March 23, 2008
Design from Fine-Tuning
The fine-tuning argument is one of the primary arguments Dr. Craig offers as evidence for God’s existence. Science has shown that intelligent life could not exist in our universe apart from an extremely precise set of initial conditions that are unlikely to have occurred by chance. Therefore one may conclude that the universe was designed for life. In this question, Dr. Craig responds to claims made by atheist Richard Carrier seeking to debunk the fine-tuning argument. He rebuts Carrier’s assertion that a Theory of Everything would make fine-tuning inevitable and argues that even positing multiple universes does not weaken the implication of a cosmic Designer.
Hi, Dr. Craig you’re my favorite Christian philosopher. From listening to your lectures and audio lessons you’re a firm believer that design is the simplest explanation for the fine tuning of the universe. I ran into an article by Richard Carrier “debunking” the fine tuning argument, in a response to James Hannam (bede.org.uk), Richard responded with this,
Hannam has failed to show that it is even possible for one constant to change while the others remain the same. For altering one constant may irrevocably alter another, greatly modifying any conclusion we can draw from modeling possible universes. Thus, just as Hannam warns against arguments based on the improbability of life forming naturally on the grounds that science might discover the natural means of forming life, so should he be warned against using a Fine Tuning argument based on the assumption of independent constants when science may soon discover, for example, a Grand Unified Theory or a Theory of Everything that shows how all the constants are causally related to each other.
Constants of nature and arbitrary quantities are a big part of the fine tuning argument, how should we as Christians who use this argument respond to a charge like this? From the same article Richard throws this argument out about constants,
in the 19th century there were some twenty to forty ‘physical constants,’ there are now only around six. All the others have over the intervening century been proven to be causally determined by more fundamental factors. For example, the boiling point of water was once considered a physical constant, but is now known to be the result of quantum mechanical laws, and thus could not be any different than it is without also changing the laws of quantum mechanics. Since the trend has been steadily in this direction, it is reasonable to predict that all the constants will end up being explained in this fashion. For example, since Planck’s constant defines the smallest possible unit of space and time, it may be the case that the speed of light is inexorably tied to Planck’s constant, so that one cannot be changed without altering the other.
Is it possible for all the constants to be explained away by some scientific theory? Also, how would you respond to this objection to Christian theism through multiple universes?
Again unlike theism, “multiple universes” has another inherent merit that Hannam does not consider: we know that a universe exists, and Hannam himself is agreeing that different universes are in principle possible, so we have a ready explanation of what is unknown by appealing to a known entity--that universes exist. In contrast, the theist tries to explain the same unknown by appealing to a completely unknown entity, that is, an entity that has never been scientifically observed and could well not exist at all. How does it make more sense to appeal to such a strange and unobserved entity when we can explain the same things by appealing to an entity that everyone agrees exists? Since a universe exists, and other universes are possible, isn’t it plausible that other universes exist? Certainly, we cannot know they do. But we cannot know they do not and thus any argument for God that supposes they do not is an argument from ignorance. Once again, agnosticism is the only justified outcome of this line of reasoning.
Does the mere fact that our universe exist make the multiple universe hypothesis more credible than the God hypothesis just because in Richards word “God is an unknown entity, who cannot be scientifically observed?”
As a guy who uses the fine tuning argument a lot it would be helpful for me as well as other Christians to have answers to these possible objections when we witness in our personal lives.
God bless you Dr Craig,
Fine tuning argument
While I’m not familiar with the exchange between Carrier and Hannam that you cite, Chris, permit me to comment on the issues raised by your question concerning the fine-tuning argument.
That the universe is fine-tuned for the existence of intelligent life is a pretty solidly established fact and ought not to be a subject of controversy. By “fine-tuning” one does not mean “designed” but simply that the fundamental constants and quantities of nature fall into an exquisitely narrow range of values which render our universe life-permitting. Were these constants and quantities to be altered by even a hair’s breadth, the delicate balance would be upset and life could not exist.
Carrier is mistaken when he asserts that there are only about six physical constants in contemporary physics; on the contrary, the standard model of particle physics involves a couple dozen or so. The figure six may be derived from Sir Martin Rees’ book Just Six Numbers (New York: Basic Books, 2000), in which he focuses attention on six of these constants which must be finely tuned for our existence. But this is just a selection of the constants there are, and new constants, unknown in the 19th century, like the so-called cosmological constant, which must be fine-tuned to one part in 10120 in order for life to exist, are being discovered as physics advances.
In addition to these constants, there are also the arbitrary quantities which serve as boundary conditions on which the laws of nature operate, such as the level of entropy in the early universe, which are also fine-tuned for life. If one may speak of a pattern, it would be that fine-tuning, like a stubborn bump in the carpet, just won’t go away: when it is suppressed in one place, it pops up in another. Moreover, although some of the constants may be related so that a change in the value of one will upset the value another, others of the constants, not to mention the boundary conditions, are not interdependent in this way. In any case, there’s no reason at all to suspect so happy a coincidence that such changes would exactly compensate for one another so that in the aftermath of such an alteration life could still exist. It appears that the fine-tuning argument is here to stay.
Fine tuning argument – How can one account for the delicate balance of the cosmos?
Now there are only three ways to account for this remarkable fine-tuning of the cosmos for intelligent life: physical necessity, chance, or design. The contemporary debate is over which of these is the best explanation of the observed fine-tuning. Carrier seems to prefer either of the alternatives to the fine-tuning argument’s design conclusion.
