The Cosmological Argument from Contingency

By Philosopher William Lane Craig

The cosmological argument comes in a variety of forms. Here’s a simple version of the famous version from contingency:

  1. Everything that exists 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 exists.

  4. Therefore, the universe has an explanation of its existence (from 1, 3).

  5. Therefore, the explanation of the universe’s existence is God (from 2, 4).

Now this is a logically airtight argument. That is to say, if the premises are true, then the conclusion is unavoidable. It doesn’t matter if we don’t like the conclusion. It doesn’t matter if we have other objections to God’s existence. So long as we grant the three premises, we have to accept the conclusion. So the question is this: Which is more plausible—that those premises are true or that they are false?

Premise 1

Consider first premise 1. According to premise 1, there are two kinds of things: things which exist necessarily and things which are produced by some external cause. Let me explain.

Things that exist necessarily exist by a necessity of their own nature. It’s impossible for them not to exist. Many mathematicians think that numbers, sets, and other mathematical entities exist in this way. They’re not caused to exist by something else; they just exist necessarily.

By contrast, things that are caused to exist by something else don’t exist necessarily. They exist contingently. They exist because something else has produced them. Familiar physical objects like people, planets, and galaxies belong in this category.

So premise 1 asserts that everything that exists can be explained in one of these two ways. This claim, when you reflect on it, seems very plausibly true. Imagine that you’re hiking through the woods and come across a translucent ball lying on the forest floor. You’d naturally wonder how it came to be there. If one of your hiking partners said to you, “Don’t worry about it! There isn’t any explanation of its existence!”, you’d either think he was crazy or figure that he just wanted you to keep moving. No one would take seriously the suggestion that the ball existed there with literally no explanation.

Now suppose you increase the size of the ball in this story to the size of a car. That wouldn’t do anything to satisfy or remove the demand for an explanation. Suppose it were the size of a house. Same problem. Suppose it were the size of a continent or a planet. Same problem. Suppose it were the size of the entire universe. Same problem. Merely increasing the size of the ball does nothing to affect the need of an explanation. Since any object could be substituted for the ball in this story, that gives grounds for thinking premise 1 to be true.

It might be said that while premise 1 is true of everything in the universe, it is not true of the universe itself. Everything in the universe has an explanation, but the universe itself has no explanation.

Such a response commits what has been aptly called “the taxicab fallacy.” For as the nineteenth-century atheist philosopher Arthur Schopenhauer quipped, premise 1 can’t be dismissed like a taxi once you’ve arrived at your desired destination! You can’t say that everything has an explanation of its existence and then suddenly exempt the universe. It would be arbitrary to claim that the universe is the exception to the rule. (God is not an exception to premise 1: see below at 1.4.) Our illustration of the ball in the woods shows that merely increasing the size of the object to be explained, even until it becomes the universe itself, does nothing to remove the need for some explanation of its existence.

One might try to justify making the universe an exception to premise 1. Some philosophers have claimed that it’s impossible for the universe to have an explanation of its existence. For the explanation of the universe would have to be some prior state of affairs in which the universe did not yet exist. But that would be nothingness, and nothingness can’t be the explanation of anything. So the universe must just exist inexplicably.

This line of reasoning is, however, obviously fallacious because it assumes that the universe is all there is, that if there were no universe there would be nothing. In other words, the objection assumes that atheism is true. The objector is thus begging the question in favor of atheism, arguing in a circle. The theist will agree that the explanation of the universe must be some (explanatorily) prior state of affairs in which the universe did not exist. But that state of affairs is God and his will, not nothingness.

So it seems that premise 1 is more plausibly true than false, which is all we need for a good argument.

Premise 2

What, then, about premise 2? Is it more plausibly true than false? Although premise 2 might appear at first to be controversial, what’s really awkward for the atheist is that premise 2 is logically equivalent to the typical atheist response to the contingency argument. (Two statements are logically equivalent if it’s impossible for one to be true and the other one false. They stand or fall together.) So what does the atheist almost always say in response to the contingency argument? He typically asserts the following:

A. If atheism is true, the universe has no explanation of its existence.

Since, on atheism, the universe is the ultimate reality, it just exists as a brute fact. But that is logically equivalent to saying this:

B. If the universe has an explanation of its existence, then atheism is not true.

So you can’t affirm (A) and deny (B). But (B) is virtually synonymous with premise 2! (Just compare them.) So by saying that, given atheism, the universe has no explanation, the atheist is implicitly admitting premise 2: if the universe does have an explanation, then God exists.

Besides that, premise 2 is very plausible in its own right. For think of what the universe is: all of space-time reality, including all matter and energy. It follows that if the universe has a cause of its existence, that cause must be a non-physical, immaterial being beyond space and time. Now there are only two sorts of things that could fit that description: either an abstract object like a number or else an unembodied mind. But abstract objects can’t cause anything. That’s part of what it means to be abstract. The number seven, for example, can’t cause any effects. So if there is a cause of the universe, it must be a transcendent, unembodied Mind, which is what Christians understand God to be.

Premise 3

Premise 3 is undeniable for any sincere seeker after truth. Obviously the universe exists!


From these three premises it follows that God exists. Now if God exists, the explanation of God’s existence lies in the necessity of his own nature, since, as even the atheist recognizes, it’s impossible for God to have a cause. So if this argument is successful, it proves the existence of a necessary, uncaused, timeless, spaceless, immaterial, personal Creator of the universe. This is truly astonishing!