Excursus on Natural Theology (Part 5): The Argument from Contingency

September 16, 2015

Argument From Contingency

It may seem strange to have begun an excursus on natural theology by arguing that we don’t really need arguments for the existence of God in order to believe rationally and even know that God exists. But we’ve seen that, in fact, arguments for God’s existence are not necessary because God can be known to exist in a properly basic way through the self-authenticating witness of the Holy Spirit.

But to say that arguments for God’s existence are not necessary in order to know that God exists or that the great things of the Gospel are true is not to say that there are not also arguments that are sufficient for the knowledge of God. In fact, I would agree with Alvin Plantinga that even though belief in God and the great truths of the Gospel are properly basic, still there are arguments and evidences that are sufficient to warrant belief in the existence of God and in the great truths of the Gospel.

Today we want to begin to look at some of these arguments for God’s existence. The first argument is the argument from contingency. [Dr. Craig hands out the outline.] Sometimes this is called the Leibnizian cosmological argument. I discuss this argument in the book On Guard and also in a deeper way in the book Reasonable Faith. We will be looking this morning at the version as it is laid out in On Guard.

I have always been impressed by the mystery of the existence of the universe. I remember as a boy looking up at the stars at night and wondering where did all of this come from? It just seemed to me that there had to be an explanation for why all of this exists. Little did I realize that my boyhood question as well as its answer had been reflected upon by philosophers for centuries, millennia even. For example, Gottfried Wilhelm Leibniz (who was the co-discoverer of the calculus; a polymath of tremendous genius and one of the great geniuses of 18th century Europe) argued that, in his words, “The first question which should rightly be asked is, ‘Why is there something rather than nothing?’” That is to say, why does anything at all exist? Leibniz believed that this is the most basic question that anyone can ask. Like me, Leibniz came to the conclusion that the answer is to be found not in the universe of created things but rather in a transcendent cause of the universe in God. God, he said, exists necessarily and is the explanation for why anything else exists.

One of my friends has said to me that it is a shame that I began the book On Guard with this Leibnizian argument because it is an argument that is very philosophical and metaphysical and which the layperson finds, I think, very difficult to grasp. So right at the beginning of the book this hurdle is placed in his path whereas it would have been perhaps better to have begun with easier-to-grasp arguments for God’s existence. But I must say, I agree with what Leibniz said – logically this is the very first question which ought to be asked. Before we ask, “Why is the universe fine-tuned for our existence?” or “Why did the universe begin to exist?” the most fundamental question is “Why is there anything at all?” This is clearly the beginning point.

Two centuries after Leibniz, Martin Heidegger, who was a very famous German 20th century metaphysician, wrote this: “Why are there beings rather than nothing? That is the question. Clearly it is no ordinary question. ‘Why are there beings, why is there anything at all, rather than nothing?’ – obviously this is the first of all questions.” That is where we will begin in our survey of arguments for God’s existence with this most fundamental question of all: why does anything at all exist?[1]

We can put Leibniz’s argument in the form of a very simple series of premises which are on your outline.

1. Every existing thing has an explanation of its existence, either in the necessity of its own nature or in an external cause.

2. If the universe has an explanation of its existence, that explanation is God.

3. The universe is an existing thing.

4. Therefore, the explanation of the existence of the universe is God.

This is a logically airtight argument. That is to say, if the three premises are true then the conclusion follows necessarily. It doesn’t matter if you don’t like the conclusion. It doesn’t matter if you have other objections to God’s existence. If you think that those premises are true then you’ve got to accept the truth of the conclusion as well. Anyone who wants to reject the conclusion has got to say that at least one of those three premises is false.

But which one will he reject? Clearly, premise (3) is undeniable for any sincere seeker after truth. Obviously the universe exists! Therefore, the skeptic is going to have to deny either premise (1) or premise (2). So the whole question with regard to this argument comes down to this: are these two premises more plausible than not? Are they more plausibly true or are they more plausibly false? Well, let’s look at each one of them in turn.

First, every existing thing has an explanation of its existence, either in the necessity of its own nature or in an external cause. You will notice that Leibniz makes a distinction here between two types of being. The first type is things that exist necessarily – by a necessity of their own nature (a necessary being). This is the idea of a being which cannot fail to exist. It is something the non-existence of which is impossible. What would be an example of a necessary being? Very many mathematicians think that mathematical entities are necessary in this way – things like numbers, sets, propositions, things of that sort. Even those who are anti-realists about these – who don’t think that mathematical objects really exist – nevertheless recognize that if they do exist then they exist necessarily. If the number 1 exists in any possible world then it actually exists. It would be impossible for the number 1, for example, to just contingently exist – to exist in this world but not in some other possible world. Even those who don’t believe in the existence of mathematical entities like numbers, sets, and geometrical figures still would recognize that it belongs to the nature of these things to exist by necessity. If they exist at all, they exist necessarily. These kinds of things are not caused to exist by something else. They simply exist by a necessity of their own nature, and it is impossible for them to fail to exist.

