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St. Thomas Aquinas’s Five Ways as a Path Back to Catholicism

Tim Staples

Tim Staples discusses St. Thomas Aquinas’s Five Proofs for the existence of God with an atheist caller who is seeking clarification, focusing particularly on the third way, the idea of a necessary being, its attributes, how we can know that this necessary being is the God of the Bible, and finally how we can reconcile God’s ultimate perfection and love with the apparent harshness He shows in the Old Testament.


Host: Let’s go to Bruno in St. Louis Missouri listening on 88.1.

Caller: Thank you for taking my call. I was raised Catholic and was an altar boy, did all those things, I still go to Catholic Church from time to time with my parents, very much enjoy it; however, I have become an atheist, and I’ve been studying recently St. Thomas Aquinas, his five ways, and I wondered what you thought of his five ways, if they were a good path maybe back to Catholicism, or get any other advice.

Tim: Okay Bruno, am I hearing you correctly that you’re reading Thomas’s five ways, and you wanted me to share with you what I think of them?

Caller: Yes.

Tim: Well I can tell you, I love Thomas’s five ways or five roofs for the existence of God. I think the first three are the most powerful; the third is perhaps the simplest, from contingent and necessary being. Bruno, let me get your thoughts on this:

When we look around in the universe we see everything in existence could either be or not be, and that is a scientific fact. You know, the Sun doesn’t have to be here, in fact the very forces in physics, you know, the essential forces, you know, strong nuclear force, weak nuclear force, electromagnetic force, gravity; these are not necessary forces. They are finely tuned, as physicists tell us, they could be something that they are not, they could even not exist at all. The universe itself, we are told, has a beginning, although some are saying it might be further than most think, 13.7 billion years, now I understand it may be longer, I don’t know, I’m not smart enough to debate that, I just read what the scientists say. But the bottom line is: there was a time when it was not. And so everything that is could either be or not be.

Bruno, St. Thomas, I think brilliantly, points out: there must be being that is not contingent, or dependent upon anything else for its existence, in order for there to be existence. Because if everything that exists is dependent on something else for its existence, well that means everything that is can’t explain existence, and can’t be the source of all existence. In order for there to be existence, there must be Being that did not receive its existence from anything or anyone else. It is simply Being. And that means infinite Being. All perfection. There’s no lack, there’s no–so that ultimate Being that we’re talking about can’t be “here, but not there.” Can’t be “part here, and part there.” No, it is simply Being. All perfection. And that, as St. Thomas Aquinas says, we call God.

I find that to be one example of a compelling argument for the existence of God, but what do you think of that, Bruno?

Caller: Well I think it’s quite interesting, and I believe I could agree that there must be a necessary being. But I don’t know how St. Thomas Aquinas makes this giant leap from “There is a necessary being” to “By the way, it happens to be the God that I worship.” How do you make that step? How do we know it’s a being that thinks or is conscious or loves us or still exists? Perhaps it’s Allah, perhaps it’s a Flying Spaghetti Monster. How does he make that big jump from “Yes, there I something that caused all this, and it just happens to be the God I worship.”

Tim: Sure. Let’s start with the Flying Spaghetti Monster. We can immediately eliminate a Flying Spaghetti Monster because it is either “here or there.” It has lack. So it can’t be the ultimate Being, because if you have a being–in fact, any being in the universe, you can know that these beings are not ultimate Being because of the fact that they’re contingent. There must be, as you say, a necessary being that is not dependent at all for its being on another.

And now, how do you make the leap then, Bruno? How do you know that this is the God that we worship? Well, here’s how you do that, Bruno. First of all, we have to acknowledge that the God that we’re speaking of has no imperfection, no lack whatsoever. It’s impossible. Because if He does, if whatever Being we’re talking about has any lack of being, well then it’s contingent. It’s composed of parts, or it’s lacking in some sense, and so therefore it is not the Necessary Being. It’s a being. And Bruno, we’ve already established that every being in the universe, every thing in the universe, by definition, could either be or not be. The argument states, “Then there must be that Being that is infinite in being, all perfection.”

