Theology

I stumbled across physicist Sean Carroll's web site at Discover and found this interesting discussion of theology springing from a review of Richard Dawkins' book The God Delusion. It provides a delightful discussion of theology, history, and physics. I heartily recommend it. Here are some of the better bits from this posting on The God Conundrum:

The development of Hebrew monotheism from its polytheistic beginnings is a long and complicated story that contemporary historians only incompletely understand; see this review of a book by Mark Smith of NYU to get some flavor of current thinking. But the crucial point is that the emergence of One God was an essentially political transformation. The ancient Hebrews, surrounded by other unfriendly nations, promoted their tribal deity Yahweh to the position of the most powerful god, promising dire consequences for any backsliders who would choose to worship Ba’al or Asherah or other pretenders (as Ahab and Jezebel learned the hard way). From there, it was a short doctrinal leap (requiring only the imaginative re-interpretation of a few Scriptural passages) to declare that Yahweh was the only God out there — the well-known others weren’t merely subordinate, they were imaginary. Even in its own right, this claim was somewhat problematic, as Yahweh had to serve double duty as the God of the Hebrews and also the only god in existence. But the conception of God as some sort of being who cared about the fate of the people of Israel was relatively sustainable; none of the Prophets went around defining Yahweh as “the condition of possibility,” or even ascribing characteristics of omniscience and omnipotence to the deity.

Meanwhile, the ancient Greeks were developing monotheism for their own purposes — essentially philosophical rather than political. They had quite the robust pantheon of individual gods, but it was clear to most careful thinkers that these were closer to amusingly anthropomorphic fairy tales than to deep truths about the structure of the universe. Unsurprisingly, the monotheistic conception reached its pinnacle in the work of Aristotle. In the Metaphysics, he presented a version of what we now know as the cosmological argument for the existence of God, which (in Wikipedia’s rendering) goes something like this:
Every effect has a cause.
Nothing can cause itself.
A causal chain cannot be of infinite length.
Therefore, there must be a first cause; or, there must be something which is not an effect.

Admittedly, this is merely an informal paraphrase of the argument. But the more careful versions don’t change the essential fact that these days, the cosmological proof is completely anachronistic. Right after step one — “Every effect has a cause” — the only sensible response is “No it doesn’t.” Or at least, “What is that supposed to mean”?

To make sense of the cosmological argument, it’s important to realize that Aristotle’s metaphysics was predicated to an important extent on his physics. (Later variations by theologians from Aquinas to Leibniz don’t alter the essence of the argument.) To the ancient Greeks, the behavior of matter was teleological; earth wanted to fall down, fire wanted to rise toward the heavens. And once it reached its desired destination, it just sat there. According to Aristotle, if we want to keep an object moving we have to keep pushing it. And he’s right, of course, if we are thinking about the vast majority of macroscopic objects in our everyday world — which seems like a perfectly reasonable set of objects to think about. If you push a book along a table, and then stop pushing it, it will come to rest. If you want it to keep moving, you have to keep pushing it. That “effect” — the motion of the book — without a doubt requires a “cause” — you pushing it. It doesn’t seem like much of a leap to extend such an analysis to the entire universe, implying the existence of an ineffable, perfectly static First Cause, or Unmoved Mover.

But the God of the Judeo-Christian Bible is very far from being “Unmoved.” He’s quite the mover, actually — smiting people here, raising the dead there. All very befitting, considering his origin as a local tribal deity. But utterly incompatible with the perfect and unchanging Aristotelian notion of God.

For the past two thousand years, theology has struggled to reconcile these two apparently-conflicting conceptions of the divine, without much success. We are left with fundamentally incoherent descriptions of what God is, which deny that he “exists” in the same sense that hummingbirds and saxophones do, but nevertheless attribute to him qualities of “love” and “creativity” that conventionally belong to conscious individual beings. One might argue that it’s simply a hard problem, and our understanding is incomplete; after all, we haven’t come up with a fully satisfactory way to reconcile general relativity and quantum mechanics, either. But there is a more likely possibility: there simply is no reconciliation to be had. The reason why it’s difficult to imagine how God can be eternally perfect and also occasionally wistful is that God doesn’t exist.

