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Defenders 3: Excursus on Creation of Life and Biological Diversity (Part 29): Methodological Naturalism
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Welcome to Defenders, the teaching class of Dr. William Lane Craig.
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Today the Creation of Life and Biological Diversity, Part 29. For more information and resources from Dr. Craig, go to reasonablefaith.org Last time I argued that, contrary to what you often hear on both sides of the creation evolution debate, that the contemporary theory of biological evolution does not assert that mutations are undirected or unguided, and that therefore the evolutionary process is purposeless. Rather, we saw that what evolutionary biologists mean when they say that mutations occur randomly is that they occur irrespective of the benefit of that they might bring to the host organism. And that definition is not at all incompatible with the evolutionary process being directed or guided by God, or even by God's miraculously intervening in the evolutionary process to cause key mutations that would bring about evolutionary advance. Now, this raises a related issue, methodological naturalism. Many philosophers and scientists would argue that science, by its very nature, is committed to a sort of methodological naturalism. Now, it's important to understand that this is not synonymous with metaphysical naturalism. Metaphysical naturalism is a thesis about the nature of reality, that reality consists simply of space, time and its contents, the physical world. That's metaphysical naturalism. But methodological naturalism holds that science seeks only natural explanations for for phenomena in the world. It's simply part of the methodology of science to seek natural explanations for various effects. And therefore supernatural explanations of some phenomenon would not even be permitted into the pool of live explanatory options. When you look at the pool of live explanatory options for some body of empirical data, science would not even look at supernatural explanations because it is methodologically committed to the quest to find natural explanations of the data. And so these supernaturalistic explanations wouldn't even come into consideration. And therefore even many Christian scientists would agree that they are restricted methodologically to seeking for natural explanations. And this would of course then preclude appealing to God as an explanation of the origin of life and the evolution of biological complexity. Now, what might we say about methodological naturalism? Well, I think what's striking about methodological naturalism is that it is not a scientific viewpoint, but rather a philosophical viewpoint. It is not an issue to which scientific evidence is relevant. Rather, it is about the philosophy of science, the nature of science. And as such, we should ask ourselves, why should we be committed to this philosophical thesis? As the Intelligent Design theorist William Dembsky has pointed out, methodological naturalism would prevent us from inferring design even if we were to discover that every atom in the universe carried a label on it made by God, you still would be prohibited methodologically from inferring that God has made these things more seriously. Suppose that life and biological complexity really were the result of creative miraculous interventions at various points in the past on the part of God. Suppose that we actually do live in a world like that, where God has intervened in the evolutionary process to bring about forms that would not have otherwise evolved. It would be a tragedy, wouldn't it, both scientifically and personally, if we were debarred from discovering the truth about reality simply because of a methodological constraint. Methodology is supposed to aid us in the discovery of the truth about reality, not hinder us in it. And so there are, I think, serious questions that can be raised about a strict methodological naturalism. But leave that point aside. The more important point that I want to make is that we are not now concerned with what a scientist might infer as the best explanation of biological complexity. Rather, our question, as we've seen, is how, from a theological standpoint, should we integrate what the Bible teaches with what we discover through empirical evidence? We are not trying to justify a design inference. Rather, we are trying to integrate our theology with the empirical evidence. We're trying to understand how these two bodies of truth fit together best. Even if the scientist works within the constraints of methodological naturalism, there is no such constraint on the systematic theologian, who is free to craft an integrative or synoptic view of the world that takes account of both the data of modern science and the data of the divine revelation. So the systematic theologian could admit that the neo Darwinian theory of biological evolution may very well be the best naturalistic theory that we've got. If, as a result of methodological naturalism, the pool of live explanatory options is limited to naturalistic hypotheses, then, at least until very recently, the neo Darwinian theory of biological evolution, driven by the mechanisms of random mutation and natural selection, was basically the only game in town. Rival naturalistic hypotheses just could not equal its explanatory power, explanatory scope, and plausibility. So it was the best naturalistic account, no matter how improbable it might seem, no matter how enormously far its explanatory mechanisms have to be extrapolated beyond the testable evidence. No matter the lack of evidence, for many of its tenants, it's still the best naturalistic explanation, because there isn't any other naturalistic explanation that even comes close to it. Philip Johnson, one of the pioneers of the Intelligent Design, Movement has said that he is quite prepared to agree to the evolutionary theorists claim that evolution is the best naturalistic hypothesis available for explaining biological complexity. It is the best naturalistic theory, he would agree. But what he protests is the claim that evolutionary theory is the best explanation simpliciter or the best explanation period. Were we to admit into the pool of live explanatory options non naturalistic hypotheses, then he thinks it would no longer be evident that evolutionary theory is the best explanation of the data. So we are going to approach our question from a theological standpoint and ask how, given the biblical data and the empirical evidence, we should best understand the origin of life and the development of biological complexity. As we do so, I want to emphasize that I approach these questions not as a professional biologist, but rather as a theologian with a layman's interest in these scientific questions. Any discussion of of methodological naturalism and the approach of our project in this class? Yes.
