Del Ratzsch is professor of philosophy and chair of the Philosophy Department at Calvin College. He specialises in the philosophy of science and has written extensively on issues surrounding design arguments.
- Interviewed for TGL* in 2006
TGL: How and why did you become interested in the philosophy of science, and in design arguments in particular?
DR: I have a love affair with science dating back to my early teens, and was initially working toward a physics/mathematics degree. Although I changed paths partway through and ended up in philosophy, I never lost my science fascination (maybe even science envy?), and gradually snuck back in a science-related direction via philosophy of science. And some of the things that had interested me in science had had philosophical overtones.
One other factor is that I was raised in a quite conservative Christian environment; my early love of science - especially a fascination with evolution and cosmology - seemed on occasion to collide rather hard with various specific beliefs I had acquired. That led to a general interest in science/religion issues, creation/evolution issues and eventually to traditional design and contemporary Intelligent Design (ID) issues.
TGL: How would you characterise the debate surrounding design in science? Why has it become so acrimonious and could it have been otherwise?
DR: The term "unfortunate" comes to mind. There is a whole battery of fascinating issues which design questions raise but unfortunately in some circles on both sides, emotion and agendas have trumped responsible investigation of issues. Fear of allowing one's opponents to make any points has led to pretty skewed caricatures, and on each side both a lack of respect for the opposition and bitterness over low blows, misrepresentations, incompetence-fueled vitriol, etc., from those opponents has resulted in some on both sides excusing themselves from the bother of getting even the positions of the opposition right.
Although the issues and groups are in fact distinct, many of the same combatants from earlier creation/evolution disputes have aligned themselves along ID/anti-ID lines respectively (e.g., some creationists adopting ID as another, seemingly more scientifically respectable anti-evolution weapon). Many have brought their pre-existing hostility with them into the new context. But that parallel alignment isn't universal. Many old-line young earth creationists have been very critical of the Intelligent Design movement, and quite a number of Christian anti-creationists have become staunchly pro-ID. (Of course, many ID advocates have blistering things to say about theistic evolutionists.) Even a few unbelieving anti-creationists have become quite sympathetic to ID. Despite the genuine distinction between ID and creationism, in anti-ID circles there have been extended, deliberate attempts to transfer the substantial intellectual opprobrium of creationism onto ID - hence the insistent use of the term "intelligent design creationism" - without acknowledging, the differences between the two. And in the other camp, many vocal anti-evolutionists have (I think mistakenly) embraced ID as inherently anti-evolution, overlooking, e.g., the fact that one of the main formative figures in the movement - Michael Behe - has repeatedly declared in print that he has no principial problems with common descent whatever. Many lay creationists also mistakenly take ID to be merely a plug for gaps they see in nature and which they think evolution can't fill and endorse it for that purpose.
I think that another part of the explanation for the acrimony is that many on both sides intuitively (and often only tacitly) correctly recognize that there are potentially some deep matters at stake - from the nature of science to the nature of human cognition to the nature of nature itself and perhaps ultimately to some basic and seriously consequential naturalism/theism issues. It really does matter how things come out.
TGL: What motivates you to continue working in this area, given the hostility on all sides that is associated with it?
DR: Well, some would say sheer perversity, but I hope it's a bit better than that. There have been times in my own life when I desperately wanted to avoid having to admit that the (of course) sleazeballs and gross incompetents on the other side of some issue from me might be right on some key point. Who wants to give people like that a chance to say "I told you so"? In such situations there has always been the temptation both to accept 'refutations' of the opposition uncritically - even gleefully - and to dismiss opposition arguments without really staring them in the eyeballs, feeling virtuously superior all the while. And the more deeply one is committed to views in the area, the stronger the temptation. But the ugly truth is that sometimes when one really does do the homework, one discovers that one's opponents are not absolutely without exception loony and morally vicious, and even if they are generally wrong they may (no doubt by sheer accident and for all the wrong reasons, of course) have gotten hold of some genuine embarrassment for one's own view which needs to be addressed.
