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Grist to the mill of ID creationism: the failed strategy of ruling the supernatural out of science by philosophical fiat.


Maarten Boudry

Stefaan Blancke

Johan Braeckman



According to a widespread philosophical opinion, the methodology of science is intrinsically naturalistic. It is simply not equipped to deal with supernatural claims, so it has no authority on questions of metaphysics. This (self-imposed) limitation of the epistemic reach of science is often used as a way to reconcile science and religion. We argue that ruling the supernatural out of science for intrinsic reasons is not only philosophically untenable, but has actually been grist to the mill of Intelligent Design Creationism (IDC), The philosophical weakness of this conception of naturalism in science has been eagerly exploited by proponents of IDC to bolster their claims about scientists’ alleged naturalistic bias and dogmatism. Moreover, we argue that it leads to a misleading image of scientific knowledge and sits uncomfortable with actual scientific investigations of allegedly supernatural phenomena. Thus, we conclude that the attempt to reconcile science and religion on the basis of this philosophical doctrine is doomed to fail.


Kewyords: Methodological Naturalism, Science and Religion, Atheism, Intelligent Design Creationism, Evolutionary Theory



For over a long time, creationists and intelligent design proponents have complained that modern science is biased towards materialism and naturalism, and that it rules out any supernatural forces by fiat (Gish 1973; Macbeth 1974; Johnson 1993; Nelson 1996; Behe 2006). In response to these charges, many philosophers and scientists have recently argued that science is only committed to something they call methodological naturalism (MN): science does not deal with supernatural causes and explanations, but that is not to say that the supernatural does not exist. However, there has been some philosophical discussion about the correct understanding of MN and its proper role in science. In an earlier publication (XXX), we have made an often neglected distinction between two conceptions of MN, which involve two quite different views on the limits of science and the proper role of its naturalistic methodology.

A widespread philosophical opinion conceives of MN as an intrinsic and self-imposed limitation of science, as something that is part and parcel of the scientific enterprise by definition. According to this view (Intrinsic MN or IMN) - which is defended by people like Eugenie Scott, Michael Ruse and Robert Pennock and has been adopted in the ruling of Judge John E. Jones III in the Kitzmiller vs. Dover case – science is simply not equipped to deal with the supernatural and therefore has no authority on the issue (Pennock 1999; Scott 1998; Haught 2004; Ruse 2005; Jones 2005; Miller 2009). We reviewed five arguments for this conception of IMN but found none of them convincing.

Instead, we defended MN as a provisory and empirically grounded commitment of scientists to naturalistic causes and explanations, which is in principle revocable in the light of extraordinary empirical evidence (Provisory or Pragmatic MN – PMN). In this view, MN is justified as a methodological guideline by virtue of the dividends of naturalistic explanations and the consistent failure of supernatural explanations in the history of science (Edis 2002; Shanks 2004; Coyne 2009).

In this paper we will analyse the strategic ramifications of this important distinction between IMN and PMN. We claim that ruling the supernatural out of science by definition or for intrinsic reasons proves a counterproductive strategy against Intelligent Design Creationism (IDC), and, for that matter, against any theory involving supernatural claims. As we will show, IMN is actually grist to the IDC mill on several accounts, and the attempts to reconcile religion and science on its basis is doomed to fail.

The theological friends of IMN

According to PMN, scientists are justified in adopting the guideline of MN in light of the huge success of naturalistic explanations and, correspondingly, the consistent failure of supernatural ones. To a reasonable scientist confronted with an empirical problem today, pursuing supernatural explanations is a waste of time and effort. However, the fact that supernatural explanations have turned out premature in the past does not necessarily mean that they are impossible. All scientific knowledge is fallible, and in principle supernatural explanations might be vindicated one day, although the prospects are rather dim, to say the least.

According to the defenders of IMN, however, supernatural explanations have to be excluded from science for more fundamental reasons. The commitment of scientists to MN is unalterable in the light of future scientific developments, and the idea of a ‘supernatural explanation’ in science is really an oxymoron.

On the face of it, therefore, PMN seems to take the claims of supernaturalism more serious than does IMN. This does not mean, however, that IMN is advocated by the adversaries of religion and metaphysics, quite to the contrary. Precisely because IMN excludes the supernatural from science by definition or for intrinsic reasons, it is often used, in the words of one of its proponents, as a way to “divorce [evolutionary science] from supposedly atheistic implication” (Ruse 2005, p. 45)

The term itself was coined in 1983 by evangelical Christian and philosopher Paul deVries, who used it to make room for “other sources of truth” besides science.

