The kalam cosmological argument is both historically and currently significant. William Lane Craig, the leading contemporary advocate of the argument, has dubbed it the kalam argument in recognition of its origin in the work of Medieval Muslim philosophers such as al-Ghazali. The argument continues to interest philosophers and theologians. Its structure is simple:
- Whatever begins to exist has a cause.
- The universe began to exist.
- Therefore, the universe has a cause.
The argument is deductively valid. This means that if the premises are true, the conclusion must be true. The conclusion, as we shall see, is theologically significant. But why accept the premises?
Support for Premise (1)
Consider three points. First, there is a plausible metaphysical insight that things do not come into being from nothing. This intuition is expressed in the principle ex nihilo nihil fit. The claim that something can begin from nothingness seems contrary to philosophical insight, scientific practice, common experience, and even literary sensibility. To elaborate, consider Edgar Allan Poe’s The Raven:
“Once upon a midnight dreary, while I pondered, weak and weary,
Over many a quaint and curious volume of forgotten lore—
While I nodded, nearly napping, suddenly there came a tapping,
As of some one gently rapping, rapping at my chamber door.
“’Tis some visitor,” I muttered, “tapping at my chamber door—
Only this and nothing more.”
Poe’s nearly napping character naturally assumes that the rapping has a cause; i.e., he assumes the principle of causation. The noise is not a tapping that begins from nothing. (This is confirmed later in the poem.)
Second, suppose (1) is false. We should expect to observe things coming into being from nothing. We might see, for example, canoes, carrots, and cats beginning to exist from nothing in our streets, parks, or beaches. But we do not experience such things. Thus, we have an experiential reason to support the principle of causation.
Third, (1) accords with widespread empirical observation. It is not merely the case that (1) is not refuted by empirical examples of things popping into existence from nothing. It is also the case that (1) is repeatedly substantiated in human experience. Given these reasons, the burden of proof is on the denier of (1). As Roderick Chisholm wrote, one should be guided in philosophy by those propositions we presuppose in ordinary life. We have an epistemic right to believe them unless there is a sufficient argument to believe otherwise. Hence, the burden of proof is on the one who denies them.
Support for Premise (2)
Note three reasons for (2): (a) an actually infinite number of things is impossible; (b) the evidence for the big bang indicates the universe began to exist; and (c) the second law of thermodynamics shows the universe had a beginning.
Why accept (a)? Consider a story that shows the absurdity of an actually infinite number of things. Suppose there is a movie theater with only 500 seats. The theater is showing The Man Who Knew Infinity. All 500 tickets are sold and every seat is occupied. You try to purchase a ticket and the agent says: “Sorry, sold out!”
Now, suppose the theater has an actually infinite number of seats. An actually infinite number of tickets are sold and every seat is occupied. You go to purchase a ticket and the agent says: “You want a ticket for The Man Who Knew Infinity? I’ll tell you what. I’m such a man. That’ll be $10, please.” Then, he moves the person in seat one to seat two, the person in seat two to seat three, out to infinity. As a result of this fancy footwork, seat one opens and you gladly sit.
But now, suppose an actually infinite number of people want to watch the film even though the actually infinite number of seats are filled by an actually infinite number of other people. The agent says: “I know infinity and I’ll prove it!” He moves the person in seat one to seat two, the person in seat two to seat four, seat three to seat six, seat four to seat eight, etc. He moves each person to the seat double his initial seat number. Since any number multiplied by two is an even number, all end up in even seats. Thus, all the odd seats become available. Now, there are an actually infinite number of open seats – all the odd ones. The agent says: “See, I know infinity! Have a seat! And to all of you who moved, an actually infinite number of apologies for the inconvenience!” Finally, the agent sits to count the actually infinite number of dollars he collected for his efforts. A daunting task!
Now, if (2) is false, the universe had no beginning. Hence, an actually infinite number of moments have passed before now. But, as the story shows, an actually infinite number of things is absurd.
How about (b)? The big bang model of the universe holds that it is expanding from an initial point, which indicates that the universe has a beginning. The empirical evidence available for the big bang makes it a reasonable position to hold.
What can be said for (c)? The second law of thermodynamics states that in a closed system, energy eventually runs out and the system dies. But the universe is such a closed system. So, if the universe were past eternal, it would have died by now. But the universe is not dead. For example, the sun is shining and burning energy. So, the universe is not past eternal. It had a beginning.
Notice that space, time, and matter began with the universe. Thus, the cause of the universe is the cause of these. But nothing can cause itself. Hence, the cause transcends space, time, and matter. Therefore, the cause is immaterial, non-spatial, and timeless. The cause is also changeless, since whatever is timeless is changeless.
Moreover, it is rational to hold that the cause is personal. Why? First, there are two types of causal explanation: scientific and personal. But a transcendent cause of the universe cannot be scientific, since such a cause requires an already existing physical universe. Hence, it is more reasonable to hold that the cause is personal. Second, the cause is spaceless and immaterial. Plausibly, the only entities having such properties are minds and abstract objects. But abstract objects lack causal power. Thus, the cause is a mind. Third, the beginning of the universe is a temporal effect from a non-temporal cause. The cause is sufficient for its effect, which means that the effect would be eternal along with the cause, unless the cause has freedom of will and freely created the universe. Now, if there is free will, there is personal agency. Hence, we have a good reason for believing that the cause of the universe is a personal agent. In short, the cause is a mind who is timeless, non-spatial, immaterial, powerful, creative, and free. This is the theological significance of the kalam argument.
In Part Two, objections to the argument will be addressed.
 Kalam is an Arabic term which refers to the practice of philosophical theology. For a thorough discussion of the argument, see William Lane Craig and James D. Sinclair, “The Kalam Cosmological Argument,” in The Blackwell Companion to Natural Theology, (Wiley-Blackwell, 2012). See also William Lane Craig, Reasonable Faith, Third Edition, (Crossway, 2008), 111-156.
 To read the entire poem, see https://www.poetryfoundation.org/poems/48860/the-raven.
The tapping is not ex nihilo. The same point is made, mutatis mutandis, in a recent article at phys.org. On May 13, 2019, a team of scientists observed a flaring from Sagittarius A*, the black hole at the center of the Milky Way galaxy. The team has been observing the black hole for 20 years and has never seen a flaring like this one, which was 75 times brighter than normal. “The question is, what made Sgr. A* flare like this? At this point, astronomers aren’t certain what caused the flaring.” Notice that this question presupposes that there was a cause of the flaring. It was not a flaring ex nihilo. To read the article, see https://phys.org/news/2019-08-milky-black-hole-flared-bright.html. Again, the same point applies as follows: the ceiling in my home is developing a wet spot. We have had four different roofing companies investigate. They disagree on what the cause is. It might be a leak in the roof which allows rain water to drip through the attic onto our ceiling. Or it might be a leak in the A/C unit. Or maybe there is some other explanation. But everyone agrees that there is a cause of the wet spot! The wet spot did not appear ex nihilo. And each of the companies wants to be hired to find the cause and fix the problem!
 Roderick Chisholm, Person and Object: A Metaphysical Study, (Open Court, 1979), 15-18.
 This is a modification of David Hilbert’s story about the infinite hotel.