Can God be proven? Yes. Even the Greek philosopher Aristotle (384–322 BC) provided a famous argument for God as the Unmoved Mover, the unchanging first cause of all change. Denying the provability of God is popular today, even for Christians. Faith and reason have been divorced, and we Christians sometimes swallow that pill without realizing it. But it doesn’t have to be that way. Faith seeks understanding, but it is built on it too. We believe in God for good reason or else we have no reason to believe in God.
While it’s true that God can be proven, a proof might not be personally persuasive. That depends not only on the argument’s logic but on emotional appeal and the character of the speaker and audience. While an argument displays the reasons for a belief, persuasion brings someone from a belief to a belief. Persuasion often requires a customized explanation to appeal to someone where they’re at and answer their specific concerns. But a good place to start is taking some serious time to meditate on weighty and historic arguments like the one below.
Interestingly enough, you don’t even need faith to prove (or believe in) God’s existence. Over the course of history, Christian theologians have adopted and adapted non-Christian proofs for God from pagan philosophers, Jews, Muslims, and others. In the end, arguments, persuasion, and even belief don’t save you, for “even the demons believe—and shudder!” (James 2:19). Rather, if you are—or will—be saved, it is “by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast” (Ephesians 2:8–9). God uses preaching and apologetics as means and tools. They may be part of your story or mine, but they are powerless to save without the work of the Holy Spirit.
Theology finishes the work of philosophy and sanctifies it. Click To Tweet One such theologian to adapt proofs for God from unbelievers was Thomas Aquinas (1225–1274 AD). He was a pivotal figure of the thirteenth century who helped establish systematic theology as the “science” we know it as today. He did this by applying Aristotle’s discoveries in logic and other fields to theology. His Summa Theologica was one of the first systematic theology textbooks, and he begins it by defending the claim that theology (special revelation) assumes, subsumes, and completes philosophy (general revelation). Faith does not leave reason behind. Theology finishes the work of philosophy and sanctifies it.
This unity of faith and reason led Aquinas to begin his study of God with Five Ways of proving God. Aquinas’s proofs are as much an act of theology as they are of apologetics. They lay the groundwork for later discussion of the doctrine of God, so it’s important to ask not only whether a proof works, but what it tells us about God.
The Fourth Way
In Summa Theologica I.2.3, Aquinas begins his series of five proofs the same way we should. He appeals to common ground between believers and unbelievers. It’s common sense to notice that things in the world change. “Change” already assumes knowledge of cause and effect. This is the Principle of Causality—all effects have a cause. But we can understand four specific kinds of change and their four causes: efficient cause, material cause, formal cause, and final cause. These answer four questions: What is the agent of change? What is something made of? What is it, or what are its qualities? What is its purpose? The Principle of Causality and the Four Causes loosely outline Aquinas’s Five Ways of proving God. Aquinas begins his Fourth Way like this:
The fourth way is taken from the gradation to be found in things. Among beings there are some more and some less good, true, noble, and the like.
This is a noncontroversial common sense observation. In everyday language we talk of things being “better” or “worse.” The fourth way relates to the formal cause. Form is a fancy word for the shape, definition, whatness, or qualities of a thing. A rose is a plant, red, thorny or other essential and incidental qualities. It’s easy for us to compare a healthy, vibrant rose with one that isn’t looking so good. Or, perhaps the rose is still on its way, budding from immaturity to maturity, changing from a kind of incompleteness to completeness, or imperfection to perfection. Whatever lack of perfection it has, we also know that it’ll never quite get to perfection. It’ll never be free from defects.
Already we notice that seeing something as imperfect already, by definition, includes some idea of perfection, however vague. To notice a lack of perfection is to imply a concept of perfection. Analogously, we can’t tell who is winning a race unless there’s a finish line. “Winning” implies a finish line. When watching children run around a playground with no track and no finish line, we wouldn’t say one child is winning.
Already we notice that seeing something as imperfect already, by definition, includes some idea of perfection, however vague. Click To Tweet If noticing imperfection implies we already have some prior idea of perfection, where did that idea come from? It comes from noticing what things are and realizing that understanding what something is already contains the idea of what it is meant to be. It’s rather common sense, actually. It doesn’t take a scientist to know that once we understand what a rose is, we realize that dry, brown leaves aren’t good and we might want to remember to water the plant. But a serious question arises. Does perfection exist anywhere or is it just our imagination? Is God just a projection of wishful thinking, as Sigmund Freud claimed? Aquinas continues:
Among beings there are some more and some less good, true, noble and the like. But “more” and “less” are predicated of different things, according as they resemble in their different ways something which is the maximum
To see whether God is just wishful thinking, we need to broaden the way we compare things. When we speak of “more” and “less” or “better” and “worse,” Aquinas is not speaking here of just any comparison. An elephant is bigger than a mouse, but that doesn’t mean the mouse is imperfect compared to an elephant. He’s talking about qualities that, by definition, imply perfection. Immature elephant implies mature elephant. Bad person implies good person. If you point to something lacking, that implies an understanding of completeness. Comparing elephants to mice or apples to oranges does not imply lack of perfection. Or does it?
Can we say that a person is more perfect than a rose? It isn’t very controversial to say that a person is more important than a rose. A rose lacks reason, love, or the ability to tell good jokes. When you understand the nature of a rose, you know it’s not imperfect for lacking human attributes, but in lacking these things, it is less good than a human. It is worth less without being worthless. A human can display more goodness, beauty, and truth than a rose. Though common sense says this, the Bible reiterates it, saying that this is because we are made in the image of God. Even the worst of humanity is more valuable than the best plant or animal.
