Question: Richard wrote me a while back asking
about Peter van Inwagen’s critique of ontological arguments—specifically, his
critique against modal versions of the ontological argument. Since I don’t have
the text of Richard’s question, I am just summarizing the issue. Basically, van
Inwagen states that the crucial step in modal ontological arguments (that it’s
possible that a maximally great being [MGB] exists) trades on an ambiguity of
premises. It is epistemically possible, for all we know, that MGB exists.
However, what modal ontological arguments (MOA’s) need is for MGB to possibly
exist in the metaphysical sense. Van
Inwagen claims our modal intuitions simply aren’t of the sort needed to
establish this metaphysical possibility, and so, as an argument, MOA’s can’t
even get off the ground. What can be said about this?
Response: This is an interesting situation, since
van Inwagen is a Christian theist. Thus, he has great sympathy for the overall
situation in which the proponent of the MOA finds herself. As a result, this
isn’t some atheistic philosopher looking for any excuse to avoid a God.
Moreover, Peter van Inwagen is a highly respected philosopher, so it is also
worthwhile to take what he says seriously. That being said, I do not think the
case is so simple as he would have us believe.
The first, and
primary, criticism that I would have of this criticism of MOA’s is best
expressed by a paraphrase of what a professor once told me. “We use our modal
intuitions all the time, in everyday circumstances. Why only now, at the
question of God, do we abandon them, or say they are not reliable guides to
truth?” Let me explain. The main and pivotal premise of the MOA is something
like: “It is possible that a MGB exists.” The critic says he’s not sure how one
can know this. The response is that we use our modal intuitions. What are
those? An intuition, in this case, is not like a feeling or a sixth sense.
Instead, it’s more like what we call “rational intuition,” or how one knows
laws of logic and reasoning, mathematical truths, and even metaphysical and
moral claims. What do I mean by “modal”? Modal logic and reasoning covers
different modes of existence: necessary and possible (or contingent). When one
claims that she has a modal intuition, then, she is claiming that she
rationally perceives that something is metaphysically possible.
Let’s go through
some examples. First, she can intuit that things are impossible. Consider the
idea of a married bachelor. Her rational, modal intuition tells her that this
is an impossible state of affairs. Then, consider the 50th President
of the United States. Even though, if she is reflecting at this present time,
there is no such referent, it is still metaphysically possible that there be
one, eventually. Finally, consider something that never actually exists, like a
unicorn, and she can have some kind of modal intuition about that, upon
reflection.
The point is
that these modal intuitions are not
merely saying, “For all we know, this is the case.” They are rather purporting
to be real guides to the
possibilities of reality. And what reason do we have for saying that none of
the examples above are justifiable? Perhaps it will be objected that God is not
like any of those other examples. “For the MGB,” they may say, “is a
necessarily existing thing. And how could you intuit a thing like that?!” It is
true that an MGB entails the property of necessary existence. But why think
that in order to modally intuit that something is possible one must know all
properties of that thing? Most everyone agrees that every source of knowledge
is at least potentially defeasible; that is to say, one’s rational or modal
intuition is still subject to defeaters, so that if he has good enough reason
to think that one of MGB’s entailments is impossible, he can go back and
override his belief formed through modal intuition. Basically, I see only good
reasons for accepting our modal intuitions.
But what if the
skeptic decides that, although he intuits the modal possibility of MGB, he
rejects the premise because he thinks MGB is impossible? This is fine, but he
has to hold the impossibility of MGB stronger than he holds his modal intuition
about MGB’s metaphysical possibility. Otherwise, he’s just engaging in
question-begging against the argument. There seems to be quite good and normal
reason to accept modal intuitions, and no good reason that would rule it out a priori.