Sean Carroll on Science and God (part 1)
Is science ruling out the possibility of God? Can the universe be "self-contained"? Dr. Sean Carroll seems to think so! Dr. Craig examines these claims.
Sean Carroll on Science and God (part 2)
Dr. Craig continues a look at Sean Carroll's article. What about the fine-tuning found in the universe?
Sean Carroll on Science and God (part 3)
What are the crucial issues concerning Dr. Carroll's article?
Sean Carroll on the Argument from Fine-Tuning (part 3)
Kevin: Does the universe need God? We’ve been checking out an article by Sean Carroll of Cal Tech on “Reasonable Faith” with Dr. William Lane Craig. Dr. Craig, this is Sean’s submission to the recent Blackwell Companion to Science and Christianity. You have a submission as well in the volume on “God and Abstract Objects,” and we’ve just got to get into that. We are planning a podcast on your article as well. For now, let’s continue where we left off last time.
Dr. Craig: Up to this point, Carroll has been arguing in the article that it’s possible for science to give a “self-contained” picture of the universe with no reference to God. That is to say, science can give a full description of the physical universe from the moment of its inception on into the future without reference to God. But, even if that were the case, Kevin, the question could still be raised, “Well, why does this self-described universe exist rather than nothing?” One could ask a sort of a meta-level question about the existence of this universe, which is described as self-contained by contemporary science.
In this section of the article, Carroll is exercised to prevent even that move. He wants to say that that kind of question is illicit and needn’t be raised, needn’t be answered. All we need is the immanent, self-contained description of the universe given by science. There doesn’t need to be any answer as to why the universe exists rather than nothing--which Gottfried Wilhelm Leibniz said is the very first question which needs to be asked, which lies at the heart of the contingency argument for the existence of God as a transcendent explanation, or sufficient reason, for the existence of the universe.
Kevin: He does refer to you:
“A final example comes from the traditional ‘cosmological’ arguments for God’s existence. In the ‘Kalam’ formulation championed by Dr. William Lane Craig, the first premise of the argument states ‘everything that has a beginning in time has a cause.’ Things cannot simply begin; something must begin them.”
Did he formulate that first premise correctly?
Dr. Craig: Well, not entirely correctly, but it’s not unfair. But it’s irrelevant, Kevin, to this section of the article. He should have discussed that premise when he was talking about the origin of the universe. In that section of the article, he explores whether or not “beginning cosmologies” require a transcendent cause to bring the universe into being. He talked about whether there are “eternal cosmologies” that are equally plausible models of the universe. That was the relevant section for discussing the kalam argument.
This section doesn’t presuppose that the universe had a beginning. This section is willing to grant that the universe is eternal in the past, and it raises the question: “Why is there this eternal entity, this universe, rather than nothing?” There needs to be an explanation why anything at all exists rather than nothing. This is a philosophical or metaphysical question about the contingent universe.
Kevin: Well, he says, “The ultimate answer to ‘We need to understand why the universe exists/continues to exist/exhibits regularities/came to be’ is essentially. . . .”
What is his answer to that?
Dr. Craig: He says, “No, we don’t.”
Kevin: “No, we don’t.”
Dr. Craig: “We don’t need to understand that.”
Kevin: That sounds like a conversation stopper!
Dr. Craig: I don’t know if it’s a conversation stopper! What it is, is a denial of the Principle of Sufficient Reason. Leibniz said that if some contingent state of affairs obtains that could equally well not have obtained--and by that, I mean that it is instantiated, that these things exist rather than not--Leibniz said there needs to be some explanation of why it obtains rather than not. For there are possible worlds, after all, in which these states of affairs don’t obtain. Why do these contingent states of affairs obtain, or why do these things exist, rather than not? Carroll, in effect, just denies the Principle of Sufficient Reason. He would simply deny the first premise of Leibniz’s argument. This is the typical move that atheists make. They say that the universe just exists inexplicably.
Kevin: He says that this answer, “No, we don’t,” “is unlikely to be considered a worthwhile comeback to anyone who was persuaded by the need for a meta-explanatory understanding in the first place.” Then he says,
“It is always nice to be able to provide reasons why something is the case. Most scientists, however, suspect that the search for ultimate explanations eventually terminates in some final theory of the world, along with the phrase ‘and that’s just how it is.’”