It seems to me that some of the design issues are too important to let heat trump light, which has undeniably been part of the story to this point, and that the vitriol from both sides is an index of that importance. There are few matters that go deeper than the nature of human cognition, the nature of the reality we inhabit, naturalism/theism questions, and so forth. So I have wanted to try to wrestle some of those issues to the ground. I don't think I've completely managed that at this point, but that is hardly a unique position - at least as I see it, no one else has either. And besides all that, I just find the issues fascinating.
TGL: In the conclusion to your book, Nature, Design and Science, you write regarding the legitimacy of involving supernatural design in science. You say that "contemporary culture has on this question opted for easy resolutions". Could you explain what you mean by that?
DR: I had several things in mind there. The question of whether or not principles involving supernatural intelligent design can play any legitimate role in science under any circumstances turns out to be a quite complex one. Indeed, that question is the focus of the entire book. But - first - many people try to answer it by appeal to some definition of science. Of course, no one has a complete and defensible definition of science, and the definitions (or partial definitions) of science generally employed for this purpose are demonstrably oversimplified, and once suitably complexified they no longer so clearly do the proposed work. Second, many assert that design theories ultimately reduce to God-of-the-gap views and that such views are scientifically, theologically, or otherwise unacceptable. Among the problems with this shortcut dismissal are that although many design theories are indeed gap theories, some are not (e.g., what ID advocates sometimes refer to as "frontloading," according to which God built all the relevant potentials and capacities and directions into the original creation, subsequent developments being the designed, natural, unbroken, and continuous unfolding of those primordial potentials).
Furthermore, gap theories turn out to be not quite as easily dispatched as often thought. At the very least, it must be admitted that they are logically impeccable - if nature, chance, humans, aliens, etc., can't produce something which is manifestly sitting in front of us, then alternatives other than the supernatural are rather scarce. (Of course, establishing that impossibility is a large and very sticky wicket.) Gap theories might not be science (at least, that is widely asserted), but that will depend again upon a definition of science.
Third, many hold that science and religion function completely in separate domains generating an easy dismissal of religion – and of course of (supernatural) design – as irrelevant to science. Unfortunately, such ‘separation’ views (e.g., Gould’s NOMA) are highly problematic – indeed, I think that they are irreparably inadequate.
Of course, in a more general sense a number of vocal disputants in the ID case take easy routes by partially relying upon stereotypes, over-generalizations, catchphrases, mockery, straw men, and secondary literature. Here is one very simple example from one side at the lay level. It is now routine for the media to specifically define Intelligent Design as the view that the world or life is "too complex" to have arisen naturally, by accident, etc. That's easy to grasp - but simply inaccurate. Not only does it not even fit many historical design arguments, but the complexity mainstays of ID arguments involve not mere high complexity, but very special and specific types of complexity - "irreducible complexity" (Behe) and "specified complexity" (Dembski). That is not to say that their proposals work (and I argued in the appendix of Nature, Design and Science that Dembski's proposal is not adequate to the task he assigns it – Dembski disagrees), but it is to say that the proposals are not as simple as they are routinely represented as being.
TGL: You also argue that design could have some possible "payoffs" for science. What are some of those payoffs?
DR: First, I'm glad that you were careful to say "could" and "possible". I don't see the Intelligent Design movement as having yet made their case here, although I don't see any principial reason why they can't. Most of what I see as possible payoffs are indirect and not necessarily near the empirical ground level. That is not a criticism, of course, since that characterizes a lot of essential and profoundly consequential components of science - e.g., shaping metaphors (17th century machine metaphors), 'maxi-theories' (Darwinian evolution), and even structuring presuppositions of science (uniformity of nature). Such things primarily guide, specify boundaries, and dictate norms for theory construction, theory acceptability, concept legitimacy, success criteria and the like.
Those sorts of things have a subtly exercised but ultimately huge impact on science. Think of the consequences of the early modern shift from organic to machine metaphors in science. (Incidentally, note that both at the time were seen as products of design.) A design outlook would offer additional perspectives, additional conceptual resources, additional explanatory themata, additional shaping metaphors. And we humans have been pretty bad at guessing what concepts wouldn't ever be of future use, as every scientific conceptual revolution attests. Historically, design ideas served as important and fruitful heuristics in various disciplines and indeed continue to do so implicitly in e.g. biology. If design ever does alter science (again) I think that this deep shaping level is one important place to look.
