Friday, August 21, 2009

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.


  1. KorkeitaYkkösiä August 21, 2009

    Can I just say that this blog is working good for me. Keep up the work, mate. M.

  2. 4simpsons August 21, 2009

    I know people throw the "stone" paradox out there as a joke but didn't realize people took it seriously as an alleged disproof of God's existence. They might as well ask, "Has God stopped beating his mother?" Loaded questions prove nothing more than the motives and/or reasoning skills of those who offer them.

  3. Leslie August 21, 2009

    I saw this article on that rock subject recently … good timing to bring that whole thing up.

    Anything You Can Do God Can Do Better

    I think the whole question is just stupid to begin with, but what do I know?

  4. Matthew August 21, 2009

    Hi Leslie,
    Nagasawa (who has some really brilliant articles on his website) is an analytic philosopher of religion, so he gives an analysis of this paradox. Nothing odd about that.

    By the way, the best defense of omnipotence to this day is a paper called "Maximal Power", you should be able to find it on the web.

  5. bossmanham August 25, 2009

    This argument seems to run somewhat parallel to Anselm's ontological argument.

  6. Brian August 25, 2009


    Yeah, it's in the same "family" of arguments (ontological) – but this one uses modal logic and semantics, so you could call it a modal ontological argument.

    Any philosophers out there please correct me if I am off. Thanks.

  7. Matthew August 26, 2009

    Any philosophers out there please correct me if I am off. Thanks.

    You can call it that, because that's what it is 😉