New Orleans Baptist Theological Seminary, New Orleans, LA, –
NOTE: Despite repeated requests Dr. Carroll has not yet furnished his PowerPoint slides or proofread his portion of the debate.
William Lane Craig – Rebuttal Speech
Thank you, Dr. Carroll, for that vigorous interaction!
Introductory Remarks
In my opening speech, I argued that God’s existence is significantly more probable given the evidence of contemporary cosmology than it would have been without it. This is due to the support which cosmology lends to key premises in the cosmological and teleological arguments.
Before we review those arguments, let me just say a word about Professor Carroll’s concluding remarks, which, I believe, are extraneous to tonight’s discussion.
He is very concerned to show that God’s existence is improbable relative to certain non-cosmological data. For example, the problem of evil, our insignificant size, and so forth. The very fact that these are non-cosmological data shows that they are not relevant in tonight’s debate. I have addressed things like the problem of evil extensively, for example, in Philosophical Foundations for a Christian Worldview.[23] So the debate tonight is not over the probability of theism versus naturalism. That would require us to assess all sorts of non-cosmological data. Rather, the question is: is God’s existence more probable given the data of contemporary cosmology than it would have been without it? And I think it certainly is.
Let’s look at those two arguments that I defended.
The Kalam Cosmological Argument
Consider, first, the evidence for the beginning of the universe from the expansion of the universe and thermodynamics.
The Causal Premise
To my surprise, Dr. Carroll challenges the first premise of this argument by saying it is based on outmoded Aristotelian concepts of causality. I protest – not at all! There is no analysis given of what it means to be a cause in this first premise. You can adopt your favorite theory of causation or take causation to be a conceptual primitive. All it requires is that the universe did not pop into being uncaused out of absolutely nothing. If that is the price of non-theism, then I think the non-theist is welcome to it. Dr. Carroll says on the Hartle-Hawking model the universe is uncaused. Not at all! The universe comes into being on such a model, and there is nothing in the theory that would explain why that universe exists rather than not. The model may be self-contained; but that is perfectly consistent with my argument. I am not arguing for some kind of interventionist deity, but rather, why does the universe exist? Why did it come into being at all?
Evidence from the Expansion of the Universe
With respect to the second premise, Dr. Carroll says there are all kinds of beginningless models of the universe. Well, it certainly is true that such models exist; but the problem is that none of them is successful.
|
Beginningless Models |
| Model average expansion history |
Condition requiring a beginning |
| 1 |
Expanding models |
Singularity theorems |
| 2 |
Asymptotically static models |
Metastability |
| 3 |
Cyclic models |
Second Law of Thermodynamics |
| 4 |
Contracting models |
Acausal fine-tuning |
As Jim Sinclair has shown in our article in the Blackwell Companion, all of the models that Dr. Carroll has mentioned have been shown to be either untenable or not to avert the beginning of the universe.[24] Alex Vilenkin says flatly, “there are no models at this time that give a satisfactory model for a universe without a beginning.”[25]
Consider in particular Dr. Carroll’s own model.
This model presupposes a reductionistic view of time according to which the direction of time is defined in terms of entropy increase. Now, in the model notice there are two arrows of time for the mother universe pointing in opposite directions. So on this view of time, we don’t really have an eternally existing mother universe here at all. Rather, you have two universes which share a common origin in the central surface. So what the model actually implies, rather than avoids, is a beginning of time and of the universe. Time has a beginning on this model, and therefore it involves all of the problems that are pertinent to the universe’s coming into being.
Be that as it may, I think it is safe to say that there is no credible classical model of a beginningless universe today.
Dr. Carroll does hold out hope that quantum cosmology might serve to restore the past eternality of the universe; but I would say that not only is there no evidence for such a hope, but I would agree with Vilenkin that if there is a quantum gravity regime prior to the Planck Time, then that just is the beginning of the universe. Dr. Carroll says you can have quantum descriptions of the universe that are eternal, and that is certainly true, but the question is: why would the universe transition to classical spacetime just 13 billion years ago? It could not have existed from infinity past in an unstable quantum state and then just 13 billion years ago transition to classical spacetime. It would have done it from eternity past, if at all.
So I think we’ve got good evidence from the expansion of the universe that the universe probably began to exist.
Evidence from Thermodynamics
What about the evidence from thermodynamics? First is the problem of information loss to baby universes on his theory. You will recall that is why Stephen Hawking rejected the baby universe hypothesis. Dr. Carroll responds, “My mechanisms for generating the baby universes don’t use Hawking’s mechanisms.” All right; but are they any more successful? I don’t think so. According to Chris Weaver in his article on the Carroll-Chen model,
The FGG [Farhi-Guth-Guven] nucleation [that Dr. Carroll uses] out of a de Sitter space-time is merely speculative and . . . Carroll’s discussion of it should be thought of as exploratory. . . . it is therefore safe to conclude that a central piece of the model is missing, and so the CC-M [Carroll-Chen model] is incomplete in that it does not have a clear recommended dynamical path from the background [space-time] to the birth of [universes] like ours.[26]
In fact, Weaver goes on to point out that for a universe described by the Borde-Guth-Vilenkin theorem (like ours), the Farhi-Guth-Guven mechanisms cannot produce such a universe. Therefore, these mechanisms fail.
I also, secondly, pointed out that there is a Boltzmann Brain problem with respect to Dr. Carroll’s model. It seems to me that he just didn’t respond to the point that I was making, namely, that since every baby universe grows into a de Sitter space, there will be vastly, vastly more of these Boltzmann Brains in the long run than there will be ordinary observers. So what Dr. Carroll would need to do is to justify some non-standard measure of probability that would make ordinary observers more probable than Boltzmann Brains. But he admits that he cannot do it.
We also then saw that quantum gravity will not avert this conclusion because of the Wall theorem, which should be valid for the quantum gravity era and requires a beginning of the universe.
Summary
So it seems to me we’ve got good evidence from the expansion of the universe and from thermodynamics that the universe is probably not past eternal but began to exist.
The Teleological Argument
What about that second argument based upon the fine-tuning of the universe?
Reality of Fine-Tuning
Here Dr. Carroll expresses scepticism that the fine-tuning is real. But a good many, if not most, of his colleagues would simply disagree with him here. Luke Barnes provides a list of just some of the scientists who have published works in defense of the reality of fine-tuning:
I can think of one more name that we should add to the list – namely, Sean Carroll! Listen to what he has to say about the low entropy condition of the early universe, which Robin Collins calls “potentially the most outstanding case of fine-tuning.”[27] Carroll writes, “If the universe we see is really all there is with the Big Bang as a low-entropy beginning, we seem to be stuck with an uncomfortable fine-tuning problem.”[28] So he tries to explain away this fine-tuning via the world ensemble, or multiverse, hypothesis.
Chance?
But then, as I argued in my opening speech, he confronts the Boltzmann Brain problem once again. Even if Dr. Carroll could show that ordinary observers predominate in life-permitting worlds, what about all of those worlds that are not life-permitting because the other constants and quantities are not finely-tuned? In such worlds – which vastly outnumber finely-tuned worlds – there will be no ordinary observers, and yet there will be untold numbers of Boltzmann Brains produced by thermal fluctuations. So the entire multiverse will be dominated by universes having vastly more Boltzmann Brains than ordinary observers like us.[29] Therefore, the data on the multiverse hypothesis is incomprehensibly improbable. The evidence is strongly disconfirmatory of the World Ensemble hypothesis.
Design?
Dr. Carroll says that theism does no better in accounting for the low entropy condition of the universe. For why, he asks, did God make the entropy of the universe so unnecessarily low in order to create us? Well, I have two responses to this. First, it is no part of the fine-tuning argument to assert that the purpose for which the universe was created is us! There may well be intelligent life created by God scattered throughout the universe. But, secondly, as Robin Collins has pointed out, even if a general low entropy condition is not necessary for our existence, it is necessary for the discoverability of the universe. God hasn’t given us an instruction manual about how the world works. But what he has done is make a world which is susceptible to rational exploration and discovery. And if God wanted to make a universe discoverable by embodied, conscious agents, he might well make it in such a low entropy condition. (You will hear more about that tomorrow when Robin gives his paper.)