If we are free to let the natural sciences be limited to their perspectives under the guidance of methodological naturalism, then other sources of truth will become more defensible. However, to insist that God-talk be included in the natural sciences is to submit unwisely to the modern myth of scientism: the myth that all truth is scientific. (deVries 1986, p. 396)

Not surprisingly, IMN is typically embraced by philosophers sympathetic to religion, by theistic evolutionists and religious liberals intent on safeguarding a special epistemic domain for religious faith (Haught 2000), but also by ‘accomodationist’ atheists who simply wish to alleviate the heated opposition between religion and science (Ruse 2001; Ruse 2005). Although these atheistic defenders of IMN have  brought forward interesting philosophical arguments for their position, it is apparent from their writings that their position is also inspired by the desire to “protect the religious sensibilities of theistic evolutionists” (Schafersman 1997) Just like Stephen Jay Gould’s idea of Non-Overlapping Magisteria (NOMA) (Gould 1999), for many IMN embodies the modern modus vivendi between science and religion. However, for the creationist and the IDC proponent eager to make a scientific case for supernatural design, this polite stand-off will just not do.

The theological enemies of IMN – confronting science and religion

With the principle of MN coming to the fore of the debate, proponents of IDC have certainly not backed down on their claim that scientists are guilty of philosophical and naturalistic prejudice. Phillip Johnson even made it the central tenet of his influential Darwin on trial. (Johnson 1993)

For all the controversies over these issues, however, there is a basic philosophical point on which the evolutionary biologists all agree. … The theory in question is a theory of naturalistic evolution, which means that it absolutely rules out any miraculous or supernatural intervention at any point. Everything is conclusively presumed to have happened through purely material mechanisms that are in principle accessible to scientific investigation, whether they have yet been discovered or not. (Johnson 2001, p. 61)

Thus, IDC proponents continue to treat MN as a token of scientists’ metaphysical prejudice, this time thinly disguised as a methodological principle: for on what grounds, other than metaphysical prejudice, could one dismiss one class of explanation in favour of another? Robert Pennock among others has claimed that Johnson simply fails to appreciate the difference between methodological and metaphysical naturalism (Pennock 1999, p. 192; Pennock 1996), but we will argue that the situation is more complicated. In fact, Johnson’s remarks show that IMN, which is clearly his focus of attack here, is actually grist to the IDC mill.

Although its defenders have claimed that IMN succeeds in avoiding a head-on collision between science and religion, we have shown elsewhere that the philosophical arguments for this reconciliation does not hold water (XXX). Moreover, we argue that IMN is a strategic failure for four different reasons.

1. A counterproductive strategy

Advocates of IMN want to the ground the naturalistic methodology of science on a philosophical basis. However, in doing so they divorce scientific methodology from the successful track record of naturalistic explanations. This makes it look as if science has never bothered to consider supernatural explanations, and has discarded them already at the outset.

IDC proponents, always eager to cast themselves in the role of the neutral and open-minded observers, have repeatedly exploited this philosophical weakness of IMN and taken it as further evidence of naturalistic bias in the scientific community. As a ‘good’ lawyer is expected to do, Philip Johnson has seized upon this weak spot in the defence of his opponents and turned it to his advantage: if science is supposed to be neutral with respect to metaphysics, as defenders of IMN claim, why is the hypothesis of supernatural design already “disqualified at the outset” (Johnson 2001, p. 67; see also Plantinga 1996; Dembski 1999, pp. 97-121)? Johnson complains that “[b]y the use of labels, objections to naturalistic evolution can be dismissed without a fair hearing.” (Johnson 1993, p. 7; see also Dembski 1999) Critical and open-minded scientists, according to Michael Behe, have to follow the evidence wherever it leads, instead of ruling out one source of evidence for philosophical reasons. (Behe 2006, p. 243; see also Nelson 1996; Nelson 1998; Dembski 2004, pp. 168-172; Bledsoe 2006, pp. 255-256). Anti-evolutionists have repeated their complaints about scientists’ naturalistic bias over and over, almost invariably choosing IMN as their target  

As an illustration of the way IMN backfires on scientific achievements, consider Plantinga’s elaboration of the idea from a historical perspective:

Well, suppose we adopt this attitude [IMN]. Then perhaps it looks as if by far the most probable of all the properly scientific hypotheses is that of evolution by common ancestry: it is hard to think of any other real possibility. […] So it could be that the best hypothesis was evolution by common descent – i.e. of all the hypotheses that conform to methodological naturalism, it is the best. But of course what we really want to know is not which hypothesis is the best from some artificially adopted standpoint of naturalism, but what the best hypothesis is overall. […] (Plantinga 2001, pp. 137-138)