Dr. Craig: Yes. Now I don’t know whether most scientists really think that. But even if they do, I think it’s just irrelevant whether most scientists suspect that the search for an ultimate explanation will just terminate in some final theory along with the phrase “that’s just how it is.” So what if that’s what most scientists think? This isn’t a scientific question. This is a metaphysical or philosophical question, and it doesn’t matter, really, if scientists think, “Well, that’s just how it is.” That position is saying that there is this contingent state of affairs, which could just as easily not have obtained rather than obtained, and yet it just inexplicably obtains.
But it’s a perfectly legitimate question to ask, “Why? Why is there a universe rather than nothing?” Indeed, I would say, Kevin, that to use the Principle of Sufficient Reason in every other case but then to deny it when you get to the universe is to commit what Alexander Pruss, a philosopher at Baylor University, has called “the taxicab fallacy.” This is a fallacy that derives from a remark by Arthur Schopenhauer that you can’t just dismiss the Principle of Sufficient Reason like a cab when you get to your desired destination! When the atheist gets to the universe, he’s not at liberty to just arbitrarily dismiss the Principle of Sufficient Reason like a hack.
The Principle of Sufficient Reason will still apply to the universe if the universe exists contingently. And I think Carroll does think it exists contingently. He says, “That’s just how it is.” He doesn’t say, “It’s necessarily that way.” He’s not saying the universe is a necessarily existing being. He’s saying the universe is a contingently existing reality, and there’s just no explanation for it. But that is to commit the taxicab fallacy.
On theism, you have an explanatory entity for the existence of the universe which carries the reason for its existence within itself because it’s metaphysically necessary. It exists by a necessity of its own nature. So unless Carroll is willing to say that the universe exists metaphysically by the necessity of its own nature, then he’s simply arbitrarily dismissing the Principle of Sufficient Reason when it comes to the universe, and that’s nothing but prejudice. That’s a naturalistic prejudice.
Kevin: He tries to speculate why some people are convinced that they need a meta-explanatory account, while others are directly happy without one, and he says what you just said. “The impetus to provide such an account comes from our experiences within the world, while the suspicion that there is no need comes from treating the entire universe as something unique, something for which a different set of standards is appropriate.”
Dr. Craig: Well, here I would say that his requirements for asking why the universe exists rather than nothing are, in fact, met. He says, “States of affairs only require an explanation if we have some contrary expectations, some reason to be surprised that they hold.” I think that is the case with the universe. The universe exists contingently. Unless you say that the universe is metaphysically necessary--which he doesn’t seem to be willing to do--, then the universe could just as easily fail to exist as to exist. There are possible worlds in which there is no universe--say, a world of only abstract objects. So why in the world does this four-dimensional, contingent, space-time reality exist rather than not? That is surprising! That is an interesting question that deserves to be asked.
So I think we have every reason to say that the Principle of Sufficient Reason applies here. If you have a contingent state of affairs which obtains that could just as easily not have obtained, then it’s plausible that there is some sort of sufficient reason explaining why it obtains rather than not. Ultimately, you have to get back to a metaphysically necessary being which exists by a necessity of its own nature.
Kevin: He brings up one more thing, Bill, that I want you to help me with because I hear it applied to many areas, such as philosophy and theology. And that is, one has to have enough background information in order to draw certain conclusions, and when it comes to the universe Carroll says, “We don’t have any broader context in which to develop expectations.” So he’s saying here that it’s difficult to make a judgement on metaphysical questions because the universe is unique, it seems.
Dr. Craig: Well, I think that metaphysics does give us that broader context. As I’ve explained, unless you’re willing to say that the universe is a metaphysically necessary being, then it is a contingent reality that exists. And that means that there are possible worlds in which the universe does not exist. I mean, think of a world, Kevin, that only is populated by abstract objects, say, numbers and sets and other mathematical objects. Yet in this world, we have the remarkable state of affairs of this four-dimensional, space-time reality, with all of its various properties, which exists, instead of a world like that. It surely makes sense to say, “Why?” What the theist can do is to provide some additional explanatory resources that make sense of this, whereas on atheism you simply have no explanation. The universe just exists, and there really isn’t any explanation, which seems to me to be quite unsatisfactory.