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Do you think the bent towards methodological naturalism is a primary cause of why so many people appeal to the God of the gaps explanation? When somebody gives.
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All right, let's define some terms. He mentioned the so called God of the gaps, and this has become almost an aphorism in contemporary culture that if there's anything that is anathema, anything that must not be appealed to, it is the God of the gaps. Now what is meant by that phrase? Well, what that phrase refers to is using God to stop up the gaps in our scientific knowledge. If there's something that is at the present day scientifically inexplicable, you can say, aha, God did it. This is where God intervened. And the danger of this kind of God of the gaps reasoning is that as science advances and closes those gaps, God gets progressively squeezed out of the picture and becomes more and more irrelevant. Now notice that that danger doesn't say anything at all about the truth of God's interventions or his activity in the world. In a sense, the person who's warning against God of the gaps is just giving a little bit of evangelistic advice. He's saying it's best not to use arguments for God that are based on scientific evidence ignorance, because they might come back to bite you. And the Christian evangelist can say, well, thank you very much, maybe that's good advice and I'll heed that. But this really isn't an issue about the truth of theism or how God brought about biological complexity. Maybe there really are gaps. Maybe there really have been divine miraculous interventions along the way. But it's Just saying it's sort of impolitic to do this because it could be counterproductive. Well, thank you very much. Now, I do think this is related to methodological naturalism in that one of the motivations for methodological naturalism would be you're not going to be trying to use God as a stopgap measure to plug up scientific ignorance. If you have a methodological naturalism in play, then you will always be seeking to find natural explanations for natural phenomena. And therefore you cannot fall prey to positing a God of the gaps, because that won't even be permitted into the pool of live explanatory options.
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Yes, well, I was just thinking, like, is that. Would that not be why the person. Like in the context of a debate with somebody who has the methodological, naturalistic perspective would. I'm just saying, would that bias them more to be like, to say, like, just to throw that out as an explanation? Anytime somebody posits God being an explanation for anything at all, well, if he
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thinks of it as a scientific inference, then he will say this is methodologically excluded. And one of the burdens of intelligent design theorists like William Dembsky has been to argue that they are not in fact, postulating a God of the gaps. Indeed, intelligent design theorists aren't positing God at all. They are very emphatic that they are not inferring to God as an explanation. Rather, they are inferring to intelligent design. And they would say that this is an inference that is common in scientific pursuits. And they will give many examples, for instance, cryptography, where you're trying to decode a message and you can tell the difference between just random letters and an encoded message, or. Or insurance fraud, where you see whether or not a fire is the result of arson, whether it's been deliberately set, or was this just the product of natural causes. You can infer to an intelligent designer who has set the fire or plagiarism charges, Is it just an accident that someone reproduced, word for word, the writing of some other person? Or is this to be attributed to intelligent design or archaeology, when archaeologists are able to infer that certain objects they discover are in fact human artifacts like arrowheads and pottery shards, rather than products of metamorphosis and sedimentation? So the ID theorists will say we are not in any way postulating a God of the gaps. Number one, we're not postulating God to begin with, but just some sort of intelligent designer. But secondly, they would say we are making a principled inference to intelligent design, not simply Appeal to ignorance. We are not using design just to stop up the gaps in our knowledge any more than a cryptographer or a SETI researcher trying to find signals of intelligent life from outer space or an insurance fraud investigator is postulating design simply to plug up the gaps in our knowledge. So this is a very hot question that is discussed among intelligent design theorists. Fortunately, it needn't be settled by us in this class because, as I say, we. We're not adopting a scientific perspective. I think that the distinctive thesis of these intelligent design theorists is that they want to argue that the inference to Intelligent design is a scientific inference, it's not a philosophical inference. In their book, I, as a philosopher, am quite prepared to make philosophical inferences of that sort. But they want to say that the scientist can infer intelligent design and that therefore he is not bound by this sort of methodological naturalism. But as I say, we are not approaching these questions as scientists in this class. I'm a theologian, a systematic theologian. And so what I'm asking is, given the different sources of knowledge that we have as Christians, physical science, biology, literature, psychology, divine revelation, how do we integrate all of these into a coherent synoptic worldview that adequately takes account of all of these different sources of knowledge?
