Reasonable Faith

Kevin Harris: Davies talks about how he's been influenced by John Wheeler's view of quantum physics in this next clip.

Paul Davies: I fell under the spell of John Wheeler, who was a very distinguished American theoretical physicist and famous for coining the term "black hole." Wheeler was the ghost in the room at the meeting I've just been at because he was the person who really wanted to take quantum physics to the extreme and involve the observer in a fundamental way. He called it a participatory universe in which acts of observation were like co-creators of reality.

Now, this is getting a bit deep rather too quickly. What I'm saying is that Wheeler developed an idea in which you didn't need to have a pre-existing agent or plan. It was somehow something that came out of the system. That's because there's a sort of retrocausality. That is to say that the existence of observers now and what they measure reaches back into the past, not in a way that can change the past, but in a way that can, if we can get into a little bit of quantum mechanics.

Quantum physics says that there is uncertainty built into nature at the most fundamental level. We normally think of that stretching into the future, that you can set up an experiment and there's a probability this will happen and that will happen. You can assign the probabilities, but you don't know for certain what can happen. But the same is true actually going back in time. The whole idea that there isn't just a single history, there's a blended amalgam of alternative histories that have led to the present. When we do an observation interrogating a past event, we cull all of those other possibilities that exist in an amalgam, which is called a superposition.

Kevin Harris: I've got a lot of reading to do on this to try to get it. A participatory universe where observation somehow plays a role in bringing reality into being? You'll have to help me understand that. For the life of me, I can't understand how the mere act of observing a particle at the quantum level can affect its measurement. I know I need to read John Wheeler, but until then, maybe you can shed a little light.

Dr. William Lane Craig: What Davies is talking about here is a hypothesis of John Wheeler that is so bizarre and so wacky that I think it's impossible to affirm. The idea is that the universe evolves over time to the point where there are observers in the universe, and the universe then is able to observe itself. So, it brings itself into being in the past.

This is clearly viciously circular because the universe would have to exist prior to itself in order to bring itself into being. As Davies said, it involves retrocausality. That is to say, backward causation, a causal loop where the present brings into being the past. But, of course, the present wouldn't exist unless the past were in being.

This is really just a crazy idea that I think is unaffirmable.

Kevin Harris: To another topic, Davies talks about his problem with the multiverse in this next clip.

Paul Davies: If you have this multiverse which has always existed, you don't really explain anything else because to say things are the way they are because they always were doesn't explain why they are as they are as opposed to some other way. So, you don't find that a particularly satisfactory explanation in the end. "Two cheers for the multiverse" is what I normally say because it has some value.

After all, if you think that the origin of the universe was a natural event, it's either a supernatural event or a natural event. If you want to go down the natural path, if something can happen once naturally, surely it can happen an infinite number of times. So, you're led to that. But where I think it goes a bit wrong is that if you look at specific models of the multiverse—and there's one due to Andrei Linde, for example—the way you do this is there's a frenetically inflating overall space.

Then you get these bubbles that the term that we use is nucleate. There's a physical process whereby a bubble universe can appear and have matter and so on. All that can be described by quantum physics. So, what you've got is quantum mechanics, actually quantum field theory and the general theory of relativity and so on. People do the calculations, they work out how these bubble universes can appear. But these are metalaws in this multiverse. Then you can say, well, where have they come from? Why can't you have some different metalaws? This would be to a different multiverse. It keeps pushing the thing further back. It's the tower of turtles problem.

Kevin Harris: Metalaws. The multiverse just pushes the issue back a step. Is that right, Bill?

Dr. William Lane Craig: What Davies is saying here is that you can explain away the unbelievably improbable fine-tuning of the universe for embodied conscious observers like ourselves by saying that there are an infinite number of universes in a kind of ensemble of worlds. These are randomly ordered in their constants and quantities. If, by chance alone, a finely tuned universe will appear somewhere in the ensemble, then it will appear infinitely many times in the ensemble. He appeals to inflationary theory to generate his many universes.

What he doesn't mention is that inflationary theory doesn't do anything to randomize the constants and quantities which are at issue. You have to marry inflationary theory to string theory. That is now widely disfavored in the scientific community, and therefore, this hypothesis is really not a credible one. Moreover, the inflationary theory, though it can be infinite to the future as these bubble universes continue to nucleate, it cannot be extended to the infinite past. That is the implication of our famous Borde-Guth-Vilenkin theorem, that inflation cannot be past eternal, which means that you've still got an origin of the multiverse at some point in the finite past to explain.

Secondly, even positing a multiverse with randomly ordered constants and quantities does not explain why we observe a finely tuned universe. The reason for that is that there are observable universes in the ensemble that have what we might call "freak observers" in them. Say, a brain that simply comes into existence by a fluctuation in the vacuum and has the illusion of an external world around it. These are called Boltzmann brains after the famous physicist Ludwig Boltzmann.