Some qualities, like truth, goodness, beauty, and unity are in all things to varying degrees. Philosophers and theologians called these qualities “transcendentals.” Click To Tweet Comparing plants, animals, and humans involves speaking of goodness, beauty, and truth in a more analogical way. As Aristotle says in his Categories, we can compare terms in three ways. A person can say univocally that a ball and a truck are both red. Someone can speak equivocally by saying they deposited money in the bank near the bank of the river. We can also speak analogically, where there is something similar but also something different. A rose and a person may both be healthy, but “health” means something quite different for each of them. In the same way, what makes a rose good and what makes a human good are different while “good” still retains a common meaning.
Even though a human does not contain the same kind of goodness as a rose, we still say that a human has more goodness, perfection, or value than a rose. This creates a kind of hierarchy of being in the world, a way to rank more and less good things. We might think of a rock as being lower than a rose, or a human as higher than an ant. Things are more valuable if they display more complex organization, beauty, understanding, and so on. Some qualities, like truth, goodness, beauty, and unity are in all things to varying degrees. Philosophers and theologians called these qualities “transcendentals.” But how does this get us to God? Aquinas finishes up his Fourth Way:
. . . so that there is something which is truest, something best, something noblest, and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being . . . . Now the maximum in any genus is the cause of all in that genus . . . . Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God.
If we can compare different kinds of things to form a hierarchy of being, then we must say the same thing about this comparison as we did about comparing an imperfect rose to a perfect one. To judge whether a rose is perfect or not, all we need is a concept of the rose itself. But when we’re comparing a rose to a human, we need a method of measurement that’s outside both of them. Similarly, knowing that there’s a runner outside doesn’t tell us whether he is winning, we need at least two runners and a finish line outside both of them to measure their progress.
This most perfect being, at the top of the hierarchy of being, whose existence defines all lesser goods, we call God. Click To Tweet Our common sense observation that humans are more valuable than roses shows us that we already have at least a vague notion of goodness or perfection that stands outside these things and measures them. While the runners are not yet at the finish line, the finish line itself is already at the end, at the point of perfection. When we compare different kinds of beings as more or less good, there must be a maximum. Without that finish line, we could not even be aware of “more” and “less” valuable things. This most perfect being, at the top of the hierarchy of being, whose existence defines all lesser goods, we call God.
Have I pulled a fast one on you? If we can’t conclude from imperfect roses that a perfect one exists, how can we conclude from less perfect beings that God exists?
Well, this proof does not give a full-blown, detailed doctrine of God. It’s just a beginning. It might only prove the vaguest notion of God and not specifically the Christian God. I’ll say something more about that in a moment. Think of it this way, if you look at a photo of Olympic track sprinters, and the finish line is cropped out of the picture, you can still tell who is winning because you know that there’s a finish line. Even if you don’t know how far away it is, you know that it is out there somewhere. You do not need a full-fledged doctrine of God to know he exists. Like seeing runners without a finish line, merely comparing different beings in the hierarchy of being already tells us that an external standard of a perfect being exists. In order to compare something, like a rose, with its own perfect end, all you need is an understanding of what a rose is. In order to compare different beings on a hierarchy of being, you’ll need to know something of the track and the finish line that stands outside of them.
What Does this Tell us About God?
This Fourth Way does not prove a trinitarian God who saves by grace through faith in the work of his self-sacrifice. But it does tell us that a supreme being exists who is good and contains the root of every good thing. It does not tell us of God’s particular acts in creation and redemption, but it tells us that God is perfect and good, and this is where theology properly begins. In fact, God is not merely the winner in a race, compared alongside the other runners. Just as the finish line is outside of and measures the runners, so God is outside of the hierarchy of being and measures it, or causes it. He is the very definition of goodness, so transcendent that we can only speak of him analogously and await the day when we see him face to face.
Just as the finish line is outside of and measures the runners, so God is outside of the hierarchy of being and measures it, or causes it. Click To Tweet This proof can also tell us a few things about God’s attributes. If love is a perfection, then God is the most loving being. If love requires personal interactions, then God is a person, not an impersonal sovereign or pantheistic life force. That rules out the impersonal logos of Stoicism, the Allah of Islam, and the god of many Eastern or New Age religions. Combined with things learned from other proofs, namely that God is Creator and self-sufficient, we can see how his love is fulfilled prior to creation and thus implies a multi-personal-while-still-singular God, such Christianity claims in the eternal intra-trinitarian love. This may rule out Judaism and leave us with only one monotheism left—Christianity.
How can this Help Hurting People?
Perhaps you are going through hard times. Will God keep his promises to provide? Where is God’s plan in my suffering? With the Psalmist, we cry out “How long, Oh Lord?” (Psalm 13:1). Perhaps your life is like Job, plagued by tragedy. This is where this proof is the sweetest. Job’s anguish is not answered by God explaining his purposes. His anguish is answered by reminding Job that God is good and in control. God is trustworthy. “The Lord is good, a stronghold in the day of trouble; he knows those who take refuge in him” (Nahum 1:7). God holds the whole world in his hands, and it is our job to have faith and trust him, even if we don’t understand his plans. If God is not good, nothing is good. The goodness of literally anything around us, and even the raw awareness of tragedy, is not possible unless there is a good God out there, a God who loves us.
All creation displays God’s glory, and this is cause to worship. That is the Christian’s goal. If you’re an unbeliever, ask yourself how it is even possible to be aware of goodness and evil in a world without God. If there is no God, there can be difference and change, but not goodness or growth. As Blaise Pascal said, if Christians are wrong, we’ve gained nothing, but if unbelievers are wrong, they’ve lost everything. The stakes are high. All our good deeds and good ideas are vain if there is no God at the end of the race who gives the ultimate good gift to those he loves: himself.