Questions on Cosmology (part 1)

Transcript Questions on Cosmology Pt. 1

Kevin Harris: Kevin Harris in the studio with Dr. William Lane Craig. Boy, do we get some doozy questions. I'm not sure what a doozy is, but we get them. This question comes from someone who's read the new book from Mario Bunge, Matter and Mind: A Philosophical Inquiry. Dr. Craig?

Dr. Craig: Oh, yes, he's a very well-known naturalistic philosopher and a philosopher of science.

Kevin Harris: What he argues for is the existence of physical, spatial, and temporal infinities, and the fact that naturalism, if true, implies that the universe is eternal. He writes,

Well, we can stop right there and say that, yeah, there are plenty of good arguments for the beginning of time.

Dr. Craig: Well, I think that this is a very interesting statement by Bunge. He says that any naturalistic ontology entails that the universe is eternal in the past. Therefore, if the evidence suggests that the universe is not eternal in the past that means that the evidence is against naturalism. So he has really put his naturalism on the line here. He is unwilling to accommodate the finitude of the past. He says naturalism entails an eternal universe. And that leads right into an argument: the universe is not eternal, therefore naturalism is not true. So this is a very interesting and bold position that he's advocating.

Kevin Harris: Regarding the Big Bang Bunge writes,

Dr. Craig: Alright. Notice his response to the theological option. It's good that he at least recognizes this as an option, that God has created the universe, and that the universe did have a beginning. That would be the option I prefer, in fact. What is his refutation of it? It's inconsistent with naturalism. [laughter] He says, if you're a physicalist then you can't believe in this. Right, right. But that's no reason not to think the view is true. So that is really, I think, just a question-begging rejection of the theological alternative.

Now, he does add that this is inconsistent with Lucretius' principle that “out of nothing, nothing comes.” And I think that's clearly mistaken because on the theistic view the universe doesn't come into being out of nothing in the sense that it has no cause. Rather it comes into being because it has an efficient cause. God created the universe and therefore it is not a violation of Lucretius' principle that “out of nothing, nothing comes.” We agree with that as theists, that things don't just pop into being uncaused out of nothing. What the theist maintains in the case of the universe is that although the universe lacked a material cause it did have an efficient cause, that is to say, it has a productive cause which brought the matter and energy into being. And therefore it is in no sense a violation of Lucretius' principle. So his arguments against the theological answer to this question are in the first place question-begging, and in the second place misconceived.

Kevin Harris: Yeah, it's just like Dawkins' “We can't allow a divine foot in the door.”

Dr. Craig: Right.

Kevin Harris: He says the second possibility when it comes to the Big Bang is,

You'll have to unpack that for us a little bit.

Dr. Craig: Alright. This is, again, I think, a rather desperate attempt to refute the idea that time and the universe had a beginning, at least in the standard model. [4] He says how do we know in addition to all the local reference frames that the Special Theory of Relativity imagines there is a kind of universal cosmic time that measures the duration of the universe? Well, that emerges in the context of the General Theory of Relativity. When it is applied to the universe as a whole there does emerge a cosmic time which measures the proper time of the duration of the universe. And when cosmologists say that the universe originated 13.7 billion years ago they are referring to this cosmic time, which is the same for every local observer in the universe, and measures the duration of the universe as a whole. And it's true that this was a feature of the simplest models, developed originally by Friedman and L'ametre, in which they assumed that the universe is homogeneous and what's called isotropic, the same in every direction, and is expanding in this way. And the discovery since those theories were first proposed in the 1920s have revealed that the universe on large scales is far more homogeneous and isotropic than early theorists ever could have imagined. The microwave background radiation that permeates the universe is isotropic down to one part out of a hundred thousand—it is amazingly uniform. So the idea that there is this cosmic time that measures the duration of the universe is very well established, and therefore gives us quite good grounds for thinking that the universe is about 13 billion years old.

As for Levy-Leblond's article, which was published twenty years ago in 1990, I actually responded to that at the time. All Levy-Leblond does is try to push back the origin of the universe to past infinity by fiddling with the metric of time so that it is, as it were, to put it in layman's terms, he takes the Big Bang singularity and he just stretches it out so that the beginning of the universe occurs infinitely long ago. But what Levy-Leblond doesn't do is get rid of the beginning of the universe. He just has it be infinity distant in the past, but on his view the universe still began to exist. So he doesn't avoid the beginning of the universe, in fact, at all. So that second alternative that Bunge suggests in unsuccessful.

