Why Invoke the Trinity to Argue Ethics?

Isn't that just appealing to religious belief?

Why is always a good question. I’ll start with a question from my daughter.

My daughter aspires to be a veterinarian, and she is well on her way. She has a summer job at a vet clinic, interned at a vet clinic last summer, and visited my cousin and her husband, who are both veterinarians with their own state-of-the-art clinic, the summer before that. One of the first questions a budding veterinarian must ask herself is whether she can handle sick and dying pets. It’s one thing, my cousin told her, to love animals but quite another to see them suffering or to euthanize someone’s pet. We talk a lot about this, and the other day we had a conversation about the difference in humans and animals. She’s heard me talk about the rational soul enough to know the philosophical answer, but she was rather surprised when other people challenged her, “If we can do it to animals, then we can do it to people?” Just saying “rational soul” didn’t cut it.

I’ve had this discussion often in Catholic circles, and I always come to the conclusion that you cannot argue about ethics or morality without getting into what it means to “be human,” and you cannot do that without talking about the rational soul, and you cannot do that without invoking the Holy Trinity. I say this as a convert who was once beholden to the materialist mindset.

But, Aristotle…?

One objection is that Aristotle concluded that humans have a rational soul that is different from animals and plants some 300-plus years before the Incarnation of Christ and revelation of the Holy Trinity; therefore, we do not need a religious argument. In his work De anima (On the Soul), Aristotle describes the soul as the principle of life and activity in living beings (“the first act of an organized natural body” at Bk2.412b4). He then names three types of souls: the vegetative soul (for plants, responsible for growth and reproduction), the sensitive soul (for animals, adding perception and movement), and the rational soul (unique to humans, enabling reason, intellect, and deliberation). For Aristotle, the rational soul is what distinguishes humans from other living beings, allowing us to engage in higher cognitive functions like thinking, understanding, and making moral choices. He sees the rational soul as something beyond the body, compared to the sensitive soul which depends on the body to sense the surrounding environment. “For whereas the sensitive power is not without the body, the intellect is separate” (at Bk3.429a29). This was the philosophical foundation that Aquinas used to later argue the immorality of the human soul.

The problem is that today people can point to science and say that some animals also seem to think, understand, and make choices (and likewise, go to Heaven). The definition of “cognition” is taken as synonymous with intellect by way of intelligence. There are thousands of TikTok clips of animals doing very human things that certainly look like they are thinking, understanding, and making choices. For example, see the Aussie named “Secret” paint a flower (over 187M views).* Animals can seem to be rational, but since they cannot speak to us, we are left to project our interpretations onto them, making argumentation difficult.

These conversations get hung up in terminology. What does it mean to think? To cogitate? To will or choose? Is there a line between rational and non-rational? For the record, I do think higher animals have some sort of intelligence that falls short of intellect per se, and I’m not ready, as Aquinas says, to agree that there is no way God allows animals into Heaven (see Summa theologiae, Supplement, 91.5). I think, perhaps, that we can love them into Heaven, but my point for now is that we aren’t entirely sure what to make of animals.

They remain mysterious, like us yet not us.

*Secret passed away in May of 2022. Story here.

So, go the other way.

The question of animals doesn’t matter if we go the other way and talk about the Holy Trinity, and that is why I think invoking the Holy Trinity is not just a good idea but is even necessary in asserting the difference in humans and animals, especially the idea that humans are rational souls and animals are not. The revelation of the Trinity helped humans understand themselves better; God told us more about who we are and why we have these powers of intellect and will.

On several bioethical questions—abortion, contraception, cloning, euthanasia, and IVF in my recent book—I have come to this conclusion repeatedly. Why must we invoke the Holy Trinity, or even God’s existence, to argue for what reason can discover? I get asked this a lot. If we can all know that killing an innocent human is wrong, then can’t we all figure out that abortion is wrong too? Yes…and no. If it were that simple, then everyone would already be against abortion.

This is really the natural law debate, of course. There are philosophical debates about how to interpret natural law (Thomistic teleology, Suárez voluntarism, Grisez/Finnis analytical, Wojtyła personalism, Maritain/Simon historically adaptive). I am in the Thomistic reason-based version of natural law rooted in human nature and divine order, so I’ll just say that, but let me explain why. My own reasons for that choice have to do with my own encounter with faith.

