MONKEY BUSINESS: Evolution and Intelligent Design

Friday, January 14, 2005

In October 2004, the school board in the small town of Dover, Pennsylvania, ordered its high school biology teachers to preface classes on evolution with the statement: "Darwin's Theory is a theory not a fact. Gaps in the theory exist for which there is no evidence." As an alternative to evolution, the school board suggested "intelligent design," a theory holding that life on earth could not have developed at random. Are there gaps in the theory of evolution that undermine its credibility? What should we make of "intelligent design"? And just what should we be teaching our children about the development of life on earth? Peter Robinson speaks with Massimo Pigliucci and Jonathan Wells.

Recorded on Friday, January 14, 2005

Peter Robinson: Today on Uncommon Knowledge: why Charles Darwin should be spinning in his grave.

Announcer: Funding for this program is provided by the John M. Olin Foundation.


Peter Robinson: Welcome to Uncommon Knowledge, I'm Peter Robinson. Our show today: science, skepticism and the debate over evolution. Last October, the school board in Dover, Pennsylvania instructed its high school biology teachers to begin classes on evolution with this statement: "Darwin's theory is a theory, not a fact. Gaps in the theory exist." As an alternative to evolution, the school board recommended teaching intelligent design, a theory that holds that life on earth could not have developed at random. Well are there gaps in the theory of evolution that undermine its credibility? What are we to make of this new theory of intelligent design and what should we be teaching our school children about the development of life on earth?

Joining us today, two guests: Jonathan Wells is a biologist and a senior fellow at the Discovery Institute's Center for Science and Culture. Massimo Pigliucci is a professor of life sciences at the State University of New York at Stony Brook.

Title: Designs on Evolution

Peter Robinson: This past winter the ACLU and the Americans United for Separation of Church and State filed a lawsuit against the school board of Dover, Pennsylvania which had voted to require biology teachers to introduce students to the alternative theory--alternative to evolution--known as intelligent design. Richard Thompson, President of the Thomas Moore Law Center, a public interest law firm, "Students will be made aware of gaps and problems in evolution. What's wrong with that?" Massimo, what is wrong with that?

Massimo Pigliucci: Nothing except the fact that intelligent design is not a scientific theory.

Peter Robinson: Jonathan?

Jonathan Wells: Well, I think intelligent design is a scientific theory but I would not require students to study it because it's too new.

Peter Robinson: But this notion of at least making students aware of his phrases gaps and problems in evolution?

Jonathan Wells: Absolutely.

Peter Robinson: Absolutely. All right. Now let's define terms a little bit--as much as television will bear. Evolution gets used a lots of different ways. How would you define evolution for the purposes of this program, of this discussion?

Jonathan Wells: Well, I would define it as Darwin's theory of evolution as modified in modern thinking. But Darwin called it "descent with modification," which has two aspects. One is the common ancestry of all living things who are descended from a common ancestor. And the second aspect is modification, which for Darwin was due primarily to natural selection acting on random variations.

Peter Robinson: Random variation--all right. Common ancestors--ancestor--and then random variation and natural selection. Is that an adequate…

Massimo Pigliucci: That's largely correct. The modern version adds several more mechanisms to the modification part. So we--modern evolutionary theory now accepts not only natural selection but a series of other developmental and genetic mechanisms that contribute to change. But it would still be true that the modern biologists consider natural selection the only known mechanism that can create adaptation which is that can create a fit between the environment--the organism and the environment.

Peter Robinson: Okay. And without yet being argumentative--that is we'll save that for a moment--but just give us a working definition of intelligent design.

Jonathan Wells: Intelligent design theory holds that some features of the universe, including some features of living things are best explained by an intelligent cause rather than undirected natural causes such as variation of selection.

Peter Robinson: So some sense of purpose or will as opposed to sheer randomness.

Massimo Pigliucci: I think that's a--I'm sorry if I cut in but that's a false dichotomy which we need to clarify immediately. The alternative, I think--it's not pure randomness because the theory of evolution by natural selection has a random component as Jonathan pointed out a minute ago which is the origin of variation through, for example, genetic mutations. But there's a non-random component. Natural selection is not a random process. It is a result of competition between organisms for--to exploit resources in the environment and that's not random at all. So when we're talking about the modern theory of evolution, there is a component that is non-random…

Peter Robinson: That is not random…

Massimo Pigliucci: …although it's not conscious of course.

