The Cosmological Argument

There are actually two forms of cosmological argument for God’s existence. Geisler calls these the “horizontal”  and “vertical” forms: the former being the way of the kalam school and the latter being the “ways” of Thomas, which have their roots in Aristotle. The vertical, he says, shows how the universe “continues to be” while the horizontal shows how it “came to be” [1]. In some ways, the cosmological argument is the simplest to grasp. There are profound complexities to be sure. It is at least the most picturesque.

Contrary to the popular misconception of fideists in the church, the conclusion to the proof does not leave us “light years” away from the God of Scripture. It is said that all that the argument does (at best) is to demonstrate a cause to the universe, but that this cause need not be a Personal-Infinite God. But this commits two basic errors. In the first place, not many of the more famous advocates of this argument have ever claimed that it tells us everything about God, or even a great many things. While God may be so much more than the First Cause, surely he is not less. Beyond that, it just so happens that the implications of such a First Cause might just be connected to our theology proper in more ways that we might think.

The Kalam Cosmological Argument

The kalam cosmological argument, so named after the medieval Muslim school of philosophy, was first articulated by al-Ghazali during the same years that Anselm was working out his ontological argument, and it has been refined by William Lane Craig in our own day. One advantage to the kalam cosmological argument is that it is the simplest to state. It has two premises and a conclusion.

1. Everything that begins to exist has a cause.

2. The universe began to exist.

∴ The universe has a cause.

Premise 1 is just the law of cause and effect. Not many would object to that. It is Premise 2 that will have to be defended. But there is another problem with it. The fact that the universe requires a cause does not seem to directly demonstrate that the Christian idea of God must be that cause. We will come back to this. For now we want to move on to the central idea behind this version of the cosmological form. This will explain why it must be the case that the universe began to exist.

The central idea of the kalam version is the impossibility of infinite regress. There are two basic reasons that an infinite regress in effects (or events) is impossible. The first reason is philosophical; and that means that this impossibility will be an absolute impossibility. The second reason is scientific; and that means that this impossibility will be a more contingent impossibility (that is, contingent upon all that we currently know about the physical universe through science). So, first to the philosophical. Another way to state the principle is that the infinite cannot be traversed, first of all, because an actually infinite sequence of things cannot exist [2]. This can be fairly complex, so we will only look at a summary. The term ‘actual infinite’ is a technical term, as in set theory in mathematics. When you or I conjure up the idea of an “infinite number” of things, what we really have in view is more correctly called a potential infinite: i. e. a set that is able to increase the number of its members, or an extension of a line in geometry. But by definition, this actual is not really “infinite,” and the potential is theoretically indefinite when applied to actual entities. Aristotle argued that the actual infinite is paradoxical. But an actually infinite set would be a set which is complete, to which not one more member could be added.

The German mathematician David Hilbert came up with a few illustrations to show why this concept is absurd. For our entertainment value, it is called “Hilbert’s Hotel.” We will let Craig tell the story,

Let us imagine a hotel … with an infinite number of rooms and suppose once more that all the rooms are full. There is not a single vacant room throughout the entire infinite hotel. Now suppose a new guest shows up, asking for a room. “But of course!” says the proprietor, and he immediately shifts the person in room #1 into room #2, the person in room #2 into room #3, the person in room #3 into room #4, and so on, out to infinity. As a result of these room changes, room #1 becomes vacant and the new guest gratefully checks in. But remember, before he arrived, all the rooms were full! Equally curious, according to the mathematicians, there are now no more persons in the hotel than there were before: the number is just infinite [3].

This rabbit hole into Wonderland gets deeper and deeper, because if an infinity of new customers shows up, the proprietor does it again, shifting the guy in room #2 into #4, #3 into #6, #4 into #8, and so on times two, making all the prior guests residing in even number rooms. And guess how greatly the number of paying customers increased? None at all! The process could be repeated an infinity of times and the result would never change. And the absurdities run the other way too. When one checks out, the number has not decreased. Now what is the takeaway? It can be perceived in the simple question: Can such a hotel exist in reality? And if not - why not? In the real world, Craig adds, “you cannot form an actually infinite collection of things by adding one member after another, because it would be impossible to get to infinity” [4]. Hold that thought when we come to some objections.