After years of wondering about a moral code without faith, it doesn’t make sense to find the gift of faith and then pretend like you can reason just fine without it. I can’t do that! Faith is like a light that illuminates the way. I am not talking about grace only. Grace is important for right reason, but I mean faith in the sense of acceptance of the existence of God and of divinely revealed dogmatic truths.

My reasoning about natural law is like this: If there is no God, then “nature” just means the universe. If “nature” just means the universe, then there is no basis for morality. If there is no basis for morality, then natural law has no meaning. That leaves everything as “laws of nature” or just physical law.

On the contrary, if there is a God, then “nature” is creation. If humans are creatures, then we are made to seek the Good, and that search is the basis for moral decision-making. The Catechism of the Catholic Church also ties natural law to God’s existence (1954-1960). It begins, “Man participates in the wisdom and goodness of the Creator who gives him mastery over his acts and the ability to govern himself with a view to the true and the good (1954)”. It goes on to say that the natural law “hinges upon the desire for God and submission to him” (1955). And quoting Aquinas, the CCC includes: “The natural law is nothing other than the light of understanding placed in us by God; through it we know what we must do and what we must avoid. God has given this light or law at the creation” (1955, also see ST.I-II.91.2). If you take God out of the explanation of natural law, you take out the answer to where the goodness, authority, and “light of understanding” originate.

No God, No Natural Law

So, I don’t see how to argue for natural law, or consequently ethics, without also affirming God’s existence and God’s revelations. I get challenged on this often by Catholic apologists, and I think the reason is that natural law is seen by them as a way to argue for Church teaching using reason alone and avoiding religious appeal. Again, that seems misleading to me. Our job is to show people what it looks like to reason in the light of faith not reason and pretend no one needs faith.

God’s existence can be known by reason alone, but divine revelation refers to the truths that Christ revealed to us that reason alone never would discover, namely the doctrine of the Holy Trinity. The debates over the meaning of how God is one God, but three divine persons led to the current Catholic understanding of “person” as it applies to humans made in the image and likeness of God. This revelation tells us that we are made for truth and love. God the Father generates/conceives God the Son by way of the intellect as Truth (see ST.I.34). God the Father and Son together as one substance generate/spirate the Holy Spirit by way of the will as Love (see ST.I.36).

For it was said above (Q. 27, AA. 2, 4; Q. 28, A. 4), that the Son proceeds by the way of the intellect as Word, and the Holy Spirit by way of the will as Love. Now love must proceed from a word. For we do not love anything unless we apprehend it by a mental conception. (ST.I.Q36.A2)

To say we are made in the image and likeness of God is to say, in part, that we are rational souls (as Aristotle said) with the spiritual powers of intellect and will (as Aquinas explains). Therefore, to be a human person means we are made to seek Truth and Love. We are made to know and be known, to love and be loved, to belong to our families and communities. And that’s why it hurts like hell when any of those ‘natural’ pursuits are thwarted. Lying and deception hurt. Bad choices hurt. Family discord hurts. Being rejected hurts. I’m convinced that a lot of individual brokenness, such as drug addiction, risky behavior, and self-harm (cutting), to name a few examples, are ways of mitigating the enormous emotional and spiritual pain. A physical pain is at least a pain with limits.

All that to say, I think I’m on firm ground when I say that natural law doesn’t make sense if you subtract God from the equation. And that’s why I invoke the Holy Trinity to argue for ethics. Ethical decisions rely on moral decision-making, which relies on a search for the Good, which relies on the pursuit of truth and love, which among creatures is a uniquely human endeavor, which means we ought to obey and submit to the Word of God. This isn’t a fanciful appeal to religious belief but a demonstration of the way to search for (capital-T) Truth.

I found all of that beautiful when I first understood it. I stopped thinking of myself and other humans as highly complex composite systems of atoms and compounds, and I realized, for the first time, that I am obligated to find out what the right thing is to do for the sake of my happiness and the happiness of my fellow humans. It was a lot better than trying to reduce myself to an animal.