The Ontological Argument: Malcolm's Formulation

This is an excerpt from Philosophy of Religion by C. Stephen Evans in the chapter for classical arguments for God's Existence. In this excerpt, Evans describes Norman Malcolm's formulation of Anselm's second ontological argument, which deals with the concept of necessary existence.
The gist of the second argument, as Malcolm formulates it, is as follows: God is by definition a being who does not merely happen to exist. God can neither come into existence nor pass out of existence, since a being who could do either simply would not be God. It follows from this that if God exists at all, then his existence is necessary. If he does not exist, then his existence is impossible. But either God exists or he does not exist, so God's existence is either necessary or impossible. Since it does not seem plausible to say that God's existence is impossible, then it follows that his existence is necessary. So if God's existence is possible, then it is necessary. More formally the argument can be put like this:

1. If God exists, his existence is necessary.
2. If God does not exist, his existence is impossible.
3. Either God exists or he does not exist.
4. God's existence is either necessary or impossible.
5. God's existence is possible (it is not impossible).
6. Therefore God's existence is necessary.1

1 C. Stephen Evans, Philosophy of Religion: Thinking About Faith (Downers Grove, IL: InterVarsity Press., 1982), p. 48.

Argument from the Definition of God and the Superiority of Existing in Reality

This continues the series of weekly posts dealing with some basic theistic arguments. The purpose here is to introduce the reader to the idea behind each argument. Strengths and weaknesses will be presented after each summary. These are only summaries and springboards for further study in the theistic arguments. See Reason for the Hope Within for more.

An Argument from the Definition of God and the Superiority of Existing in Reality

Anselm defined God as that being than which no greater can be conceived, and further assumed that it is greater to exist in reality than it is to exist only in the mind (as a thought). But given these two premises, the supposition that God exists only in the mind can't possibly be true: the greatest conceivable being can't exist only in the mind because we can conceive of that same being existing in reality as well. A greatest conceivable being (God) which exists in the mind is contradictory. Thus, God must exist in reality.

Greatest Strength: The argument requires accepting only a definition and the claim that to exist is better than not.

Greatest Weakness: It feels like a trick, even if it is hard to say why. One likely source: widespread misgivings about deriving existence from a definition.1

1 William C. Davis, Reason for the Hope Within (Grand Rapids, MI: Eerdman's Publishing Co., 1999), p. 30.

Argument from the Possibility of God

This continues the series of weekly posts dealing with some basic theistic arguments. The purpose here is to introduce the reader to the idea behind each argument. Strengths and weaknesses will be presented after each summary. These are only summaries (not debate starters) and springboards for further study in the theistic arguments. See Reason for the Hope Within for more.

An Argument from the Definition of "God" and the Possibility That God Exists

Alvin Plantinga defines God as, together with the standard attributes, a "necessary being." A necessary being, if one existed at all, would exist no matter how the world went (it would exist in every "possible world"). If one admits that it is possible that God exists (as most will), then it follows that God does exist:

in order for it to be possible at all, there must be at least some possible world in which it will be true that God exists (this is, philosophers argue, just what it means to say that something is "possible"); but (and here is the tricky part), if there is some world where it is true that God exists, then "God exists" must be true in every world. Why? Because the very definition of God demands that God is a necessarily existing being. Thus, we are forced to admit that if we "find" him existing in even one world, we are guaranteed (by the definition) that he must be found in every other possible world as well. Thus, God is found (i.e., exists) in this world.

Greatest Strength: Most opponents of theism are willing to concede that God's existence is at least possible.

Greatest Weakness: Atheists who have considered the argument can and do reject the claim that God is even possible. They argue instead that the very concept of God is incoherent since, for example, it entails paradoxes such as the paradox of the stone: Can God make a stone so big that he cannot lift it? This is supposed to show that an omnipotent being is impossible.1

1 William C. Davis, Reason for the Hope Within (Grand Rapids, MI: Eerdman's Publishing Co., 1999), p. 25.

The Ontological Argument Discussed: Peter S. Williams MP3 Audio

Philosopher Peter S. Williams discusses the ontological argument for the existence of God and its various forms. Check out his podcast here and his blog here.

Full MP3 Audio here.

Enjoy.