So it seems to me that Dr. Carroll faces uniquely a Boltzmann Brain problem for a number of reasons – a problem that does not afflict theism.
Summary and Conclusion
So, in summary, this is not a debate between naturalism and theism. Otherwise, I would be offering ontological arguments, moral arguments, other sorts of arguments. For that debate, you need to listen to my debate with Dr. Rosenberg last year at Purdue University.[30] What this debate is about is: to what degree do the data of contemporary cosmology render God’s existence more probable than it would have been if we didn’t have that data? To my mind, it is almost undeniable that God’s existence is much more probable given the evidence that we have for the beginning of the universe and the fine-tuning of the universe. Therefore, contemporary cosmology is strongly confirmatory of theism.
[23] See Chapter 27, “The Problem of Evil” in J. P. Moreland and William Lane Craig, Philosophical Foundations for a Christian Worldview (Downers Grove, Ill.: InterVarsity Press, 2003), pp. 536-53.
[24] William Lane Craig and James Sinclair, “The Kalam Cosmological Argument,” in The Blackwell Companion to Natural Theology, ed. Wm. L. Craig and J. P. Moreland (Oxford: Wiley-Blackwell, 2009), pp. 101-201.
[25] Alexander Vilenkin, “Did the universe have a beginning?” http://www.youtube.com/watch?v=NXCQelhKJ7A
[26] Christopher Gregory Weaver, “On the Carroll-Chen Model,” September 17, 2013, arXiv:1309.4976 [physics.hist-ph], p. 11. See http://arxiv.org/abs/1309.4976 (accessed March 20, 2014).
[27] Robin Collins, The Well-Tempered Universe, pre-print.
[28] Sean Carroll, From Eternity to Here, p. 365. Cf. “If our universe began at the Big Bang, it is burdened with a finely-tuned boundary condition for which we have no good explanation” (Ibid., p. 5).
[29] Thanks to Robin Collins for bringing my attention to this point!
Sean Carroll – Rebuttal Speech
Great. Well, thanks again. I think that we can just go right back to my three major points, and I think that, halfway through our forum, I believe these three major points more strongly than ever. Now, I know that Dr. Craig would disagree but I’ll try to establish that his disagreements with number one are based on misunderstandings of the science. His disagreements with number two, the evidences against theism, is largely based on using number three—the fact that theism is not well defined.
So let’s go to the kalam cosmological argument. There’s a deep philosophical difference between us. I claim that a consistent, complete model that fits the data accounts for what we see in the world is a success. There’s no right that we have to demand more than that, and I believe that Dr. Craig’s response was, “Yes there is.” I don’t think this counts as a very good response. It’s a very difficult thing because the universe is different than our everyday experience. That doesn’t sound like a surprising statement but we really need to take it to heart. To look at a modern cosmological model and say, “Yes, but what was the cause?” is like looking at someone taking pictures with an iPhone and saying, “But where does the film go?” It’s not that the answer is difficult or inscrutable; it’s completely the wrong question to be asking. In fact it’s a little technical, most of my second talk here, but I think it’s worth getting it right. Why should we expect that there are causes or explanations or a reason why in the universe in which we live? It’s because the physical world inside of which we’re embedded has two important features. There are unbreakable patterns, laws of physics—things don’t just happen, they obey the laws—and there is an arrow of time stretching from the past to the future. The entropy was lower in the past and increases towards the future. Therefore, when you find some event or state of affairs B today, we can very often trace it back in time to one or a couple of possible predecessor events that we therefore call the cause of that, which leads to B according to the laws of physics. But crucially, both of these features of the universe that allow us to speak the language of causes and effects are completely absent when we talk about the universe as a whole. We don’t think that our universe is part of a bigger ensemble that obeys laws. Even if it’s part of the multiverse, the multiverse is not part of a bigger ensemble that obeys laws. Therefore, nothing gives us the right to demand some kind of external cause.
The idea that our intuitions about cause and effect that we get from the everyday experience of the world in this room should somehow be extended without modification to the fundamental nature of reality is fairly absurd. On a more specific level we talked about my model. Again, I’m not trying to defend my model; I’m the first one to say that it has problems. None of the problems that it has are the ones that Dr. Craig raised. He says that it’s not really eternal, which it is hard to express the extent to which I think this is grasping at straws. The axis for time goes from the top to the bottom and it goes forever. The only sense in which this universe is not eternal is that there is a moment in the middle where the entropy is lowest. I made the point in my opening speech that that has nothing to do with the kind of beginning you would need to give God room to work and as far I can recall Dr. Craig didn’t address that argument.
He does say that it is speculative, the idea of baby universes coming into existence. I’m the first to agree. It’s completely speculative. He quotes a paper that says the mechanism by which baby universe are created is speculative, it might not be right. Again, it’s completely true. He claims to use it to say that unitarity is violated even though the quote he read didn’t even mention unitarity and wasn’t about unitarity. That is not a sensible objection.
I will repeat – the quantum eternity theorem, a sensible analysis of the history of the universe, might be with the rules of quantum mechanics. He claims that someone else said there might be a singularity in quantum gravity but he gives us no understanding, he simply repeats his previous analysis. So, I want to draw attention not to my model but to the model of Anthony Aguirre and Steven Gratton because this is perfectly well defined. This is a bouncing cosmology that is infinite in time, it goes from minus infinity to infinity, it has classical description everywhere. There is no possible sense in which this universe comes into existence at some moment in time. I would really like Dr. Craig to explain to us why this universe is not okay.
Now there’s a theorem by Alan Guth, Arvind Borde, and Alex Vilenkin that says the universe had a beginning. I’ve explained to you why that’s not true but in case you do not trust me I happen to have Alan Guth right here. One of the authors of the Borde-Guth-Vilenkin Theorem, Alan what do you say? He says, “I don’t know whether the universe had a beginning. I suspect the universe didn’t have a beginning. It’s very likely eternal but nobody knows.” Now how in the world can the author of the Borde-Guth-Vilenkin theorem say the universe is probably eternal? For the reasons I’ve already told you. The theorem is only about classical descriptions of the universe not about the universe itself.
So, going to the teleological argument. It is true – Dr. Craig brings up the point that people disagree with me, it is true. I attempted to give an argument and not merely an opinion poll. If we’re allowed to take opinion polls I will poll my fellow cosmologists on whether God had anything to do with creating the universe and I will win by a landslide. I suspect that Dr. Craig thinks the majority of the opinions of cosmologists is important for some issues but not for others. The entropy of the early universe is exactly backwards when it comes to being an argument for fine-tuning according to theology. Dr. Craig quotes me in a “gotcha-moment” saying, “Look, the early universe was finely-tuned with a low entropy.” That is absolutely true. The point that I raised was not that there is not fine-tuning, it’s that there’s no evidence the fine-tuning is for life to exist. Indeed, the maximum possible entropy of the part of the universe we observe is this huge number, 10122. The entropy that you would need is a little bit lower than that if you wanted life to exist. But it’s almost the same. It’s 0.999 etc. times the maximum entropy, whereas the actual entropy of the early universe is enormously smaller than that. There’s absolutely no reason why the universe would look like this if the fine-tunings were put there in order for life to exist. I’m not saying there’s not fine-tunings; I’m saying they’re not there for life.
Turning to the multiverse, again it is a completely speculative thing, but it is a completely natural thing and I don’t really see any argument against that. The multiverse, the idea that outside the universe we see there could be very different regions with very different physical parameters, is no more radical then the idea that there are different planets with different atmospheres. To a frog on a lily pad that lily pad is its universe. To us in the universe we see a hundred billion galaxies is enough but it’s very, very easy to come up with physical models that have much more out there. The main argument Dr. Craig has against this is the Boltzmann Brain argument. Again, I gave you why that’s not a good argument and it seems to have been ignored in Dr. Craig’s last speech; namely that the multiverse does not predict that everything happens. It predicts certain things happen with certain frequencies. So what you do as a working cosmologist is check that your universe is not dominated by Boltzmann Brains. Are there multiverse models that pass that test? Yes, there are. It is easily avoided. Then he brings up this weird argument, he says, “There could be the regions where ordinary observers could not exist because the parameters are not right but Boltzmann Brains could exist.” But the whole point is that Boltzmann Brains are forms of life. Boltzmann Brains can only exist where life is possible. So what one does in cosmology is look at the multiverse regions where life is possible and counts the number of Boltzmann Brains versus the number of ordinary observers—there are models that pass the test.