Now there is also a sufficient reason from science to reject the idea of an infinite series of events. Two developments in the past century and a half of cosmology have made a finite beginning to time and space an inevitable conclusion. I am speaking about the Big Bang Model and the Laws of Energy Conservation. Now if one is inclined to reject the Big Bang, very well; but for anyone who accepts it, it will come with a cost to their skepticism. I will not labor the point here since we are not studying scientific apologetics. One thing I will mention is that the empirical data that was so suggestive of that model during the 1920s was the outward expansion of the universe in all directions.

The Second Law of Thermodynamics is going to have the same effect and yet in a less controversial way. The principle of entropy - namely that all energy in a closed system passes in one direction: from heat to cold, order to disorder, from integration to disintegration - the upshot to this principle may be summarized in the words of C. S. Lewis: “If all of the energy in the universe is winding down, it would had to have at some point been ‘wound up.’” In other words, if the maximal state of order existed in an infinite past, then, in a closed system, the maximal state of disorder would have likewise occurred in the infinite past. The universe is not currently in a maximum state of disorder, which means that it is not eternal but had a beginning in the finite past. Only some sufficient cause, outside of the system, could be the source of its energy. 

When I taught philosophy to both high school and college students, I would use the same basic illustration to get things started. I would draw an incline and imagine myself holding a ball, ready to release that ball at the top of the incline. Each rotation of the ball down the incline would represent a moment, an event, or whatever. There’s only one catch. This incline is an infinite incline. And just to pull this off, I activated my “Go-go-Gadget Infinite-Arm” (anyone over age 40 will know what that is). Then I ask the class: “So, when do I release the ball?” And after a second of realizing I am not really trying to trick them, a chorus of hesitant voices chime in: Never? That’s right. The ball never gets released. If there were no first rotation of the ball, there could be no second; and if no second, no third, and so on—quite literally, ad infinitum. This is exactly the scenario with the first moment or event in the history of our universe. If there were no first moment, then there could be no intervening moments between that moment and ours. Thus our moment would have never arrived. But here we are.

The Aristotelian-Thomistic Cosmological Argument

Let us go right to the first two of Thomas Aquinas’ famous “Five Ways” to show God’s existence at the beginning of his Summa Theologica. Rather than examine the argument, word for word, we can summarize the First Way in the following eight-step argument.

1. Our senses show us that things are in motion.

2. Things move when potential motion becomes actual motion.

3. Only an actual motion can convert a potential motion into an actual motion.

4. Nothing can be at once in both actuality and potentiality in the same respect.

5. Therefore nothing can move itself.

6. Therefore each thing in motion is moved by something else.

7. The sequence of motion cannot extend ad infinitum.

∴ It is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God [5].

Now in Thomas’ Second Way, it may look as though he is saying the exact same thing, only using the language of “cause” rather than the language of “motion.” That is not quite the case.

1. We perceive a series of efficient causes of things in the world.

2. Nothing exists prior to itself.

3. Therefore nothing in the world is the efficient cause of itself.

4. If a previous efficient cause does not exist, neither does the effect.

5. Therefore if the first thing in a series does not exist, nothing in the series exists.

6. If the series of efficient causes extends ad infinitum into the past, then nothing would now exist.

7. That is plainly false (i.e., All things do exist).

8. Therefore efficient causes do not extend ad infinitum into the past.

∴ It is necessary to admit a first efficient cause, to which everyone gives the name of God [6].