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Yes, Brad, I'm very excited about this next part that you are about to do. And what I've always thought of is that those that do not believe in God at all have to have an explanation.
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So they.
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They are grasping for something out there that could have caused these things without God.
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Yes.
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And the. It's not that they're trying to find the best explanation. It's they need some explanation. And therefore I'm gonna. I'm gonna say that macro evolution actually happened, even though there's no proof whatsoever that it did happen. So I'm very interested very much in this discussion.
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And notice what Brad is talking about here is not methodological naturalism, but metaphysical naturalism. Those who are atheists who don't believe that there is anything beyond space, time and its contents. And I think, as Brad rightly says, for them it's the only game in town. It's got to be true, because there isn't any sort of supernatural alternative. And you remember last week I quoted from the naturalistic biologist Richard Lewontin when he says that no matter how absurd the scenarios, no matter what the evidence is, we have an a priori commitment to materialism, and therefore this must be true. And we're not bound by that, I think, certainly not metaphysically, and I Think that it's worth asking is, are we even bound by that methodologically? But ultimately we don't need to decide that methodological question because we're not approaching this through the discipline of science.
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One other question, science is I postulate this and I test it, and is there evidence? Is it repeatable? And all as we look back over time, it's really, there's a different type of science. It's forensic science. I'm postulating what might have caused this to happen. It's not real science. I don't mean that to sound that way, but it's not. I do it, I have a hypothesis, I test it. It's repeatable, it's never falsified. There's no way to falsify a lot of the postulates of, of how the world was created and how, how animal. We, we say, well, it must have gone from this animal to this animal. Look at the, look at the bones. Okay, well show me today, show me any evidence of how that actually happened in macro evolution.
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I, I'm not at all ready to write off the historical sciences, Brad, as pseudoscience. There are a number of sciences, such as cosmogony, which studies the history of the universe, paleontology, geology, archaeology. There are historical sciences that don't just study the present, the here and now, but attempt to study the past as well. And you're quite right. These sciences will be based upon postulating certain hypotheses to explain the observable data, like fossil evidence, for example. It would be, I think you'd agree, absurd to say that these are just, these are not the remains of animals that actually lived, that maybe God put them in the sediments to deceive us, something of that sort. I think any reasonable person would say that these are the vestiges of life forms that used to exist, that now no longer exist. And so one will need to explain that how did they come about, why did they die, how did they originate, and so forth. And immediately you're embarked upon a historical science. Now as to whether it can be falsified, Someone I think, has rightly said that these theories can be falsified. If you were to find, for example, a rabbit in the pre Cambrian rocks, that would be a decisive falsification of the scientific theory of evolution. So I, I do think it's falsifiable. But that's not to say that it is the best explanation of the evidence. We'll need to look at that more down the road.
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Okay, I'm looking forward to it.
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Okay, Bruce, hi.
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I would say in, in defensive idea in theism that it's a better explanation for what we do know, not for what we don't know. So I would say the onus on the methodological naturalist is the evolution of the gaps, not the God of the gaps.
