friends, let us elevate our minds to higher and nobler things. Today is Trinity Sunday. We Christians worship one God in Trinity and Trinity in Unity, neither confusing the Persons nor dividing the substance. But how can this be? Isn’t this doctrine either self-contradictory or unintelligible?

It is neither. Suppose, following Richard Cartwright in his important paper “On the Logical Problem of the Trinity,” we take as a summary of Trinitarian orthodoxy the following set of propositions:

1. The Father is God.
2. The Son is God.
3. The Holy Spirit is God.
4. The Father is not the Son.
5. The Father is not the Holy Spirit.
6. The Son is not the Holy Spirit.
7. There is exactly one God.

Is this not an inconsistent set? Not as it stands, it isn’t. For we need to know (among other things) what the force of “is” is in each of these propositions. (Bill Clinton wasn’t all wrong, as it turns out.) If (1) is glossed as “The Father = God” and (2)-(6) are interpreted accordingly, then we would of course have an inconsistent set. But that is not how Trinitarian theologians understand “is” in this context; that is to say, they are not using it to express what modern logicians understand by the identity relation. If instead we interpret (1)-(3) as “The Father is a God,” “The Son is a God,” etc., and (4)-(6) alone in light of the identity relation – so that (1)-(6) are understood to assert that Father, Son, and Holy Spirit are distinct members of a class of “Gods” – then, again (given (7)), we have an inconsistent set. But, again, that is not what Trinitarian theologians mean by “The Father is God,” etc.

Doesn’t that exhaust the possibilities? By no means. As Cartwright notes at the end of what is a decidedly skeptical essay, there are at least ten other possible construals of “is” that would have to be considered before one could judge that the doctrine contains an implicit self-contradiction. But suppose we considered those ten, and any others that might be brought forward, and none of them yielded an internally consistent set. Would that show that the doctrine is self-contradictory? No, because there might still be a construal on which they are consistent, but one which we have not stumbled upon, perhaps even one we will never stumble upon.

But doesn’t that avoid self-contradiction at the cost of intelligibility? It depends on what you mean. Something could be unintelligible in itself, or unintelligible only for us. What is unintelligible in the first sense has no coherent content; what is unintelligible in the second sense has a coherent content, but one which, given our cognitive limitations, we are incapable of grasping. Trinitarianism would be falsified only if it were shown to be unintelligible in the first sense, but not if it is unintelligible only in the second. Indeed, that it is “unintelligible” in the second sense is exactly what Trinitarian theologians mean when they say that the doctrine of the Trinity is a “mystery.” They do NOT mean that it contains a self-contradiction, or that it is unintelligible in itself, or even that we cannot have any understanding of it at all. They mean instead that the limitations of our minds are such that, though it is perfectly consistent and intelligible in itself, we cannot adequately grasp it.

Hence even to show that no construal yet given of (1)-(7) yields a consistent set of sentences would not be to show either that the doctrine of the Trinity contains a self-contradiction, or that it is unintelligible in the sense in which skeptics say it is.

But wouldn’t this at most show only that the set (1)-(7) might be consistent and intelligible? Could we ever have rational grounds for believing that it really is consistent and intelligible (even if we couldn’t see how)? Sure we could. We would have such grounds if we had grounds to believe that the doctrine of the Trinity is true. For if it is true, then it must be logically consistent and intelligible in itself, even if not fully intelligible to us. And our grounds for believing it to be true and (thus) consistent and intelligible would be even stronger if we had independent grounds for believing that it is exactly the sort of thing we should expect to find mysterious if it were true.

As it happens, we have all of these further grounds. For we can know through pure reason that God exists, and we can know through pure reason that God has the various attributes traditionally ascribed to him. (See The Last Superstition for the executive summary.) In particular, we can know that He is Pure Act, Being Itself, the Supreme Intelligence, and absolutely simple. But given the way the human intellect works (e.g. by grasping things in terms of genus and species), and given that God’s possession of these attributes places Him beyond any genus, we can also know that it is impossible for the human intellect fully to grasp the divine nature. Hence we can know that the doctrine of the Trinity is precisely the sort of thing we should expect to find mysterious even if it is true, indeed especially if it is true.