If we live in a randomly ordered multiverse, we could never know it because we could never know that we are ordinary observers rather than freak observers and therefore could never trust our sensory information. So, the multiverse hypothesis turns out to be literally self-defeating. If it's true, you could never have any reason to know that it's true because it defeats itself. So, this is really a quite hopeless gambit to try to explain away the fine-tuning of the universe.

Kevin Harris: But wait, there's more. Davies explains another reason that he doesn't like the multiverse interpretation.

Paul Davies: In some ways, it's because I feel it's a missed opportunity. We've been dancing around this notion of consciousness and the need for a conscious being. There's a nuance about that I'd like to get into in a moment. But basically, I felt that seeing as we are conscious beings, consciousness is part of nature. It's part of the world that we experience. It's the job of science to explain that. We can't just say it's bolted on. I think it's a scientific phenomenon and it needs an explanation.

If we think quantum mechanics is the wonderful theory of the world, then it ought to somehow incorporate consciousness in it. It ought to have something in there. But I like to call it the ghost in the design, that although we don't actually literally have to have a conscious being performing the experiment, the apparatus is designed to tease out a certain aspect of nature, a very special aspect of nature, measuring the momentum of a particle or something. These bits of equipment don't just appear in the universe; they're designed by conscious beings for a purpose.

We're back to that. I think we're never going to eliminate entirely the hand of agency of some sort because we're trying to—in doing quantum mechanics, in doing experiments—we're trying to get information about knowledge about we're learning something about the world, but in a way that we have designed in advance. So, we are the designers of interrogating a particular facet of nature. All that seems to go away if you go to the many-universes interpretation.

Kevin Harris: Consciousness and the fact that we as intelligent beings exhibit design is bypassed, so to speak, in multiverse or many-worlds theory. Davies says you can't leave those considerations out.

Dr. William Lane Craig: The expression "the ghost in the machine" was the philosopher Gilbert Ryle's way of mocking the idea of an immaterial mind or soul that we possess—body-soul dualism. Now, Davies adapts this expression because he wants to have a ghost in the design, as he says, whatever that means. It seems he wants to say that we are minds who have designed machines. But from this clip, I don't understand why he thinks that goes away under the multiverse interpretation. Quite the contrary, as we saw with the Boltzmann brains, there could be freak observers throughout the multiverse.

It could be that he's confusing the many-worlds interpretation of quantum physics with the hypothesis of the multiverse. Those are two entirely different things.

Kevin Harris: Emily spells out one of her concerns with what Davies just said in that last clip. Here it is.

Emily Thomas: My concern is that you are taking the nature of the human experiment or the limitations of the way that humans can interact with the world and then taking that as revealing something fundamental about the world itself rather than the way that our results, our findings are going to always be filtered through our own experience and through our own limitations as conscious observers.

Of course, there will be a relationship between conscious observation and the results that we get if we are conscious observers making those results. But I guess it goes back to this concern I have with anthropocentrism again. I worry that we're putting ourselves, in a way that we like to do hubristically as humans, right at the center of things in a way that feels to me without quite enough justification.

Kevin Harris: Sounds like her main objection is that Davies makes an unwarranted extrapolation from human design to design in the origin of the universe. It's anthropocentrism, as she put it.

Dr. William Lane Craig: I frankly don't understand what Emily is talking about here. Mark Steiner, the philosopher, wrote a wonderful book called *The Applicability of Mathematics as a Philosophical Problem*. What Steiner argues is that our universe is anthropocentric in the sense that it is one in which mathematics is applicable to the description of and the discovery of new physical phenomena. He says this requires some sort of explanation.

Why is it that we live in an anthropocentric universe, one in which mathematics is useful in describing and discovering physical phenomena? It doesn't seem that either of these two dialogue partners have really faced that problem.

Kevin Harris: Emily is asked why there is something rather than nothing in this next clip. Here is what she says.

Emily Thomas: I think it is one of the most important questions that we face. I don't think any of us really know the answer. I am not persuaded by arguments like the cosmological argument which says that if you go far back enough in time, you must reach a first cause, that first cause starts the universe off and is what people call God. What we are hitting up against is a boundary question.

Science can only take us as far as the boundaries of the universe that we live in because we use laws of physics or physical regularities to model what happens. Physics breaks down at the very beginning of the universe, so we can't look to purely science—well, we can't really look to science at all to answer that question. That's where philosophy and theology come in. For religious theologians, the answer is God. For me, I am quite sympathetic to the idea that we're living in an infinite multiverse which can ultimately just be explained by saying it's always existed.