Peter Robinson: Right. Right. Right. Of course. So--I'm just looking for a clear…

Jonathan Wells: I agree. I agree.

Peter Robinson: …a clear distinction. Some clear way of understanding intelligent design.

Jonathan Wells: Well that's why I said undirected natural causes. It's true that there is a non-random component but in Darwinian Theory, it's still undirected. There's no goal involved.

Massimo Pigliucci: There's no purpose and consi--consciousness.

Peter Robinson: Intelligent design does not necessarily require what? When you go to synagogue or church on Sunday, it gets described as God?

Jonathan Wells: There's correct. It does not.

Peter Robinson: Does not.

Jonathan Wells: All intelligent design does is tries to infer from evidence whether a certain feature is designed or not.

Peter Robinson: Let's take a lot at some of the alleged problems with the theory of evolution, beginning with problems in practice.

Title: The Weakest (Missing) Link

Peter Robinson: If indeed all forms of life are descended from one or a few common ancestors then as I understand it, you'd expect the fossil record to look like a tree--branchings from a common trunk. But instead what you get in the fossil record is large numbers of animal forms appearing more or less all at once in the so-called Cambrian explosion. Right? Have I described that correctly and is that a problem…

Massimo Pigliucci: Not exactly.

Peter Robinson: You comment and then you comment. Jonathan?

Jonathan Wells: Well, I would call that a fair description of the problem. Darwin himself considered the branching tree model to be the one that follows from his theory. And yet when we look at the fossil record, we don't find that branching tree pattern. And so there is a discrepancy between the pattern and the evidence.

Peter Robinson: Massimo?

Massimo Pigliucci: I don't think so--at least a discrepancy strictly not--the type of discrepancy that intelligent designs proponents would like to see. We don't know, first of all, if there was one common ancestor or a pool of common ancestors, if we go all the way back to the origin of life. That is under debate and it's not a crucial component of modern evolutionary theory. It would work either way. We also need to move a little past Darwin himself because, you know, science has this nice feature that it does evolve and progress. And so just in the same way in which modern physicists don't feel bound by what Newton said, modern biologists don't feel like Darwin is sort of a bible that needs to be followed. So the modern--so let's talk about the modern theory of evolution.

Peter Robinson: Right.

Massimo Pigliucci: The modern theory of evolution does predict a generally branching pattern, meaning that the more time that passes; the more living beings diverge from each other by a variety of mechanisms. That is largely what we see. The question here is what happened at the origin of the large group of organisms of animals that we see today way back in pre-Cambrian times? So we're talking about more than half a billion years ago. And we have very little knowledge about what happened. We do…

Peter Robinson: We have very little knowledge?

Massimo Pigliucci: Very little knowledge simply because there's very little fossil records to go about.

Peter Robinson: What is it that's special about the Cambrian period where suddenly there's a large fossil record and then you go before Cambria and it dries up?

Massimo Pigliucci: A couple things. First of all, it's not that sudden. It is a sudden explosion that actually lasted anywhere between thirty and fifty million years which is not a minor amount of time. Of course, it's minor compared to the entire span of life on earth. But it is not a minor--not a sudden thing that happened. The other thing is one of the things that probably happened in that time was the transition between forms that have a much more difficult time fossilizing because they don't have hard parts to forms that do fossilize more easily.

Peter Robinson: Because of the bones or shells?

Massimo Pigliucci: Because of bones and shells and things of that sort. So…

Jonathan Wells: Well if I may, I'll say three things briefly. One is one does not have to be an intelligent design advocate to criticize Darwin's theory. All one has to be is a scientist and look at the evidence and compare it to the theory. Second of all, I do think the Cambrian explosion was quite sudden, geologically speaking. If you can imagine walking from one end of a football field to another, it's as though you went all the way to the about the eighty yard line with single celled organisms and then in the space of a single step, the major kinds of animals appear relatively suddenly.

