William Lane Craig CV


Existence of God (part 16)

Transcript of William Lane Craig's Defenders 2 class.

Excursus: Natural Theology
§ III. Teleological Argument
Lecture 3

We have been looking at the alternatives for explaining the remarkable fine tuning that characterizes the initial conditions of the universe. We saw last time that these cannot be plausibly attributed to physical necessity. The constants and quantities are independent of the laws of nature, and the best Theories of Everything, so to speak, that are on offer today allow for a vast multiplicity of different possible universes consistent with nature’s laws but having different values of the constants. So the question is, what about the alternative of chance? Could the fine tuning be simply due to chance alone?


According to this alternative, it is just an accident that the constants and quantities all fall into the life-permitting range. We basically just “lucked out” and are lucky to be alive. The fundamental problem with this alternative is that the chances of all of the constants and quantities’ falling into the life-permitting range by chance alone are just so improbable that these odds cannot be reasonably faced.


Sometimes people will object to this sort of argument by saying it is meaningless to speak about the probability of a life-permitting universe existing. Why? Because there is, after all, only one universe. So what does it mean to speak about the probability of a life-permitting universe existing? It is not as if you can say, “One out of every ten universes is life-permitting.” Therefore, the fact that the universe is life-permitting isn’t highly improbable because you don’t have ten universes to pick from. There is only one universe, so to talk about the probability of a life-permitting universe is meaningless.

However, the following illustration from the physicist John Barrow can help us to understand the sense in which the existence of a life-permitting universe is improbable. Let’s imagine we have a large blank sheet of paper or whiteboard, and on it we place a single dot, and let that dot represent our universe. Now alter slightly one or more of the fundamental constants or quantities that has been the subject of our discussion. That would then describe a new universe – a universe that is characterized by different values of the constants and quantities. If that is a life-permitting universe, then make that a red dot; and if it is a life-prohibiting universe, then make it a black dot. Do that again and again until your paper or whiteboard is filled with dots. What you discover is that, except for a few pin pricks of color, the sheet will be completely covered with black dots – that is to say, life-prohibiting universes. That is simply what is meant when we say that the existence of a life-permitting universe is unfathomably improbable. Out of the local group of possible universes that could exist, the vast, vast majority of them are life-prohibiting, not life-permitting. I think this is a very graphic and easy way to understand what we mean when we say that an existing life-permitting universe is enormously improbable.

Very often you will hear a different objection to this claim based upon the illustration of a lottery. People will say that in a lottery in which all the tickets are sold, it is fantastically improbable that any one person you pick would win. The odds may be millions to one that any individual person would win the lottery. But if all the tickets have been sold, then somebody has got to win!1 It would be illegitimate for the winning person to say, “Wow! The odds against me winning the lottery were 20 million to 1. And yet, I won! The lottery must have been rigged! I won by design, not by chance.” It would be illegitimate for him to think that the lottery was rigged and that his winning wasn’t simply the result of chance. In exactly the same way, these critics will argue, some universe had to exist. Just as it would be illegitimate for the winner of the lottery to think the lottery was rigged because he won, so for us, as well, it would be unjustified for us to think that the universe “lottery,” so to speak, was rigged just because our universe exists. It wouldn’t follow that it was a result of design. All of the universes are equally improbable. Think of all those dots on the whiteboard: they are all equally improbable. But some dot had to be picked; some universe had to exist. So it would be illegitimate to claim that the universe that exists is therefore highly improbable and a result of design.


Question: Can you clarify how the Barrow illustration helps here?

Answer: The idea there is the critic says it is meaningless to talk about the probability of a life-permitting universe existing because there is only one universe. But I think Barrow gives a very clear sense in which we can talk about that, namely, all of these different possibilities are equally probable. They are all possible universes that could have existed instead of ours, and yet a life-permitting universe exists. That is enormously improbable because almost all of the universes on the sheet of paper are black, not red. A randomly chosen universe ought to be a black one, that is to say, a life-prohibiting one.

Now this new objection is: but some dot has to be real, and so it would be illegitimate for the people in that universe to say “Gee, we are so improbable, yet we exist! It must have been rigged!”

Actually, this lottery analogy is very helpful to us because it enables us to see exactly where the critic has misunderstood the fine tuning argument and then enables us to offer a better and more accurate analogy in its place. Contrary to popular impression, the design argument is not trying to explain why this universe exists. It is not trying to explain why this particular dot exists. The analogy of the lottery was misconceived because the lottery analogy focused on why a particular person won. But in this case, we are not asking why this particular universe exists. Rather, what we are asking is why a life-permitting universe exists.

