Is Evolution a Theory?

Dr. Craig clears up some misunderstandings surrounding the term 'theory'.

KEVIN HARRIS: Bill, you spent a lot of time researching topics related to this article, not only for your book on the historical Adam but in your continued work on your systematic philosophical theology and your work in general. Let’s look over this article by creationist Dr. Jason Lisle titled “Evolution is not a Theory.”^[1] I might mention when I say “creationist”, he is a Young Earth Creationist. That is the terminology, I think, that he would be comfortable with but we would typically put him in that Young Earth camp.

Carl Sagan once said, “Evolution is a fact, not a theory.” And he was partly right; evolution is not a theory.  He’s not right about evolution being a fact of course, unless he meant evolution in the most generic sense of change over time.  We all agree that things change over time.  But Sagan was clearly referring to a specific type of change: neo-Darwinian evolution.  This is the idea that all life on earth is descended from a common microbial ancestor: that the information in our DNA is entirely the result of mutations over time that happened to convey survival advantage.  It is this version of evolution that is neither a fact nor a theory.

Has he correctly characterized evolution?

DR. CRAIG: Well, I think that Lisle is correct that evolution is not a theory. That's because it is actually several theories. Even if we ignore the evolutionary theories prior to Darwin, commencing with Darwin there have been three major stages in the evolution of evolutionary theory. There was first the original theory of Darwin laid out in On the Origin of Species in 1859, and this consisted of the thesis of natural selection operating to select advantageous heritable traits in animals and plants over time thereby explaining their adaptedness to their environments. He postulated the thesis of common descent of all organisms from either a single or a few primordial ancestors in the deep past. Now, that thesis of common descent was very rapidly accepted by his contemporaries, but for the following 70 years after Darwin his explanation of natural selection was very widely rejected. Darwin could explain the survival of the fittest but he couldn't really explain the arrival of the fittest; that is to say, where do these heritable traits come from? Well, that problem was solved by the modern synthesis which is the second stage of evolutionary theory. Beginning around the 1930s population geneticists married Darwin's theory with the genetics of Gregor Mendel to explain the rise of these heritable traits through genetic mutations that then can be selected by natural selection thereby explaining evolutionary change over time. And this modern synthesis is sometimes I think incorrectly referred to as neo-Darwinism. That's the way Lisle uses the expression – neo-Darwinism – to refer to this modern synthesis. But then beginning in the late 1980s the modern synthesis began to be challenged and passed away so that today there is in place what is called the extended evolutionary synthesis which draws into evolutionary theory insights from many collateral disciplines especially developmental biology which is the biology of how the embryo develops in utero and forms its different tissues and limbs from a single fertilized egg to eventually a full-blown organism. With each stage of evolutionary theory, the previous stage has been exposed in its explanatory deficits. So in attacking the modern synthesis Lisle is really out of date. He needs to begin to interact with contemporary evolutionary theory which is this extended evolutionary synthesis. So evolution is not a single monochromatic theory. It is a succession of theories from Darwinism through the modern synthesis to the extended evolutionary synthesis today.

KEVIN HARRIS: Next in the article he writes,

What is a Theory?

Some creationists like to say, “evolution is just a theory” by which they mean it has not been proved.  I would certainly agree that neo-Darwinian evolution has not been proved, and yet I would discourage creationists from saying, “evolution is just a theory.”  Why?  The problem pertains to the word ‘theory.’  The word can indeed mean an unproved assumption: conjecture.  But this is not the most common definition. . . . the use of the word ‘theory’ to mean “unproved, conjecture, or speculation” is legitimate, but is not the most common meaning of the word, and therefore can lead to misunderstanding.

What is the most common meaning of the word ‘theory?’  The first definition listed in dictionary.com is “a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena.”  The listed example is: “Einstein’s theory of relativity.”  This is the definition scientists generally have in mind when they speak of a theory.  They are not referring to something that is mere conjecture or speculation.  Rather, they refer to something that has been tested, has passed the test, makes accurate predictions, and therefore has supporting evidence.

So it's the common usage of the term “theory” that he's contesting when applied to evolution.

DR. CRAIG: How does he define, or the dictionary define, a theory? “A coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena.” Evolutionary theory certainly fulfills that definition. For example, I have here a standard textbook on evolutionary biology by Douglas Futuyma about 700 pages long that’s chock full of evolutionary theory and evidence. On pages 25 to 27 he lays out the twenty tenants of the modern synthesis that we've been talking about. I realize that you probably can't read those on the screen but you can see that two pages are covered with the twenty fundamental tenets or general propositions that are regarded as correct as part of the modern synthesis. So certainly evolution is a theory. It's just silly to deny that. That's not to say that the theory is true, but to say that it's not a theory, I think, is just a fantasy.