It is crucial to note that the kind of infinite regress in the kalam argument and the kind in Thomas’ two arguments are actually different. Aquinas was operating off of the logic of Aristotle, who had made a similar argument in the fourth century B.C. But Aristotle, being a good Greek, had to believe that the material universe has always been there. So in this way of thinking, there cannot be an infinite regress even if there was never a time when time and space were not. Now don’t misunderstand: Thomas did not agree with Aristotle about the universe being eternal. What we need to see is that even if the universe was eternal, one would still have to account for a First Cause for all motion and effects. Why is that? Edward Feser, who is the most interesting Thomist in our day, answers this question in the following way:

Aquinas is not saying that if you trace the series of movers back in time you must eventually get to some temporally first mover … [rather] the immediate cause of an effect is simultaneous with that effect … [so] he doesn’t mean first in order of time, but rather first in the sense of being most fundamental in the order of what exists [7].

Craig recognizes this, saying that the “Thomist cosmological argument is based on the impossibility of an infinite regress of simultaneously operating causes” [8]. Now there is a very good reason behind even this. The force of the argument is that there must be something outside of the series of instrumental causes [9]. All of this really depends on grasping some basic concepts of Aristotle’s metaphysics. At its heart is the notion of act and potency. Again, act is the perfection of being, whereas potency is its capacity toward that end. Motion is the “reduction” of potential to act. But of course this requires some substance already in act in order to actualize that which is merely potential. 

So another way to put Thomas’ logic is this: “that the things of our experience, which are mixtures of actuality and potentiality, could not exist even for a moment apart from a cause that is pure actuality. Only something whose existence is always already actual, and thus need not and could not be actualized by anything else, could terminate what would otherwise be a vicious explanatory regress” [10]. As one last way to put it, Feser says of composite and contingent things, “Even if the thing had no temporally prior cause, it would still require an ontologically prior cause” [11]. Notice that this conclusion tells us quite a bit about this Prime Mover or First Cause. The logic already demands that this is a being in Pure Act, being in no way potential. This is going to suggest immediate implications about immutability and impassibility, just to name a few attributes. 

Objections and Evaluations

The earliest and most enduring objection among modern thinkers was leveled by David Hume. Many of his critics have thought that Hume was denying causality. Actually what he was denying was that we can know the precise cause (or matrix of causes) behind any particular effect. We only observe the surface of motion and change. But “there is not, in any single, particular instance of cause and effect, anything which can suggest the idea of power or necessary connection” [12]. Now what was Hume trying to do here? This is to break the chains of any causal connection between the present universe and God. The logic is simple: We can discern the particular cause of a particular effect only if the necessary causal connection is discernible. No necessary causal connections are discernible. Therefore no particular cause of a particular effect can be established of necessity.  

A quick rebuke to Mr. Hume: First, if no intellectual capacities are reliable to discern the nature of particular causes, then it is not only theology, but science, that falls with it; Second, if naturalism is true, then all human thoughts are nothing but cause and effect, and that means that all logical relationships are mere causes and effects.

But do you see what follows? If we cannot know their precise relations (which relation is logically the ground of the other), then the truth of every single statement would be undermined. We will come back to this in the epistemological argument. But for both reasons then, the argument against knowing specific causes is self-refuting. The very logic of the argument (and all others based upon it) depends on knowing its own specific cause.

The most serious objection to the kalam cosmological argument in my opinion is the challenge to the idea that an infinite regress is impossible. I say this is a more serious objection only because the category mistake is easy to make. And when a mathematician like Bertrand Russell makes the objection, it can seem very formidable. What he did was to object that, “the series of negative integers ending with minus one is an instance to the contrary” [13]. But there is a fundamental difference between substances as represented by numeric values as opposed to mathematical entities, whatever ontological status we assign to them. And presumably a materialist like Russell would not prefer to assign to much being to any metaphysical essences! A series of integers can never be “instances” of anything other than mathematical entities, anymore than a triangle could be “an instance” of the Trinity or even of a slice of pizza.