Kevin: Have I heard you call this a “brute fact?”
Dr. Craig: Yes, that’s what Carroll is saying. Carroll is saying that the universe’s existence is just a brute fact. I think that you can have facts without explanations if they’re metaphysically necessary. But again, when I think of all of these different possible worlds, and in this one you have this contingent reality that exists rather than these other worlds, to me that cries out for some sort of an explanation, which theism can provide but which atheism cannot provide. I think it is arbitrary, again, to use the Principle of Sufficient Reason, as scientists do, in every other case but to refuse to apply it to the universe and say that the universe is a contingent state of affairs that just exists without a reason. You wouldn’t say that of any other sort of contingent state of affairs in the world. As I’ve said elsewhere, merely increasing the size of an object to be explained, until that object becomes as big as the universe, does nothing to provide or remove the need for an explanation of that entity. Just being big doesn’t do anything to remove the need for an explanation of the existence of a contingent thing.
Kevin: We’ll conclude this podcast with how he concludes this section, Bill. He says in the last paragraph:
“We have no reason to think of the existence and persistence and regularity of the universe as things that require external explanation. Indeed, for most scientists, adding on another layer of metaphysical structure in order to purportedly explain these nomological facts is an unnecessary complication.”
Dr. Craig: Let me respond to both of those sentences. In response to the first sentence: there is a reason for thinking that the existence of the universe requires some sort of external explanation, namely, it is contingent. It isn’t metaphysically necessary. It doesn’t have to exist. So there needs to be an explanation why it exists rather than not.
With respect to the second sentence: it is irrelevant whether most scientists today think that adding on another layer of metaphysical structure is an unnecessary complication. Carroll says over and over again in the article that scientists don’t want to have supernatural entities. They are averse to supernatural realities. Now I don’t know if that’s true. I suspect that’s an exaggeration. But even if a sociological survey showed that that was the prevailing view amongst scientists, it is simply irrelevant. With respect to this argument, what most scientists would like the ultimate nature of reality to be--you might as well ask most psychologists or most historians what they would like the ultimate nature of reality to be. That’s just irrelevant. The point is that we have good reason for thinking that there needs to be an explanation for why the universe exists rather than not, and theism can give that explanation.
Kevin: Scientists cannot slice off a piece of something metaphysical and put it under a microscope and observe it. I mean, science is relegated to the realm of the material, and philosophy of science and philosophy is then engaged to draw inferences.
Dr. Craig: Yes, I think that’s absolutely right, Kevin. And that’s why I think we have to have a good deal of scepticism when scientists like Lawrence Krauss, Stephen Hawking, Sean Carroll, and others, go outside of the boundaries of science and begin to make metaphysical pronouncements about the ultimate nature of reality. When they do that, they are transgressing the bounds of their own discipline and making pronouncements on which they simply are not expert.
Kevin: I think it’s entirely appropriate to shake a scientist’s hand and say, “Thank you very much for helping us figure out how God did all this!”
Dr. Craig: Right, and I think we could say to someone like Sean Carroll, “Thank you for giving us, insofar as you’re capable, a self-contained description of the way the universe is!” That does not mean that there is not a transcendent Creator of the universe who designed and brought this universe into existence. Indeed, the evidence that we have from within this universe points beyond it to its ground in such a transcendent reality.
Sean Carroll on the Argument from Fine-Tuning (part 2)
Kevin: Welcome, come on in! It’s Reasonable Faith with Dr. William Lane Craig. I’m Kevin Harris.
Dr. Craig, we have been talking about this contribution by Sean Carroll to the new Blackwell Companion to Science and Christianity. We don’t have time to cover all the article, but we are going to focus on the fine-tuning that he brings up. “Why This Universe?”is the section in which he gives some examples of fine-tuning. Bill, what do you think is his overall view of fine-tuning when it comes to God and theories of the universe?