KEVIN HARRIS: Up next in the article he says,

Is Neo-Darwinian Evolution a Theory?

Is the idea of particles-to-people evolution a theory in this primary sense? . . .

Evolutionists often list three kinds of evidence that they believe supports evolution.  First, organisms have certain similarities (and differences) in their anatomy.  These similarities can be arranged into a hierarchy, which is what makes taxonomy possible (phylum, class, order, family, genus, species). . . . Furthermore, the DNA of two different organisms tends to be similar if those organisms are anatomically similar.

Let's pick these one at a time beginning with that one.

DR. CRAIG: OK. First of all, in laying out three evidences for common descent (which is what he's talking about here) he really doesn't survey most of the evidence. This is another evolutionary textbook – Evolution by Futuyma and Kirkpatrick. In this volume they lay out seven different lines of independent evidence in support of the thesis of common ancestry. He's dealing only with three of these, not even most of the evidence that is adduced on behalf of it. The first piece of evidence that he deals with is the similarities in anatomy and in their genetic makeup. So let's talk about those a little bit. These are called homologs. That is to say, you have similar structures or similar genetic sequences of DNA in different organisms which suggest that those organisms are descended from a common ancestor. A good example of the structural homologs would be the so-called pentadactyl limb; that is to say, the limb of tetrapods – four-limbed animals – that terminates in a five-fingered hand. This skeletal structure is common in humans, in seals with flippers, in lizards, in mammals of various sorts, bats. So this pentadactyl limb is consistent across a wide variety of animals. The suggestion is that this shows that they evolved from a common ancestor. Even more persuasive than the evidence of these morphological or structural homologs would be the genetic homologs. You have similar sequences in the DNA of diverse organisms that make them look like they're copies of each other. It's thought that this is best explained by saying they inherited these DNA sequences from common ancestors. So those would be one example of the evidence for common descent that he's talking about. These homologs of both morphology and genetics.

KEVIN HARRIS: Next Dr. Lisle writes,

. . . the lines of evidence most often presented for evolution are perfectly consistent with biblical creation.

Consider the fact that organisms can be categorized into a taxonomic tree.  But this doesn’t imply common ancestry.

Would you agree?

DR. CRAIG: I think that that is correct that you can classify organisms without saying that they're genealogically related. When Carolus Linnaeus developed in the 18th century the system of classifying animals as species, genus, family, order, and so forth, he did not imagine that these organisms belonging to the same classes were genealogically connected. For example, he would put apes and humans in the same category, but he didn't imagine that they were genealogically related in that humans and apes descended from a common ancestor. So it is possible to do this kind of classification or taxonomy without thinking that the organisms are genealogically related to each other. But the problem is if you hold that they are not genealogically related then what explains those similarities that we've just talked about? What explains the relatedness of them if it isn't because they're derived from common ancestry? He says, “It's perfectly consistent with biblical creation.” But the problem is he doesn't define what biblical creation is. It's a mystery what the theory of biblical creation means. He apparently means to deny common ancestry. If the history of life on this planet is indeed very ancient – going back around four billion years – what that denial of common ancestry would require then is what I call the doctrine of late creation. That is to say that God did not simply bring the universe into being at the beginning but that periodically throughout the four billion year history of life on Earth he intervenes miraculously with new acts of creation to create animals and plants and fungi and things of that sort all along the line. I think this is incredible and really unbiblical. I was speaking once with a creation scientist and I said, “Is it your understanding then that at some time in the past there was a calm prehistoric lake or pond with nothing on it and then all of a sudden – poof – suddenly a duck appears swimming on the water.” And he said, “Yes, except I think we would have to posit several ducks.” And I thought, oh, of course. You've got to have a breeding population, not just one duck. Now, I just find that incredible. That sounds more like magic than the God of the Bible to me. When you apply this to acts of late creation like, for example, the dinosaurs, are we really to think that several 50-ton brachiosaurs suddenly popped out of thin air or ravening Tyrannosaurs suddenly popped into existence sometime in the Jurassic? I think that's just incredible. When I look at the Bible, the God of the Bible doesn't engage in these kinds of late creation miracles. He created the world at the beginning, but then I don't see these sorts of acts of late creation. In fact, it's really interesting to me that when Jesus transforms the water into wine at the wedding in Cana he orders the servants first to fill the jars with water. Now, as an omnipotent God, Jesus could have just created the wine ex nihilo in the empty jars. But he didn't do that. Instead he said, “Fill the jars with water” and then he transforms the water into wine. I don't see the God of the Bible engaged in these sort of acts of late creation as though he were a magician waving his magic wand and all of a sudden dinosaurs and elephants and things of this sort appear. Now, the only way to avoid this kind of late creation would be to adopt Young Earth Creationism, and Lisle didn't say that in his article although you apparently indicate this is his view. Well, if that's your view that is completely in the face of scientific evidence. That is outrageous. The idea that the world was created ten to twenty thousand years ago in six consecutive 24-hour days is just indefensible. It is indefensible historically, linguistically, scientifically. It contradicts geology, paleontology, and cosmology. So if that's the alternative to common descent, I think Christians are in real trouble.