The correct analogy would be like this: imagine a lottery in which billions and billions of white ping pong balls were mixed together with a single black ball. You are told that a random drawing will be made, and if the ball is black, you will be allowed to live. But if the ball is white, then you will be shot. Notice that in this lottery, any particular ball that rolls down the chute is equally improbable. Nevertheless, it is overwhelmingly more probable that which ever ball rolls down the chute, it will be white rather than black. That is the analogy with the universe. Even though every particular ball is equally improbable, it is overwhelmingly more probable that it will be a white ball rather than a black ball.2

Similarly, out of all of the universes that might exist, any one is equally improbable; but it is overwhelmingly more probable that whichever one exists, it will be a life-prohibiting one rather than a life-permitting universe. So in the case of the lottery, if, to your shock, the black ball rolls down the chute and you are allowed to live, you ought to definitely think that it was rigged because it is overwhelmingly more probable that a white ball should have rolled down the chute. And if you still don’t see the point, then sharpen the analogy and imagine that the black ball had to be picked randomly five times in a row in order for you to live. That really would not affect the odds appreciably if the odds against choosing the black ball even one time were sufficiently great. But, nevertheless, I think everyone of us would see that if that happened five times in a row, you know that the lottery was rigged to let you live.

In the correct analogy, we are not interested in why you got the particular ball that you did – any ball you get is equally and astronomically improbable. What we are interested in is why you got a life-permitting ball rather than a life-prohibiting ball. That is not addressed by saying, “Some ball had to exist or be picked, and any ball is equally improbable.” In exactly the same way, we are not interested in why this particular universe exists. What we are interested in is why a life-permitting universe exists. That question is not answered by saying that some universe has to exist and every universe is equally improbable. We still need to have an explanation for why a life-permitting universe exists.


Question: Why must any universe exist?

Answer: I suppose you could say that there could just be nothing. But we are granting this point to the critic. We are saying, “All right, let’s assume some universe has to exist.” We are going to agree to the lottery analogy. We are going to have a universe lottery, and we are going to agree that some universe is going to exist. But you are right – if you want to press this at a deeper level, you can ask why anything exists. But let’s grant the critic that some universe or other is going to have to exist and that any universe that exists is enormously improbable. You can do that, and the argument still goes through because the question isn’t “Why does this universe exist?”, contrary to popular impression. The question is “Why does a life-permitting universe exist?”

Question: Does it require that there be an infinite number of universes?

Answer: No, even a finite number is O.K. If you remember the figure that we saw with string theory – we said that there are around 10500 possible universes with different values of the constants consistent with the laws of nature. This is an inconceivably large number, but it is not infinite. The proportion of these universes that are life-permitting is just virtually infinitesimal – it is so tiny it is incomprehensible. Again, it would be like the lottery in which the single black ball is mixed in with billions and billions of white balls, and one of them is randomly chosen, and, lo and behold, it is the life-permitting ball!

Question: When you say life-permitting, do you mean life-permitting for humans and the conditions we require?

Answer: No, I did address that earlier. When we talk about life here, we are using a very general definition that scientists use – life is the ability of an organism to take in food, process it, grow and develop, and reproduce after its kind. Anything that fits that definition counts as life. That is what we mean by a life-permitting universe. That is why it is not a good objection to say, “If the constants and quantities had different values, there might be different kinds of life that would have evolved.” We are not talking about the forms of life that exist, but just life – period! In order for life in any form to exist, on this definition, you have to have this exquisite fine tuning of the constants and quantities.3

Question: You made a statement about five black balls in a row. I’m not sure where you are going with that. Are you going to have an analogy for that later on?

Answer: I wasn’t going to push that. But remember when we talked about the oscillating universe where the universe expands and then re-contracts, then expands again, then re-contracts? That would be perhaps the analogy to having the black ball picked five times in a row. Namely, imagine five oscillations, and each one, by chance, was fine tuned for the existence of life in it. That would cry out for some sort of a Designer. That wouldn’t happen by chance. I think we all see that intuitively. The point of the illustration is simply to say that if the odds of getting one black ball are sufficiently small, then it doesn’t make all that much difference if you get it one time or five times in a row. It is just that we see the problem more clearly when we think five times in a row; but in fact even getting it once is improbable enough to say something is fishy with the lottery, that this was in fact designed. That is the point of the new analogy and the proper lottery analogy for fine tuning.4


1 5:02

2 9:57

3 14:58

4 Total Running Time: 17:16