Another British philosopher, J. L. Mackie, argued that the same principle of infinite regress ought to be applied to God: “If God exists for an infinite duration of time, and if an infinite regress of events is impossible, then it follows that such an everlasting being could not exist” [14]. But this only works against theistic philosophers who define God’s eternity as units of time rather than transcending time altogether. But that is not the God of Scripture. He is “eternal” (1 Tim. 1:17). God’s decrees are “before the ages began” (2 Tim. 1:9, cf. Ti. 1:2). Answering this objection is where Craig is the weakest as he does believe that although God is timeless prior to creation, he is in time subsequent to creation [15]. It is sufficient to say that since God is one, and not composed of parts, that the problem with an infinite set of things never arises. Only with an infinite series of things is there a contradiction.

Now a confluence of postmodern thinking and quantum physics has also given to us a kind of monster-combination of those first few objections. In its simplest form we might hear: “This idea of causality and regress only applies to the realm of causality: namely the physical universe. But beyond the cosmos, the principles of causality do not apply.”

Now aside from being a very bold claim, this objection is as misguided about the idea of causality as we saw about the Mill-Russell “brain gas” earlier. In logic, we call this the fallacy of begging the question. Whether there is metaphysical cause or only physical cause is precisely what the theist and atheist are debating; and so we cannot rationally settle that question by assuming either answer up front. Rather one or the other is going to have to be established as the conclusion to an argument. We have to keep before our minds that causality is first metaphysical, and only secondarily physical. This truth may be cashed out in terms of Feser’s Thomistic distinction between a “causal series ordered per accidens” versus a “causal series ordered per se” [16]. The former is temporal and extended through space-time, while the latter is hierarchical with members capable of acting simultaneously.

Another more clever objection is to try to turn Aristotle on his head. The skeptic could say: such a being of pure actuality must undergo change in the act itself. At one time the effect did not exist, and then the cause brought it about. The cause did something different than it previously did. At any rate, the change itself implies at least some potentiality in need of being actualized. Thus the idea of purely actual being is incoherent. But this is both a non-sequitur and a begging of the question. Simply because in our experience of moving things, there is change, it does not follow that this is the only kind. Whether it is or not begs the very question we are debating. The critic needs to establish an essential connection between (a) being an actualizer and (b) being a mixture of act and potency. He has not and, it would seem, cannot do so. Aside from change, this objection also assumes that pure actuality implies sequence, since (in all other cases), action implies sequence. But, again, whether this case (pure actuality) is of the same sequential nature as “all other cases” (all other acts) is precisely the question, and so, yes, once again we are begging the question and not establishing anything. 

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1. Norman Geisler, Baker Encyclopedia of Christian Apologetics (Grand Rapids: Baker, 1999), 160.

2. This too Craig reduces to a three-step argument: “1. An actually infinite number of things cannot exist. 2. A beginningless series of events in time entails an actually infinite number of things. 3. Therefore, a beginningless series of events in time cannot exist” (Reasonable Faith. 94).

3. William Lane Craig, Reasonable Faith (Wheaton, IL: Crossway, 1994), 95

4. Craig, Reasonable Faith. 98

5. Aquinas. Summa Theologica. Pt. I. Q.2. Art.3

6. Aquinas. Summa Theologica. Pt. I. Q.2. Art.3

7. Ed Feser, Aquinas: A Beginner’s Guide (Oxford: Oneworld Publications, 2009), 69. italics mine.

8. Craig. Reasonable Faith, 80.

9. Feser. Five Proofs of the Existence of God (San Francisco: Ignatius, 2017), 65.

10. Feser. Five Proofs, 184.

11. Feser. Five Proofs, 185.

12. David Hume, An Enquiry Concerning Human Understanding (Indianapolis: Hackett Publishing,1993), 41.

13. Bertrand Russell, A History of Western Philosophy (New York: Touchstone, 1972), 462.

14. J. L. Mackie, The Miracle of Theism (Oxford: Clarendon, 1982), 94.

15. Craig. Reasonable Faith, 94.

16. Feser, Aquinas: A Beginner’s Guide, 71.