St. Thomas can only find two arguments against the existence of God in the whole history of human thought. The first and most common is
It seems that God does not exist; because if one of two contraries be infinite, the other would be altogether destroyed. But the word “God” means that He is infinite goodness. If, therefore, God existed, there would be no evil discoverable; but there is evil in the world. Therefore God does not exist.
Or, as the kids these days say, “Shit happens. So there’s no God” (The argument from evil).
The second is this:
It is superfluous to suppose that what can be accounted for by a few principles has been produced by many. But it seems that everything we see in the world can be accounted for by other principles, supposing God did not exist. For all natural things can be reduced to one principle which is nature; and all voluntary things can be reduced to one principle which is human reason, or will. Therefore there is no need to suppose God’s existence.
In common English, this comes down to “Everything works fine without God, so there’s no God” which is basically what undergirds much of the alleged disproof of theism that seems to so many Fundamentalists, both Christian and atheist, to be found in the idea of evolution.
Again and again, the changes get rung on some variation of “We used to not know where disease, or lightning, or the Panda’s thumb came from, now we do. And the place those things and a million others come from is ‘Nature’. So God is unnecessary.” In other words, natural phenomena can be reduced to one principle which is Nature.” Apple pies can be explained by their constituent ingredients+plus heat+a cook. Nothing supernatural is required to explain them.
The work of the sciences is to drill down further and further into questions that might arise from that answer. Why are there apples? How do trees make them? Where do the trees come from? How about all the other ingredients? How do ovens work? Where did the cook come from? Why is he a cook? Where did apple pies originate? What chemical make up the ingredients? Where did they come from? Where did the elements come from?
Eventually, if you ask enough of those questions, you wind up asking the question that Carl Sagan answers. And if you keep asking, you start getting close to an old joke that St. Thomas would have enjoyed, if he had a sense of humor (something I am a bit skeptical about). It’s the one about the guy who challenged God, saying, “We don’t need you anymore! We have figured out how to make life from the dust of the earth just as you did!” He reaches down to scoop up some soil and God says, “Whoa! Go get your own dirt!”
That’s the thing: the sciences are about measuring and manipulating the metric properties of time, space, matter, and energy. Once there is something, science is a fantastic tool for understanding that something and, among other things, making apple pies out of it.
But science is worthless for answering the question “Why is there anything?”
Don’t come at me with the multiverse or quantum foam. That’s not an answer. It just pushes the question back further. Tell me *this* universe is the result of some eruption from the quantum foam or a brane intersection or (as Hawking famously claimed) the “laws of gravity” only tells me you don’t really understand what “nothing” means. For all these things are *things*, not nothing. So you are still reducing some natural phenomenon to Nature but you have not come an inch closer to answering the question “Why is there anything?” Why are there laws of gravity or branes or quantum foam? Why is there a multiverse?
For all the resentment is causes, I still think Thomas’ answer is perfectly reasonable and (ironically) similar to the explanation given in the colloquial explanation the atheist Sagan gave: the universe was “invented”.
And inventions have Inventors, just as law have Lawgivers.
Take it away, Tommy!
Since nature works for a determinate end under the direction of a higher agent, whatever is done by nature must needs be traced back to God, as to its first cause.
Praised be You Know Who for his glorious creature, the universe, without which we would not have natural causes to study and no science to study them with!