By following the logic of IMN, Plantinga arrives at the conclusion that the design hypothesis has been unfairly rejected, because the philosophical dice have always been loaded against it. “The believer in God, unlike her naturalistic counterpart, is free to look at the evidence for the Grand Evolutionary Scheme, and follow it wherever it leads, rejecting that scheme if the evidence is insufficient. (Plantinga 2001, p. 138; see also Dembski 2004, pp. 170-171)

In the eyes of IDC advocates, the principled take on naturalistic methodology makes scientists myopic to what they perceive as the self-evident fact of supernatural intervention. Sociologist and ID-sympathiser Steve Fuller characterized MN as follows: “It was as if contemporary science was so indefensible on its own merits that it required a philosophical fig leaf for protective cover.” (Fuller 2007, p. 117) Creationist Paul Nelson concurs that evolutionists apparently want to keep theology out of science so desperately that they resort to incoherent philosophical doctrines like IMN. (Nelson 1998; Bledsoe 2006).

Defenders of IMN often complain that IDC advocates simply do not grasp the difference between MN and Ontological Naturalism (ON) (Scott 1998; Pennock 1999, p. 192; Miller 2009). However, the confusion is partly due to the defenders of IMN themselves. After all, a complete disregard for possible supernatural causes makes sense only if we already have airtight a priori reasons that the supernatural does not exist, or that if it does, it never interferes with our material universe. Advocates of IMN do not provide such reasons, precisely because they do not want to commit themselves to metaphysical naturalism. However, in the absence of a sound rationale for disqualifying the supernatural, the dictum of IMN to proceed “as if” only natural causes are operative looks quite arbitrary.

This becomes clear as soon as we imagine what would happen if supernatural forces were really operative in our universe. In such a world, IMN would be a very bad methodological device indeed, because it would exclude a real and tangible factor governing the universe from scientific consideration. As Richard Dawkins wrote (see also Edis 1998; Edis 2002):

A universe with a supernatural presence would be a fundamentally and qualitatively different kind of universe from one without. The difference is, inescapably, a scientific difference. (Dawkins 1997, p. 399)

This is the reason why, despite the disclaimers of Scott and Pennock, IDC theorists conclude – albeit falsely – that MN is just dogmatic metaphysical naturalism in disguise (Johnson 1995; Dembski 1999). In the conception of PMN we defend, science provides support for, but does not collapse into metaphysical naturalism. Unfortunately, IMN makes it look like it does, something that has not escaped the attention of the more sophisticated creationists.

Thus, although IDC theorists profess to regret that the supernatural is excluded from science by fiat, their writings show that IMN is actually grist to their mill. Consider Lewontin’s often-quoted statement about materialism in science:

It is not that the methods and institutions of science somehow compel us to accept a material explanation of the world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations [...]. Moreover, that materialism is absolute, for we cannot allow a Divine Foot in the door. (Lewontin 1997, p. 28 )

Phillip Johnson lauds this paragraph as “the most insightful statement of what is at issue in the creation/evolution controversy that I have ever read from a senior figure in the scientific establishment.” (Johnson 1997, p. 23) Michael Behe quotes Richard Dickerson’s discussion of IMN in full, in which Dickerson argues that science is “a game with one overriding and defining rule”, namely that of IMN. In the discussion that follows, Behe has IMN where he wants to have it: “the clear implications is that [the supernatural] should not be invoked whether it is true or not.(Behe 2006, p. 239) Behe opposes Dickerson’s conclusion: “Science is not a game, and scientists should follow the physical evidence wherever it leads, with no artificial restrictions.” (Behe 2006, p. 243) Borrowing from IDC’s own metaphoric image, IMN may very well be the philosophical crack into which IDC theorists are now trying to drive their wedge.

Defining the supernatural out of science is thus counterproductive (Kurtz 1999, p. 28; Stenger 2008; Edis 1998) because it lends ammunition to the accusation that was already voiced by young-earth creationists in the seventies (Gish 1973, p. 24; Macbeth 1974, p. 126), namely that evolution by natural selection appears to win the scientific debate only because supernatural designers were already carefully excluded from the outset. Therefore, we think that IMN unwittingly weakens the scientific case against IDC.

