OBJECTOR: I don’t know what makes Catholics think that God exists. A rational person would ask for proof of the existence of something he could not see. It’s like living in a fairyland to believe that there is a personal God who exists somewhere out there.
CATHOLIC: Your challenge applies, of course, to historic Protestant Christians, observant Jews, and devout Muslims as well. In fact, I dare say that the vast majority of the human race, for most of its history, has believed in some form of deity. Are you implying that the vast majority of the human race has been irrational?
OBJECTOR: I don’t want to be judgmental, so I’ll refrain from answering that question, but I just don’t see any good reason for believing in a God like you Christians do. Can you prove that God exists?
CATHOLIC: You may be familiar with different forms of proof from high school geometry. One of them is called a reductio ad absurdum method. Its logical form is like this: (1) God either exists or he does not exist (both cannot be true); (2) If we can show that the statement “God does not exist” leads to an absurdity, it leaves “God does exist” as the only rational statement.
OBJECTOR: Okay, so show me that not believing in God leads to an absurdity.
CATHOLIC: First, we must distinguish between different types of absurdity. In mathematics, absurdity means a contradiction. Saying that three is not greater than two leads to a contradiction with other well-known truths of mathematics and is therefore an absurdity. In speaking of God, absurdity would mean something like this: If we deny that God exists, then we would expect the universe and human life to look one sort of way. If we affirm that God exists, then we would expect a quite different set of observations. My claim is that denying God’s existence leads to absurd conclusions about the universe and human life.
OBJECTOR: Well, I must commend you for your audacity. Do you mean to tell me that you can show me that my not believing in God is absurd? It seems to me quite the other way around. People who believe in God seem to be living in a dream world, not in the real world.
CATHOLIC: I understand why you say that. Let me begin by limiting my goal. I cannot show you that denying God’s existence is absurd in the mathematical sense of a contradiction, but I can show you one of two things. Either denying God’s existence is incompatible with some of the most basic realities of the universe and human life, or at least affirming God’s existence is more rational than denying it.
OBJECTOR: What kind of realities are you talking about?
CATHOLIC: Take the universe. Would you agree that the universe, as we see it every day and as we learn in various sciences, shows a law-like behavior? That is, do you agree that the universe displays effects that are governed by regular laws of nature?
OBJECTOR: You mean like the law of gravity or the laws of genetics? Of course. But how does that prove God?
CATHOLIC: If the universe we live in is law-like, what explains these patterns? If you deny the existence of a rational God, I suppose there might be several explanations still available, but can you agree that one of the most common explanations today is that this universe came into being by chance?
OBJECTOR: Many scientists seem to think so, at least those in the biological sciences.
CATHOLIC: Right. For example, Richard Dawkins is a biologist at Oxford University. He has tried to show in many of his popular writings that the laws of the organic world could have resulted from chaos and chance.
OBJECTOR: And he has been successful. So why do we need to invoke God to explain the natural laws of the universe?
CATHOLIC: I am not competent to judge whether or not he has been successful, although many of my biologist friends have grave doubts about his attempts. My point is a more foundational one. Even if we can show a linkage between the chance occurrences of organic history and the laws of genetics, for example, it does not follow that such laws came from those chance occurrences. At best, all it shows is that those chances occurrences are not incompatible with those laws.
OBJECTOR: What you say may be true, but do those who believe in God have any better explanation?
CATHOLIC: Which seems more rational to you: to believe in fixed laws of nature resulting from chance occurrences in the universe, that is, in law-like patterns of nature emerging from un-law-like events, or that these laws come from a being who placed these laws in the very fabric of the universe?
OBJECTOR: I am content with the idea that the laws of the universe emerged by chance. Your appeal to God doesn’t seem to me any more persuasive than my belief. And it certainly doesn’t show that my belief in chance is absurd.
CATHOLIC: I think we can speak of relative absurdity. That is, we can compare two explanations and decide that one of them seems more rational than the other. Your belief in laws emerging from chance violates a basic principle of explanation that Aristotle articulated over 2,000 years ago: The cause of an event must be greater or more powerful than the event itself. Your explanation suggests that chance caused the laws in some sense. But it is clear that the fixed laws of nature are more powerful in explaining things than are chance events. Appealing to chance would be the opposite of the normal way we do science.
Let’s take a concrete example. In physics, we explain particular events by appealing to general laws of nature. The phenomena of free fall (apples descending to the ground), projectile motion (bullets), and planetary movement are all subsumed under the law of universal gravitation, because the law is more general and powerful than the particular events.
So appealing to chance violates this basic principle that the cause must be more powerful than the effect being explained. That is why I say that your explanation of the laws of nature by appealing to chance is more absurd relative to invoking God to explain the same laws.
OBJECTOR: Invoking God doesn’t seem to me to be any more effective or powerful. Basically, you are appealing to something you can’t touch or see (non-empirical) to explain the touchable, seeable world. A vague appeal to a notion of God is not very scientific.
CATHOLIC: You’re right. That is not very scientific, but it is not because God is not an empirical entity. Science posits non-empirical constructs all the time. Take gravity. No one has ever seen it. All we can do is state the law in a mathematical equation. Black holes are even more non-empirical. If they exist, they will never be directly observed. Black holes are theoretical constructs used to explain phenomena we observe (e.g., radiation emissions), but they are very difficult to observe and can be observed only indirectly.
OBJECTOR: Yes, but that is precisely the point. Physical laws like gravity can be verified by prediction. Even though black holes cannot be verified directly, they are posited as real physical entities, not supernatural constructs. God is not like gravity or black holes. He is a supernatural entity, not a physical one. God is not something you can verify.
CATHOLIC: Yes, that is why I agreed with you that invoking God is not a scientific explanation. Science invokes only physical causes; some are directly verifiable (like gravity) and others are only indirectly verifiable (like black holes). This is what Aristotle called efficient causes. My point was that even though God is invisible, that fact is not what distinguishes invoking God from invoking non-observable entities in science. Science invokes unobservables in many instances.
OBJECTOR: Okay, I agree that science invokes non-observable entities, but you still haven’t shown that invoking God is a rational thing to do, since God is a supernatural entity and science deals only with natural ones.
CATHOLIC: Yes, I would not want to invoke God as a part of science, but I insist that the scientist—or any human being, for that matter —is more than a scientist. In other words, to be human is to ask for explanations of the universe, not just parts of it or specific laws within it. So when we ask about the universe and its laws as a whole, we are led into questions that science with its methods cannot answer. It is then that we are led to a choice. Either we content ourselves with the explanation you offered—namely, that these laws of nature came from chance occurrences—or we have a more powerful explanation of these laws by invoking a being who possesses them.
OBJECTOR: Well, as a person who has been trained to think scientifically, I am content with appealing only to physical explanations.
CATHOLIC: I suggest that is because you have unknowingly adopted a viewpoint that excludes other types of explanations. That exclusion, I dare say, is not rational but arbitrary. I agree that science as we have it today invokes only physical explanations, but I cannot agree that physical explanations alone are adequate to satisfy the human yearning to know.
OBJECTOR: Well, even if I agree with you on that point, I don’t think you’ve shown that not believing in God leads to absurdity.
CATHOLIC: All I ask is that you think of yourself not just as a scientist but as a human being who desires explanations whether they are physical or not. And the same search for explanations that guides science should guide our search for explanations that go beyond science. Remember that I spoke of relative absurdity. It is more absurd to believe that the laws of nature originated from chance and chaos than from a rational being. The universe, as we observe it and as we study it in science, demands a more powerful explanation than chance.