Even in the empirical trenches, design isn't necessarily a total no-show. Cosmological fine-tuning has a least a whiff of design about it, and least action theories - notoriously redolent of design - are, according to e.g. Planck and some others, scientifically more productive than purely mechanistic theories. Furthermore, given the role of theology in the rise of science itself, and given that the cosmos which science presupposes has a creation-esque flavor (orderly, law-governed, elegant, intelligible, coherent, unified - as one might reasonably expect of a deliberately designed creation), it may be that science itself is a design payoff. (I've discussed some of these issues in more detail elsewhere.) In any case, design theories might conceptually lock into those design-shaped foundations more elegantly than do non-design or anti-design theories.
But perhaps most importantly, if - if - the cosmos or some things in nature are designed (and surely that isn't a matter to be decided either by philosophical edict or by appeal to human definitions of science), then genuinely understanding the relevant phenomena (and isn't that what science is about?) is likely going to require employment of some design concepts. But again, the above largely represent potentials - I don't know that anyone has detailed working proposals at this point, or knows specifically what such proposals would look like.
TGL: Many design arguments have relied on the recognition of design through inference or induction. You've written about an alternative - recognizing design through perception. Could you talk about what you mean by perceiving design and what implications this view might have for design arguments?
DR: Nearly everyone realizes that old-style foundationalism is a failure. One of the more intriguing among the multitudinous proposed alternatives has been the contemporary revival and spinoff of some of Thomas Reid's proposals, including the "Reformed Epistemology" developed by Alvin Plantinga, Nicholas Wolterstorff, and others. On Reidian views, our beliefs about the past, other minds, the existence of the external world and so on are not the products of arguments (or inferences, decisions, or the like), nor, rationally, need they be - which is a good thing for our prospects for rational propriety, given the twin facts that (i) there are no known past or present such arguments that actually work and that (ii) neither that failure nor even the apparent unanswerability of skeptic arguments seems to make the slightest difference to anyone's actual beliefs in the past, other minds, the external world, etc. On the Reidian view, we have innate faculties which simply generate such beliefs (both general principles and specifics) within us, and if these faculties are operating properly and under appropriate circumstances, the produced beliefs are rationally legitimate for us. Reid catalogued a variety of belief areas in which such belief-producing dispositions operated - again, the past, other minds, the external world, as well as basic moral principles, principles and processes of reason, acceptance of the testimony of others, aesthetics, and of present interest design in nature which, by a very short inference, led to conclusions about a designing mind.
Not only do I find much to like in this general type of view, but it struck me as interesting that just as unshakeable belief in the external world continues serenely on in the face of both the failure of positive arguments and the apparent power of skeptical cases, so widespread belief in design continues serenely on in the face of both difficulties in positive design arguments and the apparent power of the well known criticisms of such cases. My "Perceiving Design" was an effort at explicating Reid's own (fairly limited) remarks on design in the context of the contemporary design discussion.
Reid's basic idea was that we perceptually (and immediately albeit often implicitly) recognize marks of design and that it is a short (inferential) step from that recognition to the thing in question being designed and the existence of a designing agent. Among the marks Reid cites were contrivance, order, organization, intent, purpose, regularity, beauty and adaptation.
Perhaps the most immediate consequence for current design discussions would be to relocate some key parts of the issue. More or less every current contribution to the discussion presupposes that design is a matter of inference - indeed, Dembski's initial book, still the technical manifesto of the design movement, is titled The Design Inference. The pervasiveness of that presupposition is why Neil Manson (editor of God and Design in which my paper appeared) refers to the paper as "disruptive".
In any case, as I argued in that paper, even if inductive inferences are essential to many design cases, the base cases from which the inference proceeds cannot be inductive (on pain of regress), but must arise in some other way. Reid's suggestion may be quite important for those cases. Indeed, alternatives are rather scarce. There has been some interest in the idea, and even one recent doctoral dissertation on the topic by John Mullen at Notre Dame.
