After a night of teenage exuberance, my friends and I would usually end up lying out on a country road, gazing up at the starlit Australian sky, discussing the meaning of it all. We considered ourselves nonreligious, and yet there was something (isn’t there?) about the enormity of the sky that humbled us, stirred us, inspired us to ask deep questions about, well, everything. We called these GLUE conversations—GLUE being an acronym for God, life, the universe, and everything.
One of the questions that always came up was, “Why did this all happen?” This brought us, without knowing it, dangerously close to the contingency argument for the existence of God.
The case for God
In my new book, 20 Answers: Atheism, I present three arguments for the existence of God. One is the moral argument, which shows that if God does not exist then objective moral facts such as “It is wrong to torture babies for fun” cannot exist. But since objective moral facts do exist—i. e., some things are wrong independent of human opinion—then an objective moral lawgiver (i.e., God) must exist.
The other two are cosmological arguments, or arguments that use the physical universe as evidence for the existence of a being that transcends space, time, matter, and energy. One of them is a first-cause argument called the Kalaam argument. It shows that if the universe began to exist, it must have a cause, since something can’t come from nothing. This is the kind of argument many people arrive at when they ponder the question, “Where did everything come from?”
Medieval philosophers such as Al-Ghazali and St. Bonaventure created and refined the argument, but it fell out of favor until William Lane Craig published a defense of it in 1979. Since then, Dr. Craig’s numerous books, articles, and debates have made the argument well known again, even in atheist circles. One reason it is popular is that it can be simply stated:
Premise 1: Whatever begins to exist has a cause.
Premise 2: The universe began to exist.
Conclusion: Therefore, the universe has a cause.
Some atheists, especially those who frequent atheist websites, might say they’ve heard this “tired, old argument” and refer you to one of the ubiquitous online videos that they claim has “demolished it.” But, to borrow a phrase from Mark Twain, the reports of this argument’s death are greatly exaggerated. Trent Horn’s recent book, Answering Atheism, has two appendices refuting the most common objections to this argument.
Instead of defending this argument, I’d like to present the third argument. This argument is less familiar than the Kalaam argument but just as powerful. It is called the contingency argument for the existence of God.
The “middle child” argument
One reason atheists attack the Kalaam argument is because it’s well known and easy to formulate. However, because the contingency argument is less well known and more complex, it ends up being treated like the middle child, the one everyone forgets about but who is just as special as the others.
In some respects the contingency argument is even more persuasive than the Kalaam argument. In order to show why, I’ll present a formal version of the argument and then defend each of its premises. The contingency argument can be formulated in different ways. Here’s one:
- Whatever exists that does not have to exist requires an explanation.
- The physical universe does not have to exist.
- Therefore, the universe requires an explanation.
- The explanation for the universe is, by definition, God.
- Therefore, God exists.
How do we know that this is a good argument for the existence of God? Well, first off, we should be reminded that a good argument is one whose premises are more likely to be true than false and does not have a logical error (i.e., a fallacy) in its reasoning. Hardly any arguments have premises that people accept with total confidence. Even basic premises like “The external world is real” can always be doubted (at least if you’ve seen The Matrix).
Since there is no fallacy in the argument—you’ll have to take my word for it—if we can at least show that the premises of this argument are more likely to be true than false, then we will have succeeded in showing that faith in God is reasonable and that to deny that God exists flies in the face of the evidence.
A reason for existing
What does the first premise of this argument—“Whatever exists that does not have to exist requires an explanation for its existence”—mean?
Think of the scientist who discovers a star or bacterium that has never been catalogued. He asks the question, “Why does this thing exist?” And, “Why does object X behave in manner Y instead of manner Z?” This is what drives science as well as every other branch of study. It’s the great question: “Why?”
For example, when astronomers discovered red stars, they tried to explain their existence. To say that there isn’t an explanation—not that we don’t know it but that there actually isn’t one—strikes at the foundation of rational thought. It rejects the premise that underlies the quest for knowledge.
We know that nearly all things need a reason to exist. However, it’s possible that some things exist because they must exist; they can’t be anything other than what they are. This brings us to the difference between what is contingent and what is necessary.
Something is contingent if it can be different or can fail to exist. My trip to Six Flags yesterday, what time you went to bed last night, the formation of the moon, and the existence of the physical universe are all contingent things. They don’t have to be. They could have been otherwise.
But the mathematical truth 2 + 2 = 4, or the existence of God, are necessary truths. There cannot be a world where 2 + 2 equals anything except 4; and no matter how different the world could have been, there could not have been any world unless God created it, and so God is a necessary being.
The contingency argument merely claims that since the universe does not have to exist, there must be a reason for why it exists. This reason must be found in something that must exist, or a necessary being—“And this,” to quote St. Thomas Aquinas, “is what everyone means by ‘God.’”
Is the universe necessary?
Notice that the contingency argument avoids a common objection leveled at the Kalaam argument. It will do no good to say that the universe is eternal and so has no explanation for why it exists—the argument works whether or not one thinks the universe simply always was.
