William Lane Craig CV


Existence of God (part 4)

Transcript of William Lane Craig's Defenders 2 class.

Excursus: Natural Theology
§ I. Contingency Argument
Lecture 4

We have been talking about the Cosmological Argument for God’s existence, and we’ve seen that the first premise of that argument (“Everything that exists has an explanation of its existence, either in the necessity of its own nature or else in an external cause”) is an intuitively plausible premise and that the atheist attempt to make the universe an exception to the rule is arbitrary and unjustified. Moreover, we saw that the second premise (“If the universe has an explanation of its existence, that explanation is God”) is logically equivalent to the typical atheist response to the argument, namely, that if atheism is true, then the universe has no explanation of its existence. And we saw, moreover, that that second premise is very plausible in its own right. Given, then, that the universe exists, it follows logically from those premises that God exists.

Objection: Universe Exists Necessarily

The reason for the reluctance of atheists to say the universe exists necessarily isn’t hard to see. When we look out at the universe, none of the things that the universe is composed of seems to exist necessarily. Planets, stars, comets, dust, radiation, galaxies – none of these things seems to exist necessarily. They could all fail to exist. In fact, at some point in the past, none of them did exist, when the universe was in a very dense state and those things had not yet formed. Since none of these things that make up the universe seem to exist necessarily, why think that the universe exists necessarily?

The atheist might say at this point, “Well, O.K., none of those things exists necessarily, but the matter of which those things are composed exists necessarily. Matter exists necessarily. And these different things are just different configurations of matter, just different shapes and formations of matter. None of them exists necessarily, but the matter itself is a necessarily existent thing.” Let’s think about that suggestion. One of the problems with this suggestion is that according to the standard model of subatomic physics matter itself is composed of tiny particles, like quarks, for example. And the universe is just a collection of all of these particles arranged in different ways. Think about those quarks of which things are composed. Couldn’t the universe have been composed of a different collection of quarks than the collection that exists today? Does each and every quark in the universe exist necessarily? Is every quark in the universe a necessary being that has to exist? I think it would be crazy to say that each and every quark in the universe exists necessarily by a necessity of its own nature and that therefore this is the only collection of quarks that could possibly have existed.

Notice what the atheist cannot say at this point. He cannot say, “Well, those quarks are all just different configurations of matter, and you could have a different set of quarks, but it would be the same matter.” He can’t say that because quarks aren’t made of anything else; they just are the basic units of matter. So if quarks don’t exist, then matter doesn’t exist. It is not as though the quarks are composed out of something else; they just are the basic units of matter. So if there aren’t these quarks, then matter doesn’t exist.

But it seems obvious that a different collection of quarks could have existed than the collection of quarks that forms our universe today. And if that is the case, then a different universe would have existed. To see this point, I want you to think about your shoes that you are wearing right now and ask yourself the question, “Could these shoes have been made of steel?” I am not saying, “Could you have had a different pair of shoes made out of steel that were in the same shape and size as the shoes you are wearing?” I am asking, “Could the very shoes that you have on, those very shoes, could they have been made of steel?”1 I think the answer is, obviously not! That would be a different pair of shoes that just was in the same shape and size as the shoes that you have on, but it wouldn’t be that very pair of shoes. And the same is true of the universe. A universe which is made of a different collection of quarks wouldn’t be the same universe. It would be a different universe.

Somebody might say at this point, “Wait a minute, think of the matter that composes my body. Every seven years or so, I am told, all of the matter, or virtually all of the matter, in my body is recycled, so that the body that I have now is made out of completely different matter than the body I had when I was 14 years old or younger. And yet, it is the same body. I still have an identical body, even though it is made out of new stuff. So in the same way, couldn’t the universe be identical across possible worlds even though in one possible world it is composed of one collection of quarks and in some other possible world it is composed of a different collection of quarks? Couldn’t it still be the same universe just as my body is the same body even though it is composed out of different stuff that it used to be?”

