The Ontological Argument Revisited

I thought I had put this to rest in my other article on this subject.  The hundreds of comments, and the hundreds of replies I thought would be enough, but I recently got into this argument on facebook where the person didn’t seem to grasp some concepts that I thought were rather simple.

The Ontological Argument

St. AnselmThere are various forms of the ontological argument.  The original, proposed by Anslem1 in the 12th century was in essence this:

  1. God is the greatest possible being that can be conceived.
  2. The idea of God exists in our mind.
  3. It is greater to exist in both the mind and in reality than just in the mind.
  4. If God only exists in our mind, we can conceive of a greater being, namely one that exists in reality.
  5. We can’t conceive something greater than God.
  6. Therefore God exists in reality.

This argument was originally shot down by Thomas Aquinas, which made it lose quite a bit of favor with Catholics, but it was further taken apart by David Hume.

…there is an evident absurdity in pretending to demonstrate a matter of fact, or to prove it by any arguments a priori. Nothing is demonstrable, unless the contrary implies a contradiction. Nothing, that is distinctly conceivable, implies a contradiction. Whatever we conceive as existent, we can also conceive as non-existent. There is no being, therefore, whose non-existence implies a contradiction. Consequently there is no being, whose existence is demonstrable.2

Then demolished by Kant in his Critique of Pure Reason.

‘Being’ is obviously not a real predicate; that is, it is not a concept of something which could be added to the concept of a thing. It is merely the positing of a thing, or of certain determinations, as existing in themselves.

Along Comes Plantinga

Alvin Plantinga, a modern philosopher, seems to ignore the arguments of those that preceded him.  He ignores the fact that existence is not a predicate.  He ignores the fact that anything that can be imagined as existent, can also be imagined as non-existent.  He instead decides to use modal logic to prove that a god must exist.

  1. A being has maximal excellence in a given possible world W if and only if it is omnipotent, omniscient and wholly good in W; and
  2. A being has maximal greatness if it has maximal excellence in every possible world.
  3. It is possible that there is a being that has maximal greatness. (Premise)
  4. Therefore, possibly, it is necessarily true that an omniscient, omnipotent, and perfectly good being exists.
  5. Therefore, (by axiom S5) it is necessarily true that an omniscient, omnipotent and perfectly good being exists.
  6. Therefore, an omniscient, omnipotent and perfectly good being exists.3

Plantinga here ignores the idea of the impossibility of necessary existence and makes, what is in essence, a circular argument.

You see, in modal logic, proposing that something is a necessary thing is saying that it is necessary in all possible worlds.  To say that something is possibly necessary in some possible world means that it is necessary in all possible worlds.  So, saying existence is possibly necessary is exactly the same as saying it is necessary.

The premise “It is possible there is a being that has maximal excellence in every possible world” is the same thing as saying, “There is a being that has maximal excellence in every possible world”, which is the conclusion.

This isn’t all that big of a problem if it weren’t that the opposite holds true as well, as it isn’t self contradictory.

Facebook Problem

The issue I was having on facebook is based on the refutation of Plantinga’s argument.  Namely that the exact opposite of what he says is true.

If something necessary if it is possibly necessary, the reverse is also true.  If it is possible, in some possible world, that there is no maximally great being, it is necessary that a maximally great being exists in no possible world.

  1. If a maximally great being is possibly necessary in some possible world, it is necessary in all possible worlds.
  2. From 1, if there is a possible world where a maximally great being does not exist, it is necessary that a maximally great being exists in no possible world (axiom S5).
  3. It is possible in some possible world that nothing exists whatsoever.
  4. From 1, 2 and 3, it is necessary that a maximally great being does not exist.

Now, this is a perfectly valid modal argument.  In fact, William Lane Craig admits this on his on blog.  As he is the largest purveyor of this type of argument, I feel he is perfectly acceptable to bring up in a discussion about this argument, even if Plantinga originally formulated it.

The odd thing is, William Lane Craig essentially retreats to “What seems more believable” when trying to explain away this argument that refutes what is supposed to be a proof for the existence of God.

The problem I had on facebook is that the person I was disagreeing with decided that it is not possible that there would be a world where nothing exists.

A World of Nothing

I have heard this argument before, and it really isn’t all that difficult to deal with, but the guy seemed stuck on trying to make strawman arguments about things I was saying instead of trying to understand why we can use modal logic for anything if there is a world where nothing exists.

When we speak of a world, we speak of a possible reality.  A reality is not the things that exist, it is what can be said of it.  If no things exist, it is a reality that no things exist, and therefore it is a world.  Saying that the lack of existence of everything makes the entire world cease to exist is tantamount to saying that if my car ceased to exist, we couldn’t say that my car doesn’t exist.  It is like saying that the number zero is meaningless.

If I have a set {1,2,3,4,5} and I remove all elements of that set, the set doesn’t disappear, it just becomes empty {}.  This seems like a completely understandable thing to me.

Everything that we can think of existing, we can imagine not existing.  Existence simply means that there is an instance of it.  We can say that something necessarily exists based on an if statement, like “If there are shapes with three sides, triangles exist.”  This is not the kind of existence necessary existence means in the modal argument though.  In that argument, necessary existence is not required by anything else.  It is simply required to be true axiomatically.  Circles must axiomatically be round, water must axiomatically be made of hydrogen and oxygen, and 1 + 1 axiomatically add up to 2.

Anyway, I thought that other people may have this kind of problem, and hopefully writing it out this way will help the guy I was disagreeing with understand better.

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