TGL: Design arguments are often associated with the idea of "gaps" in nature. How important are gaps to design arguments?
DR: For some design arguments, they are crucial. For instance, Dembski's 'explanatory filter' is completely gap-driven. I don't see that as necessarily a defect. We routinely employ gap arguments in all sorts of contexts. For instance, the SETI program is a gap-searching project - trying to find signals which nature alone couldn't or wouldn't produce, then constructing alien-civilizations-of-the-gap arguments. Further, it is nowhere written in stone that nature has no causal or explanatory gaps of the relevant sort. For all we know nature may contain gaps which can only be bridged by divine action. And that could be intentional - God might like running some things in nature hands-on, and might have created nature to allow for that in its normal operations. Anyway, gaps and gap arguments as such are unproblematic in principle.
Of course, there are serious questions concerning how we might identify supernaturally bridged gaps as such, especially scientifically. Such gaps might thus be inconvenient - or worse - for our investigative efforts and procedures, and we might have no choice but to assume continuity as a working strategy, but we can hardly demand that nature conform herself to our limitations - i.e., we cannot very appropriately issue inflexible ontological edicts propped up solely by reference to our epistemological limitations. Reality, it seems to me, is a bit more independent and robust than that. But many see gap-type arguments as having a troubled history and a troubling character.
But not all design arguments are gap arguments. In fact, during the heyday of natural theology - late 18th and early 19th centuries - non-gap arguments involving the interlocking structure of laws, cosmic order, the elegance and beauty built into nature, and the like, were very widely seen as preferable to and more powerful than gap arguments. And many contemporary ID advocates also embrace some non-gap arguments, including the 'frontloading' picture mentioned earlier. Front-loading types of design pictures go back at least to Augustine.
More specifically, gaps have to do with e.g. mechanical causal histories, whereas design has to do with intentional histories. Those are in many cases intimately related issues. Gaps can be important clues to design, since depending on the context an actual mechanical, causal gap could suggest agency as a causal factor, and it is a relative short step from there to design. But the issues are distinct, and the ritual allegation that design views are all God-of-the-gap theories is inaccurate philosophically, as well as historically and contemporarily. There are, again, many (especially lay) design-gap advocates, but the blanket universalization is straightforwardly mistaken.
It is also worth noting that if nature is designed and if it does contain causal or explanatory gaps, then any prohibition on gap theories will nearly guarantee that science - discarding one failed non-gap theory only by replacing it with another (not yet failed) gap theory - will not self-correct in the usual advertised way, and that science will never correctly understand the relevant phenomena.
TGL: It has been argued that the gradual "erosion" of scientific gaps has made religious belief unnecessary. What do you make of this argument?
DR: I'm suspicious. The "erosion of gaps" argument is both factually and philosophically weaker than usually acknowledged. Gaps have certainly evaporated in some cases under pressure of scientific advance, but I don't know of anyone who has actually done the work of constructing a historical induction for the usually assumed constant drumbeat of collapsing empirical gaps. The case is complicated by e.g. Kuhn's contention that sometimes in scientific revolutions ground is lost and previously closed gaps suddenly re-open. (Of course, from a design perspective, even one genuine gap would be of logical interest.) And intriguingly enough, at least one gap - cosmic fine-tuning - seems to be gaping ever wider the more fully it is investigated. The platform for this induction is missing a couple legs.
And beyond that, I don't think that science can even in principle provide a total account even in its own terms. Science requires a battery of presuppositions and those presuppositions are not direct results of science - they are conceptual structural materials science itself depends upon and without which there would be no science. Thus if we are rationally justified in accepting science then we must be rationally justified in accepting those foundational presuppositions. But not being results of science, their rational justification cannot rest upon science, but must lie beyond science. Thus, if we take science and its results to be rationally justified, science is not the only source of rational justification. There must then evidently be some deeper source of rational justification. Historically religion played a significant role here. But the present point is that even if the usual empirical gap-closing induction worked flawlessly, the story - even of science's own rational legitimacy - is not complete, and may require design ideas at some deeper level. (That would be an analog of Darwin's suggestion in his notebooks that design did not operate at the level of organisms, but that the deeper laws might be designed.)