I think there is a crucial disanalogy between these two cases. In the case of the universe, the difference across possible worlds is not a matter of intrinsic change. It is not as though the universe changes from one to the other by replacing quarks until you get to the other one, whereas in my body, you have material, historical continuity of my 14 year old body to my present body. Therefore, my body can be identical over this intrinsic change as the matter is replaced. But the difference between universes in different possible worlds isn’t a matter of change at all. There is nothing that endures from one possible world to another. This is more like talking about the matter that composes my body and the matter composing another person’s body – and those are two different bodies. Or, again, the example of the shoes made out of steel’s being a different pair of shoes than the leather shoes that you have now. I think that this gives us good reason to think that the universe, if it could have been composed of a different collection of quarks, wouldn’t be the same universe. Therefore, this universe does not exist necessarily.

The point that I am making here becomes all the more obvious when you reflect on the fact that it is possible that there could be a universe governed by completely different laws of nature that doesn’t even have quarks in it. They could have different sorts of particles or substances, maybe strings are the basic units of material objects, and they are governed by different laws of nature. To think that in that case, that would be the same universe as this one would be like thinking that a pane of glass would be the same pane of glass if it were made out of steel instead of made out of glass that it is made out of. That would just be a different substance; it would be a different thing with different properties. It is very plausible to think that the universe doesn’t exist necessarily. You could have had a different collection of quarks and therefore a different universe or a universe that is composed of totally different sorts of substances with different laws of nature and different properties.

I don’t think any atheist is going to be so bold as to assert that some quarks exist necessarily but others don’t – that there are certain quarks in the universe, a subset or a select number, that have this occult property of existing necessarily while the other quarks exist contingently. That is completely implausible. It is all or nothing – either they are all necessary in their being, they all exist by a necessity of their own nature, or none of them does. I also don’t think anyone would say that every single quark in the universe exists by a necessity of its own nature. Therefore, it would follow that a universe which is composed of such quarks doesn’t exist by a necessity of its own nature either.2

Notice that this is the case whether or not you think of the universe as an object in its own right. Think about a statue made out of marble being different from another statue that is made out of another different block of marble. They would not be the same statue. They would be different. Similarly, if you think of the universe as an object in its own right, it would be a different object than one made out of different stuff. What if you think of the universe, not as an object, but just as a collection of objects or just a group of the things in the universe? This would be analogous to a flock of birds’ not being the same as a different flock of birds if it is composed of different birds. A flock isn’t an object in its own right; it is a collection of objects. But if the collection is made up of different members, if one is a flock of pelicans and the other a flock of crows, it is not the same flock. Even if you think of the universe as just being nothing over and above the objects that are in it, still, if it is composed of different stuff, then you have a different universe. And in all of these cases, it would give us good reason for thinking that the universe doesn’t exist by a necessity of its own nature, that it exists contingently.


Question: Modern string theorists like Brian Greene have posited that string theory shows that strings are even smaller than quarks and compose everything. Many have proposed that these theories show the universe is in an endless cycle and the universe exists necessarily.

Answer: Let’s clarify a couple of issues. First of all, if strings turn out to be the fundamental building blocks of nature, then I will just substitute that for what I said about quarks. In other words, the identity of these things doesn’t make any difference. You can run the same argument whether the fundamental building blocks are strings or quarks, it doesn’t make any difference. With regard to these cosmological models that you are talking about, what those models attempt to show is a universe which is eternal in the past and is constantly recycling and going on into the future. But that doesn’t show that it exists necessarily, nor does it claim it exists necessarily. Leibniz’s argument is not that there has to be an eternal thing – it is that it has to be a logically necessary thing and there isn’t any logical necessity that these sort of string models have to exist. I mean, it is logically possible that they are all wrong and that quarks are the fundamental building blocks of matter. So don’t equate the eternality of the universe with its necessity – that is an error. Leibniz is quite willing to admit that the universe never had a beginning. This is not an argument for the beginning of the universe. You’ll notice in the premises that is nowhere stated. So if the universe has always existed, Leibniz would say, “Gosh, why does an eternal universe exist instead of just nothing?” Or “Why does this eternal universe exist?” That question can still be asked.

Followup: But the equations and the basic fundamental laws could actually be necessary because if you imagine each equation a puzzle piece in this massive puzzle, they may all fit together and they couldn’t have fit any other way. If the equations do all work out, doesn’t this necessitate one another and thus necessitate that the universe exist?