Dr. Craig: Well, he surveys nicely the various finely-tuned constants and quantities that have been discovered by contemporary physics, and then he lays out four explanatory options for dealing with this fine-tuning.
Kevin: And they are:
1. Life is extremely robust and would be likely to arise even if the parameters were very different, whether or not we understand what form this life would take.
2. There was only one universe with randomly chosen parameters, and we just got lucky that they are among the rare values that allow for the existence of life.
3. At different regions of the universe the parameters take on different values, and we are fooled by a selection effect. That is, life will only arise in those regions compatible with the existence of life.
4. The parameters are not chosen randomly but designed that way by a deity.
What do you think about that survey?
Dr. Craig: I think it’s a good survey of the alternatives--though the first alternative, that life would develop even if the constants and quantities had different values, is not so much of an explanation of the fine-tuning as a denial of it. It’s simply saying that fine-tuning is illusory, that these constants and quantities, despite what most physicists think, are not, in fact, finely-tuned for life, that even if the constants and quantities had different values, life would exist anyway in the universe.
Kevin: Let’s talk about that alternative then.
Dr. Craig: All right! Carroll says that he thinks that more credence needs to be lent to (1). He would like to deny the fine-tuning if he could get away with it. But I think it’s important to understand, Kevin, that when we talk about universes that are finely-tuned for the existence of interactive, embodied life, we’re not talking about universes that operate according to different laws of nature. Nobody knows what would happen in universes that operated according to totally different laws of nature! Rather what we are talking about is what would happen if the universe were governed by the same laws of nature that we have, but the constants and quantities which appear in those laws were to take different values. For example, if you were to increase the force of gravity a great deal or if the cosmological constant were very much greater than it is, what would be the consequences?
I think what people many times don’t understand is that the consequences would be catastrophic. If gravity were increased too much, the universe would simply collapse down to a single singularity, and life would obviously be impossible. If the universe were expanding too rapidly, then stars and galaxies, much less planets, would never form, where life could evolve. So in the absence of fine-tuning, it’s not as though we would have these dead planets existing, on which we can imagine life evolving. Rather in many cases there wouldn’t even be matter, there wouldn’t even be chemistry, in the absence of fine-tuning. That’s why the predominant view of the scientific community today is that the universe does exhibit this remarkable fine-tuning. That is to say, the fundamental constants and quantities of nature fall into an extraordinarily narrow life-permitting range, such that if these constants or quantities were to be altered by less than a hair’s breadth, the balance would be upset and life would not exist.
Kevin: He lists several of these that he finds very compelling.
Dr. Craig: Yes, the cosmological constant is fine-tuned to one part out of 10 to the 120th power. The initial entropy of the universe is fine-tuned to one part out of 10 to the power of 10 to the power of 123, a number which is simply incomprehensible. So he certainly grants that the universe exhibits, to all appearances, this fine-tuning, and the burden of proof would really lie on the person who thinks that this fine-tuning is just illusory.
Kevin: What about (2), the luck of the draw?
Dr. Craig: The luck of the draw! This is so interesting, Kevin, because Carroll admits that this hypothesis is not as plausible as the others and therefore he doesn’t go for it. He admits that if our universe is the only universe that there is, the chances of all of these parameters falling into the life-permitting zone by accident are just so remote that they cannot reasonably be faced. And in so saying, he is going with the consensus of physical cosmology today, which finds it necessary to advert to a multiverse in order to multiply your probabilistic resources to get a universe that is fine-tuned like ours by chance alone.
Kevin: This is option (3)?
Dr. Craig: Yes, that is option (3): If you have many roulette wheels in many casinos turning simultaneously, then the chances are increased that in one of them the ball will come up in just the number that you have selected. The third alternative is the multiverse hypothesis that the constants and quantities are randomly ordered across this range or World Ensemble of universes, and only those universes that are finely-tuned have observers in them. So, of course, observers will observe their universes to be fine-tuned for their existence! If it weren’t fine-tuned, the universe would be dead; it wouldn’t have any observers in it! So, given the multiverse, observers will evolve and exist by chance alone in some of these universes, and by a kind of self-selection effect observers can only observe universes that are fine-tuned for their existence. So there’s nothing here really to be surprised about. That’s alternative (3).