The important point above is that this "unnecessary" claim rests upon a massive induction - from an alleged unbroken track record of closed gaps to the continuation and presumably eventual closure of all or nearly all such gaps - and that neither the history nor the projection is as straightforward as widely presumed.
In any case, since as noted above both historically and currently some design arguments have no connection to gaps at all, even were the huge induction to go through compelling us to believe that someday all empirical gaps would be scientifically closed, it is not clear that that would be fatal for design positions.
But your initial question had to do not just with design views, but with whether religious belief itself would be rendered unnecessary. Although that is commonly answered in the affirmative (e.g., Weinberg holds this position), it is not clearly true. The only way to make this claim even prima facie plausible is to see religious belief as functioning solely as a competitor to science, its only function being explanatory on the same level as science. There is a lot of pretty a priori speculation about how religion must have resulted from primitive people trying to cope with the world by inventing religion as an explanatory system, but I know of no good arguments for that, and arguing that an essentially ever-incomplete science either leaves no room for religion or is complete enough to render religion superfluous - especially a religion which goes beyond mere primitive attempts at explaining nature - takes more of a case than I think anyone has yet made.
But all that said, I think that one should be very wary of identifying something in nature as indicating a gap. Creationists and some (especially lay) ID advocates have been very – overly – ready to see gaps, and some opponents of ID have made the complete absence of any gaps in the entire cosmos a matter of principle. Neither position, it seems to me, fosters a suitable readiness to see what nature might have to say on the issue. And isn't that supposed to be part of what science is about?
TGL: Theories about the relationship between science and religion vary widely. Some people think religion has no place in science while others believe that religious books can directly provide content for scientific theories. How would you describe the relationship between science and religion?
DR: To say that views "vary widely" is putting it very diplomatically. I would tend to say that they are all over - and often off the edges of - the map.
Some of the usual categories (e.g., complete separation, complementarity, conflict) are, I think, demonstrably defective - sometimes woefully so. Clearly, there are integral connections - both historically and philosophically. To reprise just one, science cannot operate except with foundational presuppositions and assumptions of (and a world actually exhibiting) order of some level, consistency, intelligibility, etc. - i.e., a world like a creation. The necessary metaphysical and conceptual resources match up to a creation-like picture pretty nicely. As Paul Davies puts it in his Are We Alone?:
Science began as an outgrowth of theology, and all scientists, whether atheists or theists ... accept an essentially theological worldview.
But saying how deep the 'internal' connections may go is a tricky business. Since we have neither innate concepts nor direct experience of most theoretical matters - e.g., quantum phenomena - we cannot escape employing metaphorically the concepts we do have, trying to refine them and make them fit. (Indeed, Mary Hesse has argued that theoretical explanations just are "metaphorical redescriptions" of phenomena.) Given that metaphor is required precisely because our human concepts don't always map one to one into or onto nature, conceptual material which is extraneous to the theoretical situation at hand but which may be an irremovable constituent part of the concept unavoidably employed, gets imported into
science. And it turns out that some of the metaphors in question have theological roots.
But would any project that took explicit account of any theological theories or resources be science? In general, I have a sort of nostalgic soft spot for the old "damn the torpedoes" conception of science as going after the truth no holds barred (the phrase originally from Bridgman, I think). From that perspective, if we have rationally defensible reasons of whatever sort for thinking that something is true, then if that truth has implications for scientifically relevant issues it is not clear why as a scientist one should always be obliged to pretend to be ignorant of that truth. So if it should turn out that, say, Scripture provides rationally justifiable grounds for some proposition relevant to some scientific matter concerning the history, function, character, or contents of the cosmos, I don't see any inviolable reason in principle why qua scientist one is utterly forbidden from taking that possible truth into account in one's attempt to understand that facet of the cosmos. (On that general principle count, I think that some creationists are right.) Of course, one might need a case for the rational justification in question, and such cases might be difficult to generate. (And some creationists have gone way off the track in this area, and also concerning what Scripture really says, what science is and says, etc.)