Answer: I understand there are these five different versions of string theory that can all be reduced to this one theory called M-Theory that is a simpler reduction of these disparate theories.3 But that doesn’t in any way show that what the theory postulates is logically necessary. You could have a universe that operates according to totally different laws of nature. All that would show is an internal coherence. That internal coherence could be replaced by a totally different picture that is also logically coherent. So you can’t say that because something is internally coherent and logically bound up with itself that that whole scenario can’t be replaced by another scenario.

Followup: I suppose I can’t really think of an alternate to this full theory. Wouldn’t we need to come up with another possible set of laws to show another set is possible?

Answer: That would be a very complex task to do. But I think that even those that develop these theories don’t show that the universe exists logically necessarily. What you are talking about is the internal coherence of the laws with each other. And Leibniz would be quite happy to grant that the internal coherence of the laws necessitate each other. That doesn’t mean that the whole scenario exists with logical necessity. You can’t judge from the internal coherence of something that the whole picture is logically necessary.

Question: If the universe is not necessarily existing in its own nature, it has an external cause. Did you just postulate the external cause is quarks?

Answer: No, not at all! What I was saying was, “Is the universe something that exists by a necessity of its own nature?” And I was suggesting that not very many atheists, if any, hold to that view because when you look out at the universe you see the stuff that it is made up of doesn’t exist necessarily. And then I was using quarks as being the ultimate constituents of which the universe is composed. One could have used strings as an alternative. But they are the stuff that the universe is made of. The universe is just either a collection of all these quarks or it is an object that is composed or constituted by these quarks like a marble statue is made up of the marble. My argument is that if the marble doesn’t exist necessarily, then the statue can’t exist necessarily because if you had different marble you’d have a different statue. In the same way, you could have different quarks, and so you would have a different universe. And that means the universe doesn’t exist necessarily. Think of the analogy of your shoes made of leather versus steel. They are not the same shoes. That is a different pair of shoes with the same shape and size.

Question: When you talked about the atheist that said he believes that the universe is inexplicable and contingent. By contingent, does he mean dependent?

Answer: Not exactly. What he means is, it doesn’t exist necessarily, that it could have failed to exist. Its existence isn’t necessary.

Followup: I was thinking, how can you be an atheist and think the universe is contingent?

Answer: If you think of contingency in the sense of dependency, that would automatically imply some higher reality on which it depends. But what he wants to say is that it exists, it is not necessary that it exists, but it just exists inexplicably. There just is no explanation for why there is a universe. And that is the typical response to this argument. But to cover all of our bases, we are looking at this hypothetical response that says, “Yes, the universe does have an explanation, namely, the necessity of its own nature.”4

Question: You are saying there are only two choices. Isn’t the atheist stating it is neither? Doesn’t the argument fall apart if you can’t agree with the first premise?

Answer: That is correct, he denies the truth of the first premise. He would say the universe just exists inexplicably. He would deny that everything that exists has an explanation for its existence.

Followup: Can you use this for an argument for the existence of God in your position if the people can’t agree on the argument? Where does this leave us?

Answer: Let’s think about what the purpose of an argument is. For any argument, if you want to deny the conclusion, all you have to do is deny one of the premises. You can’t force anybody to adopt your conclusion. All they have to do is pick one of the premises, and they can deny it and escape the conclusion. What you do in a successful argument is to try to raise the intellectual price tag of denying one of the premises, so the person sort of compromises his intellectual integrity to a degree by denying a premise which, in every other case, he would think is extremely plausible. And you begin to see that the only reason they deny it is to avoid the conclusion at the end that he doesn’t want to believe in God. If you can do that, you have been successful. You have shown him what it is going to cost him to be an atheist. And some people will be persuaded. Some people will say, “Gosh, I guess I do think that everything that exists has an explanation. That does seem plausible. So I am going to change my mind, and I am going to agree that, yes, God exists.”

Followup: Atheists seem to take the position that we don’t know. One day we will know but what we do know is there is no God. Therefore, anything you try to say to me that is proof there is a God, I am going to say that is fallacious because the sheer existence of God is an impossibility.

