God in Mathematics and Philosophy: An interview with John Lennox

God in Mathematics and Philosophy: John Lennox, Professor of Mathematics at the University of Oxford, Fellow in Mathematics and the Philosophy of Science at Green Templeton College, Oxford and renowned Christian Apologist discusses Christianity, mathematics, and C.S. Lewis.

Conducted by Luke Dickens and Stephanie Liu

Why did you choose to study mathematics?

I chose mathematics because 1) I was good at it and 2) my headmaster told me that it would get me into Cambridge. I actually wanted to be a Latinist first. Then, I wanted to do electrical engineering, and I was all set up to do it, but the headmaster said, “I think you would get into Cambridge, but only if you do math.”

How has mathematics influenced you?

It has taught me to think, because it is the most rigorous form of logic. All of the things that we deal with depend on logical analysis. In my field, you either have it 100% right or you do not publish it. That is why mathematicians do not publish as many papers as natural scientists and so on. In natural science you can say, “I took this chemical and I took that chemical, and I discovered this and that.” But you cannot do that in math. You either have to think of something entirely new and prove it rigorously, or forget it! It’s a humbling process.

How has mathematics influenced your understanding of God?

Mathematics is very powerful as an analogical tool. C.S. Lewis nearly failed to get into Oxford because he could not pass the math exam. They nearly lost him because of that! It was only because of the war that he was exempted from being required to pass the exam. Now Lewis had a very acute sense of geometry. If you read his books, you will find that many of his helpful analogies come from geometry, such as, for example, his analogy explaining a triune God.

How do you see mathematics being used to prove the existence of God?

Mathematics can be used at several levels. The first level is this: the fact that we can do mathematics is very powerful evidence of God. It means that this is a universe that has a logical structure and is mathematically describable. That is what has inspired modern science—the belief that, because there is a rational creator, you can study the universe mathematically. That is the big evidence. It is so big that most people miss it. They want some sort of mathematical equation. But it is the fact that you can do math that is the first big evidence of God.

There are certain specific branches of mathematics you can use as well, such as the field of probability. Take the Bayes’ Theorem for example. Reverend Bayes came up with this idea of probability that you can use antecedent probability to increase the probability of something being true. Roughly speaking, if you can ask yourself “What is the probability of there being a God?” then you can say, “What is the probability of there being a God granted you perceive the universe to be carefully designed?” Intuitively, the probability has become much greater! These arguments have been developed to great sophistication. The Bayes Theorem is correct, there is no question about it. The discussion generated by it is whether you can apply it to theories distinct from probabilistic, naturalistic scientific situations. One of my colleagues from Oxford, Richard Swinburne, a very famous philosopher, uses it a great deal.

Could you explain the dangers in using probability?

People often ask me, “What is the probability that God exists?” I say to them, “What is the probability that you exist?” You do not decide whether you exist based on the probability of whether you exist. You depend it on the basis of actuality. The question is not whether God is probable, but whether God is actual and if there is evidence for his actuality. People often do not distinguish between probability and actuality. The probability of you winning the lottery is very small, but if I come by your house and find that it has doubled in size and I see that you have ten cars outside, I would be prepared to believe that you have won the lottery!

What would another use of mathematics be?

This one involves math, in a way, but is more theoretical physics. Though, it is massively important! If you ask most of my atheist friends, “What is the best argument on the side of God?” most of them will say the fine-tuning of the universe. It is not strictly mathematical, but it is mathematical in that it is the math of theoretical physics. And the huge number of parameters that we now know about that have to be incredibly fine-tuned in order for life to exist is, I think, an important indicator of the existence of a God.

Can you explain how Turing machines relate to the existence of a God?

The Church-Turing thesis, which most people accept, is that the Turing machine simulates any computer, past, present, or future. Now, there is a whole series of results from theoretical computer science that have to do with the generation or nongeneration of information. The general result that is held these days is that a Turing machine cannot create any information in its input or in its informational make up.

Now, then, I will wear my biological hat (which is a fairly thin hat). The cell is at least an information processor. So, at that level, a Turing machine can simulate it. Therefore, the cell cannot create any new information. It seems to me that the demolition of the materialist thesis comes about by the results of theoretical computer science.