In his Summa Theologica, St. Thomas Aquinas held that it was impossible to prove, by reason alone, that the universe began to exist in the finite past. So he decided to meet his critics on their own terms and provide five proofs for God that worked even if the universe turned out to be eternal. His third proof was a version of the contingency argument. (Aquinas believed through divine revelation that the universe could not be eternal, but he allowed the possibility in order to strengthen his arguments).
Even if the universe were eternal, we would still want to know why there is an eternal universe instead of nothing at all. We’ve already seen that science is grounded in the idea that whatever exists has a reason outside of itself to explain its existence. We should, at least initially, try to find an explanation for the universe just as we would try to find an explanation for anything else.
As philosopher Richard Taylor points out, if you found a small, translucent orb floating in the woods, you would want to know why it exists. If your friend hiking through the woods with you said, “There’s no reason the orb exists. It exists without explanation; forget about it,” you’d think he was joking or that he just wanted to keep moving. The one thing you probably wouldn’t do is respond, “Ah! Interesting. Let’s move on, then.”
Notice that merely increasing the size of the orb does nothing to do away with the need for an explanation. If the orb were, say, the size of car, you would still ask why it exists. If it were the size of a house, you’d have the same question. In fact, even if the orb were the size of a planet or even the size of the universe, you’d still want to know why it exists. If we ask why such an orb, even as large as the physical universe, exists, then shouldn’t we ask why the physical universe itself exists?
Some atheists may bite the bullet and simply say the universe must exist; i.e., it is necessary and explains itself. As the twentieth-century English atheist Bertrand Russell put it, “The universe is just there, and that’s all.”
But is this really a viable option? At one time the universe didn’t contain stars and galaxies. Why do those objects exist now, when they clearly don’t have to? I can imagine the universe not existing, but I can’t meaningfully imagine a universe where 2 + 2 doesn’t equal 4. This shows that the former is contingent and requires an explanation, while the latter is necessary and does not require an explanation.
Is God the explanation?
Perhaps the universe has an explanation for why it exists, but could that explanation be simply another universe? The problem with this reasoning is that the argument starts all over again. Is this physical universe contingent or is it necessary? Because it is physical, this other universe could have existed in a multitude of different ways, which shows it would be contingent and require an explanation of its own. At some point the chain of explanations must terminate in something that cannot be different, so a random universe or force can’t explain why anything exists.
Whatever this explanation is, it must be greater than the physical universe. It must be something beyond space and time, beyond matter and energy, but with the power to create each of these things and to establish the laws they obey. It must be something that explains its own existence and cannot fail to exist.
Once again, that sounds a lot like God: what philosophers call a “necessary” being. God could not be different than what he is, which is what premise 3 states. Now, while some truths like 2 + 2 = 4 may be necessary, the only being that can be necessary must be a being whose essence (or what it is) is identical to its existence (or that it is). But only one being could simply be being itself and ground the existence of all other contingent realities. This, ladies and gentleman, is at the most basic level what God is.
Two common objections
So how might an atheist respond to this argument? He might make one of the following objections:
The fallacy of composition
Because everything in the universe needs a reason for its existence, it doesn’t follow that the whole universe needs a similar explanation. After all, just because theoretically every cell of an elephant could be lifted by hand, it doesn’t follow the whole elephant can be lifted in this way. Likewise, what applies to the parts of the universe may not apply to the whole universe.
But sometimes what applies to parts does apply to the whole. For example, if every piece of my Lego spaceship is red, then my whole Lego spaceship will be red. Likewise, if every part of the universe is contingent, then the whole universe must be contingent as well.
So the problem with this objection is that the fallacy of composition is an informal fallacy. It can’t be formally proven but only recognized after the fact, such as when you acknowledge that an elephant can’t be lifted with one hand even though all of its cells can be.
If the atheist wants to convince a believer of atheism, the burden of proof is on him to show that the contingency argument makes a mistaken part-to-whole reasoning. He can’t merely point out that there is some part-to-whole reasoning being used and call that a fallacy; because sometimes, as we saw in the case of the Lego spaceship, such reasoning is not mistaken. Similarly, it would become a “fallacy of composition” to say that because every part of the universe exists, it follows that the whole universe exists—which is obviously true.
To summarize, unless an atheist can give us an objective reason to think the universe is necessary and not contingent, then he can’t rely on the fallacy of composition to prove that the universe is not like all of its parts—in other words, a contingent entity that can fail to exist.
The parts explain the whole
Some atheists say that if we just explain every part of the universe then that will explain why the whole universe exists. Trent Horn refutes this objection in the book Answering Atheism:
Explaining why each part of the universe exists, even in a “circle of explanation,” does not explain why an entire universe exists at all. That would be like trying to explain why a baseball game is being played simply by explaining what each player in the game does (i.e., the batter is hitting a ball thrown by the pitcher, who takes a cue from the shortstop, who watches the man on second . . .). That strategy may explain each part of the baseball game, but it doesn’t explain why there is a baseball game happening.
The most basic question
You should encourage those who lack a belief in God to not brush off the question of why the universe exists instead of nothing at all with a simple, “Science will figure it out.” That’s because science, the universe, and everything we know fall under the umbrella of “that which does not have to be yet is, and therefore must have an explanation for why it is.” Only a being for which existence is not a luxury but the core of what it is can be capable of explaining life’s greatest mystery. And the only being who can fit that lofty description is the almighty God.