Now, having said that, I would readily agree that the standard model is over-simplified, and that it will be modified, and in all probability is going to be affected by the development of some sort of quantum theory of gravity. But that gives no reason to think that the absolute beginning of the universe that's predicted by the standard model is going to be removed by these new quantum gravity models. The origin of the universe may be non-singular, as it is in the Hartle-Hawking no-boundary proposal. So the presence of the singularity, which is a feature of the standard model, is not a necessary condition of the universe's having begun to exist.

Kevin Harris: And when you say that the universe is very isotropic, it's expanding at a very even way, rather than real haphazard or jaggedly?

Dr. Craig: Exactly. There is a, how should I say, a division of spacetime. You can slice up four-dimensional spacetime in such a way that this expansion proceeds smoothly and uniformly and yields this cosmic time which measures the duration of the universe. And that emerges in the context of the General Theory of Relativity and the application of relativity to the cosmos as a whole.

Kevin Harris: The third possible answer to the Big Bang, according to Bunge, is that,

Now, that was written in, like, 1934.

Dr. Craig: Yeah, here I think, again, you see the defensiveness. [6] You can tell that these folks are on the defensive – “We mustn't yield to theology;” “We mustn’t allow that to encroach here.” Clearly, I think, naturalists are feeling the pressure, and you'll remember the only reason he had for rejecting the theological alternative was because it's non-naturalistic. No naturalist could accept it. In effect in this third alternative he really abandons any confidence that naturalism is true. It just is agnosticism. He just wants to say, “We don't know.” And that is to abandon any confidence, then, that the naturalistic view is true. It could well be that the universe did begin to exist. In fact I would suggest that Bunge's information here is somewhat dated, because what he's thinking about here is models of the universe in which our expanding universe originates out of the quantum vacuum as some sort of a fluctuation of the energy locked up in empty space. But the problem is that inflation theorists, like Alan Guth and others, have recognized that this quantum vacuum cannot be eternal in the past. It itself must have begun to exist. Inflationary cosmology cannot be past eternal. Inflationary cosmology can be future eternal, it can go on forever. But it can't be past eternal. So even if you say that our observable universe originated out of such a quantum state that quantum state itself cannot be eternal in the past, but must have had a beginning. And therefore, in fact, he hasn't succeeded in answering the question that is put to the naturalist—doesn't the evidence of contemporary physics and cosmology give grounds for believing that the universe is not temporally infinite in the past?

Kevin Harris: Do you think he has sufficiently highlighted the three major explanations of the Big Bang?

Dr. Craig: Well, it would seem to me that those would be basically the alternatives, although what theory you enunciate under number three is going to vary wildly. I suppose another possible alternative, though I think ultimately it's incoherent, would be that the universe created itself. That's what Daniel Dennett thinks—that the universe via “the ultimate bootstrapping trick” brought itself into existence. [7]  Or I suppose another possibility, as long as we're just talking possibilities, would be to say the universe popped into being uncaused out of nothing—but that would violate Lucretius' principle ex nihilo nihil fit. So Bunge wouldn't be open to that. So I think he's listing here what he would see . . . well, I was going to say what he would see as the three credible possibilities, but he doesn't think the first one is credible.

Kevin Harris: Because it violates his naturalism.

Dr. Craig: Right, because it's non-naturalistic. But at least, to his credit, he includes it in the list. And I think the weakness of his reason for rejecting it is quite apparent.

Kevin Harris: I hear all the time that the fear of those in the scientific enterprise is that if you allow a divine foot in the door, if you allow for God and theology, something that Bunge is complaining about here, that it opens the door to irrational explanations. When the mushroom puts out certain spores it will in the morning create a circle of mushrooms called fairy rings. And the fear seems to be, Bill, that if you start allowing any kind of a supernatural explanation, well then in science class you could say, “Hey, one possibility is that fairies did indeed cause these rings of mushrooms,” rather than the fact that we've observed that the spores shoot out that way, in a circular way, and that's what causes it. So, well, in one sense it's comparing God and fairies—which is a problem. But do you see the anxiety of why they don't want to do that?

