Read Where the Conflict Really Lies: Science, Religion, and Naturalism Online
Authors: Alvin Plantinga
Tags: #Non-Fiction, #Biology, #Religious Studies, #Science, #Scientism, #Philosophy, #21st Century, #Philosophy of Religion, #Religion, #v.5, #Amazon.com, #Retail, #Philosophy of Science
So far we have seen that there is indeed conflict between Christian belief and at least some purported scientific theories, in particular in the areas of evolutionary psychology and historical Biblical scholarship. I went on to argue, however, that—due to the difference between Christian and scientific evidence bases—this conflict is superficial; it doesn’t as such tend to provide a defeater for Christian belief. It is now time to turn to concord. Now one sort of concord would be illustrated by support for theistic belief offered by science. I’ve argued that science doesn’t conflict with Christian belief: can we go further, and say science offers positive support for it? That is the question for the next couple of chapters. How could science do a thing like that? One way would be as follows: scientific discoveries provide premises for good arguments for the existence of God. And indeed two kinds of arguments of this sort have been suggested, both connected in one way
or another with intelligent design. First, there are the “fine-tuning” arguments for theism; scientific discoveries in physics and astronomy about the structure of the universe offer the premises for a theistic argument. Secondly, there are arguments from biology, arguments involving the nature and character of the living beings our world displays. This chapter will examine fine-tuning arguments. The next will do the same for those biological arguments, and go on to propose and examine a different way in which these phenomena could support theism.
I FINE-TUNING
In the epigraph at the beginning of this chapter, Isaac Newton, often said to be the greatest scientist the world has so far produced, proposes that “this most beautiful system of the sun, planets and comets, could only proceed from the counsel and dominion of an intelligent and powerful being.” Going back to the late sixties and early seventies of the 20th century and continuing to the present, there has been a remarkable burst of support for Newton’s suggestion, starting from the so-called fine-tuning in cosmology. Astrophysicists and others have noted that several of the basic physical constants—the velocity of light, the strength of the gravitational force, and of the strong and weak nuclear forces—must fall within very narrow limits if intelligent life of our kind is to develop.
Thus Brandon Carr and Martin Rees:
The basic features of galaxies, stars, planets and the everyday world are essentially determined by a few microphysical constants and by the effects of gravitation…. several aspects of our Universe—some of which seem to be prerequisites for the
evolution of any form of life—depend rather delicately on apparent ‘coincidences’ among the physical constants.
2
For example, if the force of gravity were even slightly stronger, all stars would be blue giants; if even slightly weaker, all would be red dwarfs; in neither case could life have developed.
3
The same goes for the weak and strong nuclear forces; if either had been even slightly different, life, at any rate life even remotely similar to the sort we have, could probably not have developed.
Even more interesting in this connection is the so-called
flatness
problem: the existence of life also seems to depend very delicately upon the rate at which the universe is expanding. Thus Stephen Hawking says that “reduction of the rate of expansion by one part in 10
12
at the time when the temperature of the Universe was 10
10
K would have resulted in the Universe starting to recollapse when its radius was only 1/3000 of the present value and the temperature was still 10,000 deg”—much too warm for comfort.
4
Hawking concludes that life is possible only because the universe is expanding at just the rate required to avoid recollapse. At an earlier time, the fine-tuning had to be even more remarkable:
We know that there has to have been a very close balance between the competing effect of explosive expansion and gravitational contraction which, at the very earliest epoch about which we can even pretend to speak (called the Planck time, 10
-43
sec. after the big bang), would have corresponded to the incredible degree of accuracy represented by a deviation in their ratio from unity by only one part in 10 to the sixtieth.
5
These are striking facts. One sympathizes with Paul Davies: “the fact that these relations are necessary for our existence is one of the most fascinating discoveries of modern science.”
6
Then in 1986 John Barrow and Frank Tipler’s big book
The Anthropic Cosmological Principle
emerged from the press, provoking a veritable flood of books and articles on fine-tuning.
7
One reaction to these apparently enormous coincidences is to claim that none of this ought to be seen as requiring explanation: after all, no matter how things had been, it would have been exceedingly improbable that they be that particular way. Appropriately taken, this point is perhaps right; but how is it relevant? We are playing poker; each time I deal I get four aces and one wild card; you get suspicious; I try to allay your suspicions by pointing out that my getting these cards each time I deal is no less probable than any other equally specific distribution over the relevant
number of deals. Would that explanation play in Dodge City, or Tombstone?
8
Another reaction is to see them as substantiating the theistic claim that the universe has been created by a personal God and as offering the material for a properly restrained theistic argument: the fine-tuning argument (FTA).
9
In addition to the relatively informal expositions of such arguments by John Polkinghorne and others, there are a number of recent and fuller expositions: for example, Roger White’s “Fine-Tuning and Multiple Universes,” William Lane Craig’s “Design and the Anthropic Fine-Tuning of the Universe,” Richard Swinburne’s “Argument from the Fine-Tuning of the Universe” and “The Argument to God from Fine-Tuning Reassessed,” and Robin Collins’s “A Scientific Argument for the Existence of God: the Fine-Tuning Design Argument” along with his “The Teleological Argument: an Exploration of the Fine-Tuning of the Universe” (perhaps the deepest and most technically competent presentation of the argument).
10
In a detailed and technically informed piece, Collins points out that many of the claims made for a given example of fine-tuning are at best problematic (for example, a line of reasoning involving the effect of an increase in the strength of the strong nuclear force endorsed by several prominent writers, and a claim about gravity proposed by Martin Rees).
