In Chapter 7 of “Where the Conflict Really Lies”, Alvin Plantinga advances the fine-tuning argument (FTA). FTA argues that since the conditions required for life as we know it are exacting, and we happen to be in a universe in which those conditions exist, this indicates a designer that set those conditions.
The main objection to the fine-tuning argument is the anthropic objection, which states that, well, of course things look fine-tuned, because we exist. This involves the observer selection principle: we can only observe fine-tuning because it is required for us to be here. If it was otherwise, we wouldn’t observe it.
Plantinga replies by pointing out that just because this is the case, it doesn’t mean that fine-tuning can’t say anything about how we got here. FTA is a question not just of circumstantial alternatives but of intentional intervention which he claims carries a greater probability.
However I think the main point of the anthropic objection is that we can’t discover any purpose for such tuning merely through reverse engineering, because we will see it in terms biased to our own existence. Theistic FTA works backward from the way things are (a finely-tuned universe) to argue for intelligent design. It’s like assuming a frozen lake you run across was made that way so you can ice skate. Or that a good sledding hill was explicitly made so you could sled. Or that oil deposits formed so that mankind could drive SUVs in the 21st century. It’s a non-sequitur to say these things were made for those purposes, even though they serve these purposes quite well.
We don’t make those kind of arguments about frozen lakes and oil deposits and snow covered, steep hills because it is obvious that natural processes just happened to work in our favor. More to the point, the existing use and purposes of snowy hills, frozen lakes, and oil deposits built upon natural phenomena that were not designed for those functions.
Just like we assume the natural processes occurring today were the driving force behind natural selection, so we, as a corollary, understand the emergence of life to be contingent on the natural forces that guided natural selection. Which is to say, that natural selection proceeded on the basis of those characteristics of the universe that are said to be fine-tuned. It is no wonder then, that the outcome of natural selection comports very nicely with how the universe is. Put simply, natural selection fine-tuned life for the universe, rather than the other way around.
Natural selection could have done so even if the characteristics of the universe were different than what they happen to be. The variables would have been different and the outcomes would have been different, but the universe, in that different state, would seem fine-tuned to “life”, courtesy of natural selection.
It should be pointed out, that although natural selection may proceed under the different physical laws of an alternate universe or the different chemistries of other planets, it is not a given when or if the process of natural selection begins. The particular tuning of the universe does not automatically result in life. To me this is another argument against FTA.
Plantinga offers a poker analogy, whereby he claims that, as the circumstances for life come into place, it becomes more and more exceptional that this is so, much like a poker player playing several very high valued hands in a row is exceptional. However this poker analogy doesn’t work. A succession of high valued hands is only exceptional if the hands are known to be valuable. Within the paradigm of unguided natural selection, the characteristics of the universe that we might consider fine-tuned were not understood to be “valuable hands” yet, until natural selection produced life favorable to those characteristics.
At this point the whole fine-tuning argument breaks down when you realize that FTA primarily deals with the probabilities of the universe having specific characteristics. For if we see that the characteristics in question are not, on a perfectly unbiased and objective level, necessarily favorable to anything specific at their instantiation, then the probability of the universe being fine-tuned is irrelevant (to the theist anyway), and the probability of natural selection is really the whole question. (I’ve already defended that earlier.)
Of course, Plantinga has (prematurely) dispensed with unguided natural selection by this point in the book.
Another response to the fine-tuning argument is the many universe argument. Given what we know about the big bang and the expansion and contraction of the universe, it seems that there are many universes, if not parallel with each other, than at least in succession. The big bang results in a universe with specific characteristics, which then exists for a time and collapses on itself, resulting in another big bang and a new universe with new characteristics. I think of it like a string of pearls, each pearl representing a universe. Given then, countless numbers of universes, it isn’t improbable that at least one of them would have the conditions our universe has.
Plantinga’s answer is that this doesn’t answer the probability that OUR universe had these characteristics, out of all of them. The problem with this reply is that “our universe” has no meaning in this context. Every universe belongs to whatever life-forms find themselves in it; the fact of adaptation through natural selection says nothing about how special our universe is, and much more about how ordinary it is. That fact that the universe happens to be “ours” doesn’t make it special. It doesn’t make it rarer or less likely. Unless you are a theist that believes god has made man for a special purpose and importance.
It is this last bit where Plantinga allows some of his “theist evidence base” to play a role in his argumentation. Of course, as we discussed in the last chapter, any “theist evidence base” is making a ton of assumptions, and he makes assumptions here. In arguing against the many universe argument, he says that the existence of god makes the fine-tuning argument more likely, because god would be interested in creating life. This is an assumption; why is god interested in creating life? Why would he care or take notice at all? As I said earlier, perhaps our universe is like a splotch of mold in god’s backyard that he would surely destroy if he gave us any attention at all.
One of the major corroborating arguments against fine-tuning and for natural selection fine-tuning life to the universe is the lack of optimization. The existence of life is a messy affair. Natural selection has surely adapted life to the universe in certain places but not optimized it. A designer would optimize. Natural processes merely adapt, and unoptimized adaptation is exactly what we see.
If god had a hand in fine-tuning the universe or guiding evolution, he did a sloppy job.