Given human history, it might even be the best practical strategy to take absence of rational justification as the preliminary provisional default value. But that's no big deal - in fact, that is true of scientific proposals as well, which is why scientists typically demand replication, why the scientific mindset is often described as a form of skepticism, why Popperianism takes attempts at falsification to be the definitive scientific task and so forth.
TGL: In your paper Humanness in their hearts: Where science and religion fuse, you've argued that many of the cognitive processes involved in scientific thought are the same as the ones involved in religious thought. What implications does this have for how we think about their relationship?
DR: That's a very good question, and one I've been working on for some time. It seems to me that it tells us at a minimum that any simple, sharp separation of science and religion does not reflect our cognitive and neurological architectures, that there are deep interconnections between what we take to be scientific and religious beliefs, and that cases for the two being in deadly conflict - which already fail historically and philosophically - fail at the even deeper level of neural structures giving rise to our very cognition as well. Some of the deep interconnections between science and religion I think ultimately track back philosophically to the created structure of the cosmos itself, but also back to the fact that inputs from neurological structures and systems routinely associated with science - e.g., reason - and those routinely associated with religion - e.g., emotion - are not completely separate or separable systems. There is increasing and no longer even controversial evidence that reason itself does not function properly in the absence of properly functioning emotion neural systems, and in some cases the structures themselves and their inputs and outputs are integrated - fused - prior to our having conscious access to them.
Still, I'm not sure what all the positive implications are - I'm working on that - but again at the least it tells us that the structure, foundations, and cognitive underpinnings of science and religion are not in deadly opposition, as some contend.
TGL: In that same paper you use analogies, rather than propositions, to describe the science-religion relationship. Why did you decide to take that approach?
DR: Analogies (and metaphors and such) allow us to deal with and operate productively on a much richer and more complex conceptual landscape than do strictly propositional resources. It works much the same way (to sneak in an analogy already) that a visual graph typically allows an intuitive grasp of many aspects of a function which is much quicker, broader, and more employable than that offered by a complicated string of complex equations underlying the graph. (Recall Reid again - Hesse also.) The fact is that science isn't just propositional structures and processes, religion isn't just propositional structures and processes, and we humans don't operate cognitively - much less existentially - just in some abstract presuppositional realm, so it looked like a possibly fruitful strategy. In any case - sort of bearing out the point - the specific conception of science/religion relationships I had in mind seemed promising, and I still don't know how to - or if one can - reduce it to propositions, some algorithm, etc.
TGL: In your review Design Theory and its Critics, you wrote that "If (perhaps for overwhelmingly good reasons) science is restricted (even just methodologically) to 'natural' explanatory and theoretical resources, then if there is a supernatural realm which does impinge upon the structure and/or operation of the 'natural' realm, then the world-picture generated by even the best science will unavoidably be either incomplete or else wrong on some points. Unless one assumes philosophical naturalism (that the natural constitutes the whole of reality) that will be the inescapable upshot of taking even mere methodological naturalism as an essential component of scientific procedure." This suggests that the distinction between the two forms of naturalism collapses, but there seems to be little awareness of the argument. Do you intend to develop it further?
DR: I have discussed it some elsewhere (e.g., in "Natural Theology, Methodological Naturalism, and 'Turtles all the way down'" (Faith and Philosophy, Vol 21 #4, October 2004, pp. 436-455)). And I want to emphasize that - contrary to some critics of methodological naturalism - I don't argue that the distinction between methodological and philosophical naturalism actually collapses, but that in the context of some specific presuppositions the outcomes of application are indistinguishable. But again, the claim is a conditional one - if certain other assumptions are made. To flesh it out a bit, here's a chunk from the above article.