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I think that Bruce is making a good point. Dembsky, Stephen Meyer and so forth have all said we are not inferring intelligent design based upon ignorance and it is based upon what we do know about the complex structure of proteins, for example, about the nature of biological complexity, that an intelligent design inference is warranted. Now that's arguable, certainly, but I think it is far too facile to respond to ID theorists by just saying, well that's God of the gaps reasoning that that is far too easy. Yes, Greg, is it? Yes. Yes. Dr. Greg, question I've been reading up on Dr. Bart Ehrman's stuff. As natural historian, would you say that he ends up using the methodological naturalism for his naturalist ideals? Yes. Now, as Craig very perceptively noticed, this same methodological naturalism controls historical inquiry for many historians and even biblical scholars. And if you adopt a kind of methodological naturalism in history that only natural events can explain the phenomena, that immediately means the historian could never be justified in inferring miracles. No matter what the evidence. You could never infer that a miracle has occurred. So when Ehrman comes to the evidence for the resurrection of Jesus in his teaching company lectures he grants, even argues for the historicity of the discovery of Jesus, empty tomb and his burial by Joseph of Arimathea, he agrees to the post mortem appearances of Jesus to various individuals and groups. And he agrees that the original disciples suddenly and sincerely came to believe that God had raised Jesus from the dead. But he said we cannot make an inference that God did this. That kind of inference is not one that the historian as a historian can make. And therefore he says, I simply remain agnostic about this. So that would be a perfect illustration of how in another field you have this analogical methodological naturalism at work. Jonathan.
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So you said that you were speaking of principled inferences, making inferences based on what we do know. But my question was what do you take to be the necessary and sufficient conditions for a principled inference? So for example, I could see with respect to like the Kalam cosmological argument how you can infer God because the other explanations aren't just improbable, they're completely impossible.
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Yeah, that's kind of special case.
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But with respect to this we're more so dealing with inference to the best explanations.
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Intelligent design theorists have develop different answers to this question. Dembski calls its specified complexity. It would be when you discover this feature of some event, specified complexity, that you can know that it's neither due to chance nor to physical necessity, and therefore a design inference is warranted. And this will be a combination of being able to establish the great complexity of some event or high improbability of the event, plus an independently existing pattern to which the event conforms. That's called specified complexity. Now, by contrast, the biochemist Michael Behe, who wrote the best seller Darwin's Black Box, proposes a different feature of phenomena that would justify design inference that he calls. Oh, what does he call it?
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Irreducible.
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Irreducible. There we are. Please edit the tape at this point. The B he calls irreducible complexity. And this is the complexity of a compound system which is such a, that if any one of the elements were removed, it wouldn't function at all. The function would be destroyed. All of the elements need to be present and functioning. So that would be a different approach. Another approach would be by Robin Collins, who. Avoids either of these proposals of specified or if irreducible complexity. And he argues on the basis of a Bayesian model of probability theory. He would say that the probability of, for example, the fine tuning of the universe is much higher on theism and what we know of the laws of nature than it would be simply on the laws of nature themselves, non theism, and that therefore the inference to theism is justified on probability grounds. So it's, it's a variety of approaches. But I mean, clearly these people, whatever you think of them, they're not just saying, gee, we can't explain this scientifically, so God must have done it. That, that just is not an honest interaction with their work. Yes.
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George, Bill, those of us who are trying to understand this, and the scientists included, shouldn't we divide the question of biological complexity into the origin part and then the development part? The development part would be the development or progress after based on maybe common descent or design or whatever. But on the origin part, it seems to me that at least I haven't heard maybe you know, of any credible scientific naturalistic theory to explain the origin of life. I know there were the experiments in the fifties of Urey and Miller that I think had been discredited.
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Yes.
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So would scientists be, would they admit that there is really no naturalistic explanation for the origin of life, the first cell, and so there is really no game in town that they have to explain the origin of life.
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Well, you anticipate me, George. If you look at the outline, you'll see that the next point is going to be on the origin of life. And then we'll discuss the development of biological complexity after that. And I think we'll see that what you just said is in fact correct. Yes, Cindy.
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George took my thunder. But anyway, just to clarify, so when a naturalistic method, when a scientist uses naturalistic methodological naturalism. Right. Thank you. When it gets to the point the origin of the universe or the origin of life, then they are left with such bizarre explanations that have like oscillating universe that never really had a beginning. Therefore we can't say there was a cause because there never was a beginning, or that there was an alien who came to Earth and that's how life started. It seems to me when they're pushed into a corner, they don't have an answer. So they come up with these really bizarre sort of explanations that they can't, that can't be denied. I mean, you can't go back and prove that is that I think you're
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quite correct in saying that when pushed to the limit, they will often appeal to alternatives that are desperate, that are highly improbable. For example, with regard to cosmology, you mentioned oscillating universes or the idea that the arrow of time flips over and runs in the opposite direction at some point in the past, or even revising the laws of physics, such as Roger Penrose is constrained to do in order to make his model conformal, cyclical cosmology work. So one might be pushed to desperate expediences, or I think one could simply remain agnostic at that point and just say we don't have an explanation. But given my methodological constraints, I can't infer the supernatural explanation. I am just left with no explanation. And I would say with regard to the resurrection of Jesus, that would be the main response. These naturalistic resurrection theories like apparent death conspiracy, so for these are almost universally rejected today. But scholars like Ehrman or Paula Fredrickson or Spong or others will simply say at this point, who knows? Something happened. Something incredibly powerful must have happened to birth this Christian movement in the middle of the first century. But what it was, we don't know and we can't say.