So now, when we talk about perfections, what would these perfections be? Well, one of the perfections would be rationality. Because in order for beings like Cy and Tim and Bruno to be here communicating–and you and I know we did not give this gift of rationality to ourselves–the Being that we are talking about is the source of rationality; only, His rationality is absolutely infinite, in order to be the source of all rationality. So as we move forward in reason, Bruno, we begin to see that this infinite Being with all perfections is also rational, would have to be.

And Bruno, we could go down the list: would have to be all-powerful, all-knowing, right? Could not have any lack of any of these perfections. Well that, we know to be God. Now Bruno, that doesn’t mean, though, necessarily, that that God is Father, Son, and Holy Spirit. Because that is a truth of faith that has been revealed to us by Jesus Christ. Reason, Bruno, can only take you so far. We can reason to the existence of one God, who is all-powerful, all-knowing, etc. But that God, that infinite God, has revealed Himself to us as Father, Son, and Holy Spirit; and in order to prove that, we have to get back to the person of Jesus Christ.

Which, you know, I happen to agree, Bruno, with the Catechism of the Catholic Church in paragraph 643 that tells us that the life, death, burial, and resurrection of Jesus Christ is a matter of history. It is an historical fact. The reason why I’m a Christian, Bruno, is because Jesus Christ really did live, really did die, and was resurrected from the dead, and we can know that by the testimony of over 500 eyewitnesses, we can know that through the testimony of the miracles He performed, the miracle of establishing His Church, the miracles that have occurred in every generation for 2,000 years; all of this and more proves the veracity of Christ’s claims.

And His claims ultimately were: number one, He’s God, He’s the son of God, He’s the Messiah, He fulfilled scores of prophecies to prove that, and He ultimately died, and as He Himself predicted, He raised himself from the dead, and the Resurrection, my friend, is the point at which Jesus departs from all other claimed prophets or sages down through the centuries. He proved that He in fact is God, and He established this Catholic Church of ours, Bruno, and really it’s the Church that helps us to dive into this great mystery and understand more completely what Jesus Christ taught.

You know, and of course we could we could spend months on that, but Bruno, that’s that’s kind of scratching the scratch on the surface, but does that make sense?

Bruno: Well, I certainly understand and follow your argument, but no, I am not convinced. The questions I would raise, respectfully, is that you assume that this necessary being is all-powerful and omni-beneficent and I don’t know why it would–I’m not convinced it would have these characteristics. But let’s just assume for a moment that this necessary Being–

Tim: Well Bruno, before you get there, let me just jump in real quick, and the reason why I would have to have all perfection: because, if you reduce this Being that we’re talking about to a being on the level of all other beings that we understand and we can know just using our reason, then He would be a contingent being. And that’s the argument: everything in the universe that is in existence is contingent. That’s a scientific principle. Science demonstrates that. When we see a star, we begin to calculate, “Okay, how old is that star, where did it come from, when did it begin?” We look at the universe, we calculate, “Okay, how long ago was this?” Now, we can disagree over it and such, but we understand that there’s a lifespan–to the galaxies, to the stars, to the universe itself. When I look at Cy, I can say, “Hey, when were you born, dude?” He is not Ultimate Existence, because there was a time when he was not, and the same thing with everything in the universe.

So if, Bruno, we posit a being that is, you know, just a really smart guy, he’s really powerful but he is–he suffers some lack, some lack of knowledge, some lack of power, then he, too, would be a being just like all other beings in the universe, and would be contingent, dependent upon something else for his being. And so we have to go back further, and we have to find that Being.

Now let me use a different phrase here, use some Thomistic language since you’re reading Thomas. What St. Thomas Aquinas says, especially in the Summa Contra Gentiles, he talks about how, when we look at all of the beings in the universe, we know that within their natures, they do not have the perfection of Being. It doesn’t exist, for example, in my nature to exist. I could either exist or not exist. There must be a Being that has, within its very nature, Existence itself. Its essence is Existence. My essence is not Existence. I could either exist or not exist. But this Being that we’re talking about, the source of all Being, its essence would have to be Existence. It doesn’t receive being from outside of itself, but its essence is Existence. And that’s what we mean by absolute, infinite, perfect Being. And that, we say, is God. Now again, Bruno, that doesn’t mean that that’s the Father, Son, and Holy Spirit; we come to that through Revelation.