Answer: What they have just done there is they have assumed an enormous burden of proof. They have just shouldered the burden of proof for the claim that God does not exist. And now you need to let them start giving their arguments and say, “O.K., give me your proof that God does not exist!” And that is very, very difficult to do. That is a very heavy burden to bear. In the absence of some overwhelming argument for atheism, I think their denial of premise 1 is just borne out of stubbornness and a refusal to accept the conclusion. Otherwise, I think the premise is more plausible than its contradictory, and that is all you need for a good argument. It doesn’t need to be certain, just more plausible than its negation.

Question: Explain how the intelligent design movement would interface with what we are talking about?

Answer: The third argument that we talk about will be an argument for a cosmic Designer of the universe. This is not based on the design of the universe but just the very existence of the universe cries out for some kind of a transcendent cause.

Question: It appears the atheist worships the great lucky rabbit’s foot in the sky!

Answer: In the sense that he thinks that the universe is just there and there is no explanation for it. I can sympathize with that comment.

Question: I think when you bring in the fine-tuning arguments, it just becomes absurd.

Answer: This is a good point. We are building a cumulative case here. It will not be any single argument that bears the full weight. It will be the cumulative arguments. And you start general with an argument like this, and then you get more and more specific. And I think the case becomes more and more powerful.5

Question: Is there anybody out there crazy enough to deny premise 3, that the universe exists, like it is an illusion?

Answer: I suppose in one sense, in Eastern philosophy like Hinduism and Daoism, there is a belief that the universe around us is ultimately illusory. But at least there is the illusion of the universe’s existing. And, therefore, I don’t think you can get away from the fact that there is the existence of something, and this requires an explanation. I don’t think even that will work. But for people that we are apt to encounter in the western world, people will agree that the universe exists.

Question: Romans 1 says God’s invisible attributes and divine nature are clearly seen and people have been futile to their response to that. Do you think the resistance you see to these arguments are an example of that?

Answer: I think some of it is. With regard to certain people who are willing to believe almost anything rather than theism, I think that there is clearly a kind of stubbornness there and simply an unwillingness to come to God. I don’t want to say that everyone who resists these arguments does so, but I have met certain atheists who are willing to say that the universe just popped into being uncaused out of nothing and that that is better than believing in a transcendent cause. To me, that is far too high an intellectual price tag to pay to retain one’s intellectual credibility.

Question: I know of a very bright atheist who is truly seeking whether or not God could exist. What is the very best book that I could give him to read? He is highly educated.

Answer: That would depend on the level of his education. I would direct him to the Blackwell Companion to Natural Theology if he is very highly educated.

Cosmological Evidence That The Universe Is Contingent

I want to go to my second point because that is not the only reason for thinking the universe doesn’t exist by a necessity of its own nature. I think a second reason for thinking that the universe does not exist necessarily is that we have strong astrophysical evidence that the universe began to exist. An essential property of a necessary being is eternality, that is to say, it exists without beginning and without end. Anything that comes into being at a certain time doesn’t exist necessarily because it could fail to exist. So something that is necessary in its existence has to be eternal.

In one of the most startling developments of modern science, we now have pretty good evidence that the universe is not eternal in the past but had an absolute beginning about 13 billion years ago in a cataclysmic event called the Big Bang. And what makes the Big Bang so startling is that it represents the origin of all matter and energy, even physical space and time itself, out of nothing. The physicist P. C. W. Davies writes, “the coming into being of the universe, as discussed in modern science . . . is not just a matter of imposing some sort of organization . . . upon a previous incoherent state, but literally the coming-into-being of all physical things from nothing.”6 Now, of course, alternative theories have been proposed over the years in order to avoid the absolute beginning of the universe predicted by the standard Big Bang theory. But none of these theories has commended itself to the scientific community as more plausible than the Big Bang theory. In fact, in the year 2003, the cosmologists Arvind Borde, Alan Guth, and Alex Vilenkin were able to craft a theorem which shows that any universe which is, on average, in a state of cosmic expansion throughout its history cannot be eternal in the past but must have an absolute beginning.7 Vilenkin pulls no punches. He says,

It is said that an argument is what convinces reasonable men, and a proof is what it takes to convince even an unreasonable man. With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape, they have to face the problem of a cosmic beginning.8

