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Can You Prove That God Exists?


Design proves a designer. And nature is full of design. Therefore there must be a Designer behind it all.

Peter Kreeft

Sal: I hope you're ready, Chris, because today's the day you promised to answer my big question.

Chris: All your questions are big to me, Sal I take them seriously.

Sal Thanks for that, by the way. You know, I don't think we could have really good conversations if you weren't a good listener as well as a good talker.

Chris: I'm listening now. What's the question?

Sal: Prove to me that there's a God.

Chris: This isn't just a game to you, is it?

Sal: No. I don't know what to believe. And I want to know.

Chris: What do you know?

Sal: Why do you ask that?

Chris: So we can start from there.

Sal: Well, I don't know whether God exists, but I know the world exists, I don't know if religion is true, but I know science is true.

Chris: Fine. Now we have a starting point.

Sal: But how can you bring me from science to God? There's no scientific proof of God.

Chris: This way: without God there could be no science without science there could be no God.

Sal: What? How do you figure that?

Chris: If there were no universe for science to know, there could be no science, right?

Sal: Of course.

Chris: And if there were no God to create the universe, there could be no universe. Therefore if there were no God, there could be no science.

Sal: I see your argument, but I disagree. I'm free to disagree, after all.

Chris: Yes, and I'm free to ask you why you disagree. I gave you my reason; now you give me yours.

Sal: Fair enough. Well, I don't believe God created the universe.

Chris:  Who did then? Walt Disney?

Sal: Nobody. It was always here. You say God always was, right?

Chris: Right.

Sal: Well, why can't I say the universe always was?

Chris: A fair question.

Sal: And have you got a fair answer?

Chris: I think so. I think if you look at this universe you'll find good evidence for a God who made it.

Sal:  Where? I don't see it.

Chris:  Maybe that's because you're looking only with your eyes, not your mind.

Sal: What do you mean by that?

Chris: Maybe you're not asking enough questions.

Sal: Me? I question everything.

Chris: Then question the universe. Ask it how it got there. If you do, you'll find at least five different clues that point to God. There are many more arguments for God than these five; there are clues all over life, signs that point to God. But these five are based on what you see in nature.

Sal: Sounds solid and scientific so far. Were they invented by some modem scientist?

Chris: No, by a medieval philosopher, Saint Thomas Aquinas.

Sal: Oh.

Chris: You sound disappointed.

Sal: The Middle Ages were primitive.

Chris: In technology, yes. But not in philosophy or theology. Their machines weren't sophisticated, but their minds certainly were.

Sal: Well, what are his five proofs?

Chris:  The first one is called the argument from motion. If you see some dominoes in a long row falling down, you know someone pushed them, right?

Sal: Right.

Chris: Why? How do you know that? Why couldn't they just move themselves?

Sal: Nothing moves itself.

Chris: Right. And neither does the whole universe. Think of the universe as an enormous chain of dominoes, all moving. Something outside the chain must have started the movement in the beginning. Otherwise it couldn't move, because nothing can move itself.

Sal: Wait a minute: we do. We move ourselves.

Chris: Our minds move our bodies, but our bodies don't move themselves. Ever see a corpse move itself? A corpse is just a body without a mind or soul.

Sal: So nothing moves itself.

Chris: And the universe is moving, changing - everything in it is in one great process of change. Therefore ...

Sal:  Therefore there must a first mover. But it's not God.

Chris:  What is it, then?

Sal:  Scientific laws.

Chris:  Laws are just descriptions of how things move. You need a real thing, not just a law, really to move another real thing.

Sal:  Well, why can't it just be some material thing instead of God?

Chris:  All material things make up the whole universe. Part of it can't move all of it. The whole universe needs a mover outside of it, something more than the universe, something supernatural.

Sal: Hmmm. This supernatural something is pretty vague. The God you believe in is much more than that, isn't he?

Chris: Certainly. This argument only proves that there's some supernatural cause behind the change in the universe. I know who he is from other sources: the Bible and Jesus. But it's the same God. There's only one.

Sal: O.K., what's your second proof?

