There’s much to admire about Sean Carroll. Obviously, he has an extraordinary intellect. His remarkable communication skills, and his infectious enthusiasm for physics, were clearly evidenced in his debate with William Lane Craig. Carroll has graciously, yet carefully, distanced himself from New Atheists. He does not regard theists as “the enemy” and acknowledges that he might learn something from religious traditions. Yet he remains firm in his atheism. After his debate with Craig he wrote:
It is true that Carroll did a wonderful job of explaining why many scientists think that theism is undermined by modern science; unfortunately, while his arguments give some substance to the prejudices of the Western academy, they remain unpersuasive.
By his own account, one of Carroll’s central arguments was that:
[T]heism is not taken seriously in professional cosmological circles because it is hopelessly ill-defined (no matter what happens in the universe, you can argue that God would have wanted it that way).
Now anyone who has waded through articles in analytical philosophy of religion will be surprised at Carroll’s claim that theism is “hopelessly ill defined”. A great deal of effort has been expended to clarify the meaning of God and exploring the precise nature of properties like omniscience.
However, Carroll’s point seems to be that theism lacks the mathematical precision of a cosmological model. If so, he has made a significant, and rather obvious, mistake: we are comparing the rationality of naturalism and theism, neither of which is a scientific model. Naturalism and theism are worldviews. Each has a scope much wider and deeper than any scientific model or theory. For example, each asks questions like: “why does the observable world behave with such law-like regularity?”; “why can we describe the world using mathematical models?”; “is there more to the world than the quantifiable and observable?” Simply asking these questions reveals that they cannot be answered with a mathematical model.
Indeed, naturalism is notoriously difficult to define. At its roots it contends that “nature” is all that exists. Beyond that, things get murkier. What exactly do we mean by “nature”? Can a naturalist believe that consciousness is an emergent state, radically unlike anything that exists in physics or biology? Can naturalism allow that moral and aesthetic values exist in some Platonic realm? The jury is out. Barry Stroud has written:
Naturalism seems to me …rather like “World Peace”. Almost everyone swears allegiance to it , and is willing to march under its banner. But disputes can still break out about what is appropriate or acceptable to do in the name of that slogan. And once you start specifying concretely exactly what it involves and how to achieve it, it becomes increasingly difficult to reach and to sustain a consistent and exclusive “naturalism”” (Quoted in Naturalism (2008) Goetz and Taliaferro, Grand Rapids:Eerdmans, p.6)
Carroll’s speech implies that he is a strict naturalist – even denying the reality of causality because it does not appear in physicists’ equations. Strict naturalists believe some version of physicalism – that reality is ultimately physical and everything can be explained in terms of physical parts (be they particles or fields of force or whatever) and their interactions. Now Carroll believes that: “naturalism has pulled so far ahead of theism in the intellectual race to best model our world: because it plays by rules and provides real explanations for why the world is this way rather than that way.” There are at least three problems here.
First, Carroll is conflating naturalism with the scientific method. But, as we have noted naturalism and theism are not scientific theories: they are worldviews which attempt to make sense of the universe taken as a whole rather than offering scientific explanations of items within it. Science presupposes a regular universe governed by laws. Worldviews attempt to explain why such a universe exists; worldviews must also explain (or explain away) morality, consciousness, free-will and aesthetics; they should provide wisdom to live within our world.
It is not at all obvious that science is more compatible with naturalism that theism: as a matter of historical fact, science “grew up” in a theistic culture and theism played an important part in its development. So naturalists cannot claim the scientific method as their own (any more than theists can).
Second: Carroll’s criticisms of theism’s explanatory power seem far too restrictive to be sensible.
At times, Carroll seems to assume that the best explanations are expressed in mathematical models and that the best hypotheses will make predictions which are mathematically measureable and quantifiable. He points to a few instances of fine-tuning which he believes are not predicted by theism; he seems to think that these disconfirm theism. Carroll insists that theistic responses to such counter-evidence: “come at a price: they imply a notion of theism so flexible that it becomes completely ill-defined. That’s the real problem.”
The problem is that many excellent explanations do not satisfy Carroll’s criteria. Evolution by natural selection does not make precise predictions for many features of life on Earth that it is nevertheless taken to explain. For example, most theorists agree that there is some degree of contingency in the history of life on Earth[i]. If this is right, then evolution does not predict that humans would come into existence given the early history of life on Earth. However, there is clearly a scientific consensus that evolution provides a good explanation of the existence of humans.
Or take two examples from outside science. An historian can be confident that Lee Harvey Oswald is responsible for the shots that killed JFK; he can also be confident that Hitler is responsible for the holocaust. Conspiracy theorists and Holocaust deniers can point to all sorts of facts that do not fit neatly with either explanation. For example, some witnesses put a second shooter on the “grassy knoll” in Dealey Plaza; we do not have a written order from Hitler commanding the holocaust. But historians have plausible explanations for these facts.
When assessing a world-view, then, it seems reasonable to allow room for some “apologetic moves” to deal with troublesome data. Theists have to offer defences against the problem of evil. We do not believe that it presents enough evidence to defeat theism, but we have to justify that belief with arguments. Indeed, the fact that it presents us with evidence against theism, and the fact that there is an acknowledged “problem of evil”, shows that theism is not infinitely flexible.
Third, we must ask: what evidence, exactly, does Carroll’s physicalism predict?
Physicalists – like everyone else – have discovered an ordered, comprehensible universe. But that does not mean that physicalism explains or predicts such a universe. There is no good reason to expect an un-designed and purposeless universe to exhibit order, structure and regularity. Before physicalists explain the finely tuned constants they must explain why our universe is governed by laws at all. So some physicalists have tried to use physical infinites to account for the regularity of our universe.
If everything that can physically happen does happen somewhere in an infinite universe, then it is not surprising that one region follows law-like rules. But this sort of infinitely large universe will contain “little islands of order” that assemble purely by chance. Many of these islands will have observers that have assembled by chance. It will contain many such observers in various non-fine-tuned regions; many more than exist in one finely tuned universe. So the existence of observers is explained.
However, these “little islands” of order will not exist for very long, and will be surrounded by an ocean of disorder. That’s not what we observe. We live in community of other rational observers (humans) with other embodied beings (animals) in a cosmos of exquisite beauty and order. These are not the observations that this sort of multiverse theory would predict – it is much more likely that we would observe a “little island” of order and an ocean of disorder. So physicalism simply does not predict anything like the order which we observe.
Perhaps multiverses can be used to explain away some apparent design: but they cannot explain why multiverses obey the laws of nature; nor can they explain why multiverses can be rationally comprehended by finite observers. Furthermore, there are other features of our experience which are mysterious on physicalism. If reality is ultimately physical, then consciousness is rather surprising to say the very least. Moral facts will have to be explained away as illusions or utilitarian functions. As a worldview physicalism struggles to account for the evidence; indeed, we wonder what else we would have to do to falsify it.
[i] Even Conway-Morris does not believe that a species which resembles homo sapiens sapiens in every respect is inevitable