Dr. Craig: Oh, sure. I understand it. They're saying that science needs to adopt a sort of methodological naturalism in order to prevent these boogems and other spooks from getting into science. And I think it's really important to understand, Kevin, that I'm not advocating some kind of theistic science. I'm not advocating creation science here of any sort. I'm not saying that we should introduce supernatural explanations into science. I'm offering a philosophical argument for the existence of God, and it's quite consistent with having methodological naturalism within science. What I would just say, then, is what Robert Jastrow said in his book God and The Astronomers,that science conducts us to the threshold of eternity, to the beginning of the universe, and then science is impotent to answer the question as to why the universe came into being. That's a non-scientific question—that's a metaphysical question, not a physical question.

Kevin Harris: Then philosophy takes over at that point.

Dr. Craig: Right, it's metaphysics; not physics. [8] So I'm quite happy to say, fine, adopt methodological naturalism in science. I'm not proposing any kind of theistic science. I'm not proposing an alternative to the Big Bang theory, some kind of theistic Big Bang. Not at all. I'm just suggesting that the evidence of contemporary cosmology supports the truth of the second premise of the kalam argument—that the universe began to exist. That's a religiously neutral statement which can be found in any textbook on astronomy and astrophysics, and has nothing to do with God or theism. So I'm not suggesting that we adopt theistic science or creation science. I'm not suggesting that we postulate God as an entity in a scientific theory at all. I'm doing metaphysics, not physics. So I think that that concern is simply not germane to my argument. Now, beyond that I think we could well call into question why methodological naturalism does need to be adopted. Why not allow supernatural explanations into the pool of live explanatory options? They would be assessed by the same criteria that other explanations are assessed—such as plausibility, explanatory power, explanatory scope, and so forth. And I'd be quite willing to allow that if you have a naturalistic theory and a supernaturalistic theory, and they have the same explanatory power, the same explanatory scope, the same plausibility, that we ought to prefer the naturalistic theory rather than opt for the supernaturalistic one. It would only be in the case that the supernaturalistic hypothesis exceeds the naturalistic hypotheses in either explanatory scope, explanatory power, degree of ad hoc-ness, or being free from being ad hoc, that then one would adopt the supernatural explanation over the naturalistic one.

Kevin Harris: So would everyone be a lot happier on both sides of the raging controversy if we just adopted a methodological naturalism?

Dr. Craig: Well, I don't know if people on both sides would be happy, but certainly the naturalists would be happier about that—I hope they would, anyway, because one would be meeting them halfway. One would say, “I don't agree with methological naturalism but I am not in any way trying to introduce a theistic science. I am just saying that the best scientific evidence we have supports the premise that the universe began to exist.”

Kevin Harris: This is very important, what you're saying, because it's just such a bone of contention.

Dr. Craig: Yes, this completely gets rid of the silly god of the gaps objections because you're not postulating God to fill up some explanatory gap in science.

Kevin Harris: So if educators in American said, “We should adopt methodological naturalism as a tool,” you wouldn't have any problem with that.

Dr. Craig: Well, I wouldn't say I wouldn't have any problem with it, Kevin. As I said, I think that you can defend the notion of having supernaturalistic explanations as part of the pool of live explanatory options. I don't see any good reason to adopt methodological naturalism. But I'm just saying, if you do, it has no impact upon the argument I'm offering.

Kevin Harris: What would you call your methodology then? Would you call it “Wherever the evidence points” methodology? [laughter]

Dr. Craig: Well, no, I'm just doing metaphysics is all.

Kevin Harris: Okay.

Dr. Craig: I'm not proposing theistic science. I'm just doing metaphysics; I'm offering a philosophical argument for God's existence, the second premise of which has considerable empirical evidence in its favor. As I said, in a science class one wouldn’t say anything about God if one is using methodological naturalism. You would just come to the end of science and say that this is where science conducts us but no farther. Now, where the naturalistic scientist can push the envelope further is what Bunge tries to do in option three. He can say, wait a minute, wait a minute, here are some naturalistic theories that will push the threshold of science further back. We can postulate this quantum mechanical vacuum state out of which our universe emerged, and that will provide a purely naturalistic explanation of the origin of the universe. And at that point someone who's taking the line that I'm taking will need to deal with that as a defeater, a potential defeater, of the second premise that the universe began to exist. And he will examine what science tells us about this vacuum state, and what he'll discover is that it's unstable, that it cannot procure for infinite time, and that therefore even this state must have a beginning, and he'll suddenly discover that the evidence supports, in fact, that second premise, again, that the universe began to exist. [9]