The Kalam Cosmological Argument: A Brief Overview

In a previous post, I have discussed the intuition behind cosmological arguments and gave several examples. One of these examples was the Kalam cosmological argument. By way of overview, a cosmological argument is, broadly speaking, one that reasons from facts about the universe we observe and metaphysical principles to argue that God, or at least a being very much like God, must exist. The Kalam cosmological argument lies on the nature of causes, beginnings, and both philosophical and physical angles on these two ideas. I would now like to expound my favorite formulation of the Kalam cosmological argument and provide a rough sketch of how to justify the key steps in the argument.

The Argument

The Kalam cosmological argument comes in two stages. Stage one is a deductive argument in the modus ponens form:

  1. Whatever begins to exist has a cause.
  2. The universe began to exist.
  3. Therefore, the universe has a cause.

To be clear on definitions, when we say universe, we mean something like “everything that consists of space, time, matter, or energy” or “everything that can be described in some way by physics.” So if you think there is a multiverse out there, that counts as “the universe” here. We could also replace (1) with “If the universe began to exist, then the universe has a cause” since that would be sufficient to imply (3), but there are compelling reasons to believe (1) in this form, and so we will stick with this. Finally, by “cause” we mean what Aristotle called an efficient cause. An efficient cause is roughly the source of an event. For example, if you have a painting, there is one sense in which the particles in the paint can be said to cause the painting. But this is not what we mean by cause here. The efficient cause of the painting is the painter. The efficient cause of a newborn baby is the baby’s parents, not the atoms that make up its body. The efficient cause of a book is the author, not the paper it is printed on. This is the sort of cause-effect relationship we are talking about here.

Now, if stage one is successful, we now know that the universe has a cause. We now enter stage two – understanding what this cause is like. It might seem like we can’t find anything out, but knowing that something is the cause of the universe may imply certain features about that being. For example, we the cause of a particular book must know how to speak the language the book was written in, and based on experience we know that cause is probably an adult human being. We can also learn more about the author from the contents of the book – if the book is about science, then maybe they are a scientist. This sort of reasoning will make up the second stage of the Kalam cosmological argument.

Stage 1: The Deductive Portion

The first stage of the Kalam cosmological argument involves the deductive steps listed above. Premise 1 says that whatever begins to exist has a cause, Premise 2 then tells us that the universe began to exist, and so we conclude that the universe must have had a cause. In order to check the correctness of the first stage, we should convince ourselves of whether or not the two premises are true, and whether the conclusion logically follows from the premises. These three aspects we need to check are discussed in order.

Premise 1: Whatever Begins to Exist Has a Cause

This premise is the less controversial of the two on the level of philosophy. There are a wide variety of evidences for the truth of the statement “Whatever begins to exist has a cause.” We now consider a few of them

Evidence 1: Our common experience always verifies and never contradicts this statement. If we see a chair, well we know someone made that chair. If we see a person, we know that person has parents. If we see writing on a wall, we know someone wrote it. When we see a social movement begin, we know that certain people began it. Things don’t start for no reason in our common experience – when something starts, there is always a reason why.

Evidence 2: The scientific method presupposes the truth of this. In particular, when we do science, we assume that events we can observe actually do have explanations for why and how they happen. Science is the search for those explanations. By assuming in advance that there is such an explanation, we are assuming that things that begin have causes. When the apple falls from the tree, the beginning of the fall, and in fact the entire process of the fall, must have some sort of cause – which we now call gravity. This is again and again the approach of science.

Evidence 3: Suppose this is actually false – that would mean that certain things can spring into existence for absolutely no reason. If that is so, there is nothing to prevent this from happening all the time, everywhere, with any sort of object. If certain things can arise from absolutely nothing, then it seems like anything and everything could arise this way – after all, nothingness can’t tell the difference! So if this really were possible, why don’t we see horses and villages and basketballs constantly appearing in our homes and workplaces from nothing? The obvious answer would be that things always begin to exist for some reason, and there is no reason or cause why a horse should appear from the void next to you while you read this.