There has always been something rather than nothing. It seems to fit for me in the trajectory of the development of our understanding of ourselves and our place within the world. We used to believe that the Earth was at the center of everything, that we lived in a very small cosmos, and everything revolved around us. Then we realized actually we on our planet are orbiting a star, our sun, in a solar system with other planets. Then we realized we're in a galaxy with many of these other systems. Our galaxy is one of billions of galaxies with billions of these star systems in. It seems to me not unreasonable to make that next step and say, "Well, maybe our universe is one bubble in an infinite cosmic foam and these universes pop into and out of existence, and we can explain why there's something because there's always been something."

Kevin Harris: She really embraces the multi-universe, Bill, the multiverse. She says the multiverse fits the trajectory of what we've discovered in the past—that the Earth is not the center of the universe, and there are billions of stars and galaxies. The universe keeps getting bigger, so on that trajectory, why can't it be so big that it exists eternally from the past? Speaking of extrapolation, that sounds like a big one to me.

Dr. William Lane Craig: Yeah, it is pretty large. I think as an argument for the existence of a multiverse, this is extraordinarily weak. There is no evidence that there is such a thing as the multiverse. On the contrary, there are good reasons to think that there is not. First, as I already explained, it cannot be infinite in the past as Emily suggests. It must have had a beginning, as required by the Borde-Guth-Vilenkin theorem, that inflation cannot be past eternal.

Second, if there were a multiverse, then we could never know that we are ordinary observers who can trust our observations rather than freak observers like Boltzmann brains. Her hypothesis is literally self-defeating. If it were true, you could never have any reason to think that it's true.

Kevin Harris: If I ever start another rock band, I'm going to call it Boltzmann Brains. One more clip today. Davies presents the image of a tower of turtles.

Paul Davies: Here we connect with theology because most of these arguments Emily was talking about, the cosmological argument for the existence of God—these various arguments have been dropped, I think mostly, by theologians these days. But this tower of turtles that we're talking about, the question is, you've either got an infinite regress or you've got a sort of super-turtle that can support the whole tower.

You could say that super-turtle is the laws of physics and it just magically is there. A brute fact. How could you ever get around that? The only way you could get around this is by the old concept of a necessary being. That is that the super-turtle exists necessarily, that its non-existence would not just be a fact but would be a logical impossibility.

Kevin Harris: The only way to actually stop the infinite regress is to posit a necessary being whose non-existence would be a logical impossibility. He then insisted this necessary being needn't resemble anybody's God. I know you agree with him about a necessary being in general, but is he right that a necessary being can be cleanly separated from anything like the God of classical theism?

Dr. William Lane Craig: Not at all, Kevin. The God of classical theism is a necessary being, and the God of the Bible is wholly compatible with his necessary existence. "I am that I am," God told Moses. So, the God of classical theism, the God of the Bible, perfectly fits as the candidate for this metaphysically necessary being that explains the contingent universe that we observe and inhabit.

Kevin Harris: For our own part, Emily has said that what would move her most toward theism isn't really the cosmological or design type of arguments. It's a persuasive answer to the problem of evil, which she currently thinks outweighs the evidence for a good God. You and I both know that's a very common sticking point. Maybe you can just respond to her directly on that point a little.

Dr. William Lane Craig: Sure, I would respond in two ways. First of all, I would respond by defending the various theistic arguments which are much stronger than Emily seems to realize. Secondly, I would respond by asking her to prove that evil and suffering are somehow incompatible with the existence of an all-powerful and all-good God. It is the atheist who bears the burden of proof here to show that evil and suffering are incompatible with God's existence. There's just no way for the atheist to shoulder that burden of proof.

Kevin Harris: Davies ended by saying that he's looking for a genuinely new conceptual framework, something beyond agency and mechanism to make sense of purpose and existence, and that he's hoping thinkers like Emily or perhaps future AI, he said, will help find it. Bill, you've pointed out that classical theism already supplies real explanatory resources here. For some reason, well, neither one of them, but Paul Davies, he just will not go there. He doesn't want to embrace theism. What's your reaction to that? It calls for speculation, but what do you make of this search for the undiscovered X?

Dr. William Lane Craig: In his earlier work, such as *God and the New Physics*, Davies affirmed the existence of what he called a naturalistic God. That is to say, a God who didn't transcend the universe but is in the universe and subject to the laws of nature. But I want to know why do they consistently overlook classical theism?

Classical theism explains why there's something rather than nothing. It explains the origin of the universe at a point in the finite past. It explains the unreasonable effectiveness of mathematics with regard to physical phenomena. It explains the fine-tuning of the universe and it explains other things as well, such as the objectivity of moral values and duties and meaning and purpose in life. Classical theism provides everything they're looking for.