Peter Robinson: Can I just--that's a problem--it's not quite, it's not as smooth the transition that you'd like to see if you were taking the theory of evolution and digging away and hoping to confirm it smoothly and neatly. Right?

Jonathan Wells: It's not what Darwin expected.

Peter Robinson: But it's not a fatal problem?

Jonathan Wells: It's hard to say you have a fatal problem for a theory as sweeping as Darwinian evolution. So I would not call it a fatal problem. I would call it a serious problem as Darwin himself did.

Peter Robinson: Okay.

Jonathan Wells: And if I can make my third point…

Peter Robinson: Oh yes, go ahead.

Jonathan Well: …briefly, I do not think that the Dar--that the Cambrian explosion can be explained by the appearance of skeletons and hard parts. After all, two-thirds of the animals in the Cambrian explosion didn't have them. And we have many soft-bodied animals (clearing throat), excuse me, before that in fossil records. So it was not the sudden appearance of skeletons that made the Cambrian explosion.

Massimo Pigliucci: That's correct but those animals that we do have before the pre-Cambrian--before the Cambrian, in fact, do have phylogenetic relationships with the ones that came after it.

Peter Robinson: Next practical…

Massimo Pigliucci: I'd like to make a point before we go ahead which is this idea that in science really alternative theories work by proposing--you know, science moves by proposing better theories and better explanations. It's not that one can say something is wrong therefore that's it. We should stop there. So the question is what is the alternative? And I'd like to ask Jonathan if he thinks…

Peter Robinson: No, no, no, the alternative comes later. The alternative comes later.

Massimo Pigliucci: Now I'm talking about the specific of the Cambrian explosion.

Peter Robinson: All right. Go ahead.

Massimo Pigliucci: If he thinks that the modern Darwinian--new Darwinian theory does not have a good explanation for the Cambrian explosion, does he think that therefore an intelligent design came--designer came on earth 650 million years ago and just put the animals there?

Jonathan Wells: Well Massimo, I disagree with you that one needs a better theory to criticize an existing theory. For example, what if…

Massimo Pigliucci: That's the way science works.

Jonathan Wells: Not necessarily.

Massimo Pigliucci: Give me another example.

Peter Robinson: Well there's certainly two separate steps. The first step is to say wait a minute, there are problems here and the person who says that ought to be lauded if he's right because then it opens doors to the second step which is finding a better theory. But you can't say--you can't say you must have both bundled together. You must have both the criticism and the solution or that places too high a burden on people, surely, I mean, as a matter of scientific…

Massimo Pigliucci: Philosophers of science have shown that science actually works by competing theories. It never works by somebody getting up and say well, you know, this is wrong and that's the end of the day.

Peter Robinson: No, but the person who says this is wrong can stimulate the person two rows over who says oh I think you're right about that and here's a solution.

Massimo Pigliucci: Sure.

Peter Robinson: Now on to objections to the theory of evolution on matters of principle.

Title: Putting the Cart Before the Eohippus

Peter Robinson: Michael Behe and his notion of "irreducible complexity." Behe draws a parallel with the simple mousetrap. A mousetrap is made up of a dozen or so parts. If a single one is missing, the mousetrap doesn't work. Likewise a large number of functions that take place at the molecular level, the biochemistry of light detection, for example, requires a whole series of complex interaction among many different molecules, each highly specialized. And the notion here is that the necessary combination of molecules to enable an organism to detect light simply could not be built up haphazardly or piecemeal. You have to have the whole structure spring into being at once or you don't get the adaptive advantage. Is that, in principle, a serious problem with evolution? Jonathan? Behe's onto something there?

Jonathan Wells: Well Darwin thought, in principle, that this was a problem. He said if…

Peter Robinson: He saw himself.

Jonathan Wells: Well he didn't see that particular example but he said if any example could be found of a feature that could not be built up through slight successive modifications; that would be a fatal blow to his theory. Now Behe--Michael Behe claims to have found several examples of that. Those examples are hotly debated in the scientific literature.

Peter Robinson: What's your own view? Are you persuaded by him? Are you open-minded about it or--is he onto something in principle?

Jonathan Wells: I think, in principle, he is onto something. Now whether any specific example will stand up to scientific scrutiny remains to be seen. But, in principle, there's a problem here.

