How the Universe Points to God: a summary of two cosmological arguments

The Cosmological Argument is really a family of arguments which reason from the existence of the Universe, or some fact of the Universe, to God’s existence. The word is from the Greek words kosmos, meaning “world”, and logos, meaning “knowledge” or “science”. As the late apologist Norm Geisler explained, cosmological arguments come in two varieties: vertical cosmological arguments, which reason back from the beginning of the Universe to God’s existence, and horizontal cosmological arguments, which reason from the Universe as it now exists to God’s existence. [1] This article is only meant as a brief introduction, but I will include one of each kind of argument in this article.

Like the Moral Argument, the Teleological Argument, and the Ontological Argument, there are many formulations of the Cosmological Argument. William Lane Craig is probably the most well-known apologist associated with this approach, as well as one of the best known defenders of Christianity, at least among philosophers. The vertical version of the argument I’ll summarise here is the Kalam Cosmological Argument, which Craig defends but was first formulated by a Muslim philosopher. The horizontal version I’ll expound  was originally formulated by ancient Greek philosopher Aristotle, but was defended and updated by medieval Christian philosopher Thomas Aquinas, and is defended by many modern philosophers such as Edward Feser and David Oderberg.

Read more:

Why does the Universe exist and why should we care?

Why Dawkins & Collins need God for our “hole-in-one” universe

John Lennox: The case for design in biology and the Universe

Roger Penrose can’t escape an ultimate explanation for the universe

The Kalam Cosmological Argument

One of the earliest forms of the argument comes from Islamic philosopher Al-Ghazali. Dr Craig’s argument is:

Premise 1: Whatever begins to exist has a cause of its existence.

Premise 2: The Universe began to exist.

Therefore,

The Universe had a cause of its existence.

To defend the first premise, Al-Ghazali argued whatever begins to exist does so at a specific point in time. But before that thing comes to exist, all moments are alike. So there must be some cause which determines the thing comes to exist at that time, and not any time prior or later. Hence, anything that begins to exist must have a cause of its existence. [2] Craig adds this premise is rooted in the metaphysical intuition that things don’t simply pop into existence from nothing on their own. You don’t have to worry about a bear suddenly coming into existence and threatening you as you’re walking down the road. So the premise just seems to be obviously true, at least when you consider the opposite. Another argument Craig gives is if we accept that one thing, such as the Universe, can come into existence uncaused from nothing, there is no reason why anything and everything could not also do the same.

Finally, this premise is constantly confirmed by our everyday experience. [3]

In the early 20th Century, evidence for a Big Bang event, in which all time, matter, and energy began, was discovered. This gave scientists and philosophers very strong evidence that the Universe had a beginning, rather than existing eternally as many scientists and philosophers had believed prior to that. As Al-Ghazali lived in the 11th and 12th centuries, he existed long before this scientific evidence came to light.

Consequently, Al-Ghazali’s defence of the second premise was purely philosophical. These arguments, as outlined in Craig’s Reasonable Faith, are: 

1) The series of events in the past stops with today, but an infinite number of events are never ending. Since the series of past events ended today, the series of past events cannot be eternal. Furthermore, an infinite span is impossible to cross. If the series of past events were eternal, we could never reach today. Yet here we are!

2) If the series of past events were eternal, then we would have infinities of different sizes. For example, the planets orbit at different distances from the sun and hence take more or less time to orbit around it. If we have an infinite series of past events, the planets would have orbited the sun an infinite number of times and also would have orbited the sun different amounts of times (e.g. Jupiter would have completed twice as many orbits as Saturn). But this is absurd. Furthermore, it would make sense to ask whether the orbit of each planet happened an even or odd amount of times. But an infinite amount of times cannot be odd or even. [4]

Dr Craig presents more detail for his second premise that are fairly technical and can be found in his book. I will now summarise the two scientific arguments he presents which provide empirical evidence the Universe had a beginning.

His first scientific argument is regarding the expansion of the Universe. Scientists used to believe, prior to the 1920’s, the Universe was stationary and eternal. Astronomers and astrophysicists, such as Albert Einstein and Edwin Hubble, discovered the Universe is expanding. As celestial bodies are moving away from each other, this shows the Universe once had a beginning and has been expanding outward ever since. [5]

His second scientific argument regards the Second Law of Thermodynamics, which states that in a closed system (nothing exists outside of it) processes always tend toward equilibrium. What this means is if energy is not being constantly fed into a system, the processes inside that system will tend to run down and quit. Scientists have predicted the Universe will eventually reach equilibrium and end in a “heat death”. If the Universe were eternal, this state would have been reached already. The fact it has not shows the Universe has not always existed. [6]

The argument from motion

Now we turn to another kind of cosmological argument and the work of Thomas Aquinas, who wrote a series of books called Summa Theologica. In this book he briefly outlined five ways we can know God exists. Two of these ways could possibly be considered cosmological arguments, but I’m going to just look at the first way, the Argument from Motion.

