William Lane Craig: Looking at the Interplay between Premise 1 and 2 of Liebniz' Cosmological Argument

I drive quite a bit for my job. As I drive, occasionally I will look in my rear view mirror and notice a car behind me which I would swear had not been there when I looked only seconds before. (Fortunately, it is rarely a police car with lights flashing.) Moreover, I don't remember passing any side streets or driveways where the car could have entered the road. When it does happen, I find myself wondering, "Where did that car come from?" In my more fanciful moments I speculate that perhaps it somehow materialized behind me, effectively created ex nihilo, and hadn't actually just pulled into place behind me from some street entrance I overlooked. (If no one has written this into a short story already, some enterprising science fiction writer could write a pretty cool story about how a person lives in a universe where stuff just pops into place out of nothing.)

Naturally, I know that the car didn't just appear ex nihilo. However, I cannot prove it. Still, I know from experience that cars are not the type of things that simply pop into existence out of nothing. This idea that things do not spring into existence out of nothing serves as the basis for Mathematician, Philosopher and Polymath Gottfried Wilhelm Leibniz' Cosmological Argument and the Principle of Sufficient Reason.

The Principle of Sufficient Reason (PSR) holds that everything that exists requires an explanation. While Liebniz was not the first to speak of this principle (see, the Stanford Encyclopdia of Philosophy's article on the PSR) "[N]o philosopher is more closely associated with the PSR than Gottfried Wilhelm Leibniz." Even so, Spinoza made an excellent statement of the PSR when he said,

Since existing is something positive, we cannot say that it has nothing as its cause (by Axiom 7). Therefore, we must assign some positive cause, or reason, why [a thing] exists—either an external one, i.e., one outside the thing itself, or an internal one, one comprehended in the nature and definition of the existing thing itself. (Geb. I/158/4–9 as quoted in the Stanford Article

In other words, everything that exists must have an explanation or a cause for its existence. To me, this is a very common sense principle. Just as I can readily conclude that the car that seemed to materialize behind me did not appear out of nothing, the PSR argues that I can safely conclude that nothing that exists does so without some type of explanation. The PSR asserts that the fact that anything exists tells us that there must be an explanation for its existence.

The first premise of Leibniz's Cosmological Argument begins with the PSR, and while his argument is actually quite simple it manages to inspire a great deal of dissension. For this article, I will use the formulation of Liebniz' argument set forth by budding philosopher Randy Everist on his fine blog, Possible Worlds:

Premise 1 - Everything that exists has an explanation of its existence (either in the necessity of its own nature or in an external cause)
Premise 2 - If the universe has an explanation of its existence, that explanation is God.
Premise 3 - The universe exists.
Conclusion 1 - Therefore, the universe has an explanation of it's existence.
Conclusion 2 - Therefore, the explanation for the universe's existence is God.

The logic of this argument is good. If the premises are true, then the conclusion must be true. As I do a brief, non-exhaustive review of various articles that have addressed Liebniz's Cosmological Argument, I haven't found anyone who attacks the form of the argument. Rather, the attack is on the premises, and since Premise 3 is pretty self-evident (unless one ascribes to the view that everything is an illusion, it seems apparent that the universe exists), the debate is primarily over Premises 1 (the PSR) and 2.

I do not have time in a short article to give a comprehensive review of the arguments about the legitimacy of the PSR. Rather, I want to focus on one particular objection to the PSR and the problem that this objection raises with the second premise. In doing so, I follow the path of Dr. William Lane Craig in his book, On Guard: Defending Your Faith with Reason and Precision.

Dr. Craig points out that a common response to the first premise of Liebniz' argument, i.e., the PSR, is that the critic will assert that the universe does not have an explanation for its existence. In setting forth this assertion, critics commonly have two courses they follow, i.e., either they can claim that the universe necessarily exists (or, to follow the form of the Leibniz's argument quoted above, that the universe "exists of its own necessity") or that it is impossible for the universe to have an explanation. The first option appears to be a view that professional philosophers reject because, as Dr. Craig points out, he "can't think of any contemporary atheist who has in fact adopted" the position that the universe exists of its own necessity. Dr. Craig states the reason for the rejection of this position:

As we look about the universe, none of the things that made it up, whether stars, planets, galaxies, dust, radiation, or what have you, seems to exist necessarily. They could all fail to exist; indeed, at some point in the past, when the universe was very dense, none of them did exist.

So, ordinarily the critic who argues that the universe does not have an explanation will not make the argument that the universe exists necessarily, but rather will question the PSR by asserting that it is impossible for the universe to have an explanation. On what basis do they make such a claim? As explained by Dr. Craig, they do so...

Because the explanation of the universe would have to be some prior state of affairs in which the universe didn't yet exist. But that would be nothingness, and nothingness can't be the explanation of anything. So the universe must exist inexplicably.

In my view, this is a really weak response to the PSR when it comes to the existence of the universe (which is itself pretty much a given). It is especially weak if the person asserting the objection is trying to argue for atheism. Since the universe is clearly not the type of thing that must necessarily exist, and since the universe obviously does exist, to claim that there is no way to explain its existence but to assert it can't be God seems to be a good example of the fallacy of special pleading based on a pre-existing viewpoint. That is, when the atheist-critic is asserting that we can't know that the explanation or cause of the universe but we know it cannot be God because atheism is true, the conclusion is pre-ordained by worldview and not evidence.

Be that as it may, arguing that the universe is inexplicable has a rather interesting impact on second premise, i.e., "If the universe has an explanation of its existence, that explanation is God." Specifically, if the critic adopts the view that the universe is inexplicable, then she is basically saying the following: "If Atheism is true the universe has no explanation of its existence." Dr. Craig point out that this results in an interesting problem for the atheistic critic. Using the tool of contraposition, the statement, "If Atheism is true the universe has no explanation of its existence," is logically equivalent to "If the universe has an explanation of its existence, then atheism is not true." Notice how similar this statement is to the second premise, i.e., "If the universe has an explanation of its existence, that explanation is God." In other words, as stated by Dr. Craig,

So by saying in response to premise 1 that, given atheism, the universe has no explanation, the atheist is implicitly admitting premise 2, that if the universe does have an explanation, then God exists.

Just as I can be confident that when a car appears behind me suddenly it did not blink into existence, I know that the universe - which observation and experience both confirm does exist - did not appear out of nowhere. Moreover, it is not the type of thing that must necessarily exist. To argue that the cause or explanation of the universe is inexplicable simply to avoid the obvious conclusion that God is the most likely source for the cause of the universe is both disingenuous and an unintentional admission of the truth of God as creator.