Peter Robinson: You don't buy this at all?

Massimo Pigliucci: No there's--first of all, there's no scientific debate about any of the examples that are in Michael Behe's book which I have read. Not only that but the very idea of irreducible complexity is actually being debunked from a philosophy of science perspective. Let me go back to Behe's major example as you pointed out or metaphor, I guess, of the…

Peter Robinson: The mousetrap?

Massimo Pigliucci: …the mousetrap.

Peter Robinson: All right.

Massimo Pigliucci: There's two things that are clearly wrong with that.

Peter Robinson: Okay. Good because that's something I think I can actually follow. Go ahead.

Massimo Pigliucci: Right. There are two things that are clearly wrong about the meta--first of all, in the case of the mousetrap, we do know that it was intelligently designed.

Peter Robinson: Certainly.

Massimo Pigliucci: So that's what in philosophy is called begging the question. I mean, you are sort of assuming--you're studying an example in which you already know that there is design so, of course, you're going to conclude that there is design. It's an example that it--that it makes for a poor analogy because in the case of evolutionary biology, we're trying to understand how the appearance of design, that is how the fit between organisms and environments comes about. If you said that's analogous to a clear artifact that we know is the result of intelligent design, it's not clear to me how the analogy's going to work. But the interesting thing is that there is a website put up by a biology--a biologist that actually shows that you can have simpler versions of the mousetrap compared to the ones that Behe had in his book. So in fact, by his own example, irreducible complexity doesn't stand up.

Peter Robinson: So this notion that the human eyeball or the simple sort of light detection, cell by cell light detection, the notion that that's such a complicated mechanism that it couldn't have arisen haphazardly or piecemeal--that just has no standing in…

Massimo Pigliucci: It has no standing especially in that particular example because it turns out actually that there is very good evidence of how the complex vertebrate eye has evolved. We actually do know many of the intermediate steps. Some of them are found in the fossil record and some of them are found living today. There are organism obviously the limited--the ones living today are not intermediate steps but they are simplified versions of eyes and light receptors. They are available and there is a very nice model…

Peter Robinson: Light receptors.

Massimo Pigliucci: That's right. And there are very nice models that show how you can build gradually from a light receptor to a complex eye.

Peter Robinson: So Behe's onto something in principle in your view but there's no specific example? Even light receptors could have arisen…

Jonathan Wells: Well actually Behe's argument is not about the evolution of the vertebrate eye but about the origin of the light recepting--light receiving mechanism itself. Behe's a biochemist and so he studies the molecular mechanism that actually detects photons, that detects light. And he argues I think persuasively that that is irreducibly complex. And let me just disagree briefly and say that there is a scientific controversy in the scientific in the scientific literature on this issue.

Peter Robinson: Now, a closer look at intelligent design itself.

Title: Everyone's a Critic

Peter Robinson: Is intelligent design merely a critique--is it simply a way of pointing out limits and gaps in the theory of evolution? Or is it more positive than that? Does it actually give us a framework or a new way of thinking about the evidence?

Jonathan Wells: I would say it's not merely a critique, although that critique is important because in the hands of many evolutionary biologists, Darwin's theory--the modern version of it--is used to rule out design, to make it merely an appearance. So the critique of evolutionary theory is part of the package but intelligent design theory, in order to be a science, has to stand on its own two feet. And it does that by proposing a hypothesis…

Peter Robinson: All right.

Jonathan Wells: …and providing criteria by which that hypothesis can be tested.

Peter Robinson: The hypothesis is?

Jonathan Wells: That feature X, whether in the universe or in some particular living thing is a product of intelligent design.

Massimo Pigliucci: How would you go about testing it?

Jonathan Wells: The same way we, in our daily lives, test…

Peter Robinson: Hold on. Hold on. You're moving a little too fast. A product of intelligent design means what? How do you proceed even thinking about that without ending up in the lap of God or thinking about a first mover in some sort of Thomistic way?

Jonathan Wells: Well in our daily lives, we routinely make design inferences. We look at situations or things and we know almost intuitively often that something is designed or it's not.

Massimo Pigliucci: Here's an example.

