Sep 28, 2011

If God could exist he would exist – why it’s worth getting to grips with the ontological argument

For many atheists the argument goes something like this; unless overwhelming evidence can be presented for the existence of a god the default position of a thinking person should be NOT to believe in gods.

Essentially, we should presume atheism.

However, the Ontological argument for God, first proposed by Anselm in the eleventh century, challenges that assumption.

Anselm argues that we should believe in a perfect being unless such a perfect being is impossible (note not unlikely but impossible).

So how does the argument work?

There are a number of ways of stating the argument. Read Richard Dawkins God Delusion and you will find a superficial response to just one form.

We’ll focus on the one that’s most accessible. I take it from Douglas Groothuis’s new book Christian Apologetics.

The thing to bear in mind as we start out is that there are two types of proof for God arguments.

A posterioi arguments are those which look at evidence for the existence of God. For example the cosmological argument uses the scientific evidence that the universe had a beginning from big bang cosmology to argue that whatever has a beginning must have a cause and that cause is God.

A priori arguments are not seeking to establish the existence of God from any appeal to evidence at all.  They are arguments from reason or logic alone.

Anselm begins his argument with the following statement ‘God cannot be conceived not to exist. That which can be conceived not to exist is not God.’

What does Anselm mean?

He’s NOT saying it’s impossible to think that there is no God. Clearly lots of people are quite capable of that.

What he is saying is that God has unique properties that make him unlike any other kind of being.  Other things might happen to exist but God, by definition, must exist unless his existence is proven to be logically absurd. God is a necessary being meaning if he could exist he would have to exist.

You wouldn’t say that of anything else. Everything else that we think about might exist or might not. Everything else is contingent. Groothuis gives the example of a saxophone.  Someone may have invented the saxophone but it’s quite conceivable to imagine a world in which the saxophone never existed.

God would not be God if he only might exist. God being God is ‘maximally great’ he is a ‘perfect being’ and perfect beings  don’t just happen to exist they necessarily exist.

So Anselm argues;

If God could exist he would exist. It is inconceivable, irrational and illogical to argue that like a saxophone he may or may not exist.

Therefore to argue that he does not exist we must argue that it would have to be because he could not exist.

The only reason for rejecting the notion of a perfect being, the only reason to posit his non-existence is therefore that the concept of a perfect being is in itself flawed. There is no other reason as to why a perfect being would not exist.

So Norman Malcolm in Knowledge and Certainty writes that God’s ‘existence must be logically necessary or logically impossible. The only intelligible way of rejecting Anselm’s claim that God’s existence is necessary is to maintain that the concept of God, as a being greater than which cannot be conceived, is self-contradictory or nonsensical.’

Here is Groothius’ formal structure for the argument:

1. God is defined as a maximally great or Perfect Being

2. The existence of a Perfect Being is either impossible or necessary (since it cannot be contingent).

3. The concept of a Perfect Being is not impossible, since it is neither non-sensical nor self-contradictory

4. Therefore (a) a Perfect Being is necessary

5. Therefore (b) a Perfect Being exists.

Consequences of the argument

Once we accept that the existence of God is possible, that is not inherently nonsensical, we should accept that if possible he is in fact necessary.

So we move from the possibility of God to the presumption of the existence of God.

The onus is therefore on the atheist to demonstrate that God is self-contradictory or nonsensical rather than on the theist to prove that he is there.

Why should we believe in God rather than unicorns?

Groothius writes;

The idea of a unicorn is logically possible, since it is understood to be an animal that does not possess incompatible properties. Unicorns do not exist in our world. Nevertheless, they could exist, that is, they exist in a possible world. But a unicorn is not conceived as a necessary being, a being that must exist given its very nature. God is considered as such. And there is the rub metaphysically. It the concept of God is not im-possible, then God must exist in at least one possible world, and in that possible world God’s existence is necessary. That is, God cannot not exist. So, if God exists as a logically necessary being in one world, he exists in all such worlds.



  • I can’t see how this argument works. It seems related to the argument that creation must have a creator which is outside of itself, which is a good argument, but it seems to be saying more than that.

    The main problem I have with the argument is that it leaves us as the ones who define God rather than the other way around.

    There is also the problem of what is meant by a perfect being. If different people have different definitions of a perfect being does that mean that there is more than one God?

  • I tend to agree with Plantinga who suggests that the ontological argument is only useful so far as demonstrating that God would be a necessary entity, which is a result of him being defined as a maximal being (I suppose a lot of apologetics has this presupposition though). I suspect some will simply reject the premise… I think it’s all very well to say that if a maximal being could exist, then he must exist, but I tend to think that God is not to be found at the end of a clever syllogism.. But then I also see what you’re saying, which seems to be that it’s not so much a ‘proof’ for God, but merely changes the a priori assumption.

  • Of course one can’t think of “an entity which must exist” without thinking of it as existing while one thinks of it. But that’s really not the way we decide if it is possible for something not to exist. We judge that a unicorn may not exist because we can imagine a universe in which there are no unicorns. I judge that God may not exist because I can imagine a universe in which there is no God. (In fact, it’s far easier than trying to imagine “a maximally great or Perfect being,” which I have never been able to come close to conceiving.)

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