In summary, we find that universal human experience constantly affirms Premise 1. If Premise 1 were false, lots of strange things should be expected to happen and we would have to throw out the entire scientific enterprise. So, it doesn’t make a lot of sense to deny Premise 1.

Premise 2: The Universe Began to Exist

This is more controversial. How could we possibly know that the universe began to exist? We run the danger of potentially begging the question here – we can’t appeal to the Bible or Qur’an for instance because the truth of those accounts would rely on God’s existence, which is the truth we are trying to establish. So, we can’t rely on that sort of argument. How, then, might we argue for this perhaps very odd sounding idea that the universe is only finitely old?

There are in fact several ways we can do this. I will go through six – three that come from the area of philosophy called metaphysics, and three that come from contemporary science. The three metaphysical arguments all attempt to show that the idea of an infinitely long past doesn’t make sense given other things we know. The scientific points reason from a scientific fact we know to the conclusion that the universe must have had a beginning in time.

Evidence 1: In mathematics, the abstract concept of a really infinite number of things is well-understood. We know what it would be like for a really infinite number of things to exist – and it completely confounds all intuition. The thought experiment called Hilbert’s Hotel illustrates very well the problems that arise. In later discussions about the Kalam, I will go more deeply into this paradox, but for now let’s look at just one problem we run into. Imagine that a hotel exists with infinitely many rooms with room numbers 1, 2, 3, 4, and so on, and that this hotel is completely full at the moment. If a new guest shows up, then the hotel can actually still accommodate that guest, even though the hotel is full! For if we move the person in room 1 to room 2, the person in room 2 to room 3, and so on forever, then nobody was kicked out of the hotel, and yet room 1 is now available! This is a rather odd consequence which defies the way we know the physical world ought to work. So, it would be entirely reasonable to say this kind of situation cannot happen.

Then, because really existing infinities don’t make any sense, and an infinite past would be a really existing infinity, then an infinite past makes no sense.

Evidence 2: Maybe you are willing to bite the bullet on the oddities that arise from actually existing infinities. But there are additional problems, since an infinite past is more than just actually existing infinity – it is an actually infinite sequence in time. In order for the past to be infinite, that would have to mean that, by traversing from one moment to the next, we have crossed over an infinite amount of time. But this is extremely problematic – this is like counting to infinity. How could you ever end? To see the problem, imagine that a man has existed forever and he has always been counting down towards zero. You walk up to him today, and find him count 5, 4, 3, 2, 1, 0. Finally, he is done with his count.

But hold on – why did he finish today? Why not yesterday? After all, an infinite amount of time had already passed yesterday, and an infinite amount of time is enough to count down from infinity. Why did he not finish two thousand years ago? Two million years ago? The same reasoning still applies. It appears to be completely inexplicable why our infinitely old man should finish his count on any particular day. But, as we’ve already discussed, there should really be a reason why he finishes on one day rather than another. Therefore, it makes the most sense to say that, even if a real infinite can exist, you can’t build one by successively adding one thing after another to it. Since an infinite past would be infinite in virtue of moments being added to time one after another, this rules out an infinite past.

Evidence 3: This is similar to, but not quite the same as, the second piece of evidence. The previous piece of evidence states that you can’t arrive at infinity by proceeding one step at a time, so to speak. This piece of evidence, instead of thinking of the forwards direction, views the backwards direction. It is quite commonly believed that infinite regresses are bad. If you start asking “Why?” over and over again, you should eventually reach a sort of bedrock answer that doesn’t require any further explanation. But if this is so, then we can ask “Why?” successively about the status of the universe – and if such sequences of cause-and-effect questions must always reach an end (so that we don’t have an infinite regress), then the events in the universe must all trace back to a single point – the beginning of the universe.

We have now covered some philosophical evidence that points out major conceptual difficulties in the idea of an infinite past. We now move forward to scientific difficulties with the idea of an infinite past.