Peter Robinson: Right.

Jonathan Wells: A watch is the classic example…

Peter Robinson: Bill Clinton's famous quip that if you see a turtle on a fencepost, you know it didn't get there by accident.

Jonathan Wells: I hadn't heard that one.

Massimo Pigliucci: That's a good one. Yeah.

Jonathan Wells: So the question is do we have a hypothesis that we can test against the evidence. I think we do. Now having done that, what can we say? In intelligent design theory, all we can say is this feature provisionally appears to be a product of design.

Peter Robinson: But how do--but now to Massimo's question--how do you test that hypothesis?

Jonathan Wells: Well you mentioned Michael Behe. Irreducible complexity is one criterion. William Dembski, another design theorist, has a broader criterion that he calls con--specified complexity. Now if I drop a pile of--a handful of scrabble pieces on the floor, the letters on their wooden blocks, the pattern that those blocks form will be very complicated, very complex but it won't be designed. It'll just be an accident. It's a pile on the floor. But now if I arrange those letters to spell an English sentence, the pattern is not only complex--it's specified in the sense that it fits an independently specified pattern.

Massimo Pigliucci: Well once again, that begs the question because the whole point of evolutionary theory by natural evolution, by natural selection is in fact to explain that appearance of complex and orderly patterns by means of a natural process. I don't think…

Peter Robinson: But wait, wait, wait. You posit the natural process in--in other words…

Massimo Pigliucci: Yes, but there's a difference there. For one thing natural selection can be measured empirically under field conditions. And my students do that all the time. You cannot measure the activity of the intelligent design. But there is a more fundamental problem that I see that I would like Jonathan to have a…

Peter Robinson: If he--in other words, you start by saying we're going to rule out any notion of anything a-natural or anything that cannot be…

Massimo Pigliucci: That's not just evolution. That's science in general. Science in general cannot start with the assumption that there is a supernatural intervention which is--let's make a distinction here.

Peter Robinson: Then the question to you is how do you say intelligent design explains something better than does evolutionary theory?

Jonathan Wells: Well let me say two things.

Peter Robinson: Because that's the point isn't it--to get something that's a better fit--better fit with the evidence, right?

Jonathan Wells: Yes, yes. One thing I would say is that natural selection has not and has never been shown to be able to produce specified…

Massimo Pigliucci: But that's a negative statement.

Jonathan Wells: Let me finish. Let me finish.

Peter Robinson: Go ahead.

Jonathan Wells: Let me finish. On the other hand, you have just heard another definition of science here which is not the same as the one we agreed upon a few minutes ago. The definition of science I gave--the essence of science is the testing of hypotheses against the evidence. The definition we just heard is that science starts with the assumption that everything in the world can be explained without recourse to supernatural causes.

Massimo Pigliucci: I'm sorry.

Jonathan Wells: That's a different definition.

Massimo Pigliucci: No, I'm sorry Jonathan. There's no difference there for the simple reason that you cannot test hypothesis by the supernatural.

Jonathan Wells: Ah, but if your attitude is to test hypotheses, you can reach a point where you say you know what; I don't know the answer to that question.

Massimo Pigliucci: That's correct. And scientists do that all the time. But there is a crucial difference between saying I don't know the answer which, as I said we do all the times, and saying therefore the answer is there is an intelligent designer.

Peter Robinson: So intelligent design…

Jonathan Wells: First of all, I do not think intelligent design theory is merely equivalent to saying I don't know. The problem with using natural selection as an explanation, using Darwinian evolution as an explanation is that all too often, I find it's the default explanation. That is instead of saying we don't know, we say well it must have been natural selection because we know that there's no intelligent design here. That is it's merely an appearance as you said.

Massimo Pigliucci: I never heard a scientist put it that way.

Jonathan Wells: I have read it hundreds of times.

Peter Robinson: This brings us right back to the question with which we started: what should American school children be taught?

Title: Just the Facts, Ma'am

Peter Robinson: Cobb County, Georgia--the school board put a sticker in science books saying--I don't know the exact words but they were something very close to "evolution is a theory, not a fact." And the judge ruled that they had to peel all those stickers out of the textbooks because that was an unfair endorsement of religion. I'm not asking you to parse the constitution. I'm asking you what school children should be taught. Evolution pure and simple or evolution is here and other people take this view and other people take another--how would you handle the design of textbooks?