Kevin: Alternative (3), by the way, Bill, seems to be the biggest competitor to the God hypothesis.
Dr. Craig: Oh, it is, Kevin, and I think that’s very important to understand! Alternatives (1) and (2) are not where the debate lies today among scientists and among philosophers. It is between (3) and (4). We are dealing here with two very metaphysical hypotheses: an intelligent designer or a World Ensemble of randomly ordered universes as the best explanation of the fine-tuning of the universe. So this is where the debate lies; this is the cutting edge.
Kevin: As you mentioned in the last podcast, many people would like to think that the multiverse is eternal, but our current models are just against that.
Dr. Craig: That’s right. The Borde-Guth-Vilenkin theorem that we mentioned in our last podcast applies not just to our universe, but it also applies to the multiverse, so that the multiverse itself must have had a beginning and cannot be infinite in the past.
Kevin: Carroll seems to like (3). He’s going to get into (4) a little bit, but (3) seems to be the option that he wants.
Dr. Craig: He does like (3), for obvious reasons. He wants to avoid theism. But what is so intriguing to me, Kevin, is that despite his predisposition to (3) and despite the tone of confidence in which the article is written, Carroll actually supplies the objection that shows why (3) is untenable. He actually gives the argument that shows why (3) won’t work. It’s this, namely, it is simply not true that observers only exist in finely-tuned universes. The universe does not need to be as finely-tuned as it is in order for observers to exist. This has been a point that Roger Penrose at Oxford University has pressed very forcefully against these anthropic explanations of the fine-tuning. As Penrose points out, in order for us to exist all you would need would be a universe that had an island of order, no larger than our solar system, that simply formed in an instant by the random collision of particles. As improbable as that may sound, it is incomprehensibly more probable than a finely-tuned universe like ours! Universes in which there is this tiny island of order in which the solar system just falls together by random collisions of particles to produce observers is vastly more probable than a finely-tuned universe such as we observe. Therefore, they are more plenteous in the World Ensemble. So, if we are just a random member of the World Ensemble, we ought to be observing a world that is an island of order no larger than our solar system. In fact, do you know what the most probable observable world is? It is a world in which a single brain fluctuates into existence out of the quantum vacuum and has its observations, whatever they might be. That is the most plenteous observable universe in the World Ensemble.
Kevin: Are these known as the Boltzmann Brain?
Dr. Craig: Boltzmann brains, exactly! --named after the 19th century German physicist Ludwig Boltzmann, who first noticed this problem. Remarkably, it is not, in fact, the case that the fine-tuning can be explained away as a self-selection effect of observers. In fact, the most probable form of observable universes will be the Boltzmann Brain universes, and the fact that we don’t have such observations therefore strongly disconfirms the World Ensemble or multiverse hypothesis. And Carroll admits this in his article. He admits that the fine-tuning is far, far in excess of what would be necessary to sustain observers. Therefore, you can’t really explain the fine-tuning simply as a self-selection effect of observers. It’s very odd that he likes the multiverse hypothesis and doesn’t come out and admit that it’s inadequate. Nevertheless, he does give you here the raw materials of an objection pressed by people like Penrose that shows that the multiverse hypothesis is not going to work as an explanation of fine-tuning.
Kevin: What kind of conclusions does he draw from the fact that there is this excessive fine-tuning?
Dr. Craig: Well, he doesn’t come right out and say, “This shows that the World Ensemble or multiverse hypothesis won’t work.” But what he’ll do is then go to alternative (4), and he’ll make the move that I call, “So’s your old man!” That is to say, he’ll say, “Well, but the same objection applies to the designer hypothesis. The world exhibits far more fine-tuning, far more design, than is necessary. So why did God or the designer so finely-tune the universe beyond what is necessary in order for observers to exist?”
Kevin: Beyond what is necessary. . . .
Dr. Craig: He doesn’t have an answer to this objection against (3), but he wants to simply say, “Well, but it also applies to you proponents of (4).”
Kevin: “So’s your old man!”