However, it is interesting to note that some advocates of IMN have made exactly the opposite claim, namely that only their approach provides firm ground for rejecting IDC. For example, theologian and theistic evolutionist John Haught maintains that those who place the God hypothesis within the reach of science deprive themselves of the best philosophical argument against IDC:

[I]n wedging ultimate explanation into what should be a purely scientific channel of inquiry [evolutionary materialists] are doing exactly what their ID adversaries do: they are conflating science with a worldview. […] By promoting their own peculiar alliance of science and philosophical belief they leave themselves with no methodological high ground to stand when they complain about ID’s mixing of biology with theology. (Haught 2000, p. 207)

First, Haught’s argument begs the question: of course, if one presupposes that science is not equipped to deal with supernatural claims, it follows naturally that those who think that evolution disfavours the God hypothesis are conflating science and metaphysics. But this is precisely the issue at hand. If IMN is philosophically untenable, as we claim, and scientific knowledge does bear on the God hypothesis, materialism is no longer just a “philosophical belief”, but the most rational conclusion emerging from the scientific data. Second, even in presenting the views of his opponents, Haught curiously holds on to the claim that the only way to attack IDC is to claim “methodological high ground”, whereas this is precisely what “scientific materialists” (in our terms, defenders of PMN) are trying to avoid. As Haught should know, evolutionary materialists concur with IDC proponents in their view that a supernatural designer, if any such entity exists, is in principle within the reach of science. They are not the ones to complain about any conflation of science and theology on the part of IDC, and indeed, it would be inconsistent for them to do so.

2. Soft-pedaling science

In our view, PMN is a reasonable methodological guideline for scientists because science has in the past consistently pointed in the direction of blind and purposeless processes where many had suspected the action of the supernatural and immaterial. As science made progress, most scientists were led to abandon supernatural explanations altogether. However, in their polite reluctance to make theologians face the embarrassment, defenders of IMN now pretend that there really was no discussion to begin with, because science simply cannot deal with supernatural causes in principle. IMN suggests that natural explanations inevitably had to come out at the end of the day, and that things could not have been otherwise.

But there is no compelling reason to think that this is so. The pioneers of science could very well have bumped into phenomena that defied their every attempt at naturalistic explanation (but they didn’t). In the world we happen to live in, science is capable of giving a comprehensible natural explanation for many phenomena that were previously deemed ‘mysterious’. But this perspective can easily distort our view on what is logically and metaphysically possible. We are so accustomed to the absence of any evidence for the supernatural that we are tempted to conclude that such evidence has to be impossible.

Moreover, history shows that evolutionary theory has attracted the attention of many a worrisome theologian trying to come to terms with the scientific findings in various ways. Old doctrines have been revised, metaphysical theories were converted into vague metaphors, and several attempts have been made to restrict the epistemic authority of science, or to erect philosophical walls that safeguard a place for God. (Edis 2002, pp. 53/107-108) According to Taner Edis, evolution goes even further than “forcing some painful changes on theology. It radically undermines the whole top-down universe, situating creativity squarely in the material world.” (Edis 2002, p. 55; see also Dennett 1996; Stenger 2008) Modern science has been increasingly successful in finding impersonal and blind material explanations for phenomena that were previously held to be inexplicable in anything other than supernatural terms. IDCers have rightly sensed that this enormous success of naturalism makes the idea of a supernatural Creator alarmingly implausible.

By contrast, advocates of IMN have tried to soft-pedal these implications. For example, Robert Pennock, in his otherwise very informative book on IDC, pretends that “[s]cience is godless in the same way as plumbing is godless” (Pennock 1999, p. 282). However, if the explanatory domain of modern science was as modest as one consisting of stopped drains and water pipes, of course one could comfortably resort to God on weightier matters of explanation. But as Pennock knows, modern science has extended its explanatory reach far beyond, including many domain that were traditionally reserved for the action of God: the origin of life, the beginning of the universe, the human mind, the edges of the observable world etc. That God turned out to be superfluous in all these domains is of far greater importance than that He is of no use to plumbers, so Pennock’s analogy is highly misleading.

Massimo Pigliucci, even though his position is close to IMN, has correctly pointed out that it is perfectly rational to spell out the “philosophical” implications of modern evolutionary theory:

Although asserting that evolution is purposeless is indeed a philosophical conclusion, it follows from everything we know and is consistent with the assumption in every science (not just evolutionary biology) that we can explain nature without recourse to the supernatural (gravitation seems as undirected and purposeless as evolution). (Pigliucci 2002, p. 258)

As another example, consider Christian philosopher Howard Van Till’s claim that science is “religiously inconclusive”: “[m]odern scientific theories concerning the properties, behaviour and formative history of the physical universe are logically independent of both theism and naturalism, favouring neither one nor the other.” (see also Van Till 2001, p. 153; Haught 2003, p. 776) But, as Alvin Plantinga has correctly pointed out, the claim that science cannot logically exclude theism is “a statement weak in excelsis(Plantinga 2001, p. 202) Logical possibility is a very weak criterion for belief, because there is precious little that science can logically exclude. The argument from logical consistency is a red herring that diverts attention away from the fact that science has dramatically undermined a whole class of positive arguments for the God hypothesis (Pigliucci 2002, pp. 142-145) [1].