The basic problem with pre-stipulated conceptual/theoretical boundaries is that if reality itself happens to fall outside those boundaries, theorizing within the confines of those boundaries will inevitably generate either incompleteness or error. But methodological naturalism just is a stipulated prohibition on anything outside the 'natural' playing any conceptual role in scientific theorizing and explanation. If it turns out that reality chooses to ignore our restrictions (and why on earth shouldn't it?), then theorizing forbidden to cross those boundaries will inevitably be either incomplete or mistaken.
Here is an analogy. [All right - caught analogizing again.] Suppose that during the final pre-launch crew briefing for NASA's first manned mission to Mars, the head of NASA warns the crew of the dangers of starting public panics and instructs them to make no mention in any of their reports of aliens - regardless of what they happen to find on Mars. The restriction does make some sense. But suppose that the first thing the crew sees upon exiting their lander is an utterly undeniable Martian bulldozer. The question instantly arises: where did that come from? But the crew has a problem answering that question. Given the prohibition barring reference to aliens, the crew has only two options: (i) they can refrain from addressing the question, or (ii) they can construct a theory of the chemical evolution of Martian bulldozers. But that means that their science of Mars will be either (i) woefully incomplete - leaving out perhaps the single most fascinating aspect of the mission - or (ii) outrageously mistaken.
But even just methodological naturalism conjoined with aspirations for completeness has substantive implications. First, if one restricts science to the natural, then assumes that science can in principle get to all truth, then one has implicitly presupposed philosophical naturalism. But even if one merely stipulates methodological naturalism as essential to science, then assumes only that science is competent for all physical matters, or that what science (properly conducted in the long run) does generate concerning the physical realm will in principle be truth, then if the truth of the specific matter in question is non-natural, even the most excruciatingly proper naturalistic scientific deliverances on that matter may be wide of the mark, typically in exactly the way a science built on philosophical naturalism would be. For practical purposes, that comes close to importing philosophical naturalism into the structure of science.
So whether methodological naturalism has substantive philosophical implications (contrary to the common denial) or is philosophically neutral depends upon what it operates in tandem with. At the least, methodological naturalism makes the de facto assumption that there is an identifiable realm of reality which is on the scientifically relevant level functionally self-contained, and which is on that level functionally de-coupled from the supernatural. That assumption is neither obvious, trivial, nor - since it is an empirical universal negative - demonstrable.
But to actually answer your question, I may try to push it a bit further. But despite the above (and some other) reservations and qualifications, I think that methodological naturalism is a useful - perhaps even essential - provisional strategy, and one not to be lightly overridden.
TGL: Much has been made of the importance of methodological naturalism, particularly as definitive of what makes something science. What do you think of the arguments in its favour?
DR: Arguments for its value as a provisional strategy may be right. But even as a strategy, it has to be used with care. Over-rigid adherence can (as indicated earlier) have consequences for the self-corrective nature of science, and it can have other consequences (as noted just above) if care is not taken concerning what assumptions it is employed with.
Arguments for it will depend in part on exactly what methodological naturalism is, and more care is required there than is sometimes given. For instance, it is quite common to see methodological naturalism defined as a requirement that science be restricted just to natural concepts, resources, data, and theories, that being interpreted to mean that whether or not philosophical naturalism is true, science must proceed as if it is. (That, for instance, is the position of the National Center for Science Education - or at least of its director.) But the problem here is that (as Boyle pointed out three plus centuries ago) nature in a created universe might well - indeed most likely would - be very different from nature in a random, chance universe. Thus, the typical equating of a restriction to the natural with proceeding as if philosophical naturalism is true, turns out to beg some deeper questions.