The point is, that it takes an intelligence to create information. If you make a Turing machine that is there now, it is an information processor. It cannot create any information that is not in its own internal system and its own input. The human mind is not a Turing machine. The conservation of information applies to machines but not to humans. This, however, does not bode well with evolutionary scientists since it seems that information cannot be created except by intelligences or an intelligence.

Now, let us say that I am not a Christian but have just accepted the argument that God exists. What next?

Romans 1 gives us the value and the limitations of natural theology—that is, the concept of reading God from the universe. Paul, the author of Romans, says that the invisible things of God are clearly perceived in the things that are made. He says that there is a God who is powerful and clearly seen, but that we cannot deduce things such as the doctrine of atonement from simply gazing at the stars. We need evidence of a different kind. Christianity claims to be part of history and experience, so we must draw on its history and experience. That is perfectly legitimate. We must get past the idea that science is the only way to truth. That idea, which I call scientific fundamentalism and everybody else calls scientism, is false. The very statement “science is the only way to truth” is not a statement of science, and therefore is false by its own definition. It is incoherent as a statement.

People often try to demonstrate inconsistencies in God’s properties. For example, they ask whether God can create a rock so heavy that he cannot lift it in the attempt to prove that he cannot be omnipotent. How would you respond to that?

Well, I will quote Lewis when he said, “nonsense remains nonsense even when we are talking about God.” It is nonsensical. It is wonderful to see Hawking and other theoretical physicists talking nonsense. The universe can create itself—that is nonsense. The same applies to God.

On that note with C.S. Lewis, could you tell us what you remember most about him from your personal interactions?

One thing that I remember most is his lecturing style. It was winter and very cold. The lecture room was completely full; people were on the floor and hanging in the windows. He would burst in through the double doors of the lecture room with a hat, coat, and scarf and start lecturing instantly. As he came into the lecture room and as he took off his hat and coat, he was building up to a tremendous flow of words. By the time he got to the podium, you had already had about five minutes of a brilliant lecture. He flowed on for 50 minutes, and then he would reverse the process. He kept lecturing as he put on his coat and his hat and so the last words were uttered as he burst out the door. There was no Q&A. That is my memory of Lewis.

Could you tell us about a story regarding C.S. Lewis’ memory?

Oh yes, Lewis had a photographic memory. One time he happened to be at a seminar at which a friend of mine, who later became a very famous professor of Italian, was speaking. And Lewis was so impressed that he came to him afterwards and said, “A group of friends meet with me every Tuesday, would you like to join us?” This was a great honor, so he went. He eventually got to know Lewis very well. One day he was in Lewis’ room and Lewis was in a convivial mood. Lewis said to him, “Take down any book from the shelves.” So he did so. “Open it anywhere and start reading,” Lewis said. So he started to read for a couple of minutes, and then Lewis just continued on and on and on. That was pretty awesome. He had that phenomenal of a memory.

Are there any other stories you remember about C.S. Lewis?

Yes. The chaplain at Magdalen College is a great C.S. Lewis fan. He and I were having dinner at Magdalen and he asked, “Have you ever seen the bet book?” The fellows have a betting book, and it’s very old, and they don’t use it anymore. And he said, “just look at this.” And there it is, in fine writing, that C.S. Lewis bets professor so and so that the word ‘eros’ cannot be found in any of the works of some very obscure Greek writer. The bet is dated as well. And underneath, C.S. Lewis again signs, “Received from professor so and so a crate of port.” So he won the bet!

What are you currently working on in your philosophical endeavors?

The thing that interests me most now is Thomas Nagel’s argument. He is an atheist who believes that evolutionary naturalism is false. C.S. Lewis and Alvin Plantinga both picked up on this problem, but now we have one of the world’s leading atheist philosophers who has acknowledged this issue. Briefly stated, the idea is that as long as you are thinking about the natural world, you do not exist, but the moment that you start thinking about thinking you do exist. If you argue that the mind is the result of a random evolutionary process, then you have no grounds for believing your mind. I suspect that Darwin’s theory will fall. I am not arguing that natural selection is false, but that macroevolution is wrong. You know the God of the gaps argument? Well evolution is just like that. A scientist would say, “I can’t explain why we came about, through natural means, so evolution must have done it.”