Arguments for the existence of God

An argument for the existence of God begins with a premise upon which most people agree and moves logically through a series of steps until the conclusion is reached that God exists.

In this post, I briefly sketch two kinds of arguments for the existence of God. My treatments are as brief as I can make them, and they leave out as much technical jargon as possible. My intention is not to provide an in-depth assessment of any of them. Rather, it is to provide you with some of the strategies that philosophers have employed in defense of theism.

Ontological Arguments

Ontological arguments attempt to show that God exists from premises reliant for their support solely from intellectual reflection. Its premises rely solely on the contents of our thoughts. We don’t have to check our experiences to support them.

I am using an adapted version of the argument from Murray and Rea, An Introduction to the Philosophy of Religion, 126. This is their interpretation of Anselm’s original argument. It should also be noted that there are advanced forms of the argument that go far beyond what I’m going to offer. Space does not allow for any detailed exposition. However, it will be enough to grasp the basic contours of the argument.

First introduced by Anslem (1033 – 1109), the basic idea of the ontological argument is that if we fully grasp the concept of God, we will conclude that he exists. This sounds strange at first. How can it be that merely by thinking about something that we could prove its existence? Surely, I could think about a unicorn all day but not conclude that unicorns exist. True, but the concept of God is not like the concept of unicorn.

According to Anselm, the concept of God includes the concept of ‘greater than which cannot be conceived.’ Just by thinking about the concept of God, we are thinking about the greatest possible being, a being with maximally great-making properties. If we think that he is good, powerful, knowledgeable, and present, then he is these things to the max. He is without evil, all-powerful, all-knowing, and omni-present. He is the perfect being. Thus, we have the first premise:

• God is the greatest conceivable being

(1) is highly plausible. As soon as we consider what we mean by ‘God’ we are led to his maximal perfections.

So far this is an analysis of the concept of God. It says nothing about his existence. It is merely an attempt to describe his essential nature, what must be true of God if he exists. However, it follows from the concept of God that anything that could make him great, he must possess. So, the following must be true:

• If God is the greatest conceivable being, then he possesses anything that would make him great.

But now we might wonder what we could have left off the list of great-making properties. We have omniscience, omnibenevolence, omnipresence, and many other great making properties. But one thing we have not yet considered is existence. You and I have it. We both exist. But does God possess such a property? Surely existence is a great-making property. It is better to have it than not. If so, then it follows that God must possess existence in addition to omniscience and all the other great-making properties. Thus, the following must be true:

• If God must possess anything that would make him great, then he possesses existence.

To deny (3) is to misunderstand the concept of God and since we’ve already agreed that God is the greatest possible being (in the first premise), the conclusion follows:

• God possesses existence (or God exits)

Unsurprisingly, the argument has undergone rigorous criticism. The first critic, Gaunilo, argued that one could think other objects into existence by using the same process. Gaunilo invited the reader to consider a lost island. The island is no ordinary island. It is the greatest possible island. Surely, Gaunilo contended, the greatest possible island must possess existence. Thus, the greatest possible island must exist.

Gaunilo fails to notice that, unlike God, we can always conceive of better islands. Islands are made great by things like beaches, sunshine, food and alike. But there is no clear maximally great set of trees, amount of sun, or restaurant menu. Thus, it is not true that we can conceive of the greatest possible island. In contrast, we can conceive of the maximality of the great-making perfections of the greatest conceivable being. Thus, Gaunilo’s objection fails.

A second and more powerful objection was proposed by Immanuel Kant. Kant objected to the assumption that existence is a property. Instead, when we attribute a property to something, we presuppose the existence of the thing. So, possession of existence is not possible. Something either does exist, or it doesn’t, but there is no sense to something either possessing existence or not. Thus, thought Kant, the argument can’t work.

In reply, Murray and Rea argue that existence is a property. They suggest that we assume so in much of our ordinary language. We say of many objects that they exist. In doing so we attribute the property of existence to a thing. Since there is no obvious contradiction produced when doing so, existence is a property. Further, they argue that preconditions for possessing one property can also be themselves properties. If something is red, then it must take up space (taking up space is a precondition for being red). But taking up space is also a property. Thus, just because existence is a presupposed of anything that bears a property, it doesn’t follow that existence isn’t itself a property.

In sum, ontological arguments deploy our analysis of the concept of God to generate premises that imply that God exists.

Cosmological Arguments

In contrast with ontological arguments, most arguments for the existence of God do not begin with a premise that is necessarily true such as an analytic statement or an a priori truth. Instead, they begin with a contingent truth, a truth that could have been false. Cosmological arguments begin with truths about the universe (the cosmos). They might begin with its existence, or its intelligibility, or with its beginning. The argument then goes on to show that the existence, intelligibility, or beginning implies that God exists. All of them assume that for every contingent truth, there is an explanation.