Dr. Craig: Yes! The problem is, Kevin, that the objection doesn’t apply to (4) in the same way. The hypothesis of intelligent design doesn’t depend upon a self-selection effect for observers. So while this consideration is a potent objection to saying, “Well, fine-tuning is just the result of a self-selection effect of observers,” saying that the universe is more exquisitely fine-tuned than is absolutely necessary doesn’t do anything to subvert the hypothesis of intelligent design. In fact, what it would show is that the designer is far more intelligent than even is necessary to make observers!
I think the problem here, Kevin, is that Carroll, and others like him who press this sort of objection, are thinking of God on the model of the cosmic engineer. He’s an engineer who will produce no more fine-tuning than is absolutely necessary to get the result. But why should we think of God on the analogy of an engineer? Suppose God is more like the cosmic artist who wants to splash his canvas with extravagance of design, who enjoys creating this fabulous cosmos, designed in fantastic detail for observers. In fact, how do we know that there isn’t extraterrestrial life somewhere in the cosmos that needs these finely-tuned parameters in order to exist? Or perhaps God has over designed the universe to leave a revelation of himself in nature, just as it says in the book of Romans, so that someday physicists probing the universe would find the fingerprints of an intelligent designer, who is incredibly intelligent, incredibly precise, in making this universe. So raising questions about the motivations of the designer for so exquisitely designing the universe just doesn’t do anything to say that you don’t need an intelligent designer in order to create the universe.
Kevin: I run into that! We run into that a lot, Bill: “Well, why did God create so much space? I mean, what a bunch of waste, what a bunch of wasted space!” Waste only applies to someone that has limited resources and …
Dr. Craig: Yes, or limited time.
Kevin: Yeah, yeah.
Dr. Craig: God lacks neither. He has unlimited time, unlimited resources. This whole model of God as the engineer who has to marshall his resources and use them only in the most efficient way is, I think, is just a very defective understanding of who God is, who, I think, is probably more like the artist who enjoys creating a beautifully fine-tuned universe.
Sean Carroll on Science and God (part 1)
Sean Carroll of the California Institute of Technology is an eminent contemporary cosmologist, abundantly qualified to be writing on the topic of the current state of astrophysical cosmology. When Sean Carroll speaks to cosmological questions, we need to listen and to profit from what he has to say. Unfortunately, he's also fairly hostile to religious belief. He doesn't see or want to see any implications from contemporary cosmology for arguments for the existence of God. In his article “Does the Universe Need God?” in the Blackwell Companion to Science and Christianity (ed. James Stump and Alan Padgett) he suggests that modern science will lead us to a self-contained picture of the universe that doesn't involve God in any way.
Part of the difficulty in assessing Carroll’s argument is that he never defines what he means by the crucial term “self-contained.” I think that what he means by a self-contained picture of the universe is that science could give a complete description of the physical world from the moment of its beginning, if it had one, or from eternity past on into the future. The problem is that such a conception of being self-contained doesn't answer the question of why there is a universe at all or why, if the universe began to exist, the universe came into being.
It's perfectly possible to have a picture of the universe that is self-contained in the sense that everything in the arena, so to speak, is discoverable and describable by physical science, but which is not self-contained in that we need a metaphysical explanation for why the arena exists and came into being in the first place. So there's a certain equivocation on Carroll’s part with respect to the concept of being self-contained. The universe’s being self-contained in the sense that there is a complete physical description of the universe at every moment at which it exists doesn't imply that it's self-contained in the sense that it doesn't need God or a transcendent cause to bring it into existence in the first place.
In dealing with the question of the origin of the universe, Carroll points out that in the standard big bang model, the universe is finite in the past. As you trace the expansion of the universe back in time, you finally arrive at a space-time boundary called the singularity, before which nothing existed, that is to say, it is false that anything existed prior to the singularity. It marks the beginning, or the boundary point, of space and time and all matter and energy. Carroll distinguishes two types of cosmologies that offer alternatives to the standard model, what he calls beginning cosmologies and eternal cosmologies.