Now, I think that this is, again, a philosophical point here because when I talked about the list of ways in which our expectations for theism come out completely wrong when you compare them to the world, Dr. Craig said, “Well, that’s not the point, we’re not arguing about morality” and things like that. But again that misses the point of my argument. I was not actually putting forward these as strong predictions of theism. I was making the point that there are no strong predictions of theism. It’s not that there should be no evil in the world if God exists, it’s that you can always wriggle out of the prediction that there should be no evil in the world if God exists. That’s why it’s not a good theory of the world generally, that’s why it’s not a good cosmological model, particularly. Now, Dr. Craig said that we shouldn’t expect to know things about the world simply because we say that God finely-tuned it. “Just because under theism,” he says, “God made the parameters of the universe such to allow life to exist doesn’t mean we can have any other expectation for predicting what those parameters are.” This reflects something that he said on his website earlier. In a similar context he said, “Suppose God is more like the cosmic artist who wants to splash his canvas with the extravagance of design and who enjoys creating this fabulous cosmos designed with fantastic detail for observers.” So, what this attitude is saying is that – well, my point is that – this is not some sort of sophisticated apologetic strategy. This is an admission of defeat. This is saying we should never expect theism to explain why the universe is one way rather than some other way. You know God—God is an artist. You know artists; they’re kind of quirky and unpredictable. We can’t expect to know what they’re going to do ahead of time. Anything you might possibly observe about the universe, according to this view, I can explain as saying, “That is what God would have done.”
In naturalism, on the other hand, you need to play by the rules. When we say in cosmology or physics that a certain parameter is finely-tuned, it’s not just the parameter looks funny to us, it’s that we have a prior set of expectations for what values the parameters should take on and the parameter doesn’t fit those expectations. So we look for physical models that explain it, and that drive to understand things better helps us understand physics better, helps us understand the real world better. So, unlike God who is an artist and can’t be predicted, nature is not an artist. Nature plays by the rules. Nature makes predictions. Nature provides explanations. Thank you.
William Lane Craig – Closing Speech
Perhaps you feel like you have been drinking from a fire hose this evening! But let me in my final speech try to draw together some threads of the debate and see if we can draw some conclusions.
Introductory Remarks
I hope that it has been obvious tonight that I am not offering God as a theory to compete with scientific theories about the universe. Rather, I am saying that those self-contained, secular theories provide evidence for theologically neutral premises in philosophical arguments leading to a conclusion that has theistic significance—premises like “The universe began to exist” or “The fine-tuning is not due to physical necessity or to chance.” If those premises are supported, then it follows deductively that there is a Creator and Designer of the universe. Dr. Carroll’s complaints about theism’s not making predictions would be important only if I were offering some sort of theistic theory of the world. But I am not doing so. I am simply appealing to the cosmological evidence in support of these theologically neutral premises that go to deductively imply the existence of a Creator and Designer.
Let’s look again at those arguments that I defended.
The Kalam Cosmological Argument
The Causal Premise
First, the kalam cosmological argument. Dr. Carroll challenges the first premise, that if the universe came into existence, there is a transcendent cause that brought the universe into being. Honestly, I am quite astonished that he would think that the universe can literally pop into being out of nothing. Let me just give three arguments for why there must be a cause.
First of all, it seems to me a metaphysical first principle that being doesn’t come from non-being. Things don’t just pop into existence from literally nothing. Nothingness has no properties, no potentialities. It is not anything. So it seems to me inconceivable metaphysically to think the universe can come into being from nothing.
Secondly, if the universe could come into being from nothing, then why is it that only universes can pop into being out of nothing? Why not bicycles and Beethoven and root beer? What makes nothingness so discriminatory? If universes could pop into being out of nothing, then anything and everything should pop into being out of nothing. Since it doesn’t, that suggests that things that come into being have causes.
Finally, all the empirical evidence we have supports the truth of the causal principle. When Dr. Carroll says, “The universe is different than our experience,” this is really committing what Alexander Pruss calls the taxi-cab fallacy, that is to say, you go with the causal principle until you reach your desired goal and then you think you can just dismiss it like a hack because you don’t want there to be a cause of your entity – the universe. But if the universe came into existence, if the universe is not eternal, then surely it would need to have a cause. In fact, to deny this is unscientific because the whole project of contemporary cosmogony is to try to find what is the cause of the universe! So on his principle, it would be a science-stopper and would destroy his very field of expertise.
Evidence from the Expansion of the Universe
With respect to the second premise that the universe did begin to exist, he denies that he actually has an origin of time going in two opposite directions.
But this is a different diagram of his model.[31] Notice that on this diagram, you have a non-reductionistic arrow of time that goes from past to future. This is not an arrow of time that is determined by entropy increase, as he had in the other diagram. This is a non-reductionistic view of time, that Professor Maudlin and I accept, where the direction of entropy increase doesn’t define the direction of time. On this model, the universe contracts down from eternity past from infinity to a relatively low entropy point and then begins to expand again. That kind of model is physically impossible. It contradicts the second law of thermodynamics. That is why you have got to have the arrows pointing in both directions, if you want to hope for this model to be realistic. But if you have a double-headed arrow of time in both directions, then you have a beginning of time and of the universe. So I want to co-opt Dr. Carroll’s model for myself! On his model of the universe, the universe began to exist, along with time.
I also pointed out that on the Borde-Guth-Vilenkin theorem, there are no classical models that succeed in showing the universe to be beginningless. He rightly points out this is just classical space-time. But then I never heard a response to my claim that if there is a quantum gravity era prior to the Planck time, then it would have to be itself finite because otherwise it becomes inexplicable why classical spacetime only came into being 13 billion years ago rather than from eternity past.
So I think we have got good evidence for the beginning of the universe from the expansion of the universe.
Evidence from Thermodynamics
As for thermodynamics, here I argued that in order to explain why we are in a low entropy state, the standard answer is that the universe began relatively recently with its low entropy condition at the beginning. By contrast, his model, I charged, violates the unitarity of quantum physics. He says, “No, because I am not using the same mechanisms as Hawking.” But then I pointed out that the mechanisms that he appeals to are both conjectural and actually incompatible with a universe described by the Borde-Guth-Vilenkin theorem, as Christopher Weaver points out in his critique of the model.
Secondly, the Boltzmann Brain problem. I don’t think that Dr. Carroll has really come to grips with this, quite honestly. There are at least two reasons why Boltzmann Brains would dominate. First, because on his multiverse model, in the long run every baby universe becomes a de Sitter space and will become dominated with Boltzmann Brains. Secondly, in all of the other worlds that are not fine-tuned, there just aren’t any ordinary observers; but there will be thermal fluctuations that will produce Boltzmann Brains. So he is the one who has to justify some non-standard measure of probability in order to explain why ordinary observers like us should exist rather than Boltzmann Brains.
Then I appealed to the Wall theorem to show that even on a quantum gravity theory you are not going to avoid the beginning of the universe. Dr. Carroll may have responded to this, but if he did, it went by so quick I didn’t hear it. So it seems to me we’ve still got the Wall theorem showing that even with a quantum gravity era there has to be a beginning.
The Teleological Argument
Design?
As to the teleological argument from fine-tuning, he seems to have rested his entire case here on the fact that entropy would be way, way unnecessarily too small on theism. But I gave two responses to that. First, there may be life throughout the universe, not just us. Secondly, as Robin has pointed out, the low entropy condition is suitable for the discoverability of the universe. By contrast, on his view, it is incomprehensibly improbable that we should exist, given the equilibrium or the heat death state at which the universe would more probably exist.
Summary and Conclusion
So, in sum, in seems to me that on balance that we have got good evidence that the universe began to exist and that, therefore, there must be a Creator that brought it into being. Moreover, this is a personal Designer of the universe in view of the fine-tuning of the universe for intelligent, interactive agents like ourselves.
