The Fine Tuning Argument--What's the Big Deal?
In his recent article for the Secular Web, "An Atheist Defends the Design Argument," Toby Wardman argues that the fine-tuning version of the design argument is not as weak as many secular thinkers suppose. I've never thought that fine-tuning arguments carry much weight, so when smart people claim that there is really some substance in this line of reasoning, it always surprises me and makes me wonder if I've missed something. Below is my attempt to convince myself--and you the reader--that I haven't.
The fine-tuning argument springs from the observation that the various basic characteristics of the universe allow intelligent life to arise and persist, and the fact that we can at least conceive of universes with characteristics that wouldn't allow for intelligent life. Since, perhaps, we can imagine many more sets of physical laws that would be incompatible with the existence of sentience than sets that would be compatible, the apparent fine-tuning of our universe is something that needs explaining.
The theologically-inclined conclude that the best explanation for the happy state of affairs in our world is a god who purposefully designed a cosmic habitat for us. As arguments for god go, fine-tuning is pretty rarified and bloodless, which may in part explain its appeal for certain otherwise sensible people. The argument accepts wholesale the findings of science, proposing only that some sort of creator-god equivalent might help to explain the origin of our familiar laws of nature, which currently operate in a strictly mechanical fashion.
The fine-tuning argument normally comes equipped with a long list of constants from physics and cosmology that supposedly couldn't have varied by much if our universe was to be hospitable to advanced organisms. There will also be one or more analogies about gambling, intended to drive home the point that the odds of getting a friendly universe by chance are abysmal. But these sorts of details and embellishments are peripheral, and it is the core of the fine-tuning argument that bothers me. I'm still left wondering how anyone can draw deep conclusions about the nature of reality from the observations that:
It has been proposed that the fine-tuning argument would fail if it turned out that our familiar physical constants were in fact likely or inevitable, perhaps because of some higher-order, but still-impersonal laws of nature. Such speculations are reasonable, given that we have no idea how physical constants might be chosen by a natural process--or by an intelligent designer, for that matter. In terms of the usual casino-analogy, we don't actually know what cosmic game of chance we played, what the odds were, whether we won anything, or if there really was a casino.
However, as Wardman points out, a fine-tuning enthusiast could start asking awkward questions about why the higher-order laws should favor certain types of universes. In response, a secular philosopher might suggest a third level of constraints imposed by even more fundamental physical principles. And so on. The resulting infinite regression wouldn't be very satisfying to anyone, but perhaps that's the best that modern design-argument partisans can hope for.
But let us assume now, for the sake of the discussion, that our universe has been shown to be fine-tuned, after all. A question immediately springs to mind: fine-tuned to do what? Produce self-aware organisms who study philosophy and physics, purchase consumer-goods, and maybe go to church once in a while, obviously? Or maybe it isn't so obvious. Right here on our own planet, species of insect outnumber species of philosophical primate(s) by millions to one, and because of the basic workings of ecology, annual production of plant biomass must always be vastly greater than the production of human biomass. In our solar system, most of the material for planets is tied up in gas giants, which probably can't support any form of life. The pattern continues on up to the scale of the universe as a whole, which consists (to a close approximation) entirely of empty space thinly contaminated with hydrogen atoms.
One could pursue this game indefinitely, coming up with an endless list of "Things the Universe is Fine-tuned to Do." "Spawning intelligent life" is lost in an ocean of other possibilities, somewhere between "separating iron/nickel alloy from silicate rocks" and "sphinx moth pollination of orchids." None of this is fatal to the classic fine-tuning argument, though it is clear that if you play with the argument's assumptions, it starts to suggest deities with some peculiar or disturbing motivations. And these alternative deities are legion.
The ultimate flaw in the heart of the fine-tuning argument becomes obvious, I think, when we look at it from a different perspective. The original version claims that, in some sense, we should be surprised that a life-friendly universe could originate without help from outside. However, precisely the opposite can be demonstrated if we compare the expected probabilities of observing a habitable universe, under the competing hypotheses of natural origin versus designed origin.
Under the hypothesis of a natural origin, the probability that we will observe laws of nature that allow sentient life to evolve and persist is 100%. Disregarding the nonscientific ideas of creationists (a whole other can of worms), the laws of nature that govern our world are of this type. Under the hypothesis of a designer universe, it's not obvious how we'd arrive at the exact probability of observing life-friendly laws, but it could very well be less than 100%. It could, in fact, be 0%, depending upon the unknowable characteristics of whatever hypothetical superbeing is out there, slapping universes together. Any transcendental entity that is able to create the laws of nature from scratch might also be willing and able to bend those laws enough to allow life to exist, even in a universe that is, on a basic level, hostile. I see no way around the need to account for the possibility of uninhabitable universes where consciousness is sustained by divine providence.
Given what we know about the world we live in, the probability of getting a universe like ours from a natural cause is 100%, while we must estimate the probability from a designed origin as being less than 100%. This inverted fine-tuning argument is, like the original version, probabilistic in nature. So, while it by no means disproves the existence of a divine creator, it neatly cancels fine-tuning arguments in favor of such entities. It also seems to cast doubt equally upon the infinite hoards of weird parallel creator-gods that are suggested by modifications of the original fine tuning argument.
So farewell, Xjluvihk, God of Selenium Nucleosynthesis! We hardly knew you.
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