Most of the actual arguments for methodological naturalism being a definitive, unchallengeable rule of science seem to me to be problematic. Very briefly, the three most common types of arguments are (1) arguments that anything non-natural is outside the realm of empirical detectability or testability, (2) arguments that allowing the non-natural into science is destructive in that it allows scientists to take the lazy way out in difficult scientific situations (simply saying "Well, God must have done that - no point in trying to figure it out", then wandering off to find the coffee pot) and (3) historical arguments claiming that the history of science has shown the bankruptcy of non-natural considerations in science. The first is the most prima facie plausible, but I think that there could be possible empirical cases in which the most reasonable conclusion would be that something supernatural was at work. (That's one of the cases I try to make in Nature, Design and Science.) Regarding the second, it is often the conviction that something is a product of design that keeps scientists in the hunt. Any company trying to reverse engineer a competitor's new computer model pays particular attention to puzzling components - refusing to give up trying to understand it precisely because they believe it to be a product of design. And of course historically most scientists took nature to be a product of design, and saw themselves as in effect reverse engineering nature - trying (as Kepler is alleged to have said) to think God's thoughts after him. The fundamental intelligibility of nature consequent upon its being designed by God was one of the key motivations underpinning the whole scientific project. But surely, it is argued, the history of science itself has established that allowing reference to the supernatural into science at ground level has simply failed - a la argument (3). But that argument too I think doesn't perform quite as advertised when one looks at the actual historical detail. (I won't go into the complications, but that's the case I tried to make in "Intelligent Design: What does the history of science really tell us?" (in Scientific Explanation and Religious Belief, eds. Michael G. Parker and Thomas M. Schmidt, (Tubingen, Germany: Mohr Siebeck, 2005), Chapter 8, pp. 126-149).)
TGL: Why should people be interested in the debate about design?
DR: There is a lot tied up in the debate - everything from the possible existence of a designer, to whether or not there is genuine empirical evidence of a designer, to the nature of science, to the nature of the cosmos (designed or not), to some vexed political issues, is bound up directly or indirectly in the issue. And those are pretty large matters.
Education policy has, of course, been the recent flashpoint. If the general design outlook is right, theories that deliberately exclude such considerations may well be subtly but seriously inadequate, and if teaching those inadequate theories in public schools is mandated by law, and if teaching the (ex hypothesi) true design theories is forbidden by law, the situation is problematic. Indeed, if we teach students the very best theories we can construct under methodological restrictions, neglect to point out that that restriction could have implications for the truth (vs. just the scientific legitimacy) of those theories, and present them as true, we are, I think, engaged in shady practice. So the issues of what ID is (vs. the heavily pushed caricatures), whether it could be legitimate science (the basic philosophy of science question), and whether it might be right (the scientific question), are potentially consequential beyond the level of mere academic interest. And of course, if ID is right, some pretty pressing questions about the character and intentions of the designer - whether supernatural or not - immediately arise. And those are significant regardless of what classificatory label - science, religion, philosophy - one sticks on them. But as mentioned earlier, I don't think that the ID movement has yet delivered the relevant goods on the scientific question.
TGL: How can philosophy shed light on this and other debates concerning science? What is the relevance of the philosophy of science in general?
DR: Philosophy of science can't, of course, dictate science to scientists (much less to reality itself). There are a lot of things it cannot even legitimately pronounce on. But although there is no known precise, complete definition of science, and although the competencies and boundaries of science are matters of dispute, philosophy of science can still underwrite some useful assessments, and sometimes needed refutations, of contentions concerning what science is and is not, what it can and cannot do, where its boundaries are and are not, and what its limitations are and are not - contentions which are invariably deployed in science/religion discussions. And often particular positions and arguments depend upon such contentions which are pretty clearly demonstrably mistaken. More generally, I think it can help us recognize instances where science is not given its proper due (which is now fashionable in some circles, and historically endemic in others) or where too much is claimed for science (which is typical in various anti-religious polemics and even among some proponents of religious belief).
TGL: What are you currently working on?
DR: I'm currently working on a book MS exploring some of the possible implications of recent neurophysiological research for science/religion relationship - trying to track in more depth some of the themes initially developed in "Humanness in their hearts" mentioned above. Longer term, I want to look in detail at evolutionary accounts of religion. And as department chair, a lot of energy goes into trying to keep my rambunctious colleagues in line.
TGL: Who have been the main influences on your thought?
DR: Lots of people, in many different ways. But if I were to pick one, it would be Alvin Plantinga.
*Please note: For personal reasons unrelated to the content, the author of this interview has asked to remain anonymous. Any errors are the fault of the site owner, who transcribed it.