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Ontological Arguments and the Necessity of God

October 15, 2010

In a recent post I talked about the Cosmological Argument (“CA”) as put forward by Aquinas. The idea of a CA is to provide an argument based on experience. They follow in the tradition of Aristotle in that they require arguments to be backed up by evidence.

Plato on the other hand felt that arguments could be made from definitions and other a priori considerations. This view was held by Anselm, who put forward what Kant later called the Ontological Argument, a term that now covers a range of arguments from a priori conditions.

Anselm’s arguments runs roughly as follows.

  1. God is the greatest being that can be conceived.
  2. Suppose God does not exist.
  3. We can imagine a being that is God-like but that also exists.
  4. A being is greater if it exists than if it doesn’t exist.
  5. We can therefore imagine a being greater than God, contradicting 1.
  6. Therefore God exists.

Anselm argues that “even a fool” (or an atheist) would agree with premise 1, and that therefore the argument follows no matter what viewpoint you start from. This is obviously contentious. There are a number of problems. The main counter argument says that no non-theist is going to accept both of statements 1 and 4, which between them define God into existence. It is also obvious that this argument, if successful, doesn’t lead to the existence of the Chistian God, or indeed to any God. It merely leads to the existence of some x which is the greatest thing conceivable. What is this thing? Who knows. I guess it could be labelled “God” if you want.

There are a numbers of other forms that this argument can take. A feature that they have in common is that they all argue for the necessary existence of God (see my post on the cosmological argument). God’s necessary existence has some interesting implications. First though, and interesting form due to Malcolm.

Consider the statement “God necessarily exists”. This statement is either impossible, probable to some degree, or true.

  1. There are no logical contradictions in the statement. We are therefore led to say that “God necessarily exists” is possibly true.
  2. The statement is either true or false. The word “necessarily” leaves no room for half measures.
  3. Therefore the statement is true. God necessarily exists.

From an anti-realist point of view this argument is incredibly effective. Vardy argues that seen from this viewpoint the argument works, and that inside a believing community this argument justifies belief in the necessary existence of God.

I have a couple of problems with it. Firstly, I would want to insert the phrase “If God exists then…” into the beginning of the statement being considered. This stops the argument leading to the conclusion it does.

Secondly, an argument that came to me in the middle of the night when I was trying to sleep in a crappy hotel – what about the statement “God does not necessarily exist”? Here “necessarily” is to be taken in the context of necessary existence, not to imply some degree of uncertainty.

  1. There are no logical contradictions in the statement. We are therefore led to say that “God does not necessarily exist” is possibly true.
  2. The statement is either true or false. The word “necessarily” leaves no room for half measures.
  3. Therefore the statement is true. God does not necessarily exist.

Surely if the first version of this argument works then so does the second! We have used the same form of argument to reach two opposing conclusions. This suggests that there is something seriously wrong with the form of argument used. I suppose a theist would say that they do not consider the statement to be even possibly true, but then that are starting the original argument with the conclusion already certain in their mind. If I am required to start the argument by accepting that the statement “God necessarily exists” is possibly true, then surely it must be admitted that it is possibly false?

An alternative way of looking at these arguements and interpreting the word “possibly” is to consider the “many worlds” approach, favoured by Plantinga. We define a statement to be possible if there is a world in which it is true. If it is possible that God necessarily exists then there is a world in which this is the case. Therefore God has to necessarily exist in every world.

There are some weaknesses with this approach. It assumes that whatever things are possible but be instantiated in a world somewhere. Really? Frye gives an example (paraphrased): “I can imagine a pink elephant in the next room balancing on it’s
trunk drinking tea with one hand and shoting a water pistol with the other. It’s possible, but I doubt it’s instantiated anywhere.” It also assumes that any statement that is coherent must be true, which it’s pretty easy to think of counterexamples to.

Kant and Hume were both very critical of ontological arguments. They said that existence cannot be a predicate – that is, the statement “God exists” cannot be verified without looking outside of the statement for supporting evidence. My first reaction to this would be to agree, but it’s something that requires a lot of though. Not sure I’m quite there yet.

The issue of the necessary existence of God causes some problems. Is it even possible for something to exist necessarily? I would probably have to admit to being a mathematical platonist, so I’m naturally led to accept that some abstract objects exist necessarily. But God as an abstract form is very different from a God that has any meaning to live on Earth.

Admitting the necessary existence of abstract objects and the necessary existence of God, how do these necessities interact? The theist would argue that the number 4 only exists because God makes it so. However, if 4 necessarily exists then how does God cause something that’s necessary? Are the properties of God necessary? If not, they could be otherwise and God is less than most theists would accept. If they are necessary then how are the to be treated when looked at seperately from God’s existence?

That’s probably enough for now. Take home message: ontological arguments are great if you already believe, but to a non-theist they provide next to no justifcation for belief.

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