The other type of thing would be things that exist contingently. That is to say, they are contingent beings. Contingent beings are things that exist but they don’t have to exist. It is possible for them to fail to exist. They exist but their existence isn’t necessary; they could have failed to exist. This is the case with the world of objects around us – things like people, chairs, planets, galaxies, and so forth. These things exist but they are not necessary in their being. We can imagine a possible world in which any or all of those things fail to exist. These kinds of things, if they exist, have explanations outside of themselves for why they exist. They don’t exist by a necessity of their own nature. If, for example, a unicorn exists in this world, there must be some explanation for why it exists rather than not exist.[2] There are lots of possible worlds in which there are no unicorns, like the actual world. If a unicorn does exist, there needs to be some sort of explanation that is apart from the nature of a unicorn that would explain why the unicorn actually exists rather than is a mere possibility.

So when Leibniz says that everything that exists has an explanation of its existence, that explanation could be one of two sorts. The explanation could be that it exists by a necessity of its own nature – it is a necessary being. Or the explanation could be that it is a contingent being that has a cause outside of itself that produces it in being. If God exists, God is a being that would exist by a necessity of his own nature. It is impossible for God to be caused by anything else. If God were to be caused by something else then there would be something greater than God and therefore he wouldn’t be God. So by the very concept of God, God cannot be something that would be caused to exist by something else. If there is a God then he would exist necessarily. Leibniz’s argument is driving us toward a very powerful concept of God, namely, the idea of a metaphysically necessary being – a being that exists by a necessity of its own nature. Not merely a contingent being that happens to exist, but a necessarily existing being.


Student: A contingent being would require a necessary being?

Dr. Craig: That will be the argument, yes. A contingent being requires some sort of cause or explanation outside of itself. Ultimately, this is going to have to be grounded by a metaphysically necessary being. That is right. You are already seeing the implication of Leibniz’s argument.

Student: Could you explain further more necessary-being philosophy. Obviously the concept of God is huge and hardly comprehensible. The same thing as math – like numbers or time. Do you have something else to relate that to that would make it more understandable?

Dr. Craig: I don’t. The difficulty here is, at least on a Christian view of things, everything physical – everything in the space-time universe – is created by God and is therefore contingent. So one really has to cast about to find non-theological examples of necessary beings. The only place that you can really find these would be in these so-called abstract objects – things that are not concrete, made out of matter and energy, existing in space and time. Things like mathematical objects, propositions, properties, possible worlds. These are called abstract objects. I think that the example of mathematics is the clearest. Most of us in math class have thought about whether or not numbers exist or is there a perfect circle? We all know there is no perfect circle in the physical world, so are all these approximations to some sort of abstract perfect circle? Does that thing sort of exist as an abstract object? If it does, it would exist necessarily. It would be impossible to say that there just happens to exist a perfect circle in this world but it doesn’t exist in these other worlds. Mathematical objects, for me, is the most accessible example of something that exists necessarily if it exists. If you want some explanation beyond that all I can do is ask a question and I’ll try to respond to it.[3]

Student: I struggled for a long time with this concept of a necessary being. I finally arrived at something that at least helped me and maybe it will help other people, too. There are an infinite number of things that could have happened to keep me from existing. So I am not a necessary being. There is nothing that could have happened to keep God from existing. Why is this? In my mind (maybe it is a little too narrow) I’ve distilled it down to the fact that he has no beginning. Anything that has no beginning is necessary because nothing could have happened to prevent his existence. There is only two things that I could think of that have no beginning – God and (we won’t get into time but) his time (I think they are probably different times). Both of those entities had no beginning. The second thing about abstract numbers and all – to me, those are concepts, and a concept can only exist if there is an intelligence. If there is no intelligence or comprehension there is no number 7. There is no square root of this, that, and the other. But since God is necessary, he is the intelligence. So they are necessary, too, because he is here to have them as a concept.