Evidence 4: Edwin Hubble is famous for discovering what is called Hubble’s Law, which says that galaxies are moving away from our galaxy at rates proportional to their distance from us. Hubble was able to reach this conclusion by looking at the red shift of these galaxies, which is a measure of how the speed of those galaxies relative to ours slightly stretches out the light waves via the Doppler effect (think of the sound of a fast-moving car before and after it passes by you). The explanation for this observation is that the universe is expanding in all directions, analogously to a balloon being inflated. Physicists have since accumulated a body of evidence, including theorems by such esteemed physicists as Stephen Hawking and Roger Penrose, that lead very directly to the conclusion that a finite amount of time ago, the universe was infinitely small and sprang into existence in “the Big Bang.” This, of course, would mean that the universe as we know it began to exist. Even if you hold to an inflationary multiverse theory, as many do, a theorem by Vilenkin and others effectively rules out an infinite past for multiverses as well.

Evidence 5: The Big Bang theory predicts that the universe started off in a fireball. If this were so, there should be some leftover radiation from that fireball spread more or less uniformly throughout the entire universe. This leftover radiation, now called the cosmic background radiation, has been discovered and measured to high degrees of accuracy and found to match exactly the standard Big Bang theory, which of course tells us that the universe began to exist.

Evidence 6: One of the most foundational and best established scientific laws of all time is the Second Law of Thermodynamics. Intuitively, the second law tells us that over time, disorder increases. This is exemplified in the wear-and-tear on human structures as well as erosion in natural structures, as well as the aging process for all animals. Things break down over time – this is the second law. Now, if the universe has existed for infinitely long, then shouldn’t there be, so to speak, as much disorder as possible? An infinite amount of time should, if the second law is true, destroy all order and leave the entire universe in a state of complete disorder. We are obviously not in that condition at the moment – a state of complete disorder is embodied by the emptiness of outer space, and there is certainly a lot of order and organization of the universe into galaxies, solar systems, and so on – all of which don’t exist in a totally disordered condition. Therefore, the second law of thermodynamics would then predict that the reason things like planets, stars, and human beings still exist is because there has only been a finite amount of time for the universe to run down, and there is still enough order left for us to exist.

By way of summary, we have the following six pieces of evidence for Premise 2:

  • 1: It doesn’t seem like an infinity of things can really exist.
  • 2: You can’t actually form an infinite by adding on things one after another.
  • 3: Infinite regresses of cause and effect are impossible.
  • 4: The expansion of the universe points to a Big Bang event.
  • 5: The cosmic background radiation points to a primeval fireball, and thus to a Big-Bang event.
  • 6: Matter always becomes disordered over time, and since we are not yet at maximum disorder, it must be that the universe has only had a finite amount of time to move from order to disorder.

To me, this is a strong case – at least strong enough to suspect that probably the universe began to exist. Perhaps you don’t think this is totally conclusive – but remember, it doesn’t have to be 100% beyond-any-possible-doubt proof in order to be accepted. If the evidence is convincing enough to conclude that it is more likely than not Premise 2 is true, then it is completely reasonable then to accept Premise 2 as true. You might, of course, revise that decision later or come to believe it even more firmly as you obtain more and more evidence – that is to be expected. But with this body of evidence, I think it is quite reasonable to conclude that the universe did, in fact, begin to exist.

A Brief Remark: Note that I am not here trying to prove anything, say, about the book of Genesis, or the creation accounts in the Qur’an, or any other religious tradition. The claim that the universe began to exist can be evaluated independently of any religious tradition, and that is what we have done here. Whether or not Genesis or the Qur’an tell the right story would be a completely separate discussion.

Premise 3: The Universe Has a Cause

There isn’t much to this point. The final premise is a deductive conclusion from the first two via the logical rule of modus ponens. This rule states that if we know “if A, then B” and if we also know A, then we know B. There may be a bit of confusion seeing the fact that Premise 1 in our argument is actually of the form “if A, then B”. If this is difficult, then rephrase Premise 1 as “if a thing begins to exist, then that thing has a cause.” If we know Premise 2, that the univese began to exist, then the universe is one of the thing that Premise 1 would tell us must have a cause. This makes the Kalam cosmological argument deductively valid.