[31] The different diagram in Fig. 17 is from Sean Carroll, From Eternity to Here: The Quest for the Ultimate Theory of Time (New York: Plume, 2010), p. 363, Fig. 87.
Sean Carroll – Closing Speech
All right, congratulations to everyone for having made it this far. I will confess a bit of frustration in this final talk because I think almost everything that Dr. Craig had said in his last talk he had already said, and I tried to give my best response to it. They weren’t always matched. So, I’m going to take advantage of that to do something bizarre and unpredictable, which I’ll get to in a second.
First, I want to notice some of the things he did say. He said he was astonished that I refused to accept the fact that things need causes to happen. To which I could only quote David Lewis, “I do not know how to refute an incredulous stare.” I tried to give the reason why the causation analysis that we use for objects within the universe does not apply to the universe but that more or less whizzed on by. Dr. Craig gets a lot of mileage out of the presumed nuttiness of things just popping into existence. “Why don’t bicycles just pop into existence?” Again, I tried to explain what makes the universe different but more importantly the phrase “popping into existence” is not the right one to use when you’re talking about the universe. It sounds as if it’s something that happens in time but that’s not the right way to do it because there’s no before the beginning, if there’s a beginning. The correct thing to say is there was a first moment of time. When you say it that way it doesn’t’ sound so implausible. The question is, is there a model in which that’s true? Do the equations of the model hang together? Does the model fit the data? And we have plausibly positive answers to all of those.
He spends a lot of time on my own model, more time than I would have spent on it. He is upset that I did not include an arrow at the bottom in my axis when I drew the graph previously. I don’t care about that to be very honest. The double arrows here are just to express the fact that there’s no intrinsic arrow of time. The arrow of time that we experience is because of the behavior of matter in the universe—the entropy increasing. And he says that’s in violation of the Second Law of Thermodynamics. Yes, it is an explanation of the Second Law of Thermodynamics. This is the reason why we in our little part of the universe observe the second law. He mentions once again Boltzmann Brains and he says that there should be more Boltzmann Brains than ordinary observers. I again explain why that’s not true because it’s a model dependent statement. In this particular model it turns out to be easier to make a universe than to make a brain. That’s a selling point of the model.
So, with that under our belts, I want to actually just completely go off the topic and talk about issues beyond naturalism and theism. We’re having a discussion here about God and cosmology but let’s pull back the curtain a little bit. There are very few people in the modern world who become religious, to come to believe in God, because it provides the best cosmology or because it provides the best physics or biology, or psychology, or anything like that. And that includes Dr. Craig. There’s a famous quote by him that says, “The real reason, the primary reason, for believing in Christianity isn’t cosmological arguments.” I’m not mentioning this as a criticism; it is simply an observation of fact. There are other reasons to be a theist other than cosmology, and I think that is true. I think that makes sense. Most people who become religious do so for other reasons—because it gives them a sense of community, a sense of connection with the transcendent, it provides meaning or fellowship in their lives. The problem is that the basis of religion in the modern Western world is theism, belief in the existence of God. I’ve tried to make the case that science undermines theism pretty devastatingly. Five hundred years ago it would have made perfect sense to be a theist. I would have been a theist five hundred years ago. By two hundred years ago science had progressed to the point where it was no longer the best theory. By a hundred years ago after Darwin it was a rout. And by these days with modern cosmology there’s no longer any reason to take that as your fundamental worldview.
So what do you do if you identify as a member of a religious tradition in this situation. I think there are three options. One is to deny the science, to think that the world is six thousand years old. Happily, nobody up here on this stage today takes that attitude. That was a previous debate from a couple weeks ago. But there is a second attitude which is to accept the science but deny the implications—to say that none of the progress of modern science has in any way altered the fundamental view of reality that we put together two thousand years ago. I think that there’s two reasons why that’s not a good idea. Number one, I think it’s wrong, as I tried to explain throughout the debate, but number two, I think it’s a strategic mistake. I think that if one believes in theism that must be central to one’s view of the world for many, many other reasons, and because theism has been undermined by science it takes theists and it marginalizes them as part of the wider intellectual conversation. Humanity is at a crossroads. It’s at a very important time in the history of the world. We need to have deep discussions about who we are and where we’re going, and people who cling to the belief in God after science has undermined it are increasingly not going to be part of that discussion.
We talked about cosmologists and physicists, here’s what philosophers believe. There’s a recent survey that asked philosophers thirty big questions. And you know philosophers don’t agree on anything, but here are the three questions they had the greatest amount of consensus on: external reality exists, science tells us something about that external reality, and God does not exist. Now, again, get three philosophers in a room and they don’t even agree that there are three philosophers in the room. So, the fact that there’s only 73% is a still very impressive, and this includes professional philosophers of religion.
So I claim that there is a third option. Here’s the point where I start giving people advice who did not ask me for any advice. So, I ask your indulgence here. The third option, as I see it, for the person who is religious is to say, “Look, we admit we were wrong. We were wrong hundreds of years ago when we based our belief system on the idea that God was in charge of it all. Of course we were wrong, it was two thousand years ago! We didn’t have microscopes or telescopes. What right do we have to think that we would have gotten the fundamental nature of reality right but,” this person could hypothetically say, “religion is much more than theism. It’s not just the belief in God. There is the fellowship we feel for our fellow human beings.” For centuries, religious traditions were the place where human beings did their most careful, sustained, and rigorous contemplation about what it means to be human, about what it means to experience joy or suffering, to feel camaraderie with your fellow man, to be charitable, and so forth—to have meaning and purpose in your lives. So, maybe this person could say there is something to be learned even for naturalists from the outcome of all that contemplation. Maybe there is wisdom in Scriptures and the Sermon on the Mount, in the art and the music and the lives of the saints, or for that matter, the Bhagavata Gita or the Daodejing. I don’t know whether there is wisdom there, I’m asking for guidance. At the end of the day we’re all human beings trying to figure out our way in this confusing world.
The point is that naturalism replaces theism but it doesn’t replace religion. It doesn’t necessarily provide answers to the hard questions of meaning and fulfillment and purpose. I think that it can. I find naturalism, personally, to be an inspirational and profound view of the world. Ironically, the part I find most inspirational is the fact that some day I will die. Everyone in this room will someday be dead and there will not be an afterlife, a continuance, a judgment. The lives we lead now are not dress rehearsals. They are the only performance we have; therefore, what matters is what is here—the people we know and love, the lives we can change, the good we can do for the world. That is all there is, so of course that is what matters. Another way of putting it is naturalism has addressed the easy questions, the basic physical features of how the world works, but there are hard questions of meaning and purpose and fulfillment yet to be answered. What I like to say is we have picked the low-hanging fruit off of the tree of knowledge but there’s a lot of succulent goodies up there on the higher branches, and we’ll get there faster if we all climb together. Thank you.
Question and Answer Session
MODERATOR: Let’s give them both another hand. [applause] This was just amazing. The one thing I am amazed by is that there are great disagreements about time but both of them stayed on time. [laughter] Thanks, guys! Come on up to the podium. Let me explain how this is going to work. I need to get my notes here. My wife gets very nervous when it’s just my stream of consciousness working. [laughter]
We have a microphone in each aisle for questions. The aisle over here on Sean’s side is for questions for Sean Carroll. The aisle over here by Bill’s side is for questions for Bill Craig. And we’re going to alternate from one to the other, and we’ll have an even number of questions—alright? When a question is asked to Sean, Sean will have two minutes to answer. If Bill wants to respond he’ll have up to one minute. And vice versa—when a question is asked to Bill he has up to two minutes to answer, and Sean has up to one minute.