Dr. Craig: Let me address the second concern first. Do you remember in our discussion of the attributes of God we talked about divine aseity or self-existence and the challenge posed to that by Platonism, which is the philosophy that there are these sorts of abstract, necessarily existing, uncreated entities like numbers and sets and geometrical shapes and so forth. One of the Christian responses, indeed the mainstream Christian response, to this challenge is exactly what you said; namely, these are divine concepts. So they don’t really exist independently of God. They are ideas or concepts in the mind of God. I think that is a defensible perspective. As I emphasized in appealing to this example, even people who are conceptualists would recognize that if there were these sort of Platonic entities like numbers and sets and so forth they would be necessary beings. They would be things that exist by a necessity of their own nature. But he thinks there aren’t those sort of things. He thinks instead these are concepts in God’s mind. They aren’t really abstract objects. While I tend to agree with you that these things don’t have any sort of independent existence of God, I don’t think that robs the illustration of its power because it is the best example of a necessary being that is not God if the Platonist is right.

I liked very much what you said in your first question about nothing could prevent God from existing whereas with contingent beings they could be prevented in their existence. There are other possible worlds where these things never happened or never come to be. But I want to resist, however, your explanation of why God can’t be prevented from existing and why other things can. You found that in the fact of a temporal beginning. I don’t think that is right. Indeed, Leibniz emphasizes that you cannot evade his argument by saying the universe is eternal whereas if you gave your explanation you could evade his argument that way. But Leibniz says even if the universe has existed from eternity, it is still possible for it not to have existed. It is logically possible that there be no universe at all, or that there be a universe with a beginning instead of an eternal universe. Even saying that the universe is beginningless and eternal in the past does not answer Leibniz’s question, “Why is there something rather than nothing?” While I like what you said about God’s necessity entailing that nothing can prevent his existence, I wouldn’t find that in his being beginningless because I think that is incorrect and it would also allow the atheist a way out of this argument.

Student: It seems like what we are saying is if there is a God as we’ve defined God he is a necessary being.[4] But it requires us to say our definition of God is this, and therefore he would be a necessary being. It is not a proof that God exists. Am I understanding that correctly?

Dr. Craig: Sort of. Wait until we get to premise (2) where it says, “If the universe has an explanation, that explanation is God.” That is where God will get pulled into the argument. But not in premise (1). Premise (1) is just a principle that things that exist have explanations for why they exist, and those explanations can either be in some external cause or that they exist by a necessity of their own nature. In philosophical literature, and in Leibniz’s own writing, this is called the principle of sufficient reason. Leibniz stated a very radical version of this principle. The version that I have here is a quite modest version of the principle that I think is very plausible as I’ll say. It requires that simply any existing thing has an explanation for why it exists rather than not. We’ll talk about whether or not premise (2) is true, and we are justified in calling this being God.

Student: It seems to me that only God has his existence by necessity because even time began to exist. Also when you think of numbers you are looking at numbers are ways to consider objects. It is a concept but I don’t know how you could have even a concept that is separated from God because I can’t even imagine anything that can exist that hasn’t an origin of God.

Dr. Craig: You mean apart from God? Again, I want to refer back to our discussion of divine aseity when we talked about the attributes of God, and where I argued precisely this point. Everything that exists other than God is contingent and dependent upon God. But what that just means is I am not a Platonist. But many mathematicians are Platonists. They don’t ground these objects in God as his concepts. They think that the number 1 and the set of natural numbers and the perfect circle and other geometrical shapes are real objects that actually exist. They are abstract objects. I am saying that on Platonism we have an illustration of a non-theological necessary being. I am trying to find something here that illustrate for lay folks what a necessary being is that doesn’t appeal to God. That is the best example that I can come up with. If you are a Platonist you are loaded with these things.

Student: Even on that score, not to belabor the point, you have to have a mind to conceive of a contingent or necessity . . . it is a concept of a mind. But then does the mind not have a necessity?

Dr. Craig: This is interesting. Plato had a concept that he called the demiurge. This is sort of “god” with a small “g.” He is the creator of the physical world. What Plato says is that these abstract objects or Forms are the most real things. They exist independently of anything else and “god” looks to the Forms and then he fashions the physical world on their model. So the perfect circle is the model for these approximations that “god” makes. These numbers are the ideal entities when “god” makes three things, say, then there are one, two, and three in the realm of the Forms. Yeah, the concrete world on Plato’s view is due to the action of this demiurge but he isn’t responsible for this realm of Forms or abstract objects. They exist quite independently of him. As you rightly point out, this is utterly incompatible, I think, with Christian theism or Jewish-Christian theism.[5] The church fathers rejected Platonism and they tended to put these things in the mind of God – these are God’s ideas. They internalized Plato’s realm of the Forms into the mind of God. When I appeal to this illustration, I am appealing to (for the most part) non-theistic mathematicians and philosophers who still endorse Platonism. Sadly, the truth is there are a good many Christian philosophers who endorse Platonism as well. I am thinking of people like Peter van Inwagen and Keith Yandell who are Platonists. I am baffled by that, but there are Platonists today who think that these things are necessarily existing beings.