So is it true? Well, consider further that the immateriality and immortality of the soul are also knowable through pure reason. (Again, see TLS.) And with the existence of God and the immortality of the soul in place, the stage is set for the defense of the resurrection of Jesus Christ as a historical fact. For while the evidence for Christ’s resurrection is strong even apart from these pieces of background knowledge, it is overwhelming in light of them. If we already know through pure reason that there is a God who could raise a man from the dead and an immortal soul the re-embodiment of which could guarantee that the resurrected man is the same man as the one who had died, then the standard dodges skeptics use to avoid accepting the resurrection (e.g. Antony Flew’s Humean appeal to the a priori improbability of resurrections) won’t fly.

Now, we can also know (I claim) that Christ claimed to be divine, and made reference to the Father and the Holy Spirit as Persons distinct from Himself. Since He was resurrected – something which (based on the correct metaphysical analysis of the soul and its relationship to the body) only God could accomplish – it follows that a divine seal of approval was, as it were, placed upon Him and upon His teaching. Hence we can infer that what He taught – which includes (by implication) the doctrine of the Trinity – must be true.

Obviously all of this raises many big questions. I realize that. I’m summarizing. (See the work of writers like William Lane Craig and Richard Swinburne, and the esteemed Tim and Lydia McGrew’s recent lengthy article on the resurrection, for some of the details.) But supposing all of this can be made out, as I claim it can be, the doctrine of the Trinity would be rationally justified. To be sure, we would believe it on faith, but where “faith” means, not a groundless “will to believe,” but rather the acceptance of the teaching of an authority whom reason itself has told us is infallible.

More can be said; again, to say that the Trinity is a mystery does not mean that reason cannot make any headway at all in understanding it. The great Trinitarian theologians have real insights to impart to us. (See here for part of Brian Davies’ fine summary of Aquinas’s Trinitarian theology in chapter 10 of The Thought of Thomas Aquinas.) There is also the crucial consideration – powerfully emphasized and developed by Gyula Klima in a series of articles – that the work of the medieval philosophers cannot properly be understood apart from the logical and semantic doctrines they were committed to, doctrines often different from, but every bit as rigorous and defensible as, the logical and semantic presuppositions contemporary philosophers tend to take for granted. These doctrines must inform our understanding of their work on the Trinity no less than our reading of their more purely philosophical works.

We should keep in mind too that several prominent and formidable contemporary philosophers of mind – Chomsky, McGinn, and Fodor, for example – have at least tentatively put forward a kind of “mysterianism” of their own as a way of explaining why certain phenomena seem incapable of naturalistic explanation. It may be, they say, that our minds are closed off from an understanding of (say) consciousness. Perhaps there is a correct naturalistic explanation, but one our minds cannot grasp given the limits nature has put on them. Now Trinitarians are often accused of resorting to obfuscation or mystery-mongering as a desperate and dishonest way of avoiding the falsification of their creed. And yet somehow these naturalistic “new mysterians” are never themselves accused (at least not by their fellow naturalists) of intellectual dishonesty or desperation. Funny, that. In any event, if there is a God, then given what He is supposed to be, it is even less likely, indeed far less likely, that our minds would be able adequately to grasp Him than it is that we should be able to understand consciousness (or whatever). That is to say, if an appeal to “mysterianism” is a plausible way of defending naturalism – I’m not saying it is, but suppose it were – it is far more plausible as a defense of Trinitarianism.

There is this difference, though: Naturalism is demonstrably false (again see TLS), while Trinitarianism is true. So, mysterianism is a moot point in the first case. Awful luck for naturalists, but there it is.

Anyway: The skeptic’s claim that the doctrine of the Trinity is rationally unjustifiable – a claim which formed a key component of my own youthful atheism – is itself unfounded. God is real, and He is Father, Son, and Holy Spirit.