Let me give some instructions to those who are asking questions. Number one: state your question in a hurry, like twenty seconds, okay? Number two: make sure that it’s a real question. [laughter] The way to make sure that you’re asking real questions is ask yourself a question. Ask yourself this question: was I paid to come here? [laughter] Exactly! If you were not paid to come here then you are welcome to ask a question but you are not invited to lecture. So make sure it’s a real question. Second, ask yourself this question: will everyone benefit from hearing this question? Is it a question that’s going to shed light, to get at more truth? Or is it more akin to some interesting thoughts you had one night after your third highball? You’ve heard it said, there is no such thing as a stupid question. That’s not true. [laughter] That’s a stupid saying. And my last instruction would be: you only get one question. When you ask your question, step away from the microphone. No follow-ups, unless Sean or Bill asks you. If they don’t understand what you’re saying and they ask you a question, you can clarify it. So we can get more questions in and everyone will be happier. So come to the microphones now, and we will begin.
One other thing: here at the Greer-Heard forum we follow Robert’s Rules. My name is Robert, I make the rules. [laughter]
Question 1: Hey, Dr. Carroll, how are you doing? Thank you for being here tonight, sir. In your polemic tonight on theism you said something like, “Look, if you have a fully explainable model, why do you keep looking for something else to add?” Okay? Now, my question is something like this: if you took as a metaphor for the universe, say, that we have a complete and entire physical explanation for the existence of the jet engine – you know, we can talk about internal combustion, all the things that go into making it and so forth – but does that complete knowledge mean that Frank Whittle didn’t exist? Does a fully accurate mathematical model make this so? My question is this, exactly: isn’t this a category mistake to assume that it does; namely, that law and mechanism does away with personal agency?
Dr. Carroll: Great. This is being recorded, I don’t need to repeat the question—right? So his question got on to the tape? Okay. Yeah, so, it’s a very good question and I think the answer is the universe is different than things inside the universe. As I tried to explain, there is a reason why there are reasons why. There are reasons why in our everyday life it is perfectly correct to speak a language of causation and explanation and invention and creation, and when you look carefully what those reasons are, they don’t apply to the universe. The universe isn’t part of a bigger structure in which there are patterns, evolution laws, arrows of time, expectations for what should happen. So a jet engine and a universe are just not very analogous to each other.
Dr. Craig: It seems to me that that’s just fantastic, to think that the universe could just come into being from non-being; that it just pops into existence. And, as I said, if one says that that is possible, then you’re confronted with the difficulty: why only universes? It seems to me then that everything and anything would come into being from nothing because there’s nothing about nothing that could make it discriminate between universes and anything else. So it seems to me that this is a difference without a difference. I would say that the condition that applies to the universe that makes the causal principle relevant would be its beginning to exist. If a horse begins to exist, there’s got to be a cause for that. If a building begins to exist, there’s got to be a cause for that. Similarly if the universe begins to exist, there needs to be a cause for that. And in that respect the conditions for the causal principle do apply. Sorry, I’m out of time!
Question 2: Dr. Craig, what would you say to a Thomist, a follower of Thomas Aquinas, who says, “I have good arguments for God such as Aquinas’ Five Ways that are based on indubitable metaphysical principles. It would be imprudent to advance a theistic argument that rests even partly on modern science since science can change and if some theistic argument loses face as science changes so does theism.?” Dr. Craig, what about this charge of imprudence from the Thomist.
Dr. Craig: Yes, I would say that Thomas Aquinas’ own metaphysical principles are highly dubious and in doubt, and that therefore I have little confidence that his arguments are, as he claimed, demonstrations. Aquinas was familiar with the kalam cosmological argument. This is a very ancient argument, and he was aware of the Muslim medieval thinkers who championed it. And Aquinas said if the universe did began to exist, then clearly there had to be a cause of the beginning and of motion. But he thought you couldn’t prove with demonstrative certainty that the universe did begin to exist. (Of course, they had none of the modern empirical evidence.) But I am persuaded, and I think Aquinas would agree, that the philosophical arguments for the beginning were good probability arguments, even if they weren’t mathematical demonstrations. So I think Aquinas simply raised the bar too high for what constitutes a good argument for God’s existence. We don’t need to have certainty or mathematical demonstrability. All we need to do is offer arguments that are logically valid, have true premises, and the premises are more plausibly true than not. And if that’s right, then that’s a good argument for the conclusion. And I think we’ve got such arguments today, and we shouldn’t be preoccupied with Aquinas’ concern for metaphysical or mathematical demonstration.
Dr. Carroll: One of the architects of the Big Bang model was George Lemaître, who’s a Belgian physicist, mathematical physicist, MIT and Harvard graduate, and also a Jesuit priest. And later in life, in the 1950s, he was serving on a papal commission because the Pope at the time wanted to put forward a statement that said, “Look! The Big Bang! Excellent evidence for the existence of God.” And Lemaître stopped him from doing that. He said, “No, you can’t get your peanut butter of theology mixed up with the chocolate of science. It does not actually taste great together because, who knows, someday some smartass will come up with a theory of the universe that is eternal and there isn’t a Big Bang anymore.” Dr. Craig and I are on the same side. We think that Lemaître was wrong to make that kind of statement. We both believe that if you’re going to be an intellectually honest theist you need to accord with the best data from the universe. And as we both agree, science isn’t in the job of proving things with metaphysical certitude. It says that models get better and better at fitting the data. I think that works just as well for theism as it does for naturalism.
Question 3: Dr. Carroll, thanks for being here tonight. My question: at the end of your first speech you mentioned how, in a nutshell, the theist weasels his way out of predictions that we would make based on the evidence. My question is, though: coming at it, that seems to be assuming that naturalism is some sort of default position and that theism is just adding one step on. My question would be that: do you not find that naturalism is a sort of a bent, an angle, that you’re coming at in that you allow nothing in that realm? Because, I mean granted I know that’s what naturalism is, but that you’re so shut off from the beginning that nothing could ever, ever, ever meet the evidence. Like Lawrence Krauss says, even if it was written in the sky, he would maybe consider it.
Dr. Carroll: That’s right, yeah, I think this is a good point. Personally I think that there would be no problem for me to be persuaded out of naturalism. Alright, the roof is not falling on me. [laughter]. But I think it’s a matter of what is the model that best fits the data. Again, five hundred years ago I would have been a committed theist because that was the best we could have done at the time. So I think that it is not an assumption. Some people try to sometimes say that science or naturalists start from an assumption of naturalism so they just simply won’t consider alternatives. I’m very happy to consider alternatives. I think that if there were some phenomena in the world which really looked exactly like some religious tradition was saying should happen and was miraculous, was seemingly violating the laws of physics, what would scientists do in that situation? They would not say, “Oh, we’re not allowed to think about this because we agreed yesterday at faculty tea that the world was a natural world.” I think they would try to come up with the best explanation. If the best explanation is not naturalism, then I would buy that. I will say that naturalism seems to me to be a priori simpler than theism because naturalism is the natural world, theism has the natural world and something else that I think is ill-defined. But I didn’t actually use that. I think in a proper quantitative Bayesian probability analysis my prior for naturalism is higher than my prior for theism, but overwhelming evidence will always take care of that. I just don’t think it’s there.
Dr. Craig: Both the naturalist and the theist can be stubbornly committed to their worldviews and not allow contrary evidence to overthrow it. Naturalists are just as adept as theists at explaining away evidence that they find inconvenient—I mean, even to the extent of asserting that the universe popped into being out of nothing! So that’s a charge that, I think, goes both ways. It would be possible to falsify theism, for example, by showing a contradiction in the concept of God, as some have sought to do – that there could not be, for example, an omniscient person or a timeless person or something of that sort. So that would be a means of falsifying theism if one could go that route.
Question 4: Dr. Craig, I’d like to understand whether the kalam argument (because I am struggling with this) . . . You’re stating that the universe has a beginning, and then you evoke cause and effect, but cause and effect is a temporal concept. So if there is no time?
Dr. Craig: Is a what?
Question 4: It is a temporal concept; it makes sense if time exists. But before the universe there’s no time, and considering that, why would you need a cause when the concept of cause and effect does not make really any sense?
Dr. Craig: Now, when you say that cause and effect are temporal concepts, what do you mean by that?
Question 4: Well, that you have a cause has always precedes the effect.
Dr. Craig: Ah, that’s what I thought you might think! Yeah, I don’t think that’s at all true. Don’t you think that causes and effects can be simultaneous?