Student: Are these not then just a character of God? These concepts? In essence, they are saying they believe in this concept but they are not giving that as part of God’s character.

Dr. Craig: They don’t think they are concepts. They think they are real objects. They are as real as this chair or you. In some ways they are more real in one sense in that they exist necessarily whereas the chair and you are just contingent.

Student: You can’t objectify these things without a mind. You can’t have a concept of oneness and numbers in abstraction unless there is a mind which presupposes you could understand such a thing.

Dr. Craig: Again, we are reverting to our earlier discussion about divine aseity. I don’t want to rehearse that again here because all I am trying to do is illustrate the idea for you of a necessary being. I agree with you that Platonism is false. We are on board with each other, right? But do we understand the idea of a being that exists by a necessity of its own nature – a being that cannot fail to exist? If you get that idea then fine. That is all we want to establish. And how that is distinct from a contingent being which happens to exist but could fail to exist if things had gone otherwise and therefore has some cause outside of itself.

Student: Can we use a substitute description for necessary being as a set of divine concepts? Because John 1:1 says, “In the beginning was the Word.” The Word is just divine concepts. As we have the ability to think of concepts there may be a law that the concepts can come together and become a set and that set we call it God.

Dr. Craig: I’ll go with you part way on that. In the beginning was the Word, or the Logos. This is who Jesus Christ is said to be. He is the incarnate Logos. As I indicated in response to earlier questions, the church fathers located these abstract objects in the Logos. The Logos is the mind of God. These things are concepts in the mind of God. But all of these questions concern the previous lesson that we’ve already finished about divine self-existence or aseity. All we are talking about here now is: is it true that everything that exists has an explanation of its existence? There are two types of explanation. I think you get that. You just want to talk about this other thing.

Student: Maybe we are looking for more literature on this?

Dr. Craig: Oh, that’s easy to give.

Student: I asked my friend this question – why is there something rather than nothing? – this probably was a month ago. He walked away asking to think about it. About two weeks ago I again asked him, “Did you come to a conclusion?” He said no. He is still looking. Now I am going to look into it, too, to help him out. There are some articles out there but they are very complex. I don’t know where else we can turn to on this particular question and this argument.

Dr. Craig: Have you read the treatment of this argument, for example, in Reasonable Faith yet?[6]

Student: I have not.

Dr. Craig: OK, that is a place to begin. There are footnotes that you can follow to read further literature on Leibniz’s argument. You can go back and read Leibniz himself.

Student: Is there a particular chapter in there that I should look into?

Dr. Craig: Yes, it is chapter 3 in the book. That is a place to look. As I say, there are citations to further literature and bibliography there.


What reason might be offered for thinking that premise (1) is true? Why should we think this is true? I think when you reflect on it there is a kind of obviousness about the premise. If something exists contingently – like, say, if there is a unicorn rather than no unicorn – then there needs to be some sort of explanation for why one of those alternatives is actualized rather than the other. Why does the unicorn actually exist rather than not when its non-existence was possible?

Richard Taylor, who was a prominent 20th century American philosopher, gives a wonderful illustration for this. He says imagine you are walking through the woods and you suddenly come upon a translucent ball lying on the forest floor. He said you would naturally wonder why it exists. How did it come to be there? If your hiking buddy said to you, “Forget about it! It just exists inexplicably! There is no explanation of its existence.” Taylor says you wouldn’t accept that. You’d think that the guy was either just joking or wanted you to keep moving. But it is obvious that there would be some kind of an explanation for why that ball exists.

Notice that merely increasing the size of the ball, say, until it is the size of an automobile does nothing to explain its existence. Or making it even bigger to the size of a house. Same problem. Suppose it is the size of a planet. Same problem. Suppose it is the size of a galaxy. Same problem. Suppose it is the size of the entire universe. Same problem. Merely increasing the size of the object does nothing to provide an explanation for its existence.

If you have the sense that finding a ball in the woods requires an explanation for its existence, that, I think, will lead inevitably to saying that bigger and bigger objects (even the universe itself) will have to have an explanation of its existence because merely increasing the size of the ball does nothing to either provide or remove the need for an explanation of its existence.

With that we will close today. I will take up next time some atheist responses to premise (1) to try to exempt the universe from this principle.[7]



[1] 5:05

[2] 10:07

[3] 15:00

[4] 20:00

[5] 25:01

[6] 30:00

[7] Total Running Time: 33:20 (Copyright © 2015 William Lane Craig)