Chris: It's the argument from the very existence of things, not just their movement. You need a first cause of existence just as you need a first cause of motion, because nothing can make itself exist if it isn't already there. Nothing can cause itself.

Sal: All right, nothing can cause itself. Nobody can be his own parents. So how does that prove God?

Chris: If there's no God who eternally exists, how can existence begin? If there's no God who has existence by his own nature and doesn't get it from any cause, how can the gift of existence be passed down the chain of creatures, who borrow it from each other? If nobody has a certain book, how can others borrow it? If nobody has the authority to give a soldier a weekend pass, how can he ever get it? You can't give what you don't have. So somebody must have existence and not just borrow it.

Sal: But why couldn't this being that always has existence be a part of the universe? Why does it have to be a God outside the universe, outside of space?

Chris: Outside of time too. He has to be eternal, to be uncaused, to have no beginning.

Sal: Why? Kids ask, "If God made everything, who made God?" What do you say to that? Why doesn't God need a cause?

Chris:  Because he's first. If nobody's first, nobody can be second, or third, or fourth. But things in the universe are second, and third, and fourth, and fifteen-millionth. Therefore there is a first.

Sal: Again, your argument doesn't tell you much about God. Just some thing that's first.

Chris: It tells us that he exists eternally, without beginning, and that he causes the existence of everything else. That's something, at least - enough to bother the atheist, isn't it?

Sal: Yes. What's the third argument?

Chris: It's from observing that everything dies, or ceases to exist. Now if there were no God who never died, who never ceased to exist, then eventually everything would die and nothing could begin again. And then there would be nothing at all. But that's absurd. There is something.

Sal: Maybe there just hasn't been enough time yet for everything to die, even the stars.

Chris: But if there's no God, no Creator, then there's no beginning to the universe, right?

Sal: Right. The universe always was.

Chris: Well, "always" is enough time for everything. If the universe had no birthday, then there's been an infinity of time already, enough time for everything that could possibly happen to happen. Including the possibility of universal death, universal destruction. So then how come we're still here?

Sal: The universe is only about 15 billion years old. The scientists say the Big Bang happened then.

Chris: And there's another piece of evidence for you. If there's no God, the universe always was. But science itself says the universe came into being 15 billion years ago.

Sal: That's a different argument.

Chris: Yes. The point of this one, Aquinas' third proof, is that without an eternal God everything would eventually cease to be and not be able to create itself anew. Zero, forever.

Sal: Won't that happen? The second law of thermo-dynamics says all energy gets dissipated, wears down. Even the galaxies get cold, like great big coffee cups.

Chris: The point is, why didn't that happen already if the universe is all there is and has always been there?

Sal: I don't know. Fourth proof, please.

Chris: The fourth one is an easy one. In the universe some things are better than others, right?

Sal: Of course.

Chris: So there must be a best, a standard of goodness to judge all the relative "betters". One thing is closer to it than another. And this standard has to be absolute goodness.

Sal: Why? Everything is relative. There's no absolute.

Chris: Absolutely?

Sal: Oops. Another contradiction. But everything is relative.

Chris: To what?

Sal: Not to any absolute. To each other, to everything else. There's just perpetual progress. Nothing is unchanging.

Chris: Progress to what goal? If the goal or standard moves too, how can you ever make progress toward it? How can you steal a moving second base? Progress implies an absolute, unchanging goal or standard.

Sal: So this argument says that if one thing is better than another there has to be a God?

Chris: An absolute good, yes. That's God.

Sal: Well, maybe one thing isn't really better than another. Maybe that's just our way of looking at things.

Chris:  You mean maybe people aren't really better than cows?

Sal:  Maybe.

Chris: Then why not eat people as well as cows? And why not preach hate as well as love? If goodness is only our prejudice, why pay attention to it?

Sal: You've got me there. I'm not that crazy. Of course love is better than hate, and people are better than cows.

Chris: Then there must be a standard of goodness, a God.

Sal: What's the fifth proof?

Chris: It's the easiest of all. It's called the argument from design. Design proves a designer. And nature is full of design. Therefore there must be a Designer behind it all.

Sal: Can you make that a little less abstract?

Chris: Sure. Suppose you were shipwrecked on a desert island, and you found a message written on the sand in English. Would you think it was written by chance, by the wind?

