What is Cosmological Fine-Tuning Evidence For?
A favorite argument of ID folks is that cosmological fine-tuning is evidence for the existence of God (or at least some sort of supernatural designer). The argument is essentially this: There are many properties of the universe around us that have to work out just right for intelligent life to be possible. We could consider things like the ratio of the mass of a proton to the mass of an electron, or the relative strengths of the fundamental forces of nature among other examples. Time and again we find that were the values of these constants even slightly different from what they are, then life of any coneivable sort would be impossible. Meanwhile, there is nothing in current cosmological theorizing to suggest that one particular set of constants was pe-ordained by the conditions of the Big Bang. We therefore have a probabilistic conundrum. It is asking too much of chance that sheer dumb luck could have led our universe to arrive at just the right collection of constants to make life possible. The most plausible explanation, therefore, is that an intelligent designer is lurking behind the properties of the universe as we see them.
I believe this argument is very weak. For the purposes of this blog entry, however, I will focus on just one aspect of it.
Even supporters of this argument concede that if it were shown that ours is just one of an essentially infinite collection of universes, then the probability problem goes away. The idea ia that unlikely outcomes become likely if you repeat the experiment enough times. One supporter of cosmological ID, David Heddle, expresses the issue this way:
I am in the cosmological ID camp. As you are probably aware, cosmological ID theory is based on two observations about our universe: its fine tuning and its uniqueness. Take either support beam away, and the cosmological ID house falls down.
If there is no fine tuning, then there is no evidence for design.
If our universe is not unique, i.e., if we are but one of perhaps an infinite number of parallel universes, then one can logically posit that our particular universe is fine-tuned only because if it were not, we wouldn't be here to talk about it. The multitude of universes, those that are not fine tuned, being sterile, contain no intelligence pondering why they exist in an ordinary, run of the mill cosmos.
So the question is this: Let us assume that we have three options for explaining the apparent fine tuning of the fundamental constants:
- Fine-tuning is an illusion. Things appear to be fine-tuned only because we have an imperfect understanding of all of the natural laws of the universe. Were our understanding better than it is we would realize that the values of the constants were sharply constrained by natural laws, or that quantities whose values appear to be independent of one another are actually related.
- Our universe is only one of a large number of universes, thereby making it rather easy to explain the fine-tuning of our own universe.
- The universe is the product of a supernatural intelligence that deliberately adjusted the constants to make things hospitable for life.
Which of these three explanations is the most likely?
I would argue that either of the first two possibilities is more likely than the third. Let me begin with two historical analogies.
By the nineteenth century Newton's theory of gravitation had been applied with great success to the problem of predicting the trajectories of the planets. But then it was noticed that the orbit of Uranus, then the most distant known planet, differed measurably from what Newton's laws said it should be. To explain this, some scientists of the time suggested that Newton's laws simply didn't hold as widely as was previously thought. Perhaps for planet-size bodies separated by vast distances we needed some different law to guide us. This is rather like argument one above.
Another explanation was that the odd orbit of Uranus was evidence that there was another planet beyond Uranus. Of course, with the discovery of Neptune this turned out to be the correct explanation.
As far as I know, nobody suggested that the anomalous orbit of Uranus was evidence for the intervention of a supernatural entity. Given the other options, would anyone at that time, or ours, have considered that to be the most plausible explanation?
Now for the second example. In the nineteen twenties various experiments revealed what appeared to be a violation of the principle of energy conservation at the atomic level. To explain this, many scientists of the time suggested that energy conservation simply didn't hold at the atomic level. In other words, our understanding of the natural laws of the world was imperfect.
An alternative explanation was that the apparent violation of energy conservation was actually evidence for a previously undiscovered particle. The energy of this particle would account for the apparently missing energy revealed by the experiments. Many scientists of the time regarded this as a ridiculous ad hoc hypothesis concocted merely to preserve energy conservation, but with the subseqeunt discovery of the neutrino it turned out to be correct.
Again, as far as I know nobody suggested supernatural intervention as the most plausible explanation for the missing energy.
Let's return now to the fine-tuning argument, and consider what case can be made for each of the three options I listed above.
It is almost a sure thing that our current understanding of the laws of physics is terribly imperfect. This applies all the more strongly to our understanding of the earliest moments of the universe, where the data we have to work with is minimal indeed. Since the history of science shows that nature seems to have almost limitless resources for surprising us, simple humility makes option one seem pretty plausible.
What about option two? Well, multiple universes are a logical consequence of current mainstream thinking in cosmology. As William Jeffreys put it in in his recent review of the pro-ID book The Privileged Planet, by Gonzalez and Richards:
Gonzalez and Richards's “refutation” of the MWH [Many Worlds Hypothesis] is unconvincing. It consists of a bland dismissal that an actual infinite set can exist (p 268 -- where did they learn their mathematics?) together with a claim that “we have no evidence to think that other universes exist,” a claim that happens to be false, for several reasons. One reason is that it is a prediction of the best-supported theory in cosmology, one that is strongly supported by evidence. And the second is that under that model, our own existence evidentially supports the MWH (since under that hypothesis a selection effect is involved: we can only exist in one of the very small proportion of worlds in which “the constants are right,” so our own existence implies the existence of these other worlds).
