#82

November 10, 2008

Scepticism about the Neo-Darwinian Paradigm

Dr Craig as a fellow Christian but also one with a keen interest in science I was very disappointed by your recent podcast on the doctrine of creation. You seem to express considerable skepticism of macroevolution, which has in fact been frequently observed. Microevolution is defined simply as variation within a species whereas macroevolution is defined as variation at the level of, or above the level of, species. Speciation which is an example of this has been observed under various conditions and documented many times in the scientific literature so I was rather dismayed by you apparent readiness to emphasize the difference between the two.

I also feel that you did a very poor job in attempting to describe the state of the fossil record. The only transitional fossil that you mentioned was archaeopteryx which is not even the only such fossil in the transition from dinosaurs to birds. There are huge number of fossils showing other transitions such as those from fish to amphibians, invertebrates to fish, and also the other major transitions. We also have extremely good fossils documenting the evolution of the whale, the horse, the elephant, and of course us, homo sapiens. I feel that this form of progressive creationism that you appear to espouse makes God into some kind of meddler and bungler, constantly having to help along the process that he must have originally set in place but which was inadequate for producing everything he required it to. Some things are apparently able to evolve as he requires whereas at other stages he has to directly intervene to essentially create new creatures. This also makes the fossil record full of his mistakes, which might suggest he is not very good at what he is doing, and this is not a God that I feel comfortable worshiping. You also mention books by people such as Phillip Johnson who is not a scientist, and Michael Denton whose book was written over 20 years ago and was not well regarded by scientists even then and is now very outdated, Then there is Michael Behe, who appears to accept common ancestry among all life but seems to think that God is required to fiddle about with bacteria flagella, and this again, I feel, rather demeans the glory of his creation.

Nobody taking an objective look at the facts, such as the fossil record, existence of shared endogenous retroviruses and pseudogenes, and the fusion of human chromosome number 2, can doubt that we share a common ancestor with chimpanzees and, as this seems to be the main point of contention among evolution doubters, I can see no reason why we should not extend this line all the way back to LUCA.

I hope you can clarify your views on this, which as I say caused me considerable dismay after having enjoyed your previous podcasts.

Steve

As I explained in my exposition of the Doctrine of Creation, when it comes to questions of the origin of life and biological complexity, biblical Christians enjoy the advantage over the naturalist of being truly open to follow the evidence where it leads. Since I think, for the reasons explained in the podcast, that an evolutionary theory is compatible with the biblical account in Genesis 1, the question of biological origins is for me a straightforward scientific question: what does the evidence indicate about the means by which God brought about life and biological complexity? My honest, layman’s assessment of the evidence makes me sceptical of the neo-Darwinian account and leaves me with a probing agnosticism about the theory.

The neo-Darwinian paradigm is a synthesis of two overarching theses: the Thesis of Common Ancestry and the Thesis of Random Mutation and Natural Selection as the means of evolutionary development. The evidence for these two theses is anything but compelling; indeed, the theory involves a enormous extrapolation from evidence of very limited ranges to conclusions far beyond the evidence. We know that in science such extrapolations often fail (take, for example, Albert Einstein’s failed attempt to extrapolate a general principle of relativity that would relativize acceleration and rotational motion just as his special principle had successfully relativized uniform motion). Such failures make very pressing the question: how do we know that the extrapolation from local instances of evolutionary development to the grand story of evolution is a valid one?

Let’s first get our terminology clear. You misconstrue the notion of microevolution when you equate it with the claim of the fixity of species. Steve, not even six day creationists, not to speak of progressive creationists, limit microevolutionary change to variation within species! Certainly that’s not the way I was using the term, as should have been clear from the examples of evolutionary change which I considered. Microevolutionary change is simply change within certain vague limits, limits which fall far short of the wholesale development envisioned by the Thesis of Common Ancestry.

To give you a feel for the sort of extrapolation from evidence of microevolutionary change to macroevolutionary conclusions, consider the following chart, which displays some of the major phyla within the Animal Kingdom:

Notice that just the single phylum of the vertebrates (Chordata) includes all fish, mammals, birds, reptiles, etc. Seen in the context of the wider picture, typical examples of evolutionary change are seen to be microevolutionary changes. The evolutionary development of whales, horses, and elephants you mention are trivialities compared to the grand scenario envisioned by the theory. The transition from lower primates to humans is nothing compared to what the theory postulates on the grand scale.

You’ll remember my quoting Michael Denton to the effect that for a bat and a whale to have a common ancestor there should be literally millions of transitional forms, which are not there in the fossil record. But even that illustration obscures the fact of how trivial in the grand scheme of things such a development would be, for it would have taken place entirely within the class of Mammalia (mammals) in the phylum of Chordata. Even the evolution of amphibians from fish or birds from reptiles is miniscule compared to whole tree of life postulated by the theory, for it still only involves evolutionary development within a single phylum.

By contrast, what is the evidence that a bat and a sponge are descended via mutation and natural selection from a common ancestor? And now reflect that the above chart shows only some of the phyla within the Animal Kingdom, which is only a part of the domain of the Eukarya, which also includes the whole of the Plant Kingdom, and that in addition to the domain of the Eukarya we’ve also got the domains of the Bacteria and the Archaea to account for! Clearly we’re dealing with a mind-boggling extrapolation from limited instances of microevolutionary change to conclusions that far outstrip the evidence. Caution certainly seems appropriate here.