Physical necessity is the hypothesis that the constants and quantities had to have the values they do, so that the universe is of physical necessity life-permitting. Now on the face of it this alternative is extraordinarily implausible. It requires us to believe that a life-prohibiting universe is physically impossible. But surely it does seem possible. If the primordial matter and anti-matter had been differently proportioned, if the universe had expanded just a little more slowly, if the entropy of the universe were marginally greater, any of these adjustments and more would have prevented a life-permitting universe, yet all seem perfectly possible physically. The person who maintains that the universe must be life-permitting is taking a radical line which requires strong proof. But there isn’t any; this alternative is simply put forward as a bare possibility.
Fine tuning argument – The Theory of Everything fails to explain fine tuning
Sometimes physicists do speak of a yet to be discovered Theory of Everything (T.O.E.), but such nomenclature is, like so many of the colorful names given to scientific theories, quite misleading. A T.O.E. actually has the limited goal of providing a unified theory of the four fundamental forces of nature, to reduce gravity, electromagnetism, the strong force, and the weak force to one fundamental force carried by one fundamental particle. Such a theory will, we hope, explain why these four forces take the values they do, but it will not even attempt to explain literally everything.
For example, in the most promising candidate for a T.O.E. to date, super-string theory or M-Theory, the physical universe must be 11-dimensional, but why the universe should possess just that number of dimensions is not addressed by the theory. Moreover, M-Theory fails to predict uniquely the values of the constants of nature. It turns out that string theory allows a “cosmic landscape” of around 10500 different universes governed by the present laws of nature but with different values of the physical constants. Moreover, even though there may be a huge number of possible universes lying within the life-permitting region of the cosmic landscape, nevertheless that life-permitting region will be unfathomably tiny compared to the entire landscape, so that the existence of a life-permitting universe is fantastically improbable. Indeed, given the number of constants that require fine-tuning, it is far from clear that 10500 possible universes is enough to guarantee that even one life-permitting world will appear by chance in the landscape!
All this has been said with respect to the constants alone; there is still nothing to explain the arbitrary quantities put in as boundary conditions. The extraordinarily low entropy condition of the early universe would be a good example of an arbitrary quantity which seems to have just been put in at the creation as an initial condition. There is no reason to think that showing every constant and quantity to be physically necessary is anything more than a pipe-dream.
Fine tuning argument – The multiple universe hypothesis seeks lower the odds
So what about the alternative of chance? This is the “multiple universe” hypothesis mentioned by Carrier. The multiple universe hypothesis is essentially an effort on the part of partisans of chance to multiply their probabilistic resources in order to reduce the improbability of the occurrence of fine-tuning. (The more spins of the roulette wheel, the better the chances of your number coming up!) The very fact that otherwise sober scientists must resort to such a remarkable hypothesis is a sort of backhanded compliment to the design hypothesis. It shows that the fine-tuning does cry out for explanation. But is the multiple universe hypothesis as plausible as the design hypothesis?
I’m not at all impressed by Carrier’s appeal to familiarity as an argument for preferring the multiple universe hypothesis. For we have no experience whatsoever of other universes—the multiple universe hypothesis is a bold venture in metaphysical cosmology. Our familiarity with our universe does nothing to warrant the appeal to other universes as familiar entities—at least not more so than the design hypothesis. For while we are likewise not familiar with designers of universes, we certainly are familiar with minds and the products of intelligent design, so that the appeal to a designer as the best explanation of the fine-tuning is an appeal to a familiar explanatory entity. Indeed, theists have sometimes been accused of anthropomorphism in this regard!
Moreover, while we have no evidence of the existence of multiple universes, we do have independent reasons for believing in the existence of an ultramundane designer of the universe, namely, the other arguments for the existence of God, which I have defended elsewhere.
Fine tuning argument – Multiple universe hypotheses and a lethal objection
Finally, Carrier is mistaken when he opines that we cannot know that multiple universes do not exist and therefore agnosticism is the only justified conclusion. (Interesting to compare this conclusion with the frequent atheist claim that in the absence of evidence for God we should conclude that God does not exist! Do you see the inconsistency?) He is unaware of the potentially lethal objections to the multiple universe hypothesis that have been lodged by physicists like Roger Penrose of Oxford University (The Road to Reality [New York: Alfred A. Knopf, 2005], pp. 762-5). Simply stated, if our universe is but one member of an infinite world ensemble of randomly varying universes, then it is overwhelmingly more probable that we should be observing a much different universe than that which we in fact observe.
Penrose calculates that the odds of our universe’s low entropy condition obtaining by chance alone are on the order of 1:1010(123), an inconceivable number. The odds of our solar system’s being formed instantly by random collisions of particles is, on the other hand, about 1:1010(60), a vast number, but inconceivably smaller than 1010(123). Penrose calls it “chicken feed” by comparison! So if our universe were but one member of a collection of randomly ordered worlds, then it is vastly more probable that we should be observing a much smaller universe. Observable universes like that are much more plenteous in the ensemble of universes than worlds like ours and, therefore, ought to be observed by us if the universe were but one random member of an ensemble of worlds.
Or again, if our universe is but one random member of a world ensemble, then we ought to be observing highly extraordinary events, like horses’ popping into and out of existence by random collisions, or perpetual motion machines, since these are vastly more probable than all of nature’s constants and quantities falling by chance into the virtually infinitesimal life-permitting range. Since we do not have such observations, that fact strongly disconfirms the multiple universe hypothesis. Penrose concludes that multiple universe explanations are so “impotent” that it is actually “misconceived” to appeal to them to explain the special features of the universe.
Since the alternative of chance stands or falls with the multiple universe hypothesis, that alternative is seen to be very implausible. It therefore seems that the fine-tuning of the universe is plausibly due neither to physical necessity nor to chance. It follows that the fine-tuning is therefore due to design, unless the design hypothesis can be shown to be even more implausible than its competitors. On that question, see my critique of Dawkins’ objection the design inference in the Question Archive.