Question 4: If they are then God and universe came into being at the same time, then why would you need God to explain the birth of the universe because they’re born at the same time?
Dr. Craig: Okay, so you are willing to grant that causes and their effects can be simultaneous—right?
Question 4: Sure.
Dr. Craig: Okay, yes, I think that that’s evident. So, what I would say is that God’s creation of the universe is simultaneous with the universe’s coming into being. And what could be more obvious than that, when you think about it? When else could it come into being than at the moment when God created it? So my own studied view of God’s relationship to time – which is a terribly interesting subject – is that God is timeless without creation and he is in time from the moment of creation on. The exercise of causal power by which God brings the universe into being marks God’s entrance, as it were, into time in virtue of his causal relationship with the effect that he brings about. So I don’t think causes do need to precede their effects temporally; they can be simultaneous with them. And in the case of creation I would say the universe comes into being at t=0, and that is the same moment at which God causes the universe to come into being.
Dr. Carroll: I’m pretty sure nobody cares about my opinion of God’s atemporality, [laughter] so I will use this as an excuse to reiterate my objection to the language of coming into existence or popping into existence. That is not what the universe does even in models where the universe has a beginning, a first moment. Because the verb popping, the verb to pop, has a temporal connotation, is the word I’m looking for. It sounds as if you waited a while, and then, pop, there was the universe. But that’s exactly wrong. The correct statement is that there are models that are complete and consistent in which there is a first moment of time. That is not the same as to say there was some process by which the universe popped into being. That’s yet another difference between the universe and things inside the universe.
Question 5: Dr. Carroll, you said in prior talks that in the laws of physics that we observe today there’s no room for free will. I’d like to know – granted that I consider you to be a rational, critical thinker – how do you reconcile critical thinking if at the same time you believe we don’t have the free will to choose between true and false premises and valid and invalid logic. If those choices are made for you how is anything anybody says not immediately irrational?
Dr. Carroll: I know I’m in trouble when someone says “I consider you to be a rational thinker” before they ask me the question. [laughter] I’m not exactly sure what you read. I think if you read carefully, I believe in free will. I’m pro-free will. I think of free will as an emergent concept in a universe which at the fundamental level is completely mechanistic. I think there are laws of physics that do not involve what we call a libertarian approach to free will. I do not think that human beings supersede the laws of physics. I think that human beings are collections of elementary particles interacting according to the laws of physics. And if I were to, say, write down every single particle in my body and I had a Leplace’s demon level of computation ability, I could predict what I would do. But I don’t have any of that. I don’t have the information, the micro-state of my quantum mechanical wave function, and therefore the vocabulary I use to describe myself is as human being making choices according to rational principles. And I think that it is absolutely legitimate in that framework to say free will is real. The most I ever wrote on free will was a short blog post called “Free will is as Real as Baseball.” Baseball is nowhere to be found in the fundamental laws of physics. It is a description at a collective level of things that happen in the macroscopic world. That doesn’t mean that baseball doesn’t exist, it just means that it’s not there in the fundamental laws. I think that free will is exactly the same way. I think there is nothing wrong with using the language of people making choices, people being correct or incorrect.
Dr. Craig: Well, it seems to me that on your view, free will is ultimately illusory because everything we do is determined by what goes on on the fundamental level. And therefore, even though I have the illusion of free will, if I could really understand it, I would see that, in fact, I am determined to do everything that I do—including believing in determinism, which makes my choice to believe in determinism, it seems to me, irrational—or arational, I should say. I’m simply determined to believe in determinism. So I don’t think it’s helpful to talk about free will as an emergent reality when at a fundamental level you’re affirming determinism. Then it’s freedom only in name and not in reality, and in that case I think the questioner is right—it’s very difficult to see how anything I do is rational. It’s just like a tree growing a branch. It’s all determined by mindless forces.
Question 6: Dr. Craig, it’s an honor to speak with you tonight. I was going to ask Dr. Carroll something, but the line was so long, and I like short lines. So I came over here. [laughter] I’m not an atheist.
Dr. Craig: You could say, “If you were Dr. Carroll, what would you . . .” [laughter]
Question 6: There you go! I’m not an atheist, an agnostic, or a classical theist. I feel like there’s a middle camp between the two of you that’s ignored, and I’m more along the lines of a panentheist and along the lines of Spinoza and Einstein, and I think that that whole discussion gets lost here tonight. But the real question I want to get to and the important one, I think, is what Roger Penrose talks about with the necessity of conscious observation and the neglect of the Copenhagen interpretation of quantum mechanics among practicing physicists who seem to ignore the necessity of conscious observation creating quantum decoherence. And I wanted to find out what you thought about Roger Penrose and his ideas. Thank you.
Dr. Craig: Well, there are at least ten different physical interpretations of the equations of quantum mechanics, and they’re all empirically equivalent, they’re mathematically consistent, and no one knows which, if any, of them is the correct physical interpretation. I’m inclined to agree with philosophers of science who think of the traditional Copenhagen Interpretation as really just quite unintelligible. And I’m therefore more inclined to some sort of deterministic theory of quantum mechanics, like David Bohm’s quantum mechanics. [laughter] Now I know that Sean Carroll holds to Everett’s Many Worlds Interpretation; but that, again, seems to me to be just fantastic and has difficulty making sense out of the probabilities in quantum theory. But basically I don’t think we need to decide. No one knows for sure what is the correct physical interpretation. It works, and that’s what the practicing scientist is concerned with. But it remains a matter of deep debate as to how to understand it.
Dr. Carroll: Well, I’m glad we found another very important area of agreement between Dr. Craig and myself. The Copenhagen interpretation is basically nonsense. No thoughtful person still holds to it, and yet we teach it to all of our undergraduates—that’s kind of a scandal. [laughter] And no one knows what the right answer is; I would also agree with that. I do hold to the Many Worlds interpretation. I think that you see it’s kind of a consistent split that we have because people, when faced with the statement of the Many Worlds interpretation, it bothers them at an emotional level. I mean, where do you put all of those worlds? How do you fit them into the universe? But when you look at the level of the equations, it is the simplest possible interpretation of quantum mechanics. There are important questions that are still raised about it. I’m also writing papers about that. I think these are important issues to be addressed. But I judge simplicity by the number of ideas and concepts, not by the number of universes.
Question 7: Well, thank you for taking my question. Assume we had a model of the universe that corresponds to reality concerning all material things. Is it still logically possible to affirm the existence of a God?
Dr. Carroll: Yes. [laughter]
Dr. Craig: I didn’t hear the final words – is it still possible, what?
Dr. Carroll: Yeah, maybe say the whole thing over again.
Question 7: Yeah, one more time; I’m sorry. Assume we had a model of the universe that corresponds to reality concerning all material things. Is it still logically possible to affirm the existence of a God.
Dr. Carroll: Good. So, yes.
Dr. Craig: Sure.
Dr. Carroll: You can. It’s logically possible to assert a whole bunch of things. I mean, it’s logically possible to assert that Isaac Newton had the right theory of gravity and Einstein didn’t. It’s logically possible to assert the steady state theory. You can probably find . . . I get emails from people who believe this. They’re not very logical people, admittedly. But the way that science goes about deciding on theories is not on the basis of logic alone. You want your theories to be logical—I think that’s the minimum requirement. But there are many, many logical theories. One of them is that we’re all living in a computer simulation, there’s a mad scientist out there. One of them is that none of you exist and I’m a brain in a vat. These are all logical possibilities. And about a similar level of plausibility in my mind is there’s the logical possibility that we live in a world that always obeys the laws of physics and yet God created it and is hiding from us. So it is absolutely logically possible—I don’t give it a lot of credence.
Dr. Craig: Yeah, logical possibility is simply too easy. And therefore, I think, you probably meant something, perhaps, different than just mere logical possibility. What we’re talking about is, maybe, metaphysical possibility, or plausibility? Those are the real issues that, I think, are important because it would be pretty surprising if you could show that something like this would be logically impossible.
Question 8: Dr. Craig, you’ve been very skeptical about the idea of universes just popping into existence. Does cosmology have anything to say about where God might have come from? Or are we allowed to think that he could have popped into existence?