So consider now your objections to my presentation. Take first the Thesis of Common Descent. In my podcast, I shared some reasons to be cautious concerning this claim, while acknowledging the biomolecular evidence in its favor. You complain that I mentioned only Archaeopteryx as a transitional fossil. But my purpose here was to provide an example from the fossil record for the most significant sort of transition afforded by the evidence. Most of the examples you cite are trivialities by comparison, for they don’t involve change across large categories. To mention them would only have weakened the case for macroevolution from the fossil record, which is what I was trying sympathetically to present. Michael Denton’s point that we ought to see millions of transitional forms if the neo-Darwinian paradigm were true is hardly out of date and remains a pressing problem. (Your cheap shot against Denton, who is, by the way, a fine scientist, is all too typical of those who turn to ad hominem attacks when they can’t refute the evidence.) So I don’t see that you said a whole lot beyond what I shared to greatly strengthen the case for the Thesis of Common Ancestry.

In any event, as I emphasized, the Thesis of Common Ancestry is really the less important of the two claims of the neo-Darwinian paradigm: far more important is the Thesis of Random Mutation and Natural Selection. As you note, theorists like Michael Behe embrace the Thesis of Common Ancestry. Their bone to pick (no pun intended) is with the postulated explanatory mechanisms of the neo-Darwinian synthesis. Here you had nothing to say to show that the staggering biological complexity which our world exhibits could have been created by such mechanisms in the span of four billion years. Recall Barrow and Tipler’s claim that there are at least ten steps in the evolution of homo sapiens, each of which is so improbable that before it would have occurred the sun would have ceased to be a main sequence star and incinerated the Earth! Here is where my greatest hesitation about the neo-Darwinian paradigm lodges. I haven’t seen any evidence that the hypothesis of random mutation and natural selection has the sort of explanatory power which the neo-Darwinian paradigm attributes to it. It seems to me that even given the Thesis of Common Ancestry, a theory of progressive creationism fits all the facts and could well be true.

All this occasions the question: how could a theory which is so speculative and so weakly confirmed as neo-Darwinism be held with such confidence and tenacity by the scientific community? Here’s where Philip Johnson’s insight is relevant to the discussion. (Of course, he’s not a scientist, as you note, but his contribution is philosophical, not scientific.) As I explain in my article “Naturalism and Intelligent Design,” in Intelligent Design, ed. R. Stewart (Minneapolis: Fortress Press, 2007), pp. 58-71, Johnson’s insight is that the neo-Darwinian theory’s status as the best explanation of biological complexity depends crucially on excluding from the pool of live explanatory options non-naturalistic hypotheses. Johnson has often said that he would have no objection to evolutionary theorists’ claiming that evolution is the best naturalistic hypothesis available for explaining biological complexity. What he protests is the claim that evolutionary theory is the best explanation simpliciter. Were we to admit into the pool of live explanatory options non-naturalistic hypotheses, then it would no longer be evident that evolutionary theory is the best explanation of the data. It is in that sense that the theory presupposes naturalism. The theory itself doesn’t imply naturalism; rather it is the theory’s current exalted position as the reigning paradigm which depends crucially on excluding from consideration non-naturalist alternatives. For if naturalism is true, then as Alvin Plantinga likes to say, evolution is the only game in town. No matter how improbable, no matter how weak the evidence, evolution’s got to be true because there just isn’t anything non-natural to account for biological complexity. Hence, the confidence.

Ironically, Steve, your own letter illustrates precisely the point I am making. It is evident that you object to non-naturalistic theories on theological grounds. You don’t like the image of the tinkerer God meddling in the evolutionary development of things like the bacterial flagellum. You think it makes God into a meddler and a bungler, and you don’t want to worship a God like that. Don’t you see that you have abandoned an objective assessment of the evidence, following it where it leads, in favor of following your theological predilections? Frankly, I find this over and over again in discussions of this sort: it is philosophical and theological presuppositions that determine where people end up, not the evidence itself.

As for your personal theological preferences, I caution you not to presume that God has to conform to your preferred theological outlook. It is enormously presumptuous to think that we can say with confidence what God would or would not do when it comes to His creating life on this planet. Better to keep an open mind and look at the evidence to see what He did, in fact, do!

Moreover, maybe your model of God is all wrong. Maybe God is not like the engineer who can be faulted if his machine doesn’t function perfectly without his meddling. Maybe God is instead more like the artist who enjoys getting His hands dirty in the paint or the clay to fashion a spectacular world. Why not?

In any case Intelligent Design of the world needn’t involve God’s intervening in the series of secondary causes in the way you imagine. If God has middle knowledge, then He can create a world in which the appropriate counterfactuals are true such that from certain chosen initial conditions a designed world will issue naturally (see again my article referenced above). Such a view doesn’t commit you to interventions at all.

So be not dismayed, my brother! There’s good reason to be cautious about the current paradigm in evolutionary biology. Here, for a change, Christians get to play the role of the sceptical inquirer.