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Why Students Eat Up the Classical Proofs of God

May 7, 2020


My best teaching experience ever came when I followed the example of Bishop Barron’s high school religion teacher, Fr. Thomas Paulson, and presented to my students the classical proofs for the existence of God. 

My intention wasn’t defensive; I wasn’t trying to convince my skeptical students that God exists. I simply wanted to share with them arguments that contributed to my own religious awakening in high school, hoping to enkindle their desire for God. 

Most were unimpressed, but some thanked me later for introducing them to the idea that theology involved critical thinking, as much as it did faith.

These proofs are simple enough for high school students to grasp, and given that disbelief in the existence of God is growing (and happening at a much earlier age), religion teachers should make it their priority to teach them. They’re easy to learn, and teaching them requires only a little preparation. 

Like Bishop Barron, I first heard the classical proofs of God as put forth by St. Thomas Aquinas and St. Anselm in high school. Regrettably, my philosophy teacher dismissed them all, saying Kant and other modern philosophers had sufficiently rebutted the arguments. But I was not so sure about that. Perhaps I was naive, but the rebuttals seemed to be strawman arguments, something my teacher told us never to accept. To my mind, they were not disproving the existence of the God of classical theism or the God of Revelation but the supreme being “God” most atheists take theists to believe in. The classical proofs are much sounder than most moderns think, and they do a good job preparing the soul for faith. 

So, during this weird time of COVID-19, as many high school religion teachers search for materials students can read at home, I’d ask them to consider sending an outline of the classical proofs for the existence of God, such as the first part of the Aristotelian proof as philosopher Edward Feser presents it in his book The Five Proofs of God. This proof is no harder to follow and understand than geometric proofs taught at the sophomore level. I am confident that high school students will be intrigued and want to learn more about God. 

Here is how I would present the lesson. Before introducing the proofs, I would explain the basic distinction between act and potency. Give examples such as an acorn’s potential to be a fully grown oak tree. An oak tree is the actualization of the main potency in an acorn. The argument assumes change occurs—I assume none of the students are disciples of Parmenides who did not believe change exists, so no need to argue for this premise. From this premise it can be shown that all instances of change require a changer and that this agent of change is not the first cause of a linear series but the ground of a hierarchical series and that ground—as lacking all potentiality (there is nothing else it can become)—is pure actuality itself or what Feser calls “an unactualized actualizer.” I recommend giving students Feser’s helpful outine of the argument. Here is the first part of the argument as taken from his book: 

  1. Change is a real feature of the world.
  2. But change is the actualization of a potential. 
  3. So, the actualization of potential is a real feature of the world. 
  4. No potential can be actualized unless something already actual actualizes it (the principle of causality).
  5. So, any change is caused by something already actual. 
  6. The occurrence of any change [C] presupposes some thing or substance [S] which changes. 
  7. The existence of S at any given moment itself presupposes the concurrent actualization of S’s potential for existence. 
  8. So, any substance S has at any moment some actualizer [A] of its existence. 
  9. A’s own existence at the moment it actualizes S itself presupposes either (a) the concurrent actualization of its own potential for existence or (b) A’s being purely actual. 
  10. If A’s existence at the moment it actualizes S presupposes the concurrent actualization of its own potential for existence, then there exists a regress of concurrent actualizers that is either infinite or terminates in a purely actual actualizer. 
  11. But such a regress of concurrent actualizers would constitute a hierarchical causal series, and such a series cannot regress infinitely. 
  12. So, either A itself is a purely actual actualizer or there is a purely actual actualizer which terminates the regress that begins with the actualization of A. 
  13. So, the occurrence of C and thus the existence of S at any given moment presupposes the existence of a purely actual actualizer. 
  14. So, there is a purely actual actualizer. 

Feser then continues the argument showing that “there exists a purely actual cause of the existence of things, which is one, immutable, eternal, immaterial, incorporeal, perfect, fully good, omnipotent, intelligent, and omniscient,” and “for there to be such a cause of things is just what is for God to exist”; thus, God exists. 

The variable C can stand for any change. Take the act of “growing.” Variable S can be “an oak tree.” From such examples, students will be fascinated that they can derive the existence of God from any change. The goal of the lesson is for the students to see all change as presupposing the existence of God with the clarification of God as “the purely actual actualizer.”

I realized the importance of covering the proofs by accident. In my Church History course, as an aside from the main content of the lesson, I thought the students would be interested in Anselm’s ontological argument and Aquinas’ cosmological arguments. I thought they would be more interested in learning about the Crusades or see the proofs of God as relics of the past, but the proofs fascinated them, perhaps because it was the first time they were exposed to thinking about the existence of God in a clear, deductive manner. It surprised and fascinated them that we can know that God exists and that it is not simply a matter of faith. In fact, many of the students asked for book suggestions on the proofs. Happily, I lent them some of my own. I guess they were intrigued because I never saw some of those books again.

In a time when the Church tries to find creative ways to educate and evangelize within the schools, perhaps we need look no further than the classical proofs of God.