Ironically, this conspicuous absence of God from modern science, which is the logical result of His superfluity on every level of scientific explanation, is now presented by some defenders of IMN as an indication of science’s metaphysical neutrality. For example, Robert Pennock writes that

[n]owhere in evolutionary theory does it say that God does not exist, for the simple reason that, like cell theory and relativity theory and every other scientific theory, it says nothing at all about God. But to say nothing about God is not to say that God is nothing.” (Pennock 1999, p. 333)

But nowhere in biology does it say that Bigfoot does not exist either. Surely Pennock does not want to conclude that biologists are completely neutral on the question of Bigfoot’s existence?

In this context, defenders of IMN often set up a straw man for the alternative position, namely the argument that science has proven that atheism is correct. Evolutionary biologist and Roman Catholic Kenneth Miller sets up this false dilemma:

[T]he conflict depends […] on an unspoken assumption. That assumption is, if the origins of living organisms can be explained in purely materialistic terms, then the existence of God – at least any God worthy of the name – is disproved. (Miller 2000, p. 190; see also Scott 1998)

Of course science cannot do this, but neither can it prove that Russell’s teapot does not orbit the earth, though that doesn’t make its existence a bit more plausible. Although it is impossible to definitely prove that God does not exist, it does not follow that scientific findings have no bearing whatsoever on the plausibility of the God hypothesis.

Defenders of IMN think that the mere logical consistency of science with the God hypothesis closes the case, but they ignore the other important ways in which science can bear on the God hypothesis. Although this strategy may be well-intended as a means to protect religious sensibilities, and may look like a convenient solution in the context of the separation of Church and State in the US, it does not hold up to philosophical scrutiny and is arguably a little sanctimonious.

3. Good fences make good neighbours

Defenders of IMN hold that the epistemic authority of science is limited to the natural realm. In the words of Keith B. Miller:

Science is a methodology that provides a limited, but very fruitful, way of knowing about the natural world. This method works only if science confines itself to investigation of natural entities and forces. (Miller 2009, p. 117)

Because of this ‘neutral’ metaphysical stance, IMN suggests that there exists a domain beyond the natural realm which just happens to fall outside the scope of science, and that religion and science are two equally valid but non-overlapping sources of knowledge (McMullin 2001, p. 168). For example, Reformed Christian Howard Van Till is a strong defender of science and IMN, but he doesn’t buy any of its naturalistic conclusions :

As I see it, granting the limited competence of natural science is not a concession to naturalism; rather, it is simply a recognition that we have empirical access only to creaturely phenomena. […] science [provides] an incomplete picture of reality because of its inability to probe beyond the creaturely realm.” (Van Till 2001, p. 161)

Theologian John Haught for his part has embraced IMN in almost lyrical terms, as it fits nicely with his idea that theology offers us ‘deeper’ knowledge than science can attain:

theology is now freed from moonlighting in the explanatory domain that science now occupies, so that it may now gravitate toward its more natural setting - at levels of depth to which science cannot reach. (Haught 2004, p. 236)

But as we have shown in our other article on MN (XXX), if the supernatural were knowable at all, there is no reason why science would in principle be incapable of telling us anything about it. If supernatural forces were to intervene in our material universe, as IDC proponents and other theists maintain, they would have empirically detectable consequences, and these are in principle open to scientific investigation.

If religion really were to constitute an equally valid source of knowledge, as defenders of IMN suggest, it would be all the more unreasonable to refuse taking into consideration its metaphysical claims for such questions as the origin of life. As Alvin Plantinga wrote, “surely the rational thing is to use all that you know in trying to understand a given phenomenon.” (Plantinga 2001, p. 341). Thus, by setting up an artificial diving line between science and religion, IMN shoots itself in the foot.

4. Why investigating supernatural claims?

From the perspective of PMN, the proper way to attack IDC is to confront its claims with empirical and conceptual arguments, not to reject the theory by philosophical fiat. Defenders of IMN, by contrast, inadvertently sabotage this scientific line of critique. After all, if supernatural explanations are already ruled out from the outset for intrinsic reasons, it makes little sense to argue that the empirical evidence speaks ‘against’ it. From the perspective of IMN, the design hypothesis can be evaluated by scientific means only if the purported designer is some sort of extraterrestrial being on a distant planet, which would situate it firmly within the natural realm.