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I just wanted to make a comment. It seems like the general public seems very willing to accept an alien brought life to Earth or the oscillating or string theory, rather than to be open to a supernatural explanation, even though the evidence seems to be more in favor of that. I've heard people say, well, life, you know, there was an alien, and they don't have any trouble repeating that, as if that has, you know, that that has more credibility than.
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Well, I think you're making a point there, Cindy, that I tried to make in the question of the week on our Reasonable Faith website with respect to the resurrection, namely that postulating a supernatural cause for an event like this carries with it all kinds of worldview implications that are going to affect you in how you live your moral life, your spiritual life. All sorts of implications and ramifications are going to come with that that many people just are not willing to make. And therefore, as you say, desperate alternatives will be preferred, like that Jesus of Nazareth was an alien from outer space and that the ship beamed him up or something like that from the empty tomb. Any other question or comment? All right, well then let's turn to the question of the origin of life. What does the evidence indicate about the origin of life? Well, you remember in our discussion of the fine tuning of the universe in our excursus on natural theology, we saw that for life to originate and evolve on any planet, anywhere in the cosmos, there have to be finely tuned initial conditions present in the Big Bang itself in in order for this to happen. But even given those incomprehensibly finely tuned initial conditions, there's still no guarantee that life will originate somewhere in the universe. These fine tuned conditions of the universe are necessary conditions for the origin of life, but they are not sufficient conditions. In order for life to originate, other conditions have to be in place on earth which are astronomically improbable. Now, as George alluded to a moment ago, most of us were probably taught in high school or elementary school that life originated in the so called primordial soup. By chance chemical reactions, and perhaps fueled by lightning strikes. Back in the 1950s, a scientist named Stanley Miller was able to synthesize amino acids by passing electric sparks through a methane gas. Now, of course, amino acids are not alive, but proteins are made out of amino acids and proteins are found in living things. So the hope was that somehow the origin of life might be explained. Now you might think, well, wait a minute, that's a pretty big extrapolations. Amino acids constitute proteins, proteins are found in living things. Therefore the ability to synthesize amino acids meant somehow that life can be originated chemically. And I would agree with you. I think that's a pretty big leap. But that is what most of us were taught, I think in school, in the primordial soup that either covered the earth in its oceans or, or else perhaps in warm pools on the land, through lightning strikes and chemical reactions, somehow primitive life was formed. Now, it could be that God set up these natural conditions that he knew would result in the origination of life. But is this the way he did it? Well, all of these old chemical origin of life scenarios have in fact, as George says, broken down and are now rejected by the scientific community. This fact was documented in the groundbreaking book by Roger Olson, Walter Bradley and Charles Thaxton called the Mystery of Life's Origin. Reassessing current theories, they point out that there probably never even was such a thing as the so called primordial soup. For the natural processes of dilution and destruction would have prevented the chemical reactions that supposedly led to life. Miller's experiments were performed in a tiny glass enclosed artificial environment in the laboratory where the natural processes of destruction and dilution would not come into effect. But of course, in the primordial oceans of the Earth, these sorts of destructive processes could not be precluded and therefore they would have prevented the chemical reactions that would supposedly have led to the formation of life. Now that's just Bradley Olson and Thaxton's first point, that the natural destructive processes in the primordial oceans would have prevented these chemical reactions that supposedly led to life. That allowed Miller to synthesize his amino acids. But they have much more to say about this and that's what we'll look at next time. So let's close with a word of prayer. Our Father, who is the source of physical life, but also of spiritual life as well. We pray that as we walk this week in the fullness of your holy spirit, that you would fill us with your divine life and with power and strength to do your will and to be your witnesses in a lost and dying world through Christ our Lord. Amen.
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The copyright for the preceding material is
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held by Dr. William Lane Craig. For more go to reasonablefaith.org.