Then, the HMS Beagle made its famous voyage to the Galàpagos Islands, where Darwin observed his famous finches. A huge variety of birds, each on different islands and looking dramatically different, each well suited to the conditions of its own island – but they all turned out biologically to be finches, closely related to each other and to the finches of distant South America. It seemed needlessly complex to suggest that God would create so many different birds in so many different places and yet make them all part of the same family. A more straightforward hypothesis was that the different finches had evolved from a common ancestor, by natural selection. God was no longer needed as a scientific hypothesis – and hasn’t been needed since.

In retrospect, the point that God was once a legitimate hypothesis seems obvious to me now. But when I encountered it, it came to me as something of a surprise, because I’m so used to living in a world where any attempt to find empirical evidence for God’s existence looks like a desperate grasping at straws. The worst of these is the “First Cause” version of the cosmological argument for God’s existence, that you need to have something setting the world in motion. Even if that argument works, it proves nothing like the existence of any God that has been ever worshipped. A mere First Cause is no more significant than any other cause. If God is a mere Divine Watchmaker who sets things in motion and then goes away and is no longer involved – as this hypothesis would suggest – then the universe with him is hardly different from the universe without him. This is not a God that matters.

Rather, nowadays, if you’re going to get rationally to anything like the traditional Abrahamic God, you need to keep science at arm’s length. This is one of the beauties of Anselm’s argument – it has nothing whatsoever to do with empirical evidence, it is 100% a priori, and therefore natural science simply can’t touch it. If it is wrong, its wrongness can and must be demonstrated without reference to natural science. The same seems to be true for ibn Rushd’s First Explanation cosmological argument when properly understood, though not for First Cause arguments in the usual sense. For here the question is not “what caused everything?” but “how can there be causation in the first place?” It is an explanation going much deeper. Unlike Anselm, it doesn’t necessarily get you to an omnipotent or omnibenevolent God; but it does seem to get you to something like the brahman of Śaṅkara’s or Rāmānuja’s Vedānta, a cosmic principle underlying everything, and such a principle does a lot to change the way we see the rest of the universe.

To me it’s been clear for a long time that any attempt to find God must go a priori, must not try to look in the empirical world. But looking back on Darwin’s story, it’s easier for me to realize that many people don’t see it that way. And that helps me understand contemporary views that have always struck me as a little curious. Not just the intelligent design movement, but the arch-materialistic atheists of contemporary analytic philosophy, like Paul and Patricia Churchland, who look at neuroscience and conclude that consciousness and free will don’t exist. They actually think that consciousness and free will are empirical hypotheses whose existence can be refuted with empirical evidence. Once upon a time, they, like God, might even have been exactly that.

MacIntyre notes that aitia, the Greek word usually translated simply as “cause,” also means “explanation” – as does its Arabic equivalent, illat. And Aristotle and ibn Rushd identify an aitia or illat as “that which explains, that which makes intelligible.” All of which suggests (MacIntyre doesn’t go quite this far) that we should render these phenomena as the “four explanations,” not the “four causes.” Then suddenly it makes sense that only one of these four (the efficient cause, the agency that brought a thing about) sounds like a cause to us – it’s the only one that is a cause in the way we understand the term. An “efficient cause” is just a cause; then there are formal, material and final explanations.

So to explain something means to be able to answer four questions about it: its form (what it is), its matter (what it’s made of), its cause (in a conventional sense), and its purpose (what it’s for). I don’t know if I think that these questions are exhaustive of explanation, but it seems reasonable enough to propose them as the questions one must ask of a thing in order to understand it. Understood this way, Aristotle now makes a lot more sense to me.

But perhaps more importantly, with this reading, I gain a new respect for the “First Cause” argument for God’s existence – with God now being understood as the First Explanation, not the First Cause. Rather, when we offer explanations of anything, those explanations in turn need explaining. Suppose we’re trying to explain a table in front of us. We ask:
What is it? It’s a table – but then what’s a table?
What is it made of? Wood – but then what is wood made of?
What produced it? A factory – but then what produced the factory?
What’s it for? Putting stuff on top of it – but then what’s the purpose of putting stuff on top of it?

Each such “but then” question can be answered, but the answer leads to a further question. Does this series of questions ever end? Aristotle and ibn Rushd, according to MacIntyre, consider the possibility that the series is simply infinite, that the explanations never stop. But if that’s the case, if there is an infinite chain of explanations, the infinite chain itself still needs to be explained. And explaining the series “can terminate only with a being, not itself a member of the series, which makes it the case that this particular series exists.” (MacIntyre, p. 53) That being must be a necessary being, not contingent or dependent on anything else; it must also be unchanging, and therefore immaterial. This much comes from Aristotle; ibn Rushd then identifies the being with the Abrahamic, monotheistic God.

Does this argument work? I’m skeptical, at the least. But here’s the reason I’m excited by all this: as with Anselm’s God, if this God exists, he (or she?) matters. He’s no longer just an empty First Cause, an ethically neutral Divine Watchmaker that creates the world and then wanders off to have a beer. He’s also the first formal and material explanation – so that in more than one sense, everything ultimately is God. More than that, he’s the first final explanation – so that God is the purpose of everything too. I doubt that all this is true. But if it were true, it would really matter – and that makes it worth investigating.