From Aristotelianism to Newtonian physics, relativity, quantum mechanics and string theory, cosmologists have produced ever more accurate and plausible explanations for the origin and operation of the universe. For Carroll this march of progress seems inexorable. Are we not headed for a completely naturalistic explanation of the world?
Consider, for example, the multiverse idea where instead of a single universe, there are a great many universes. This multiverse allows evolutionists to overcome the low probabilities of this world, such as the fine-tuning of nature and the evolution of life. Astronomically unlikely events don’t matter if you have an astronomical number of chances. And while the multiverse hypothesis is often criticized as a just-so story, in fact it arises from what seem to be a reasonable set of hypothetical natural laws. The inexorable march of progress continues and Carroll concludes:
Most modern cosmologists are convinced that conventional scientific progress will ultimately result in a self-contained understanding of the origin and evolution of the universe, without the need to invoke God or any other supernatural involvement.
Carroll’s thesis, it would seem, is a robust appeal to the successes of empirical science. From a scientific perspective, the world just happened, or so it appears. Any appeals to anything more than natural law is just an argument from ignorance.
But there are some flies in this Leibnizian ointment. For instance, what if there is no multiverse? For this Carroll falls back on the hypothesis that life is extremely robust. Yes, life seems to need this finely-tuned world, but who knows what other types of life there are. Carroll laments that not nearly enough credence is given to this option. Perhaps that is because it is so weak. It is not merely an argument from ignorance, it goes against what science is telling us. Yes, we certainly can’t make any firm conclusions, but the idea that life is extremely robust is not what science indicates.
Then there are those aspects of nature that are finely-tuned beyond what life requires. While fine-tuning to the requirements of life can be explained, in principle, as a result of selection in the multiverse (if there is one), what about those extremely fine-tuned parameters.
One such example is the universe’s initial entropy which is way too low. It is one part in a number that is so large it is difficult to describe. Usually with large numbers we use the exponential form. For example, for a one followed by fifty zeros, we write 10^50. But for the universe’s initial entropy, even the exponent is too large. It is, as Carroll writes, “a preposterous number,” and well beyond what is required for life.
For this problem Carroll once again appeals to our ignorance. Yes, it seems strange, but researchers are working on this problem. Perhaps they will succeed in figuring out why life would, in fact, require such an incredible level of fine-tuning.
But this is only Carroll’s warm up argument. He merely needs to show that a naturalistic account is not impossible. The strength of his argument is that god wouldn’t do it this way so, as usual, a naturalistic account is mandated.
If anything, the [excessive] tuning that characterizes the entropy of the universe is a bigger problem for the God hypothesis than for the multiverse. If the point of arranging the universe was to set the stage for the eventual evolution of intelligent life, why all the grandiose excess represented by the needlessly low entropy at early times and the universe’s hundred billion galaxies? We might wonder whether those other galaxies are spandrels – not necessary for life here on Earth, but nevertheless a side effect of the general Big Bang picture, which is the most straightforward way to make the Earth and its biosphere. This turns out not to be true; quantitatively, it’s easy to show that almost all possible histories of the universe that involve Earth as we know it don’t have any other galaxies at all. It’s unclear why God would do so much more fine-tuning of the state of the universe than seems to have been necessary.
So the excessive fine-tuning renders the multiverse impotent unless we can somehow manage to make life contingent on such a preposterous quantity. But no matter, this is really a problem for the god hypothesis. After all, such grandiose excess is capricious. If god were to create the world, he would do it to mimic selection. Evolutionists usually argue that god would not mimic selection, but when the need arises god’s role can always be reversed.
Finally there is the problem of why there is anything. If science is ultimately to provide “a self-contained understanding of the origin and evolution of the universe,” as Carroll confidently expects, then how will it explain why there is anything? Does not a beginning, according to Kalam, necessitate a cause? The answer, for Carroll, is simply “no.” Some things we simply need to understand as brute facts:
It can be difficult to respond to this kind of argument. Not because the arguments are especially persuasive, but because the ultimate answer to “We need to understand why the universe exists/continues to exist/exhibits regularities/came to be” is essentially “No we don’t.” That is unlikely to be considered a worthwhile comeback to anyone who was persuaded by the need for a meta-explanatory understanding in the first place.
Granted, it is always nice to be able to provide reasons why something is the case. Most scientists, however, suspect that the search for ultimate explanations eventually terminates in some final theory of the world, along with the phrase “and that’s just how it is.”
Here Carroll’s special pleading reaches new heights. Where naturalism can explain the world, it serves as evidence for a materialistic understanding of ultimate reality. And where naturalism is inadequate, well so what. That doesn’t matter.
The fact that “most scientists” suspect ultimate explanations will never really be ultimate does not resolve the problem; rather, it is an acknowledgment of the problem. It is simply a reflection of their intuition of the limits of science.
For evolutionists the world spontaneously arose all by itself. No amount of evidence will change that conclusion, because the conclusion is theologically mandated. Without an evolutionary account we would have to conclude that god created the world. And we can do much better than that.