The Cosmological Argument 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).
Logically, this argument is sound: that is, the conclusion follows from the premises. The question is whether the premises (1-3) are probably true or not. On the basis that we can all get together on #3, here’s William Lane Craig’s defence of #1 and #2:
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…
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.
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.
This doesn’t prove that God exists, of course. But it does highlight, fairly simply, what is involved in contending that he doesn’t.