Dr. Craig: No, obviously cosmology would not have anything to say about where God came from because God is a non-physical, transcendent entity beyond the universe. That’s why I used the word transcendent in that argument – this is something beyond the universe. The universe is defined as all contiguous physical reality. But I do want to take this opportunity to highlight for you a very significant difference between Sean and myself that is a philosophical difference that has tremendous impact upon this whole debate. And that has to do with this idea of “popping into existence.” If I’m not mistaken, Dr. Carroll holds to what is called a tenseless theory of time. That is to say, past, present, and future events are all equally real. Temporal becoming is merely a subjective illusion of human consciousness. There is nothing privileged about the present, ontologically speaking. I hold to quite a different view of time. I think that temporal becoming is a real and objective feature of the universe. The future doesn’t in any sense exist; things really do come into being and go out of being. And that’s why I use the language of popping into existence. Not because I illicitly presuppose time prior to the origin of the universe, but because I believe in a tensed theory of time which affirms the objectivity of temporal becoming. And on that view the beginning of the universe does not just tenselessly exist. The universe comes into being, and surely that requires a cause. Now this is not just an unfounded metaphysical assumption on my part. I’ve written two books on this in which I defend the tensed theory of time, giving arguments for it and answering objections against it, and then I attack the tenseless theory of time, giving arguments against it and answering arguments for it.[32] But this is a huge metaphysical assumption that underlies this debate and divides us.
Dr. Carroll: So I will confess, I don’t know. This is not answering your question but it’s a confession that as a scientist there is this enormous temptation that I am constantly resisting when I am in dialogue between science and theology which is that as theologians talk about the relationship between God and time, or God’s status as necessary or anything like that, there’s a big part of me that wants to say, “Why are you working so hard to extract yourself from these dilemmas when you can just say God doesn’t exist?” It just sounds crazy. And then I realize I’m a cosmologist. And the same people could say the same thing about everything that I say. There’s plenty of things that I say that sound crazy. So all I’m saying is that these are difficult, interesting questions, and it’s very, very hard on the basis of thinking alone to get the right answers. That’s why scientists have this huge advantage – we collect data.
Question 9: Dr. Carroll, you asserted that theism is unreasonable at least in part because the term God is poorly defined. So at the end of your first talk you said, “The solution to the problem that, from a theist’s point of view, the world is not as we would predict, is easily solvable because of the flexibility of the terminology of God. So the theist can simply form any of hundreds of models of God that explain why the world is the way it is while maintaining the creative agency of God. And that’s unreasonable.” But when you want to show the plausibility of an eternal universe you build a model and you showed seventeen of those and you said that all of them could work, but you don’t think that any of them are right. They could be right but you don’t think they’re right. And that is reasonable. And I’m just wondering if you could clear up for me how that’s consistent.
Dr. Carroll: Sure, that’s fine. I think there is a difference in principle between the theist trying to use the idea of God to explain all these different aspects of the universe and the scientist developing many, many mutually inconsistent models and not know which one is right until they’re developed. I think that with every one of these scientific models there is an expectation, indeed a demand, that when we understand the model perfectly it will make absolutely unambiguous “unwiggle-out-able-of” predictions about what the universe is like. I think this is not in principle possible in theism. I think – and different theists probably have different expectations about this – but I think that theists would not claim that once we understand God perfectly we can predict the mass of the Higgs Boson. But a physicist would claim that once we have the correct theory of everything we will be able to predict the mass of the Higgs Boson, and I think that’s an absolutely crucial distinction.
Dr. Craig: I love this question because in the same way that the scientist develops models of the universe in order to understand it, the theologian does the same thing with respect to God – different models of God, understanding what he’s like. And for Christians, the biblical data concerning God is underdeterminative. There’s a great deal of latitude in developing your model or concept of God. For example, one of the classic questions is, “Is God timeless or is he infinite throughout all time?” And theologians develop different models of God and time, and then these models are tested. They’re not tested by predictability; but they’re tested by their coherence and by how well, for example, they would explain how an eternal being could create the universe, or how he could know, for example, tensed facts. I’ve written a great deal on this, and so you’re quite right in saying it’s analogous or parallel.
Question 10: Yeah, Dr Craig, you use the Borde-Guth-Vilenkin theory to justify an absolute beginning of the universe, and I was curious how you would address the point that was brought up about Guth probably holding that the universe in fact was eternal.
Dr. Craig: I haven’t spoken to him about it. I have spoken with Vilenkin. I think that they would agree that the theorem under this single stated condition shows that classical space-time did have to have a beginning, and Guth doesn’t dispute that. He says that. Now when he holds up a little sign saying “I think the universe is probably eternal,” that’s probably just reflecting a sort of personal preference or skepticism that maybe we’ll find a quantum theory or something that will be a non-classical model that will restore the eternality of the universe. That could be his predisposition or his hope or hunch or something of that sort. But in terms of scientific evidence, there’s no evidence at all that the universe is beginningless. As Vilenkin said, all of the evidence is on one side of the scale, that the universe began to exist, and there are no models of a beginningless universe that are successful. So I don’t know exactly what he meant by that. But I think we do know that the implications of the theorem are that any model that falls under its single condition will have a beginning to classical space-time. And also I would say that models that don’t fall under that condition usually always have other problems, as well. And then I argued that this quantum gravity regime, if there was such a thing that preceded the classical space-time regime, that marked the beginning of the universe, if the universe didn’t begin at the classical space-time boundary.
Dr. Carroll: So I don’t think it’s the right thing to say that the Borde-Guth-Vilenkin theorem says that the classical universe had a beginning. The part of the universe that we can describe using classical space-time had a beginning just like this room had a beginning. But that says nothing at all about the universe as a whole. Alan Guth does not believe the universe is eternal because it’s a hunch or personal preference. It’s because he’s a scientist and he’s trying to develop models that fit the data. We have puzzles in cosmology. Given his knowledge of the models, he believes the best way forward, the most promising way forward, are the models in which the universe is eternal. He knows that there is a theorem saying if you obey the rules of quantum mechanics under the assumptions I gave the universe must be eternal. He knows the early universe had a low entropy and the best possible explanation we currently have for dynamically explaining that involves an eternal cosmology. This is exactly how scientists work all the time.
Question 11: Dr. Carroll, someone actually got to this question earlier, so just kind of a repeat and maybe you have some further comment on it. But suppose there was, you know, a naturalistic model for the universe and everything. What would your rebuttal be for someone who said there is yet a God that still works outside that model? Those might kind of be unfalsifiable but I’d still like a comment on that.
Dr. Carroll: Sure, I think that, again, it is absolutely conceivable. Let’s go all the way to the extreme. I completely can conceive of a universe that was brought into existence by God who was omnipotent and so forth and for whatever reason God has chosen to be completely invisible and the universe runs by purely naturalistic principles. In that case I’m not saying that it is logically possible or even that it is illegitimate to conceive of that possibility. I just say it gets you nothing. By all of the conventional standards of scientific or even philosophical explanation, if I have two possible models that fit what we observe about the universe and one of them has less stuff, less ideas, it is more self-contained, is more rigid and well-defined than the other one, I’m going to prefer that one. I’m never going to say I completely rule the other one out. And this is not a completely hypothetical circumstance. Cosmology, quantum mechanics, quantum field theory, particle physics are full of many, many models that are in principle compatible with the data, but only if you take some parameters and push them out to where they shouldn’t be, make them very, very small, make them very, very invisible. We put limits on our theories. We do not rule them out entirely. But when the limits, the constraints, becomes so strong the theories become uninteresting. We have a better way of moving forward. To me that’s the situation with naturalism vs. theism.
Dr. Craig: The arguments that I’ve offered tonight are consistent with the universe’s being self-contained in the way that Dr. Carroll described. So that needn’t be an issue of debate between us. But I don’t see any reason to think that the universe is self-contained. I don’t see any reason at all to think that the transcendent God doesn’t act miraculously in the world. And there’s simply no way that Dr. Carroll, as a scientist, could know that God never acts miraculously in the universe. So that the idea that the universe is causally closed or self-contained is really a naturalistic article of faith. It’s a metaphysical presupposition, not an inference drawn on the basis of science.