The beginning cosmologies, he explains, try to replace that initial singularity with some sort of quantum mechanical event. He identifies the most important of these quantum models as the Hartle-Hawking model, the so-called No Boundary Proposal promoted by Stephen Hawking. Although such models don’t involve an initial singular point, still, Carroll points out, “On these models, time is still finite.” Carroll explains that according to these models there was a time in the past which is such that there was no earlier time. I think that's a good description of what it means to say that the universe began to exist. There is a time before which there was no time, and so, on these models, the universe has a beginning.
By contrast, on the eternal cosmologies, one attempts to remove the singularity that marked the beginning of the universe in the standard model and extrapolate back to infinity, so that the universe has always existed.
Carroll argues that regardless of which type of cosmology eventually proves to be correct, science can give a completely self-contained description of the universe, such that any sort of appeal to God as Creator is unnecessary.
With regard to the beginning cosmologies, Carroll maintains that even if the universe had a beginning and there was a first moment of time, that doesn't imply that science can't give a self-contained description of the universe. He says, "The important point is that we can easily imagine self-contained descriptions of the universe that have an earliest moment of time. There is no logical or metaphysical obstacle to completing the conventional temporal history of the universe by including an atemporal boundary condition at the beginning."
I found Carroll’s characterization interesting, because it is, in a sense, a description of the view that I defend concerning God's relationship to time. I’ve argued elsewhere that God is atemporal, or timeless, without creation and in time subsequent to creation, so that the conventional history of the universe goes back to an atemporal boundary condition, which is the eternal God, who brings it into being.
What’s curious about Carroll’s characterization is that it is also descriptive of the standard model itself. In the standard model, the initial cosmological singularity is not a space-time point. Rather, it's a boundary to space-time. What we must keep in mind, however, is that this initial cosmological singularity is not permanent in the way that an eternal God is. This initial cosmological singularity is evanescent. It exists only for an instant, and then it immediately transforms into the physical universe, and conventional time then begins to exist. So postulating the initial singularity as the boundary point for the universe does nothing to give us a self-contained description of the universe in the sense that there doesn't need to be an explanation of why the singularity exists and why the universe came into being. Even if you say that the singularity is the first physical state of the universe, you still have to explain why it came into being at that point. Why isn't the universe past eternal?
Here's where Carroll makes a very interesting move. He claims that the fact that there is a first moment of time does not in any way necessitate that an external something is required to bring the universe about at that moment. Why not? Why wouldn't there need to be an external cause that brought the universe into being? In response to this question, Carroll quotes Stephen Hawking: “So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really self-contained, having no boundary or edge, it would have neither a beginning nor an end. It would simply BE. What place, then, for a creator?” Here Hawking appears to be endorsing what philosophers call a tenseless theory of time, according to which all moments in time are equally real and temporal becoming is an illusion of human consciousness. On this view the initial space-time chunk just exists tenselessly and never really came into being.
Now, granted, if you adopt that metaphysical view of time, then I don't think you do need an explanation of why the universe came into being because it didn't really come into being. It just exists tenselessly as a four-dimensional block, a geometrical entity. The question that would then be appropriate to ask is Leibniz's question, Why is there something rather than nothing? Why is there this four-dimensional space-time block rather than nothing?
But does the Hartle-Hawking model in fact imply a tenseless theory of time? No, it does not. This fact evident in Hawking and Mlodinow's more recent book, The Grand Design. In this book the authors describe how this early four-dimensional chunk can be interpreted as a time during which the spatial universe continues to contract, until one finally gets to the so-called South Pole of the southern hemisphere of this space-time chunk. This South Pole is like any other point in space time. Nevertheless, this South Pole, though not a singularity, does represent, according to Hawking and Mlodinow, the beginning of time and the origin of the universe. So on the Hartle-Hawking model, thus interpreted, the universe most definitely does begin to exist. As John Barrow, the British physicist, points out, on these quantum cosmologies, the universe does come into being, just as it does on the standard cosmology, only it doesn't do so at a point of infinite density. The universe doesn't come into being at a singular point, but the model still involves an absolute beginning of the universe.