However, to claim that the empirical evidence speaks against supernatural design, while at the same time ruling this idea out of scientific court from the outset, seems like an incoherent approach. The problem reminds one of an old Jewish joke: someone borrowed a copper kettle from B and after he had returned it, he was sued by B because the kettle now had a big hole it. His defence was: "First, I never borrowed a kettle from B at all; secondly, the kettle already had a hole in it when he gave it to me him and thirdly, I gave the kettle back undamaged.”[2]

If supernaturalism fails on empirical grounds, this entails that, at least in some sense, it might have succeeded, something which is only allowed by PMN. Indeed, on numerous occasions, scientific sceptics have investigated extraordinary claims which, if corroborated, would point in the direction of immaterial and supernatural phenomena (Humphrey 1996). According to these researchers, science has rejected fairies and demons not because it refused to consider them, or was not equipped to do so, but because supernatural phenomena seem to vanish into thin air each time scientists try to capture them (and because defenders typically resort to all sorts of immunizing strategies to explain away their failures ). As Paul Kurtz wrote:

Skepticism is a method of inquiry primarily, not an attitude or posture or philosophical viewpoint that denies entities or phenomena. (Kurtz 2004, p. 32)

IDCers have been quick to point out that these investigations of the supernatural sit uncomfortably with the widely advocated principle of IMN in science (Nelson 1996; Nelson 1998; Dembski 1999; Woetzel 2005), and on that particular point they are quite right. Indeed, the problem has been apparent in the ambivalence of defenders of IMN themselves concerning the epistemic reach of science. For example, Robert Pennock acknowledges the historical failure of supernatural explanations, but he thinks this cannot be the “main reason” for rejecting IDC explanations, and he then gives several intrinsic reasons for ruling the supernatural out of science (Pennock 1999). Or consider Barbara Forrest’s discussion of scientific naturalism. On the one hand, she offers a definition of the ‘supernatural’ that renders supernatural explanations in science procedurally impossible or even a contradictio in terminis. On the other hand, she proposes a “tentative rejection” of the supernatural “in light of the heretofore consistent lack of confirmation of it” (Forrest 2000, p. 23), which is certainly in line with what we call PMN and with the attitude of many sceptical investigators. However, we submit that the two conceptions of MN are mutually exclusive and need to be distinguished from each other: either one defends PMN, implying that supernatural explanations might have succeeded, or one chooses IMN, which is to rule them out a priori.

Functional Integrity and God as a Creature

On the question of how to attack IDC, we have sided with scientific rationalists who confront the claims of IDC head on, and against the accomodationist policy of IMN. For the most part, this is an internal dispute among scientists and philosophers who are in any case firm advocates of evolutionary theory. Some defenders of IMN are metaphysical naturalists and atheists all the same, but they simply think that this is a philosophical discussion which has to be separated from the scientific issues.

However, it is interesting to have a look at a parallel debate which has been going on between those who concur on the alternative metaphysical picture, that of theism, but disagree over the proper way to support their case and the correct relationship between their beliefs and scientific knowledge. Both camps disagree over this fundamental question: is there any sound theological argument to endorse the strictures of IMN, and hence to accept that supernatural claims fall beyond the epistemic reach of science?

As far as we can see, only a world in which God does not intervene directly is a world in which IMN makes sense. After all, if He performed miracles and answered prayers, these actions would have empirical consequences, and it would only be reasonable for scientists to take these into account. But liberal theologians think that a worthy deity must have a non-interventionist policy. The theological rationale of Diogenes Allen is a good example:

God can never properly be used in scientific accounts, which are formulated in terms of the relations between the members of the universe, because that would reduce God to the status of a creature. According to a Christian conception of God as creator of a universe that is rational through and through, there are no missing relations between the members of nature. If in our study of nature, we run into what seems to be an instance of a connection missing between members of nature, the Christian doctrine of creation implies that we should keep looking for one. (Allen 1989, p. 45)[3]

Allen refers to the theological position which Howard Van Till termed the thesis of “functional integrity”:

In such a Creation there would be no need for God to perform acts of 'special creation' in time because it has no gaps in its developmental economy that would necessitate bridging by extraordinary divine interventions of the sort often postulated by Special Creationism. (Van Till 1996, p. 21)

This theological position safeguards religion from direct confrontations with science, provided that scientists are themselves prepared to honour the same philosophical boundary with rationalizations of their own. On the other side of the theological debate, however, we find IDC proponents like Alvin Plantinga and William Dembski, who dismiss these arguments as half-hearted rationalizations of an untenable retreat of theology. Although we certainly think that the argument of IDC proponents against evolution are ill-conceived, it is difficult not to sympathise with them on this point. As Johnson wrote in an exchange with Van Till about the strictures of IMN:

Effectively, that means that God must be exiled to that shadowy realm before the Big Bang, and He must promise to do nothing thereafter that might cause trouble between theists and the scientific naturalists. (Van Till and Johnson 1993)

According to Dembski, the thesis of the self-sufficiency of nature “artificially constricts the range of things God may ordain.” (Dembski 1999, p. 64; see also Plantinga 2001). Liberal theologians, however, think that the idea of direct interventions by God in the course of nature is equivalent to the God of the gaps theology. This theological view postulates divine action in those aspects of reality which science has left unexplained. Many theologians find the idea unacceptable, because it would reduce God’s action only to particular aspects of reality, which science might be able to explain later on. However, Plantinga among other defenders of IDC has pointed out that believing in divine intervention does not commit one to the ‘God of the gaps’ theology at all, a position which he himself forcefully dismisses as an “anemic and watered-down semideism” (Plantinga 2001, p. 350). One can still perfectly maintain, as Plantinga does, that ­God constantly and directly sustains the whole of his creation, natural laws included.

Why, then, is the idea of God of the gaps theology used as a red herring in the context of IMN, and why do theologians like McMullin, Van Till and Allen accept this retreat of God into the “shadowy realm before the Big Bang”? We think it suggests a different explanation: theological defenders of IMN seem to be aware, unlike Plantinga and the IDC proponents, that appealing to supernatural explanations in the face of unsolved scientific problems has always been premature, and that science has steadily made progress on problems that were for a long time deemed unsolvable. From their perspective, pursuing arguments like ‘irreducible complexity’ is a guaranteed dead-end for theology. Because they do not share Plantinga’s misconceptions about evolutionary theory, they do realise that the scientific evidence for evolution by natural selection is overwhelming. If science has failed to uncover any evidence of a supernatural Creator of the universe, what better solution than to pretend that it simply has no bearing on the supernatural at all? In this light, it is not surprising that some theologians have tried to reach a mutual understanding with those scientists who, for their part, have no intention to tread on the domain of metaphysics. Faced with a pending defeat, liberal theologians have simply opted for a draw.

On the other side of the debate, Plantinga, Johnson and Dembski are well aware that, if the theory of evolution by natural selection is true, this constitutes an enormous threat to religious belief. In fact, it makes God completely superfluous and reduces Him to a mere logical possibility, which is a very weak basis for belief. In the words of Dembski:

Atheists, materialists and naturalists had been offering promissory notes that natural laws were sufficient to explain life. It was Darwin’s theory, however, that put paid to these promissory notes. […] By giving a plausible picture of how mechanization could take command and make life submit to mechanistic explanation, [Darwin] cleared the ground for the triumphant march of mechanistic explanations in biology. (Dembski 1999, pp. 83-84)

The only solution from their perspective is simply to challenge the claim that naturalistic evolution tells the whole story. As they are confident that the existence of God can be scientifically demonstrated, they will have none of these theological rationalisations for the epistemological retreat of religion (Van Till and Johnson 1993; Dembski 1999; Plantinga 2001). In a certain sense, they can’t be blamed.

Confusion about MN

As is clear from our discussion, we think the real issue in the debate about MN with respect to IDC is not the confusion between metaphysical and methodological naturalism, as Eugenie Scott and others like to think, but the distinction between IMN and PMN. We think that the current divergence of opinion on the subject of MN deserves more attention. IDC theorists often present the Intrinsic version of MN as the consensus opinion among scientists, because they obviously perceive it as an easy target (see for example Johnson 2001, p. 61; Dembski 1999, pp. 117-119; Dembski 2004, pp. 170-171). This is not altogether unsurprising, as some scientific and philosophical advocates of IMN themselves write as if IMN simply is the solution to the demarcation problem in philosophy of science (for a critique of the demarcation project, see Laudan 1996; Edis 1998; Sarkar 2009).

Unfortunately, even some writers who are in line with what we call PMN fail to notice the popularity of the alternative view. For example, in his excellent critique of IDC, Niall Shanks has no patience with the suggestion that science is by definition restricted to natural causes and explanations, and labels this as a “smoke-and-mirrors strategy” (Shanks 2004, p. 139) of IDC advocates. But this is to underestimate the confusion on the issue among defenders of evolutionary theory. Shanks is right to dismiss Dembski’s complaint that “methodological naturalism is the functional equivalent of a full-blown metaphysical naturalism” (Dembski 1999, p. 119), because in Shank’s presentation it amounts to no such thing. However, Shanks seems to be unaware that the popular IMN version that Dembski attacks (but wrongly assumes to be the scientific consensus view), indeed only makes sense if we have prior reason to accept metaphysical naturalism (see for example Dembski 2004, p. 191).