Therefore, if we know both Premise 1 and Premise 2, we must accept that the universe has a cause.

Stage 2: The Role of God

But what sort of cause does the universe have? This is the goal of stage 2 of the Kalam cosmological argument. If we know that the universe must have had a cause, what sort of thing could have caused the whole physical universe to spring into existence? Perhaps the idea of “a cause of the universe” seems rather abstruse and hard to grasp, but we can actually do some conceptual analysis and begin to get a grip on what such a cause must be.

How is this so? Well, to begin recall what we mean by universe – we mean by that everything that depends on time, space, matter, and energy for its existence. This means that whatever our cause of the universe is, that being must have caused everything inside spacetime to exist. This means this being itself cannot be made up of that sort of thing – the source of all space, for example, cannot be spatial. That would mean that space is the source of all space, which would mean that space existed before space… which doesn’t make a lot of sense. So it seems only logical to conclude that whatever created the universe must exist beyond space.

For a similar reason, this being must exist beyond time (or in the very least must exist beyond time “prior” to creating time). This is for the same reason as before – the source of all time cannot be temporal, for there wasn’t any time yet, so to speak. So, our cause must be timeless. For again the same reason, our cause must be immaterial – the cause of all material cannot be material itself.

Another rather straightforward point is that whatever caused the universe must have enough power to cause universes. I think it is rather obvious that this is quite a lot of power – certainly no living human being has that sort of power – and so I think it is fair to say that the cause of the universe must be extraordinarily powerful.

So far, we’ve arrived at a “cause of the universe” that exists beyond all space, time, and matter, and possesses an almost incomprehensible amount of power. That sounds somewhat like the idea of God – after all, God is understood by all major religions to exhibit such qualities. But it would be a quite fair point to say that this is not yet a convincing argument – because an extremely important idea about God is yet to be seen. God, as viewed by all major religious groups I know of, is personal – for our purposes, by that I mean that God has the ability to choose one thing over another. For the sake of simplicity, let’s call all of this free will – after all, that’s what mostly how we think of free will – as the ability to choose.

Much can be said for why the cause must be personal. By way of summary, I will make only one point. We already know the cause of the universe has always existed. Now, if a mechanistic process has existed forever, you’d expect the product of that mechanistic process to also exist forever. Since the universe hasn’t existed forever, but the cause has existed forever, the cause of the universe can’t be mechanistic. When we then slow down and think about what kinds of cause-and-effect processes exist that are not mechanistic and do not depend on a preexisting material universe (since, remember, the universe does not create itself), the only solution I’ve ever heard that works is that the cause must be the free will of an immaterial mind. Free will clearly allows for something that has always existed to produce a cause that begins to exist. So, it makes a lot of sense that the cause of the universe can truly be said to be a Creator of the universe.


A lot of details have been skimmed over, but this ought to serve as a good jumping off point for thinking about the Kalam cosmological argument in greater detail. In future posts on the blog, I will go into the various points of the argument in much greater detail and provide lots of academic resources from both sides of the discussion on this very interesting argument. But for now, I hope I have given a general idea of why this argument has caught the attention and interest of so many people.

One thought on “The Kalam Cosmological Argument: A Brief Overview

  1. Greetings, from my notes, your Premise 2 Evidence 2 is incoherent.

    3. Infinity as a Number

    There are situations in which it is legitimate to use infinity as a number. But there is no situation in which it is legitimate to assign infinity a numerical value.

    a. In count-up to infinity, “finite” + 1 = “finite”
    b. In count-up to infinity, infinity is never reached.
    c. In count-down from infinity, “infinity” – 1 = “infinity”
    d. In count-down from infinity, zero is never reached.
    e. In count-down from infinity, the corresponding/parallel count-up is always finite: infinity can never be reached.


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