KEVIN HARRIS: I've noticed the same thing. Just looking at the Scriptures, God seems to really like process. That's a good example that you mentioned – that turning water into wine. I don't know. There's something about going through a process that God values. The destruction of evil is certainly a process that is ongoing and will ultimately culminate one day in its destruction. So, yeah, I see that. Every once in a while he may do something that is a miracle – that is a little out of the ordinary.

DR. CRAIG: A lot out of the ordinary. Clearly I'm not denying God's miraculous interventions in history, but what I am questioning is these acts of what I call late creation – like making dinosaurs pop into existence out of thin air. I don't see that.

KEVIN HARRIS: God wouldn't have to use angels but he chooses to – to be messengers. And he allows us to participate and he chooses to use us when he could just snap his fingers and make things happen. So I see real value in what you're saying. Going back to the article he says,

Second, all organisms have basically the same genetic language. . . .

But then again, all organisms have the same creator. So that’s perfectly consistent with creation.

DR. CRAIG: The evidence that he speaks of here is the near universality of the genetic code. The genetic information that is encoded in DNA tells the cells how to make proteins. These DNA genes come in little triplets of DNA bases, and they code for amino acids that then makes the proteins that make the cell run. And it is remarkable that there is a nearly universal genetic code characterizing all of life from human beings to pineapples to worms to bacteria. They all operate pretty much on the same genetic code with a few variations – a few sporadic variations. Now this seems to point very powerfully to common descent. This is widely regarded as the best evidence of common descent – that all of life shares the same genetic code. What Lisle would say is the creationist can explain it by saying God has created everything on the basis of the same fundamental plan. Well, that's possible. But there are some reasons, I think, to doubt it. One would be the sporadic variations in the genetic code that I mentioned. There are some variations, and it looks very likely that these are the result of evolutionary change. The code has changed over time as it has been modified in the course of evolution, and that would support common ancestry. Moreover, this explanation becomes less convincing when you consider the non-functional genes that we carry in our bodies. To give an example, in our body there is a duplicated gene called CMT1. It duplicated itself so that it appears twice on a strand of DNA close to each other. The result of this duplication of CMT1 is that the protein that is coded for in between it tends to mutate and get duplicated. What happens is that people who wind up with this mutated protein develop a neuromuscular disease called Charcot-Marie-Tooth Syndrome (that's what CMT stands for – Charcot-Marie-Tooth Syndrome). This identical gene duplicate and the mutated intervening space is found in chimpanzees on exactly the same chromosome at exactly the same place with the same mutations. That is too improbable to explain by chance. It looks like this mutation or duplication occurred in a common ancestor of chimps and humans and so both of us have inherited this broken gene that leads to this neuromuscular syndrome. This would be like thinking of Ford and Chevrolet manufacturing a similar car. We could imagine that Chevrolet would, say, make a car that would have a very similar door handle to the Ford. But if the door handle on the Ford were broken and didn't work, the manufacturers at Chevrolet would not make a duplicate broken handle in their car. And yet that's what we find, for example, in chimps and humans – these broken genes. So this is strong evidence, I think, that chimps and humans do share a common ancestor. When I read this, I was bowled over as you can imagine because I, myself, have Charcot-Marie-Tooth Syndrome that I inherited from my mother. I never dreamt that this syndrome that I've struggled with all my life is actually among the best evidence for common ancestry of chimps and humans. That was quite a revelation. Finally, the last thing I want to say about this evidence for common descent is that, again, the so-called creation alternative would mean that you've got to have acts of late creation. If the genetic code is shared, not because of common ancestry but because every organism was created anew with the same genetic code, you're right back to late creation again which I think is just fantastic and unbiblical.

KEVIN HARRIS: Back to the article.

Finally, the fossil record shows variations of organisms that no longer exist. . . .