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In other words, the universe runs all by itself. The planets orbit the Sun, not because anything is “causing” them to do so, but because that’s the kind of behavior that obeys Newton’s (or Einstein’s) equations governing motion in the presence of gravity. Deeply embedded as we are in this Galilean/Newtonian framework, statements like “every effect has a cause” become simply meaningless. (We won’t even bother with “A causal chain cannot be of infinite length,” which completely begs the question.) Conservation of momentum completely undermines any force the cosmological argument might ever have had. The universe, like everything in it, can very well just be, as long as its pieces continue to obey the relevant equations of motion.

Special pleading that the universe is essentially different from its constituents, and (by nature of its unique status as all that there is to the physical world) that it could not have either (1) just existed forever, nor (2) come spontaneously into existence all by itself, is groundless. The only sensible response such skepticism is “Why not?” It’s certainly true that we don’t yet know whether the universe is eternal or whether it had a beginning, and we certainly don’t understand the details of its origin. But there is absolutely no obstacle to our eventually figuring those things out, given what we already understand about physics. General relativity asserts that spacetime itself is dynamical; it can change with time, and potentially even be created from nothing, in a way that is fundamentally different from the Newtonian conception (much less the Aristotelian). And quantum mechanics describes the universe in terms of a wavefunction that assigns amplitudes to any of an infinite number of possibilities, including — crucially — spontaneous transitions, unforced by any cause. We don’t yet know how to describe the origin of the universe in purely physical terms, but someday we will — physicists are working on the problem every day.

The analogy to a penthouse apartment atop a high-rise building is quite apt. Much of the intricate architecture of modern theology is built on a foundation that conceives of God as both creator and sustainer of the world and as a friendly and loving being. But these days we know better. The Clockwork Universe of Galileo and Newton has once and for all removed the need for anything to “sustain” the universe, and the “creation” bit is something on which we are presently closing in.

In fact, although it is rarely discussed in history books, the influence of the conservation of momentum on theological practice is fairly evident. One response was a revival of Pyrrhonian skepticism, which claimed that it was simply wrong even to attempt to apply logic and rationality to questions of religion — claiming that you had “proven” the existence of God could get you accused of atheism. The other, more robust response, was a turn to natural theology and the argument from design. Even if the universe could keep going all by itself, surely its unguided meanderings would never produce something as wonderfully intricate as (for example) the human eye? The argument doesn’t hold up very well even under purely philosophical scrutiny — David Hume’s devastating take-down in Dialogues Concerning Natural Religion, interestingly, actually pre-dates William Paley’s classic statement of the argument (1779 vs. 1802). Hume, for example, points out that, even if the argument from design works, it allows us to conclude next to nothing about the nature of the Designer. Maybe it was a team? Maybe our universe is a rough first draft for a much better later universe? Or even just a mistake? (Okay, that has something going for it.)

But then, of course, Darwin’s theory of natural selection undercut the justification for the design argument just as thoroughly as classical mechanics undercut the justification for the cosmological argument. Indeed, the unpurposeful meanderings of matter in the universe can produce the wonderful intricacies of the human eye, and much else besides. Believers haven’t given up entirely; you’ll now more commonly find the argument from design placed in a cosmological context, where it is even less convincing. But for the most part, theologians have basically abandoned the project of “proving” God’s existence, which is probably a good move.

But they haven’t given up on believing in God’s existence (suitably defined), which is what drives atheists like Dawkins (and me) a little crazy. Two thousand years ago, believing in God made perfect sense; there was so much that we didn’t understand about the world, and an appeal to the divine seemed to help explain the otherwise inexplicable. Those original motivations have long since evaporated. In response, theologians have continued to alter what they mean by “God,” and struggled to reconcile the notion’s apparent internal contradictions — unwilling to take those contradictions as a signal of the fundamental incoherence of the idea.