So even if, on these quantum cosmologies, you can give a complete description of the universe from the South Pole all the way into the future, that doesn't mean that the universe is self-contained in the sense that there's an explanation of why it came into being, of why it exists instead of nothing. Here Carroll's argument simply doesn't go through. He’s presupposing a metaphysical, four-dimensionalist, tenseless theory of time, which is not at all implied or required by the Hartle-Hawking Model, as Hawking himself points out.
But what about eternal cosmologies? Here Carroll mentions bouncing cosmologies, in which a single big crunch evolves directly into our observed big bang, cyclic cosmologies in which there are infinite numbers of epochs separated by big bangs, and baby universe scenarios, in which our big bang arises spontaneously out of quantum fluctuations in an otherwise quiescent space-time. Carroll asserts that these eternal cosmologies represent equally plausible models of the universe as the beginning cosmologies. But if such an eternal model is correct, then a transcendent Creator becomes superfluous.
Here Carroll’s article disappoints. Carroll does not share with his readers accurately the contemporary state of cosmology. He makes no mention whatsoever of the work of Borde, Guth, and Vilenkin and the theorem that they developed that shows that precisely those cosmological models mentioned by Carroll cannot be extrapolated to past infinity and that the universe therefore must have had a beginning. One would expect in a survey of this sort by an eminent cosmologist to have at least a mention of, if not detailed interaction with, the Borde-Guth-Vilenkin Theorem, which was formulated back in 2003. Carroll says nothing to show how these speculative models can escape the implications of the Borde-Guth-Vilenkin Theorem. In that respect Carroll’s article fails as a response to or update on the article that Jim Sinclair and I wrote for The Blackwell Companion to Natural Theology on the kalam cosmological argument, in which Jim surveys these same cosmological theories and shows again and again that either they cannot avoid the Borde-Guth-Vilenkin Theorem, or else in order to do so, they have to resort wild conjectures that are scientifically implausible in light of empirical cosmology.
Carroll makes a good point in this regard that I would like to highlight. He writes, “Science isn't in the business of proving things. Rather science judges the merits of competing models in terms of their simplicity, clarity, comprehensiveness, and fit to the data. Unsuccessful theories are never disproven, as we can always concoct elaborate schemes to save the phenomena. They just fade away as better theories gain acceptance.” And the point I want to make is that these models that involve no beginning, these eternal cosmologies, fail precisely those tests that Carroll is describing: simplicity, clarity, comprehensiveness, and fit to the data. Sure, you can concoct elaborate schemes to try to save the phenomena and postulate an eternal universe. But that serves only to underline the implausibility of such models.
At a recent conference at Cambridge University, Alexander Vilenkin delivered a paper entitled, “Did the Universe Have a Beginning?,” in which he described three attempts to generate an eternal cosmology. The first was what he called a cosmic egg hypothesis, according to which there is an eternal static state that then decays into an expanding universe. The second was the cyclical models mentioned by Carroll, according to which the universe expands and contracts from past eternity. The third type was inflationary cosmologies, also mentioned by Carroll, according to which our big bang is simply an event within a wider mother universe. Vilenkin shows, on the basis of the Borde-Guth-Vilenkin Theorem, that none of these eternal cosmologies works. None of them can be extrapolated to past infinity in light of the cosmological evidence. Vilenkin concludes, “All the evidence we have says that the universe had a beginning.”
Now that's a remarkable conclusion, one that is very different from the impression Sean Carroll gives. Vilenkin, notice, does not say that the evidence for a beginning outweighs the evidence against a beginning. Rather, he says that all the evidence we have says that the universe had a beginning. Indeed, I can't think of any evidence that the universe is eternal in the past. I know of no evidence on the side of the scale supporting the claim that the universe is beginningless. What you have on that side of the scale is what Carroll aptly describes as “elaborate schemes concocted to save the phenomena” and so avoid the beginning of the universe.
An honest assessment indicates that the scientific evidence today strongly supports the beginning cosmologies. But if that is true, then we do not, in fact, have a metaphysically self-contained description of the universe. Even if science could describe the universe from the moment of its inception on into the future, that would not explain why the universe came into being. In order to avoid the implication of a transcendent cause, one has to resort to metaphysical hypotheses about tenseless theories of time that are no part and no implication of scientific models themselves.