And regarding the fossil record, we do indeed find evidence of variations within kinds.  We find different varieties of horse, some now extinct.  We find different varieties of elephant, some of which are now extinct (such as mammoths).  But this is a prediction of biblical creation; God created organisms with the ability to diversify within certain limits.  Some of these variations have been lost over time.  What we do not find in the fossil record is copious evidence of transitions between created kinds.  There are always a handful of disputed specimens, but clear evidence of evolution between kinds is lacking.  This is consistent with biblical creation, but is not consistent with new-Darwinian evolution.

Bill?

DR. CRAIG: I agree that this is a problem for the modern synthesis. That has been adjusted in the extended evolutionary synthesis that I spoke of. What this calls into question is “gradualism” – that is to say, that evolutionary change proceeds by small increments. But to say that gradualism is false is not to deny common ancestry. For example, Michael Denton in his book Evolution: A Theory in Crisis accepts universal common ancestry but he denies gradualism. He does not think that evolutionary change proceeds by small increments. He believes in what is called saltation (from the Latin saltus which means “jump”). And on this view evolutionary change can occur through jumps or fits and starts rather than through slow incremental changes. Indeed, I think that this does tend to fit the evidence better than gradualism, but it doesn't call into question the thesis of common ancestry.

KEVIN HARRIS: He asks, from the article,

In fact, can you think of any successful predictions of the evolution model that are contrary to the predictions of the creation model?

Bill?

DR. CRAIG: That's easy! The age of the Earth! The evidence is overwhelming from history, science, linguistics that the world is more than ten to twenty thousand years old. Moreover, the progress in the fossil record shows that there is a long history of life on this planet. Even if you don't have the sort of transitional forms in the fossil record, nevertheless the fossil record attests that life has been around on this planet for around four billion years beginning with primitive single-celled organisms like bacteria that then developed further and you had multicellular organisms evolve and then after that more complex organisms in the Cambrian explosion and so on and on up until the appearance of man on this planet. Now, even apart from the theory of evolution, suppose that those life forms are not connected genealogically. Nevertheless, the progress in the fossil record shows that there has been a long history of life on this planet, and that decisively falsifies what Dr. Lisle is calling the creation model. Moreover, evolutionary theory certainly does make predictions. Let me just give one. For a long time evolutionary biologists predicted that whales were evolved from land-dwelling tetrapods (animals that walked on the land and had four limbs), but there weren't any intermediate or transitional fossils between land animals and whales. Well, evolutionary biologists calculated where in the evolutionary sequence these transitional forms ought to appear. They identified a particular stratum that is available or extant for exploration in Pakistan. So they sent an expedition to Pakistan to hunt for fossils in this particular stratum, and lo and behold what they found were these multiple intermediate forms between whales and terrestrial land animals. That was a prediction of evolutionary theory that was dramatically confirmed.

KEVIN HARRIS: Finally, he writes,

I would encourage Darwinists to think through the implications of their network of presuppositions, because it is inherently irrational.  Namely, if neo-Darwinian evolution were true, there would be no basis for rationality or science, and hence no way to actually know that it (or anything else) is true.

Is this presuppositionalism that he's describing?

DR. CRAIG: Oh! This is Alvin Plantinga's evolutionary argument against naturalism! What Plantinga argues is that the conjunction of naturalism and evolution is self-defeating for precisely the reason that Lisle mentions. And that therefore it is irrational to believe in naturalism and evolutionary theory. But you don't have to give up evolutionary theory. You give up naturalism! That's the real problem. So what Lisle has failed to see is that the problem here is the philosophy of naturalism, not biological evolution. If God chose to use biological evolution to bring about biological complexity on this planet, that would not undermine rationality and our knowledge of the truth.

KEVIN HARRIS: Here is Jason Lisle's conclusion,

It is certainly the case that neo-Darwinian evolution has not been proved.  But we probably shouldn’t say that it is “just a theory” because a theory (in the primary, scientific sense of the word) has supporting evidence, whereas neo-Darwinian evolution does not. . . . Therefore, it would be best to refer to evolution as a speculation or unsubstantiated conjecture about the past.

Your conclusion, Bill?

DR. CRAIG: I would say that if he is concerned that Christians not look foolish, that it would be well for them to acknowledge that evolutionary theory is indeed a theory (or a series of theories) and to acquaint themselves with it. By contrast, Young Earth Creationism (or creation science) is a speculation and unsubstantiated conjecture about the past. This is the pot calling the kettle black. I think that Christians will only make themselves look silly if they launch these kinds of attacks upon contemporary evolutionary theory.^[2]