Sal: Of course not.

Chris: Or if you found a house there, would you think it just evolved by chance?

Sal: No. It would mean there was somebody on the island.

Chris: Well, the universe has more design in it than a house. How could it have happened just by chance? You know, there were two scientists talking to each other as the first moon rocket took off back in the '60s. One was a believer and the other was an atheist. The believer said, "Isn't it wonderful that our rocket is going to hit the moon by chance?" The atheist replied, "What do you mean, by chance? We put billions of hours of planning into that rocket." "Well, if you don't explain the rocket by chance, why do you explain the universe by chance? It's much more complicated than our rocket. We can design a rocket, but we can't design a universe." The same two scientists were walking past an antique store, and the atheist, who was an art collector, saw a painting in the window that attracted him. "Who painted that?" he asked. "Nobody", said the believer. "It just happened by chance."

Sal: It doesn't sound likely, but it just could have all happened by chance, you know. If you put a million monkeys at a million typewriters for a million years, they'll eventually type out Hamlet just by chance.

Chris: Maybe so. But if you found a copy of Hamlet, you wouldn't believe monkeys made it by chance, would you?

Sal: No. It's very improbable. But just possible.

Chris: Why then do you use different standards of explanation when it's a question of God? You don't use the tremendously unlikely explanation for Hamlet, or the rocket, or the picture, or the house on the desert island; the only reason you use it for the whole universe is to avoid admitting a God.

Sal: Hmmm. I'm not sure of that. I'll have to reexamine my motives.

Chris: Good. And here's another thing. Would you trust a computer programmed by chance? by a fall of hailstones on its keyboard, for instance?

Sal: No.

Chris: Or if you were flying in an airplane and the public address system announced that the plane was being flown by a computer that had been programmed by a football player in spiked shoes walking over computer cards, would you trust the airplane to land you safely?

Sal: No way.

Chris: Then why do you trust your brain and nervous. Why trust the system? It's like a very complex computer. If it's been brain programmed only by chance, by blind nature, and not by God, not by any Designer, why trust it when it does science, and when it tells you about nature? Or about itself? If you can't trust the programmer of the human brain, then you can't trust the brain when it tells you about the brain!

Sal: O.K., Chris, they're good arguments. But as I told you, I can't base my life on an argument.

Chris: And as I told you, I don't do that either. But they are strong clues, at least signs, evidence all pointing to God.

Sal: I'll have to admit that much, if I'm honest. But I still don't believe in God.

Chris: You will. Honesty is the beginning of the love of God.

Sal: Why do you say that?

Chris: Because honesty is the love of truth. And God is truth.

This is J. Fraser Field, Founder of CERC. I hope you appreciated this piece. We curate these articles especially for believers like you.

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Kreeft, Peter. "Can You Prove That God Exists?" In Yes or No: Straight Answers to Tough Questions about Christianity (Ignatius Press: San Francisco, 1991), 31-39.

Reprinted by permission of the publisher.

Yes or No: Straight Answers to Tough Questions about Christianity

The Author

kreeft1kreeftPeter Kreeft, Ph.D., is a professor of philosophy at Boston College.  He is the author of many books (over forty and counting) including: Ask Peter Kreeft: The 100 Most Interesting Questions He's Ever Been AskedAncient PhilosophersMedieval PhilosophersModern PhilosophersContemporary Philosophers, Forty Reasons I Am a Catholic, Doors in the Walls of the World: Signs of Transcendence in the Human Story, Forty Reasons I Am a CatholicYou Can Understand the Bible, Fundamentals of the Faith, The Journey: A Spiritual Roadmap for Modern Pilgrims, Prayer: The Great Conversation: Straight Answers to Tough Questions About Prayer,  Love Is Stronger Than Death, Philosophy 101 by Socrates: An Introduction to Philosophy Via Plato's Apology, A Pocket Guide to the Meaning of Life, Prayer for Beginnersand Before I Go: Letters to Our Children About What Really Matters. Peter Kreeft in on the Advisory Board of the Catholic Education Resource Center.

Copyright © 1991 Ignatius Press

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