But you had one more thing?

Caller: Oh thank you, and and certainly you’ve explained it in quite a cogent sense, and and I can see where this necessary being might have all these perfections that you so adequately describe. So if I compare that necessary Being to the God of the Bible, I have a hard time lining the two up. The guy the Bible seems somewhat capricious, hateful, cruel, murderous, somewhat Greek, and so I don’t see how those two line up, if you could help me there.

Tim: Bruno, that is a great question, and I’m going to recommend a book, too, that one of our apologists, Trent Horn, just wrote called Hard Sayings. Excellent book, I did the apologetic review on it, it is outstanding and he deals with a lot of these, you know, hard sayings in the Old Testament.

But Bruno, let me just give you a general principle that helped me many years ago to understand this. A lot of folks think for some reason that the Bible has to be, if it’s inspired by God, it has to be a book that has all beauty and all perfection, there can be no sin there can be nothing in it morally objectionable, and that’s just not true. That’s a false notion of what Holy Scripture is. Scripture is the inspired Word of God. But remember, Bruno, that Scripture–God took an ancient people–now if we go all the way back, Bruno, to Adam and Eve, Adam and Eve were created in perfection, no pain, you know, everything’s great, they chose to reject God, original sin comes in, sin and death, and then sin proliferates. God respects our freedom, Bruno. That’s a very important principle that you see from Genesis to Revelation; and when we choose to walk away from God, God steps back and a lot of bad things happen. And then God gives us grace. He woos us back. But He doesn’t coerce. He respects our freedom.

So that’s what happens in the early chapters of Genesis, when Adam and Eve fall, sin proliferates, but then God begins to reveal Himself. He reveals Himself to Abraham, for example, a dramatic revelation there, right around 2000 BC. He begins to reveal Himself as the one true God, but again, He reveals Himself in bits and pieces, Bruno. He takes Abraham from a very violent, tribal situation, tribal warfare, and He chooses not to give Abraham, you know, the fullness of the revelation of Jesus, the Sermon on the Mount immediately.

That’s not the way God chooses to work with us. He respects our freedom. He gives them bits and pieces. In fact, Bruno, Hebrews 1:1-2 in Sacred Scripture, in the New Testament, the inspired author says, “God spoke in various and partial ways through the prophets.” He gives them more and more truth as they can handle it, and He gives them more and more grace, and He brings them up until “the fullness of time came,” as Galatians 4:4 says, and He sends His son and gives us the Sermon on the Mount. He gives us the fullness of the revelation of who He is, as well as who we are, that the Old Testament people God did not know.

So, when you have situations, for example, like the slaughtering of the Amalekites or the Amorites and such in the Old Testament, we’re talking about, again, a tribal people where God allows things to happen that are not His antecedent will, He doesn’t want to see tribal warfare and such, but there are situations that arise, because of the proliferation of sin, where God has to deal with things in what we think today are very harsh ways. I said this the other day, Bruno, to another caller: if you think of it the way Saint Irenaeus describes it when he was dealing with a heretic named Marcion, he says, “Think of the Old Testament people of God like a two- or a four-year-old, versus the New Testament people of God that have reached the age of maturity,” right? So 18 and over. You don’t deal with a two- or four-year-old the same way you deal with an 18- or a 20-year-old.

And that’s the way we see the Old Testament. God permits a lot of things to happen. He’s giving them more and more light, more and more truth, He’s stemming the tide; but at the same time He’s allowing freedom, so that a lot of bad things happen–and they still happen today–but ultimately now we have the hope in Jesus Christ that everything will finally be rectified. And I know we don’t have time, Bruno, to get into all the particulars of the Old Testament, but there are answers, and I think Trent Horn’s book would be a great first step for you.

Host: Thank you very much, Bruno, for occasioning such an excellent discussion. Really happy to have you with us, please call another time.

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