Aristotle is one of the first philosophers to construct this argument. Thomas Aquinas’ formulation is perhaps the most famous. Norm Geisler summarised the argument as follows:

1. Things move. Motion is the most obvious form of change.

2. Change is a passing from potency to act (I.e. from potentiality to actuality).

3. Nothing passes from potency to act except by something that is in actuality, for it is impossible for a potentiality to actualise itself.

4. There cannot be an infinite regress of actualisers or movers. If there is no First Mover, there can be no subsequent motion, since all subsequent motion depends on prior movers for its motion.

5. Therefore, there must be a first, Unmoved Mover, a pure actualiser with no potentiality in it that is unactualised.

6. Everyone understands this to be God. [7]

Once again, this argument does not depend on the Universe having a beginning. Early Christians didn’t know if the Universe was eternal or began at some point. Genesis 1 says the Universe had a beginning, but the Bible is also not a science book. It’s possible God used figurative language to explain the creation of the Universe. So this argument works even if the Universe is eternal. It’s important to note when we speak of the beginning of a chain of causes, we are speaking causally, not temporally, prior. Sometimes an example of a golf club is used. When you move a golf club, several things must occur. Your brain tells your arm to move, your muscles contract, your arm swings backward, and the club goes along with it. This all happens simultaneously but there is still a causal chain of events that occur. Your brain telling your arm to move happened at the beginning of this chain. This is the sense in which certain events have priority over others.

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The argument is called the Argument from Motion, but “movement” in the Aristotelian sense is a change from potential to actual. This can include locomotion but doesn’t always. If you are sitting, when you stand you have actualised your potential to be standing. When you strike a match, you have actualised the match’s potential to catch on fire. These acts are movement, according to the terms used.

The argument can get pretty complicated but I’m going to keep things simple. There are several types of potentiality, for example, but these distinctions are not important for a basic defence of the argument.

Premise one is obvious. You can prove it by simple observation. Premise two is definitional, letting the reader know what is meant by “movement”.

Premise three is easy to show. A match has the potential to light on fire, but it won’t light on fire by itself. It must be acted upon by something outside itself to actualise its potential. In this case, it requires someone who knows how to light a match to strike it and then use it. But one might think, what about living things? Living things can perform tasks in themselves, such as the sitting person who stands. But if we think about it, what is involved in standing up? Well, my legs have to extend and push me upward. But what must happen before that? My muscles have to contract. But what must happen before that? My brain has to tell the muscles to contract, etc. So the potential for my legs to extend and cause me to stand has to be actualised by forces outside of itself to work, namely my muscles contracting and my brain telling my body what to do.

For premise four, as whatever moves must have its potential acted upon from outside it, there must be a beginning at the chain of causes. Otherwise, nothing would explain why anything at all moves, and this motion would be impossible since nothing could be actualising its own potential to move.

For premise five, this means that there must be something at the beginning of the causal chain that has no potential whatsoever and is pure actuality. This concept can be difficult to wrap your mind around but it is implied necessarily by the argument. If the prior premises are correct, then this conclusion follows necessarily, whether or not it is easy to understand. And as premise six states, this is what we call God.

As I said, it can be difficult to understand what exactly it means to be “pure act”. Explaining that it simply means there is no potential in this thing to actualise doesn’t exactly make it easier to grasp. But I can say this entity being pure act with no potency actually helps explain philosophically many things Christians believe about God. Here are just two:

1) God is immaterial. Material things have potency (there are always things that could be done to it, such as melting it), so for something to lack potency it must be completely immaterial.

2) God never changes. Something that actualises a potential changes in some way. But Christians believe that God never does (e.g. see James 1:17). 

The heavens declare the glory of God

To reiterate, the cosmological argument argues from the existence of the Universe to God. The Kalam Cosmological Argument doesn’t establish God’s existence but merely that the Universe began to exist. It is one link in a chain of arguments for God’s existence. The Argument from Motion can more properly be said to argue for the existence of God. The Kalam argument argues from the Universe’s beginning and the Argument from Motion doesn’t need the Universe to have a beginning to be successful.

Pointing to the existence of the Universe to God can provide powerful evidence for God’s existence. We cannot see God but we can see his handiwork throughout Creation. If God created the heavens and the Earth, as Scripture tells us he did, then he will certainly have left evidence of his work behind.

[1] Norman L Geisler, Baker Encyclopedia of Christian Apologetics, Baker Books, Grand Rapids, MI, 2000, p. 160.

[2] William Lane Craig, Reasonable Faith, Crossway, Wheaton, IL, 2008, pp. 96.

[3] Ibid., pp. 111-112.

[4] Ibid., pp. 96-97.

[5] Ibid., pp. 125-140.

[6] Ibid., pp. 140-150

[7] Geisler, op. cit., 161-162.

Clinton Wilcox is a staff apologist for Life Training Institute. He specializes in training pro-life people to make the pro-life case more effectively and persuasively. He is also a certified speaker and mentor for Justice for All. You can read his blog and follow him on Twitter.