From the Mailbag: The Ontological Argument

P. M. writes,

Thank you for your work on the Ontological Argument for the Existence of God.  I would really appreciate if you could answer some of my questions that are bulleted below:

 

You discuss the following Ontological Argument in your paper: "Has the ontological argument been refuted?." Religious studies 29.1 (1993): 97-110. 

1. If the concept of an x is internally coherent, then an x exists in some possible world.
2. The concept of the GCB is internally coherent.
3. Therefore, the GCB exists in some possible world. (1, 2)
4. Either the GCB is impossible (exists in no world) or the GCB is necessary (exists in all worlds).
5. Therefore, the GCB is necessary. (3, 4)
6. Therefore, the GCB actually exists. (5) 

(Where GCB is of course the "Greatest Conceivable Being").

• Is the above ontological argument a good one? If not, what are its flaws?
  
• In your opinion what is the strongest version or case for the Ontological Argument today?

Is the above argument good? Well, it's valid.  All that means is that the conclusion follows from the premises: necessarily, if the premises are all true, then the conclusion is true. A further condition on argumentative goodness is soundness: an argument is sound just in case it is valid and all of its premises are true.  But if an argument is sound, it doesn't follow that it is probative, i.e., that it proves its conclusion.

For an argument to be probative, it must not only be sound, but must also satisfy a relevance constraint: the conclusion must be relevant to the premise(s). The following argument is valid in the sense that it is impossible for the premise to be true and the conclusion false, and its premise is true. Yet it surely does not amount to a proof of its conclusion:

Trump is president
ergo
7 + 5 = 12.

The following argument is valid, sound, and satisfies the relevance requirement, but is not proof of anything:

7 + 5 = 12
ergo
7 + 5 = 12.

This is because the argument is circular. Every circular argument is valid and satisfies relevance, and some circular arguments are sound; but none are probative.  So we add freedom from informal fallacy to our list of conditions on probativeness.

But this is still not enough to have a probative argument.  We add: the premises must not only be true; they must be known to be true.

So I deny that the modal ontological argument above is probative. It does not constitute a proof of the existence of a GCB because we do not know whether (1), the possibility premise, is true.  I explain why in Is the Modal Ontological Argument Compelling?

Of course, one could argue for the possibility premise. I've done it myself. Just last month the following paper of mine appeared:

Vallicella, William F. (2018). "Does God Exist Because He Ought To Exist?" In Mirosław Szatkowski (ed.), Ontology of Theistic Beliefs. De Gruyter. pp. 205-212.

In this paper I essay a deontically supercharged modal ontological argument.  Very briefly, I argue that since a greatest conceivable, or maximally perfect, being ought to exist, and since whatever ought to exist is possible, a greatest conceivable, or maximally perfect, being is possible.  I conclude, however, that not even a deontically supercharged modal OA gets the length of a proof.

In fact, I hold that none of the so-called theistic 'proofs' are proofs strictly speaking. The existence of God cannot be proven or disproven. (Thus no argument from evil disproves the existence of God.) One cannot rationally compel belief in God, though I think one can render theistic belief rationally acceptable. My friend Ed Feser disagrees strenuously.

I refer you to his Five Proofs of the Existence of God (Ignatius Press, 2017) which is available via Amazon for less than fifteen semolians.   Ironically, the onto-cosmological argument I deploy in A Paradigm Theory of Existence (Kluwer 2002) a book that  is also available via Amazon for a paltry 170 semolians, ends up as one of Ed's proofs in Chapter Two, "The Neo-Platonic Proof." Ed's discussion of my argument, which I do not consider a proof, commences on p. 75.  He doesn't present my argument in its full subtlety and richness, but then his book is more of a high-level survey than a technical treatise. I thank Ed for the citation. A version of my onto-cosmological argument is presented here:

Vallicella, William F. (2000). From facts to God: An onto-cosmological argument. International Journal for Philosophy of Religion 48 (3):157-181.

Finally, I should say that I am not fully versed in all forms of the Ontological Argument. So I won't offer an opinion on the reader's second question. For further instruction I recommend the work of Graham Oppy and Alexander Pruss.