Tackling the Kalam Cosmological Argument


The Kalam cosmological argument is an argument for the existence of God defended most notably by William Lane Craig, research professor of Philosophy at Talbot School of Theology. The argument has its roots in Islamic philosophy and can be stated as follows [1] :


The purpose of this blog post is to focus on the premise (1) by providing a succinct defence of it and then responding to some objections.

Reflections on the Causal premise

Craig (1992) believes that the causal premise strikes us as so intuitively plausible that an argument in support of it would be less plausible than the premise itself. He claims that it is a “metaphysical first principle, one of the most obvious truths we intuit when we reflect philosophically.”[2] Later he states that “our conviction of the truth of the principle is not based upon an inductive survey of [empirical facts], but rather upon the immediate metaphysical intuition that something cannot come from nothing.”[3]

Though Craig does not state this explicitly, I suspect that the intuitive appeal of premise (1) can be sharpened by reflecting on the nature of potentiality and actuality.

In the 13th Century, Thomas Aquinas argued that if something becomes actual (by beginning to exist), then it must move from potentiality to actuality, which implies that there must at least be a potential for its beginning.[4]  Conversely, if there were no potential for it to begin, then its beginning would not be possible, since things cannot come to be if there is no potential that to happen.

Furthermore, if something can only begin by having the potential to do so, then we are faced with three options: either that potential is grounded in (a) the thing that begins, (b) something else, or in (c) nothing at all.

Aquinas dismisses option (a) because it would require that something be the cause of its own existence and therefore be causally prior to itself, which is impossible.

But what about option (c)? That option is untenable for different reasons – for if potentiality is not grounded in something actual, then potentiality alone would be sufficient to make things actual! But this conclusion runs into absurdities –

The mere potential for a glass to be filled with water does not actually fill the glass.
The mere potential for a glass to be filled with water does not actually fill the glass.

For example, an empty glass may have the potential to be filled with water, but that potential alone would not be sufficient to fill the glass. Something else, like a restaurant waitress pouring a jug of water, would be needed to fill the glass. If this were not so, then we would be observing empty glasses being filled at random for no reason at all. But this is absurd! Why? Not merely because we fail to observe empty glasses filling up in this way. It’s because we understand that potentialities are grounded in actual things which have the power to bring them about.

With option (a) and (c) eliminated, we are left with option (b): the potential to begin must be grounded in something else. But how might we get from (b) to Craig’s causal premise?  Simple. We’ve already concluded that actual beginnings presuppose the potential to begin, and those potentials must be grounded in actual things which can bring them about. Therefore, actual beginnings are grounded in actual things which can bring them about. In other words, everything that begins to exist has a cause.[5]

Two Objections

One might object to my reflection on premise (1) by saying that it confuses the meaning of two distinct terms: possibility and potentiality. My reflection presupposes without argument that if something is possible, then there must be a potential for its existence.  By why should we assume this is the case? Certainly, Aristotle (as well as Aquinas and Leibniz) believed that possibilities were based on the powers (or potencies) of actual things which could bring them about. But what if Aristotle was wrong?

Unfortunately, I do not have space in this blog post to argue for an Aristotelian account of possibility, but I have written about it elsewhere, and it seems that Aristotle’s account is a better than its main competitors, specifically Platonism and Extreme Modal Realism.

A second objection has to do with quantum physics, according to which tiny particles seem to pop into existence from nothing without a cause.  Does the existence of such particles pose an exception to the premise that whatever begins to exist has a cause? Tune in for my next post to find out!


[1] For a more detailed exposition of the Kalam Cosmological Argument, see William Lane Craig’s The Existence of God and the Beginning of the Universe. San Bernardino, California: Here’s Life, 1979.

[2] William Lane Craig (1992). “God and the Initial Cosmological Singularity: A Reply to Quentin Smith.” Faith and Philosophy 9 p.11.

[3] Ibid. p.5

[4] Aquinas implicitly relies on this line of reasoning to argue that the admission of a beginning to the universe would render theism virtually inevitable. He states that “if the world and motion have a first beginning, some cause must clearly be posited to account for this origin of the world and of motion. That which comes to be anew must take its origin from some innovating cause; since nothing brings itself from potency to act, or from non-being to being.” Summa Contra Gentiles 1.13.30

[5] Of course, there is no contradiction in the idea that something can come to be without any potential for its existence – as is evident from the logical coherence of the idea. So premise (1) is not logically necessary in the sense that its denial entails a contradiction. But the defender of the Kalam argument need not defend the logical necessity of premise (1). It will suffice if the causal premise is actually true, not necessarily true.


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