Jonathan Wells: Well I absolutely think science students should be taught Darwin's theory of evolution and the modern version of it because it's so important and so influential in modern biology. But I also think they should be taught scientific evidence and arguments against it as well as for it. And if you question whether there's a controversy, you have here two biologists and you've heard the controversy, at least a little snippet of it. So there is a controversy here and I think students should be aware of that. Now should they be forced to study intelligent design? I don't think so but if the question comes up, why not look into it?

Massimo Pigliucci: I think the wording that the judge used in that particular decision you refer to is important there. The judge said that the sticker is--needs to be eliminated because it unfairly singles out the theory of evolution. It makes, in other words, makes the student think that there's something special about the theory of evolution that is particularly controversial as opposed to other scientific theories. So if we're talking about--which is not true--the scientific theory of evolution is as controversial in biology as quantum mechanics or relativity theory are controversial in physics. And by the way, they are controversial because, for example…

Peter Robinson: True?

Massimo Pigliucci: …relativity theory makes some certain predictions that are at odds with quantum mechanical predictions in certain areas which is one of the reasons why there are still active physicists working out there and having a professional career as researchers. At the same--in the same way, of course evolutionary theory does not explain everything that we know about living organisms which is why there are active professional biologists like myself trying to work on these things. But one thing is to point out to the students that science is always in the making, it always changes so what we think is correct today--a correct interpretation today--may be different. And here are the areas of actual progress.

Peter Robinson: So as a working scientist then, you have absolutely no qualm about saying to students look, this is a theory, this is a theory, this is a theory. They all have their limitations. Science is always in the making. Now would you also however have no qualms about including a paragraph or two on intelligent design?

Massimo Pigliucci: I do have qualms for the simple reason that at the moment, and as far as I can see forever, but at the moment certainly intelligent design is not a scientific theory and as such, should not be brought up in a science class. Now if we did have philosophy classes in high schools--in European high schools, you do have to teach philosophy for about three years or so in the curriculum. And in a philosophy class, intelligent design theory does have a place. But it is not a scientific theory. In fact, Jonathan agreed basically much with it a few minutes ago…

Jonathan Wells: That it's not a scientific theory?

Massimo Pigliucci: That's right.

Peter Robinson: What's the Massimo solution? The Massimo solution is teach intelligent design but teach it in philosophy class. What do you think?

Jonathan Wells: Well I do think intelligent design is a scientific theory. I don't think it gets you to the intelligent designer. That may be the aspect you're talking about. The problem is students are already being taught about intelligent design. The State of Texas last year adopted a bunch of textbooks several of which have sections on intelligent design.

Peter Robinson: And the ACLU isn't all over them?

Jonathan Wells: Well because those sections caricature the theory and…

Peter Robinson: Oh I see.

Jonathan Wells: …and discard it. Okay, now students are going to be forced to read about intelligent design as they will be in Texas if these textbooks are used, then shouldn't the theory be presented fairly and with adequate time for students to debate the…

Peter Robinson: Last question: a decade from now--I'm not asking you to say whether you think intelligent design is worthy of this treatment or not--I'm asking you to give me a prediction about the way you think things are moving. A decade from now will intelligent design receive at least a brief and respectful treatment in American science textbooks? What do you think?

Massimo Pigliucci: Not unless there is some major change in the Supreme Court which will allow the teaching of creationism in the public schools. That may happen but they will be a result of politics not science.

Peter Robinson: Jonathan?

Jonathan Wells: I don't think intelligent design is creationism. I don't think the Supreme Court will have anything to do with it. I think intelligent design will win the scientific community and therefore…

Peter Robinson: Within a decade, you think things are moving reasonably quickly?

Jonathan Wells: Oh I'll give it two decades.

Peter Robinson: Two decades. All right.

Jonathan Wells: But it'll be on its way in a decade.

Peter Robinson: Massimo, Jonathan, thank you very much.

Peter Robinson: I'm Peter Robinson for Uncommon Knowledge. Thanks for joining us.