11
He also notes that in several important cases, we have solid evidence only for “one-sided” fine-tuning. Two-sided fine-tuning occurs when the value of a parameter (the strength of gravity, for example) falls within a life-permitting range, and the life-permitting range is small compared to the total range within which that parameter could fall. One-sided fine-tuning occurs when we know one edge of the life-permitting range, but don’t know the other, and the actual value of the parameter in question is close to the known edge; Collins argues that one-sided fine-turning will do about as well as two-sided. He then presents six detailed and, as far as present knowledge goes, solid examples of fine-tuning, which he explains in illuminating detail. These involve the cosmological constant, the strong and electromagnetic forces, carbon production in stars, the proton/neutron difference, the weak force, and gravity.
12
The degree of fine-tuning in these cases ranges from 1 part in 10 to one part in 10
53
.
We may think of these cases in terms of a set of dials: here we have six dials that must be tuned (in order for life to be permitted). In the most moderate case, the dial has to be tuned to a value somewhere in a range that is one-tenth the total range; in the most exacting case, the dial has to be tuned, with incredible precision, to a point in a range that is 10
53
of the total range. If we think of these cases of fine-tuning in terms of probability, then the probability on chance that the first dial will be properly tuned is about .1, and that of the second 10
-53
. Assuming the values of these parameters are independent of each other, the fine-tuning is of course multiplicative: the probability (on chance) that all six of the dials will be tuned to life-permitting widths is less than 10
-100
. Now of course these figures are not totally secure, and they are also just approximations. Also, it isn’t known that the values of these parameters
are
independent. On the other hand, there are many more proposed examples of fine-tuning, some of them with numerical values attached, and others merely qualitative.
13
On balance, the
sensible conclusion seems to be that there is indeed an enormous amount of fine-tuning, although the precise amount isn’t known, and it is possible to quarrel with many of the specific examples proposed.
So several of the cosmological constants are fine-tuned; how do we turn this into an argument for theism? The basic idea is that such fine-tuning is not at all surprising or improbable on theism: God presumably would want there to be life, and indeed intelligent life with which (whom) to communicate and share love. Of course this life could take many different forms (indeed, perhaps it
has
taken many forms). But it doesn’t seem at all improbable that God would want to create life, both human life and life of other sorts; and if he wanted to create human life in a universe at all like ours, he would have been obliged to fine-tune the constants. On the other hand, on the atheistic hypothesis according to which these constants have their values by chance (that is, those values are not the result of anyone’s choice or intention) it is exceedingly improbable that they would be fine-tuned for life. This seems to offer support for theism: given theism, fine-tuning is not at all improbable; given atheism, it is; therefore theism is to be preferred to atheism.
II OBJECTIONS
Naturally enough there are objections to the FTA; I’ll consider four. One of the most interesting begins with the
anthropic principle
, which is exceedingly hard to understand and comes in several varieties but (in the version that makes most sense) points out that a necessary condition of anyone observing these values of the constants is that those constants have very nearly the values they
do
have.
14
We are here to observe these constants only because they have the values they do have; if the universe were not fine-tuned, we wouldn’t be here to note that fact.
15
This seems right, but how is it an objection to the FTA? It is still puzzling that these values should have been just as they are, and it still seems that this fact cries out for explanation. It’s no explanation to point out that these constants have to be fine-tuned for us to observe that they are fine-tuned—anymore than I can “explain” the fact that God decided to create me (instead of passing me over in favor of someone else) by pointing out that if God had not thus decided, I wouldn’t be here to raise the question. According to Elliott Sober, the anthropic criticism is the “standard criticism” of the FTA; but exactly how do we get an objection to the FTA out of the fact that it’s impossible that we should have observed that the universe is not fine-tuned?
16
The problem is supposed to be that with respect to our evidence here (that the universe is fine-tuned) there is an “observational selection effect” (OSE): we are arguing that the universe is fine-tuned, but it isn’t possible that we should observe that it is
not
fine-tuned. We could not have failed to have the evidence we do in fact have; we could not instead have observed that the universe is
not
fine-tuned; and this fact is supposed to invalidate the argument.
Many arguments that involve an observational selection effect are clearly mistaken. So, for example, suppose I propose a straightforward inductive argument for the conclusion that all amoebae are within one inch of a microscope. I point out that all
observed
amoebae have been
within one inch of a microscope; reasoning in the ordinary inductive way, I conclude that
all
amoebae are within one inch of a microscope. Here there is an obvious OSE: even if there were amoebae that were not within an inch of a microscope, I wouldn’t be able to observe them. As a result, my sample class (amoebae I have observed) is such that it couldn’t have contained a counterexample to my conclusion even if there were one; there is excellent reason, therefore, to doubt that the sample class is representative; and this ruins the argument. Similarly for the inductive argument for idealism, the idea that there aren’t any unobserved physical objects. All observed physical objects have been observed (naturally enough); therefore probably all physical objects are observed, and there aren’t any unobserved physical objects.
These arguments are obviously crazy, and the craziness results from the OSE they involve. But the FTA isn’t of the same form. These crazy arguments are efforts to determine the composition of a certain class of objects: what proportion of amoebae are within an inch of a microscope? What proportion of physical objects have been observed? The method of sampling involved, however, guarantees that the sample will contain a certain proportion of amoebae with the property of being observed (in this case, 100 percent) no matter what the composition of the whole class of amoebae. The FTA isn’t an argument of this form, however. To be of the same form, the argument would have to go as follows:
All observed universes are fine-tuned.
Therefore,
Probably all universes are fine-tuned.