Thus Shanks writes that “the methodological naturalist will not simply rule hypotheses about supernatural causes out of court” (Shanks 2004, p. 141), whereas this is exactly what authors like Eugenie Scott, John Haught and Michael Ruse do. In a review of Shanks’ book, IDC sympathizer Del Ratzsch unsurprisingly accuses Shanks of misrepresenting even the views of his evolutionist allies, and he confronts him with a catalogue of favourite quotes from IMN advocates (Ratzsch 2005, pp. 39-48).

In his discussion of MN, philosopher of biology Kelly C. Smith rightly points out that science “is not in the business of ruling things impossible” (Smith 2001, p. 713), and he emphasizes that whenever supernatural explanations were invoked in the history of science, they never survived critical scrutiny very long. However, Smith’s article gives the reader the impression that there is no discussion among philosophers of science about this line of defence, whereas many of his colleagues hold views incompatible with his own. For example, would Eugenie Scott agree that in principle science is always open to the possibility of supernatural explanations?


At a certain point in David Hume’s Dialogues concerning natural religion (Hume 2007 [1779]), Philo and Demea take sides together against Cleanthes’ a posteriori arguments for the existence of God. They maintain that the human mind is simply too limited to be able to grasp the unfathomable nature of God, and that His existence is self-evident and a priori. Arguably, Philo (or Hume) is also just being careful to avoid that his sceptical arguments against the design argument collapse into outright atheism. Demea for his part does not want to make God’s existence dependent on something as mundane as an a posteriori argument, because these are fallible and imperfect and would make the foundation for religious faith too fragile. Thus, they would give atheists a dangerous advantage in the debate.

In a similar manner, the philosophical principle of IMN has tried to consolidate a truce between science and religion, by providing a common ground between scientists and religious believers who do not want to think too much about their conflicting worldviews. In the context of the ongoing efforts by IDC advocates to get their pseudoscience in the classroom, this may look like a convenient and well-intended solution to uphold the separation between church and state (Scott 2004; Jones 2005). However, as we have shown elsewhere (XXX), the attempt to rule IDC out of science with intrinsic arguments does not hold up to philosophical scrutiny. As Young and Edis succinctly wrote, “scientists reject claims of intelligent design because of their failure, not because intelligent design is indelibly stamped with a philosophical scarlet letter.” (Young and Edis 2006, p. xii)

In this paper, we developed our argument further and demonstrated that IMN also fails from a strategic perspective: not only does it fail to counter the classical creationist accusation of naturalistic bias in science, but it ­actually makes matters worse. The philosophical weakness of IMN has been eagerly exploited by IDC theorists to repeat their old accusations, to cast themselves in the role of neutral and scientific observers, and to point out the discrepancy between the letter of IMN and actual scientific practice (e.g. sceptical investigations of ghosts, Extra-Sensory Perception, the healing power of prayer). With IDC proponents becoming ever more prominent and philosophically sophisticated, IMN will be subjected to more and more philosophical pressure. In that respect, excluding supernatural explanations from science with muddled philosophical arguments is certainly a bad idea. Moreover, IMN compromises the epistemic status of science and suggests that it is just ‘one way of knowing’ among many others. Finally, it soft-pedals the metaphysical reverberations of modern science in general and evolutionary theory in particular, and it is therefore a somewhat sanctimonious strategy.

That last point shows that maybe IMN does not fail so much as a strategy, but because it is conceived as a strategy in the first place. The main motivation behind IMN seems to be a desire to reassure the faithful and retain the support of theistic evolutionists and religious liberals in the battle against creationism. Understandable as this may be from a political perspective, the purported reconcilement between science and religion on the basis of IMN happens at the expense of philosophical and scientific integrity, and is therefore misguided.


The authors would like to thank John Teehan and Filip Buekens for stimulating discussions and comments.







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[1] Defenders of IMN often point out that many prominent scientists were religious believers and MNists nonetheless. Gregor Mendel, for example, was a metaphysical supernaturalist, but he developed his knowledge of the laws of heredity using MN. First, simply because Mendel used only naturalistic explanations in his particular domain does not commit him to the idea that science in general is only allowed to use naturalistic explanations. Maybe he found naturalistic ones simply the most successful or fruitful explanations in the science of heredity? Second, and more importantly, the case of a scientist professing to be a religious believer only proves that believing in God and defending science are psychologically compatible for some people, not that it makes much philosophical sense.

[2] The example is given in Freud’s The Interpretation of Dreams.

[3] Cited in Plantinga (2001, p. 347)