For simplicity, I am going to expound two cosmological arguments. The first is a simplified version of what you might find in Aristotle and in some arguments given by Thomas Aquinas. I have drawn most of the material from Ed Feser’s book, Five Arguments for the Existence of God. The second is a version of the kalam cosmological argument as presented by William Lane Craig.

The first premise of the Aristotelian argument comprises a basic and fairly obvious truth about the world:

• Change occurs

To understand this premise, we have to understand Aristotle’s notion of change. For Aristotle, change involves moving from potential and actual. Feser asks us to consider a coffee cup on a desk. What changes could the coffee cup undergo? It could undergo a qualitative change by cooling, it could change location by falling, or it could undergo a quantitative change by being reduced (by you drinking the coffee). Those are some of the potentials that the coffee possesses.

Consider the cooling of the coffee. While the coffee is hot the coffee is not cold. But the coffee has potential coldness. It also has the potential to spill, or be consumed, to make you more alert etc. It does not have potential to become chicken soup. Since it is not cold but only has the potential to be cold, it requires something actually cold to cause it to actualise its potential to be cold.

What is required for the coffee to change? It can’t change on its own. Potentials cannot do anything (that’s what potential means). Only what is actual can do anything. The potential coldness of the coffee cannot make itself cold. Only something already cold can make the coffee cold (the air around the coffee). Thus, the coffee needs something actual in order to actualise its potentials. Cooling requires the air to be a lower temperature than the coffee, falling requires you knocking it over, and reduction requires consuming the coffee.

If something with a potential requires something else to actualise its potential, then we can have chains of changes and changers. Consider again the relationship between cold air and the coffee. The actual coldness of the air changes the coffee from hot to cold. The coffee’s potential to be cold is actualised. But the air is only potentially colder than the coffee until the air conditioning actualises the air’s potential for coldness. Further, the air conditioning only actualises its potential for cooling the air if it is actualising its potential to run. Presumably, you can imagine an endless series of actualisers are required to cool your coffee. Thus,

• If change occurs, there is a series of changes and changers.

Other kinds of chains can also be examined. For example, the coffee cup’s potential to be four feet from the floor is actualised by the desk holding it up and the desk’s potential to hold the cup up is actualised by the floor holding up the desk and the floor’s potential to hold the desk is actualised by the foundation holding up the building and the foundation’s potential for holding up the floor is actualised by the earth.

Existence is another actualised potential. If your coffee is actualising its potential to be hot (or cold), then your coffee exists. But what keeps your coffee in existence? The potential of the coffee to exist here and now is actualised, in part, by the existence of the water, which in turn exists only because a certain potential of the atoms is being actualised, where these atoms themselves exist only because a certain potential of the subatomic particles is being actualised. Again, we have a series of changes and changers.

But now we face a problem. It seems that there must be some unchanging changer at the beginning of a series. The cup has no capacity to hold itself up and neither does the desk, the floor, or the foundation. A cup can’t cause its own existence. But nor can there be an endless series of changes and changers. If every change requires a changer and every changer itself requires and changer, there would never be any change! Hence, every series of changes and changers always requires a changer who itself does not require any change.

• If there is a series of changes and changers, there is an unchanging changer.

Once we accept the previous premises, the conclusion of the argument follows. There must exist an unchanging changer, one who capable of beginning the series of actualisations of potentials. Hence, we have the conclusion:

• There is an unchanging changer.

What is an unchanging changer? Simply, it is a being that lacks potentials. It is fully actual. It follows from the nature of a first cause (unchanging changer) that it has no potentials. Proponents of the cosmological argument suggest that we can derive a number of truths about the unchanging changer by considering what would be necessary to be the unchanging changer.

First, anything that has no potentiality cannot change. Thus, the unchanging changer is immutable. Second, anything that exists within time changes. Since the unchanging changer does not change, the unchanging changer exists ‘outside’ time. Third, anything that is material changes and exists in time. Since the unchanging changer does not change, the unchanging changer is immaterial and incorporeal. Fourth, anything that lacks nothing is perfect, so the unchanging changer is perfect.

Finally, something is good the degree to which it can realise the potentials of the kind of thing it is. (for example, a painter is good the degree to which he can skillfully paint and bad the degree to which he fails to paint skillfully). A purely actual being cannot fail to actualise his potentials. Thus, the unchanging changer is fully good (Omnibenevolent).

One can see that the attributes generated by such reflection lead one to the attributes of God. Hence, at the end of the argument, we can add, as Aquinas does, “to which everyone gives the name of God.”

Kalam

We’ve seen how an Aristotelian argument moves from the observation that change (actualising of potentials) requires the existence of God, but, as I have mentioned, cosmological arguments can begin with other observations. Some arguments begin with the plausible fact that the universe is not eternal and that, sometime in the past, it came into existence. One such argument is the kalam cosmological argument. It is an ancient argument developed by Muslim scholars and recently introduced to the Christian community by Christian philosopher, William Lane Craig. The following is my summary of his presentation of it in his book, Reasonable Faith, p. 111-156.