So the beginning of the universe shows that the universe doesn’t exist by a necessity of its own nature. It is contingent; it came into being at some point in the finite past. But not only that, the beginning of the universe shows the universe to be contingent in a very special way, namely, it came into existence from nothing. This is significant because it not only undermines the claim that the universe exists by a necessity of its own nature, but it also puts the atheist into a more difficult position. Against Leibniz, the atheist could say the universe has existed from eternity past without any explanation. And you can give the atheist a run for his money there. Essentially, he says, the universe is not necessary but it is eternal, it has always existed, and it just exists inexplicably. But this evidence requires us to say that the universe is contingent in the sense that a finite time ago, it just popped into existence for no reason whatsoever, with no explanation at all! And it seems that that is so outlandish that theism looks like a welcome alternative compared to that. So this second argument gives us not only good reason to think that the universe doesn’t exist by a necessity of its own nature but that it is contingent in a very special way that points to its ground in a transcendent, external cause.


Question: Three things. One, could you talk about the problems of dismissing premise (1) and just say, “I don’t know; isn’t that more humble?” Two, could you talk about when somebody offers the retort, “Just give us time. Science will figure it all out, and we’ll answer all these questions at some point in the future.” Three, could it be possible that nothing exists necessarily?

Answer: Actually, the third and the first question are the same. There I simply appeal to the intuitive obviousness of premise (1) when you think about it. I like the illustration that Richard Taylor gives of finding the ball in the woods. It just obviously needs some sort of explanation for why there is this ball lying on the floor of the forest, and merely increasing the size of the ball until it becomes the size of the universe doesn’t do anything to remove the need for the explanation of the universe. So the atheist needs to give me some reason for thinking that the universe is an exception. And when we looked at the reasons the atheist gives, we saw they were question-begging. And therefore it seems the first premise is plausibly true and more plausibly true that its opposite. I’m not saying it is certain; but you don’t need certainty for an argument to be a good one. As for the materialist retort, I do not think that that is relevant because we are not saying here that matter hasn’t always existed or that it always will exist. We haven’t even said that everything in the universe isn’t composed of matter. The question is, does matter itself exist necessarily? That isn’t a scientific question, that is a metaphysical question. There isn’t any further research you could do to show that matter exists necessarily. That is a metaphysical point.9

Question: If the universe is all that exists and the bang is the beginning of some period of time, what is the argument for what is before?

Answer: Let’s be very careful here. Did you notice how you defined the universe? You said, “if the universe is all there is.” That already is smuggling in atheism through the back door. That is atheism! You are reasoning in a circle if you say that. You are assuming there is nothing beyond the universe. That is arguing in a circle. The question is, is that true, that the universe is all there is, and does it exist necessarily? That is the whole question we are exploring.

Question: I have heard R.C. Sproul say that if the universe is a finite system with beginning and end, it could have been brought about by another finite system, and that could keep going for a long time but not forever. At some point, there has to be an infinite that spawned a finite.

Answer: That does seem to be the implication of the Borde-Guth-Vilenkin theorem. There are theories of the universe which are called multiverse theories in which our universe is just a bubble in a wider reality which is composed of many bubbles, many universes. What the Borde-Guth-Vilenkin theorem shows is not simply that each universe must have a beginning, but that this entire multiverse system cannot be eternal in the past but must have a beginning. So you can’t escape the beginning of the universe and its contingency through simply saying our universe is part of a wider reality that is greater than it. The Borde-Guth-Vilenkin theory requires that even that greater realty has a boundary at some point in the past and therefore came into being and therefore doesn’t exist necessarily but is contingent.10


1 5:10

2 10:04

3 15:15

4 20:14

5 25:07

6 ABC Science Online, "The Big Questions: In the Beginning," Interview of Paul Davies by Phillip Adams, http://aca.mq.edu.au/pdavies.html, as quoted on ReasonableFaith.org at http://www.reasonablefaith.org/does-god-exist-1

7 30:20

8 Alex Vilenkin, Many Worlds in One: The Search for Other Universes (New York: Hill and Wang, 2006), p. 176

9 34:54

10 Total Running Time: 38:37