Question 12: Dr. Craig, I really have enjoyed listening to both of you today. My question is . . .
Dr. Craig: Can you speak directly into the mic, please?
Question 12: Can you hear me now? [laughter]
Dr. Craig: Yes!
Question 12: Oftentimes when particularly believers or theists are talking about religion inside the arena of religion they are very, very comfortable, they know what they’re talking about, but when they leave that arena and they go into places and talk about cosmology or they talk about medicine, it seems like that they are trying to make their religious beliefs fit into that sphere. So my question is this, and given that you said a few seconds ago God is not of this world or bigger than this world, why would he find it important to have a discussion about medicine, or find it important to have a discussion about the stars? Why would that be significant or relevant to him? Because, I mean, he is omnipotent.
Dr. Craig: As a systematic theologian, I am committed to having what I call a synoptic worldview, that is to say, a worldview that takes into account all of the data of human experience, not only what we learn from revealed truth in theology, but also from science, from history, from psychology, and the humanities. As a Christian I want to have a world and life view that makes sense of reality. And so I think that’s why the Christian is vitally interested in these subjects and why I as a philosopher and theologian am terribly interested in these scientific theories about the origin of the universe, about the fundamental nature of physical reality, about the origin and evolution of biological complexity. I want to have a worldview that makes sense of the data of science. And I think that’s one of the great things about the Christian worldview, that it does form a coherent worldview that answers our deepest questions and yet is consistent with what we learn from other sources of knowledge. So that’s why I am committed to the project of developing this sort of synoptic world and life view.
Dr. Carroll: I hesitate when it comes to my job to tell believers what to think. And then I do it. So I’m not a believer but if I were a believer, if I were a theist, to me I would think that the fact of my theism would be absolutely central to everything I believed about the world in all of its aspects. I think that there’s a modern tendency to try to shield religious belief and practice from the encroachment of scientific knowledge by saying, well, my religion has to do with my practice and my values but nothing to do with the physical world, the biological world, the scientific world. I think that that is actually a much less intellectually honest point of view than one like Dr. Craig’s that engages with the full picture.
Question 13: Dr. Carroll, I’m going to try to phrase this without using terms I know you don’t like—make this a how question instead of a why question. If our universe, our observable universe, had a first moment in time, and naturalism is true then it would seem that we need to explain that with some sort of eternal existing set of conditions, and they would have to be necessary and sufficient to produce the effect, which is our universe coming into being or having a first moment in time. So the difficulty seems to be that if we have an eternally existing set of causal conditions that are sufficient to produce the effect, why isn’t the effect coeternal with the cause? It seems like that’s very problematic, and it seems like the easiest explanation or the most plausible explanation to how the universe with a first moment in time could come about is to say that agent causation is where we need to look; that it was a personal agent endowed with freedom of the will who can spontaneously exercise causal powers to bring about a new effect. So if that’s not true how is naturalism to provide an explanation for that case?
Dr. Carroll: Yeah, I think this is a good question in the sense that this is the kind of issue that tugs at our ability to make sense of these large cosmic questions given our everyday experience with reality. But I will give you a frustrating answer to it by denying your premise. I do not think that if the universe has a first moment in time that means there is any sort of eternal or preexisting conditions or rules or laws or anything like that. It simply means that our best and maybe the correct description of the cosmos is one that had a first moment in time. The question is, can that be self-contained in the sense that I’m using it, which is that if I write down the equations and the conditions and so forth that describe the universe with an earliest moment, am I done? Are there questions that I might have about that universe that cannot be answered by that formalism? And I think there is no obstacle whatsoever to coming up with such models. And so I would simply un-ask the question. I would say, no, there aren’t preexisting or eternal rules. There is the universe and the universe has a first moment and the universe obeys rules during those moments when the universe exists. During those moments when the universe does not exist, there are no moments, there is no time, there are no rules.
Dr. Craig: This question is very closely related to the argument that I gave against the quantum gravity regime’s being past eternal. Namely, if the causal conditions that are present there are sufficient for the effect, then the effect would always have been there. But if they’re not sufficient, then it becomes incomprehensible why the effect appeared just 13.7 billion years ago. And therefore it seems to me, I argued, that this regime would itself have to have a beginning and come into existence. The contrast with this is, when you have a libertarian agent with free will, he can exist from eternity and then freely decide to produce an effect in time without any antecedent determining conditions. And so in that sense theism provides, I think, an explanatorily superior account of the origin of the universe because it’s got the explanatory power that is vested in an agent with libertarian free will.
Question 14: Yes, I’m really afraid I’m going to ask that stupid question, so please excuse me. But I don’t really understand how you come up with the probability – or improbability, as you have been saying – of the universe, if it’s a universe, when a universe has only begun once? How do you come up with that? Don’t you have to have more scores to calculate such a probability?
Dr. Craig: Yeah, now, which argument is this relevant to, in your mind?
Question 14: Before you said there is a universe, and then you have been repeating a lot that it’s highly improbable that it just popped out of nothing.
Dr. Craig: Oh, like the finely-tuned universe—okay. I don’t think this is a good objection to fine-tuning because what we can do is simply conceptualize a multitude of universes by varying these constants and quantities and seeing what would result. So, for example, the physicist John Barrow gives the following illustration: he says, put a red dot on a piece of paper and let that be our universe. Now, alter slightly one of the constants or quantities. That will make a new universe. If it’s life-permitting, make it a red dot. If it’s life-prohibiting, make it a blue dot. Now, do it again, and do it again, and do it again, until your sheet of paper is filled with dots. And what you will come up with is a sea of blue with only a couple pin-points of red. It is in that sense that one can say that these finely-tuned universes are enormously improbable. You don’t need the universes to actually exist in order to say they’re improbable. All you need to do is have this, so to speak, logical space of possible universes described by these different quantities and constants in order to say that finely-tuned worlds are extremely rare.
Dr. Carroll: I think this is a great question because we do have this tendency to speak informally of probabilities and likelihoods and so forth. And even professional cosmologists do this when we talk about the early universe – “That seems improbable, unlikely, unnatural” is the usual term that we use. And sometimes we’re just totally wrong about that. As so the example that Dr. Craig just gave about the blue dots and the red dots sadly almost never applies in cosmology because it assumes there is a discrete set of dots that we can color blue or red. Usually in cosmology there is a continuous spectrum of possibilities, and in that case it’s much harder to even imagine assigning probabilities consistently. The example I gave, which was then sort of not talked about later, was the expansion rate of the early universe. There was a naïve argument that says it’s very improbable. When you look more carefully you realize it’s extremely probable. So there’s not a definitive answer as to what the correct answer is, but I’m agreeing with your implication that we should be very, very careful when using words like that.
Read more: http://www.reasonablefaith.org/god-and-cosmology-the-existence-of-god-in-light-of-contemporary-cosmology#ixzz3J33R1EuX
I saw the movie Interstellar a couple nights ago, and I’m still thinking about it now. It’s a mind-bending meditation on the meaning of life set within an epic intergalactic journey to save humanity. Superficially, it’s a sci-fi flick. But most fundamentally, it’s about metaphysics and theology.Here’s the plot in a nutshell. At some point in the not too distant future, the world becomes increasingly uninhabitable to humans. The food supply is afflicted by blight, and the world becomes a giant dustbowl. America no longer has a military and has ceased to lead the world in innovation and technology. In this dystopian future, the decline of American greatness seals the fate of the planet. It is only a matter of time before human beings on earth will all die of asphyxiation and lung disease.A farmer and former astronaut named Cooper (played by Matthew McConaghey) is tapped to lead a mission into deep space to find a habitable world in order to rescue the human race from extinction. If the mission succeeds, there are two plans for saving humanity. Plan A involves evacuating humans to the new world. Plan B involves leaving humans to die on earth and starting a new human colony artificially by bringing to life thousands of frozen human embryos.At the heart of the movie is the relationship between Cooper and his daughter Murphy (played by Jessica Chastain). Murphy has already lost her mother to cancer. And she cannot bear to lose her father as well. As Cooper leaves his family to save the world, Murphy falls out with her father.
The Daily Hatch 