You're quite right that "The fact (at least Thomists consider it such) that God doesn't exist the way things do doesn't mean the existence of God can't be proven from the existence of the world of things." As you say, Thomas certainly thinks the existence of God can be demonstrated (deum esse quinque viis probari potest) because "there are two types of demonstration," the first "propter quid," that is by arguing from cause to effect; the second "quia," by arguing from effect to cause (Summa theologiae 1.2.2resp). The first he thinks is impossible regarding God, but not the second. The "effect," however is the existence of the world: the "viae" are ways to point out that the existence of the world poses a question -- not *how* it is (that would be the province of what he would call philosophy and we would call science) but *that* it is.
Bertrand Russell said famously that you couldn't ask why the world existed -- it just did. That view is sometimes confused with Thomas' opinion that you can't prove the world isn't eternal -- a different matter. Thomas I think is actually closer to Stephen Hawking, who's said several times, "Why does the universe bother to exists? If you like, you can define God to be the answer to that question." --CGE
On Sat, 27 Dec 2003, Jon Johanning wrote:
> Sorry but I don't have a copy of the Summa Theol. handy, and anyway
> aren't we getting rather far afield from LBO's usual area (whatever
> that is)? So I can't tell for sure whether you are right about what
> Thomas calls them. All I can tell from what I have on hand is that
> Antony Flew, in his _A Dictionary of Philosophy_ (s.v. "Five Ways"),
> quotes the following from the Summa: "We must say that it is possible
> to prove the existence of God in five ways" (IQ2A3); I can't vouch for
> the accuracy of that translation, not having the original text here to
> check.
>
> But anyway, looking at the references I do have, Frederick Copleston,
> the ever-reasonable-minded Jesuit, calls them "proofs" in Vol. II of
> his _History of Philosophy_ (Chapter XXXIV: St. Thomas Aquinas-IV:
> Proofs of God's Existence), and of course considers them sound , or at
> least defensible, arguments.
>
> The fact (at least Thomists consider it such) that God doesn't exist
> the way things do doesn't mean the existence of God can't be proven
> from the existence of the world of things. In fact, the Thomist view
> is that that is the only way to prove it -- a careful consideration of
> the nature of the world of our experience shows, they think, that it
> can only be explained by the existence of a unique being, the First
> Cause, or God. As Copleston explains, the human intellect has *all*
> being as its primary object, but being an intellect embedded in a
> body, it depends on the senses for its operation, and therefore has to
> start with what it knows about perceptible beings. But, knowing this,
> Thomas thinks it must conclude that the First Cause is needed to
> explain their existence. The "embeddedness" of the intellect explains,
> for Thomas, why humans don't have a clear enough understanding of
> God's nature to use an a priori argument like the ontological, or
> Anselmian, argument.
>
> I also see that John F. Wippel's article on Thomas' metaphysics in
> _The Cambridge Companion to Aquinas_ (Cambridge U. P., 1993) treats
> them as arguments.
>
> He doesn't say that God's existence is *completely* unknowable, just
> that it's not "per se notum quoad nos" (knowable "it itself" -- a
> priori -- with respect to the human intellect), but it is "per se notum
> secundum se" (knowable a priori in itself, not with respect to the
> human intellect). In other words, he thinks that we have *enough*
> knowledge to make the "five ways" work, at least.
>