As Mark Perakh (2004) has pointed out in another context, there is nothing particularly unparsimonious about the multiverse hypothesis. For one thing, it is based on the observational fact that our own universe definitely exists, and since it does exist, it is reasonable to presume that naturalistic processes would produce other universes, just as different versions of our own. If physics can produce one universe, there is nothing in principle to prevent it from producing infinitely many. Indeed, it would be expected. By contrast, the hypothesis of an intelligent designer of universes is completely speculative; there is, as Perakh points out, not a single observational fact that points to the existence of such an entity other than ancient, conflicting legends.
Jeffrey's hits an important point here. The MWH is not an ad hoc hypothesis designed to circumvent the anthropic principle. It is something physicists have been discussing since at least the nineteen fifties, and follows from other well-supported theories of physics.
It's also a bit rich for ID folks to protest that these multiple universes can not be detected empirically. Their preferred explanation suffers from the same defect, after all. As far as I know they have never produced any evidence that God exists. And if they are inclined to say the fine-tuning itself is evidence that God exists, I reply simply that actually fine-tuning is evidence that multiple universes exist. Hence the title of this blog entry.
So option two receives support from current cosmological thinking, and does not require that we hypothesize into existence something fundamentally new. What about option three? Here there is no case to be made at all.
In fact, if we look at the products of intelligent causes that we see all around us, we would have to conclude that altering fundamental constants and bringing worlds into being are things far, far beyond anything intelligence is capable of. As far as we know (the existence of God is something we're trying to prove here, not something we are assuming), human beings possess the highest level of intelligence in the universe. But we can't do anything close to what the intelligence in ID apparently did. So we are simply making something up out of whole cloth. It is not a simple extrapolation from known examples of intelligent causation.
I don't believe anyone would choose option three as the most likely one unless they already had emotional reasons for wanting to believe in God already.
In this blog entry, David Heddle offers the following thoughts about the MWH. He is responding to the Jeffreys quote I provided above:
Jefferys is engaged in some Clinton-speak here. It is true that we have evidence to think (i.e., speculate) that other universes exist. However, we have no actual evidence that they do. No parallel universe has ever been detected, period. The fact that some current theories are consistent with parallel universe does allow one to think about them, but it is not to be confused with evidence that they exist. Theories are famous for incorrect predictions upon extension. Maybe Jefferys believes that highly successful classical electricity and magnetism is evidence for the fact that electrons will radiate and spiral into the nucleus (which is what it predicts.) He then goes on to argue that assuming the multiverse hypothesis is correct, once again disingenuously implying that actual evidence exists (this “evidence”, permit me to repeat, being that multiple universes is a prediction—and he conveniently neglects to mention that it is an untestable prediction) then, surprise surprise, Gonzalez and Richards are wrong. Woulda-coulda argument, Mr. Jefferys.
When an ID person gets that smug, it's a sure sign that he's making a really bad argument.
- I can think about the possibility of multiple universes without any physical evidence at all, thank you very much. After all, ID folks routinely think about God's wishes and desires without a shred of direct evidence for God's existence.
- If a well-supported theory has as a consequence that entity X exists, that constitutes actual evidence that X exists. It's not conclusive proof that X exists. It is not the best sort of evidence you can possibly imagine for the proposition that X exists. But it is important evidence nonetheless.
We saw that in the historical examples above. We had good evidence for the existence of Neptune on the one hand, and the neutrino on the other, simply on the grounds that their existence would allow us to preserve other well-established physical theories (Newton's laws on the one hand, energy conservation on the other). To believe otherwise is to believe that the scientists who used that sort of reasoning to look for the planet Neptune, or to find physical traces of the neutrino's presence, were behaving irrationally.
And the fact that the MWH is supported by current theories in cosmology is certainly better evidence than what can be produced for the eixstene of God, which is Heddle's preferred explanation.
- I'm afraid I can't find anything disingenuous in Jeffreys' review.
He quotes Gonzalez and Richards as claiming that we have no reason to believe that multiple worlds exists. In reply Jeffreys points out that we do have reasons for so believing. Seems clear enough.
And he does not argue that Gonzalez and Richards are wrong by assuming the MWH is right. He argues simply that the plausibility of the MWH in light of the reasons he provides shows that Gonzalez and Richards are wrong to pick the supernatural option as the most likely explanation for fine-tuning. I'm not sure what Heddle finds so complicated about that.
- Heddle wants us to believe that scientists are making unreasonable extrapolations when they say that current cosmological theories imply the reality of the MWH. That's possible, but if it is true it would simply play into option one. It would suggest that we still have an awful lot to learn about the origins of the universe.
The reasoning that leads from “The universe is fine-tuned for life,” to “God exists!” rests on a mountain of unsupported, and probably false, assumptions. You may as well simply assume that God exists and be done with it.