The basic form of the argument is as follows:

• Whatever begins to exist has a cause
• The universe began to exist
• Therefore, the universe has a cause

It is a valid argument but are its premises true? Craig gives three reasons to believe that premise (1) is true. First, something can’t come from nothing. Nothing can’t do anything let alone make something. Even talking about nothing is strange. I’m not talking about anything! Second, suppose something could come from nothing. It would follow that we wouldn’t have any explanation for the existence of anything. Yet we clearly do. Thus, something can’t come from nothing. Finally, none of us have seen anything pop into existence without being caused to exist. Thus, though we can imagine something just appearing from nothing, we don’t have any experiences of it happening. This lends credence to premise (1).

Someone might ask: If something can’t come from nothing, then how can we explain the existence of God? Surely God himself requires some explanation. How does he come into existence? In reply, it should be noted that the argument is talking only about things that are caused to exist. But God does not come into being. God exists eternally and thus is not caused by anything. If so, then no explanation is required for the existence of God.

What are some reasons to believe that premise (2) is true? Craig gives both philosophical and scientific defenses for the claim that the universe began to exist. First, it can’t be true that the universe never began to exist because this would entail that, prior to this present moment, the universe has existed for an infinite number of instances. But an infinite number of instances cannot exist. Therefore, the universe began to exist at some point in time.

To show that there cannot be an actual infinite set of instances, one needs an argument to show that an infinite number of things cannot actually exist. Someone might say, “we can all count one more number (1, 2, 3, 4, …).” However, this only shows that we can have a potential infinite (by always adding one more), but it doesn’t show that you can have an actual infinite set of things all collected together.

Craig employs an argument given by the mathematician, David Hilbert. He asks us to imagine a hotel with a finite number of rooms. All the rooms are occupied. If you want a room, you can’t have one. Simple as that. Now imagine a hotel with an infinite number of rooms. Again, all the rooms are occupied. You turn up and ask for a room. This time the hotel owner merely has to move every occupant to the next-door room (1 to 2, 2 to 3, 3 to 4 …). Since the rooms are infinite there will always be a room for you! In fact, you could bring the entire population of the planet to the fully occupied hotel and there would be room for everyone. You end up with a hotel that’s full and has room for the whole world. Such a situation is absurd and thus proves that there cannot be an actual infinite.

Second, if there were an infinite series of instances in the past, then we could never reach the present. This is because if there is an infinite series of instances in the past, there is no first instance. Imagine standing over a series of dominoes all lined up and ready to fall. Now imagine that there is no first domino. Will your series of dominoes ever be knocked over? Not unless there is a first domino! Thus, the universe must have a first instance in which it exists.

Finally, Craig argues that scientific theories also confirm that the universe has a beginning. The so called ‘big bang’ model for the universe rests on the idea that the universe is expanding over time. The model suggests not only that planets and those sorts of things began, but so did space itself. This strongly supports the premise that the universe began to exist. There are all sorts of alternative models, but none is as coherent or as plausible as the standard expansion model.

Another scientific theory that confirms the premise is the theory of thermodynamics. The second law of thermodynamics states that “processes taking place in a closed system always tend toward a state of equilibrium.” (p. 140-141). If you put cold water into a tub of hot water, it tends to make all the water cooler. If the theory is true, then, given enough time, the universe will just die. However, if the universe has no beginning, it would be dead by now. It isn’t, so it must have a beginning.

If premise (1) and (2) are true, then the conclusion follows. But what does the conclusion tell us exactly? It only tells us that the universe has a cause. It doesn’t tell us what the cause must be. It could be anything that itself doesn’t have a cause. We might think that we are left with not much of a conclusion.

However, a little reflection on what must be true of the cause leads us to a much richer conception of the cause. For example, the cause must be atemporal and non-spatial. If it were not, then it would be subject to all the problems of an eternal and spatial universe. Anything outside space and time cannot change since any change requires space and time. Anything that doesn’t change must be immaterial since for every material object, the object is subject to destruction (it is possible for any material object to be destroyed). But if an object cannot change, then it cannot be destroyed. Thus, it cannot be a material object.

Further, to create the universe, the cause must be immensely powerful, and the cause must deliberate as to whether to create the universe. If it did not deliberate, then it would have created the universe out of necessity. If it created the universe out of necessity, then there would never have been a time at which there was no universe. But we already know that the universe cannot have existed for eternity. Thus, the cause of the universe deliberated about creating the universe. Anything that can deliberate is a personal agent. Only personal agents can make decisions.

Thus, just from reflecting on what the cause of the existence must be like, we have arrived at much of the contents of what we mean by God. Thus, the most likely candidate for the cause of the existence of the universe is God.

Further reading: Ed Feser’s Five Arguments for the Existence of God is very good introduction to arguments for the existence of God. You can find Anselm’s arguments in chapter 2 of his Proslogion. William Lane Craig’s Reasonable Faith contains his version of the kalam cosmological argument.