Filotheya: Prudence, you are an agnostic, right?
Prudence: I am, yes.
Filotheya: By ‘agnostic’ do you mean there is equal evidence both for and against the existence of God or something else?
Prudence: No, nothing else. I hold that there are equally compelling reasons to believe in God’s existence and not to believe in God’s existence such that God’s existence is as equally likely as God’s non-existence.
Filotheya: And, in this context, by ‘God’ what do you mean?
Prudence: By ‘God’ I have in mind a more or less traditional western Abrahamic conception. A being is ‘God’ if and only if it is omnipotent, omniscient, and morally perfect. That is to say, if a being is ‘God,’ then it must possess power, propositional knowledge, and moral goodness maximally. Which in turn means that God, so defined, is the greatest of all possible beings.
Filotheya: Perfect! I accept that, albeit partial, definition of God and since you do as well, I would like to run an argument by you if I may.
Filotheya: I think that, given the aforementioned, I can demonstrate that you must accept God’s existence.
Prudence: You’ve tried to do this before…
Filotheya: Yes, I have not been successful in the past, I admit, but I think this time will work. I am confident that after this you will become a theist.
Prudence: Ah! I have no doubt that it will be successful and my theism is imminent and only awaits the resolution of a few mere formalities!
Filotheya: You jest when you should not. No worries, though- you cannot defeat this one!
Prudence: Fine, fine. Present your argument.
Filotheya: It is really very simple. If it is possible that God exists, then He does exist, because if He does not, then He could not be conceived without contradiction, but, as you have admitted, He can be conceived without contradiction. Now, if…
Prudence: Hah! I know this one: It is St. Anselm’s ontological argument!
Filotheya: No, not quite; close, but not identical. Despite its strengths, St. Anselm’s version is problematic, though perhaps not for the same reasons you may suspect. My argument is newer and, I contend, better. St. Anselm went wrong when he tried to deduce existence from the concept of a perfect being. As Kant and Russell have demonstrated, existence is not contained in the concept of a perfect being.
Prudence: I see. An updated version then?
Filotheya: If you want to want to view it as such, sure, why not? Properly speaking, though, my argument is a modal argument for God’s existence. But we tarry; may I present my argument now?
Prudence: By all means, please do.
Filotheya: Thank you. Now, God, by definition, is that which nothing greater can be conceived, and, since that which nothing greater can be conceived cannot be conceived not to exist, then..
Prudence: How is this different from…
Filotheya: Dear Prudence! Won’t you open up your ears and permit me to finish before you begin with your inquiries?
Prudence: I am sorry! But… ah nevermind, continue.
Filotheya: [Furrowing her brow] Thank you! Now, since God is that which than no greater can be conceived, then His existence cannot be a contingent existence. (If God’s existence were contingent, then the other, upon whose existence God’s existence would rely, would exist necessarily and hence would be God.) If God’s existence is not contingent, then His existence is necessary. If His existence is necessary, then God must exist in all possible worlds. Since this world is a possible world, then God must exist in this world. Thus, God exists.
Prudence: Hmm. I am not sure I follow.
Filotheya: [grabbing a pencil and a piece of paper] Allow me to clarify and simplify:
(1) The concept of God is without contradiction. (Assumption)
(2) God is that which than no greater can be conceived. (Assumption)
(3) God’s existence is not contingent. (From 2)
(4) All existence is either contingent or necessary. (Assumption)
(5) Therefore, if God exists, then His existence is necessary. (From 3 and 4).
(6) If the concept of God is without contradiction, then there exist at least one logically possible world PW where God exists. (From 1)
(7) God exists necessarily in PW. (From 5 and 6)
(8) If God exists necessarily in PW, then He exists necessarily in all logically possible worlds. (Premise)
(9) Therefore, God exists necessarily in all logically possible worlds. (From 7 and 8 )
(10) This world is a logically possible world. (Assumption)
(11) Therefore, God exists in this world. (From 9 and 10)
Prudence: [Looking down at the paper] I don’t know if I want to be an agnostic anymore…
(P.S. One need not be an equal-probability agnostic atheist like Prudence in order for this argument to work. Even if an agnostic atheist were, say, .95 confident that the Abrahamic God did not exist, insofar as he (1) allows for the self-consistency and (2) coherency of the God concept, he will, I think, fall prey to this argument.)