To put it mildly the Trinity is a difficult concept to grasp. To say there is one God and that the Father, the Son and the Holy Spirit are equally God, and equal to one another, yet are different from one another clearly stretches logic. This is something that even Trinitarians implicitly admit when they call the Trinity a “mystery”, that is, a theological truth beyond human logical comprehension. Even though they will heartily affirm it, the overwhelming majority of Trinitarian Christians cannot make sense of it. Most believers tend to avoid it altogether often out of fear of flirting with heresy if they press the matter just a little further. It is therefore unsurprising that both Christian and non-Christian critics tend to primarily attack the rationality of it.
I am a Christian who does not believe in the Trinity but I do not find the logical argument against the Trinity that convincing. I do still think it is a serious problem with the doctrine, especially combined with other problems, but I personally do not think it is the most potent standalone argument against the Trinity. In my view, there are better theological arguments, which I am going to address in two parts. In the first part I want to explore the weaknesses of the logical attack and in the second part how to strengthen it.
I think the reason why most critics of the Trinity do not realise the logical argument is not as strong as other arguments is because they misunderstand what Trinitarians mean when they say it is a mystery. Quite understandably, it seems like a cop out to call something that is apparently logically inconsistent a mystery. There are other difficult topics but few that Christians jump through as many hoops to defend. There is a reason behind this seeming irrationality.
What critics fail to understand is when Trinitarians call their doctrine a mystery is that they are fundamentally making a philosophical claim about the limitations of logic as it relates to the nature of truth. Since the Trinity is a highly philosophical doctrine, I think it is important to understand the philosophical claims proponents are making about the nature of truth.
In modern philosophy, there are five major theories of truth but two that are most dominant. They are the correspondence and the coherence theories of truth, both of which presuppose that truth is a property of statements. People are actually very familiar with these theories and use them every day. The correspondence theory, as the name suggests, is that truth is whatever corresponds to reality. The coherence theory on the other hand says something is true if it is logically consistent with other true claims. So roughly speaking correspondence is about “facts” while coherence is about “logic.”
While these are rather intuitive theories of truth, that is to say something is true if it is factual or logical, philosophers have pointed out they can be at odds with one another. Certain statements might correspond to reality but are logically inconsistent with one another. On the other hand, some beliefs are logically consistent but do not correspond to reality. “Facts” and “logic” do not always agree when it comes to discerning the truth. For example, in a court both sides draw on the same evidence in making opposing claims. One party could make a logically consistent argument that fits the evidence but it may not actually be what happened. It is also possible the other party makes an inconsistent argument yet it actually corresponds to what happened.
The tension between these theories of truth helps explain how the logical hurdle of the Trinity is cleared by proponents. The Trinitarian argument is it might not seem to meet a coherence standard of truth but it does correspond to the reality of God nevertheless. As puzzling as this might seem, it is not a farfetched idea. If our experience of the world contradicts what seems rational, and there is no evidence to suggest our perception is wrong, we will most likely accept what we have perceived as true. Correspondence is the most dominant theory of truth. So when the Trinity is called a mystery, it is not necessarily a “logical” claim being made but a “factual” one. This is why despite all the logical difficulties of the doctrine it is nevertheless asserted as true.
Even in science, which is highly logical, there are many time correspondence takes precedence over the coherence model. The late doctor and Christian apologist Nabeel Qureshi an article writes,
…there are certain things in science that we know to be true, but are inexplicable at the macro level.
He used the example of chemical resonance structures as one argument for the credibility of the Trinitarian claim that one thing can equally be three different things at the same time. As Qureshi himself suggests in the article, I think there are better examples for the Trinitarian case from quantum physics because it was developed to explain observable macroscopic phenomena in physics that seemingly defied reason. Superposition (made famous by Schrödinger’s cat) and entanglement are two quantum phenomena that seem logically impossible yet they have all experimentally found to be true. Both these phenomena have real world applications in the development of quantum computers, where there was a recently breakthrough that was widely reported. Wave-particle duality for example, the famously counterintuitive notion that physical things have both the characteristics of waves and particles, is practically applied in electron microscopes where electrons behave like light waves.
There are many other examples of quantum phenomena that are seemingly irrational but nevertheless true. As celebrity astrophysicist Neil deDegrasse Tyson often says, the universe is not obligated to make sense to you. Trinitarians levy the same kind of argument. If the universe is not obligated to make sense to us, how much more its creator? They are therefore presenting the Trinity as simply the discernible nature of God’s being. Since the creator transcends the creature, the Trinitarian nature of God transcends human comprehension. Even though they consider the doctrine the very pinnacle of systematic theology, the logical awkwardness of Trinitarian language is as it should be since God far surpasses the best of human language and reason.
As bizarre and confusing as quantum theory is, even for professional physicists, it is the most successful scientific theory that has been developed so far, having been observed and experimentally confirmed countless times as well as having real world applications. Similarly, Trinitarian theologians argue that their doctrine corresponds to the facts about God even though it is not quite coherent in terms of human logic. While acknowledging and even embracing these logical difficulties, they are not saying the Trinity is completely devoid of logic either.
When scientists were beginning to make sense of what we now know as the quantum realm, they slowly realised that it operated on different rules from the world of classical physics. Just as quantum theory has its own logic, it could be said that the doctrine of the Trinity has its own peculiar logic. Theologian and former archbishop of Canterbury Rowan Williams argues that those who formulated the Trinity were not just importing Greek thought but making novel philosophical innovations of their own as well in how they developed the doctrine. It is a logic that does not fully make sense to us but you could say that in some sense the Trinity is its own logic.