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Australian philosopher, literary critic, and professional writer. Author of FREEDOM OF RELIGION AND THE SECULAR STATE.

Monday, October 25, 2010

Boudry, Blancke, and Braeckman on methodological naturalism

This important paper (well, I've actually linked here to a publicly-available late draft that contains a few typos) in Foundations of Science merits careful reading. Authored by Maarten Boudry, Stefaan Blancke, and Josef Braeckman, it deals - very well, in my opinion - with the capacity of science to investigate the supernatural. It's refreshing to read something like this, which goes a long way towards setting the record straight.

Of course, science cannot investigate the supernatural if we define "the supernatural" as "whatever cannot be investigated by science"! But once we define the supernatural in some other plausible way it is by no means apparent that science can't investigate it, just as it can investigate things that no longer exist (such as dinosaurs), things that are very distant (such as the moons of Jupiter), and things that are very small (such as atomic nuclei). None of the latter can be perceived directly with our senses, but they can interact with our senses in other ways - by leaving traces on the world that we can perceive, by interacting with scientific instruments to create images that we can perceive, by affecting experimental apparatus in predictable ways, and so on. In the end, we can use distinctively scientific means to investigate many things that interact with our senses only indirectly. Depending on the situtation, we can sometimes establish a lot about those things. We do, in fact, know a lot about the moons of Jupiter, dinosaurs, and atomic nuclei, even though none of these things have ever been directly observed with our senses (the moons of Jupiter have been observed via scientific instruments such as telescopes, and we have various reasons to think that these are reliable, but they have not been observed by unaugmented human eyes).

For example, let's take a toy definition of the domain of "the supernatural": imagine that it relates to the existence, characteristics, and activities of disembodied intelligences. Can science investigate this domain? In principle, yes, at least sometimes.

If a disembodied intelligence such as a spirit or a demon is said to exist and to interact with the world in a certain more-or-less regular way (perhaps because this being has a particular power set and particular psychological dispositions), we can go and look for corroborating evidence. Of course, we may be caught short if we're told that this intelligence is capricious or is hiding or works in mysterious ways, or whatever, so that its existence ends up being compatible with any observations at all. People who posit capricious, etc., disembodied intelligences as explanations for phenomena are in fact making their claims immune to scientific investigation (and they are certainly not doing science, themselves!). But what makes their claims immune is reliance on the capricious, etc., nature of these beings, not the fact that they are said to be disembodied.

Hypotheses that refer to capricious intelligences or to intelligences that are described so vaguely that we can't get a handle on them at all, or to beings that are described in internally contradictory ways, are non-starters. And, indeed, there are many reasons why it is difficult to settle the truth of supernatural claims by scientific investigation. But that doesn't mean that all hypotheses about beings or intelligences or principles that meet some intuitively plausible definition of the supernatural are non-starters in principle. The practical difficulty in testing many of the claims made by, for example, Intelligent Design theorists is that they use immunization strategies. Again, that is a hallmark of non-science or pseudoscience (or at the very least science that is so fundamentally flawed that there can be no rational pedagogical purpose in teaching it to children).

Boudry and his colleagues make astute remarks about all this:

However, we have to be careful not to misconstrue the immunizing strategies and ad hoc amendments of creationists as intrinsic problems with supernatural claims. It is true that IDC proponents are guilty of immunization strategies, but as far as we can see, this unwillingness to take empirical risks is just an indication of the dismal state of their research programme. After all, resorting to immunization strategies is a typical feature of pseudo-science, supernatural or otherwise (Boudry and Braeckman 2010).

Thus, if only they chose to do so, IDC proponents could easily equip an alleged supernatural Designer with specific attributes and intentions in such a way that the design hypothesis would yield unexpected predictions and is not “compatible with any and all observations of the natural world”, as Scott claims (Scott 2004, 20; Richter 2002, 21). For example, if one supposes that the Designer is benevolent and has created the universe with good purpose, as almost any theist does, one is confronted with the problem of evil and suffering in the world (Hume 2007 [1779]; Kitcher 2007, 130). As Reed Richter pointed out, in response to Scott’s defence of IMN, “‘[s]upernatural’ does not automatically imply arbitrary, capricious action as Scott implies”

Do consider the whole article, which contains plenty of detail to chew on. It won't escape long-term readers that Boudry and his colleagues are putting essentially the same view that I have long argued for (see here for example). They are giving it a more formal and concerted defence, and hopefully their argument will carry more weight than my occasional blog posts on the subject.

Of course science has learned over the years that explaining natural phenomena in terms of the actions of supernatural ones (e.g. disembodied intelligences) is not fruitful - that is because of the very poor track record of such hypotheses. The procedures of science now strongly discourage supernatural hypotheses, and a scientist resorting to them would, quite rightly, not be taken seriously. This is the practice of methodological naturalism.

But that does not mean that scientists must, in principle, have nothing to say if others advance claims about supernatural phenomena. If the claims are not sufficiently immunized, scientific investigation may even be able to show that they are false.

H/T to Jerry Coyne who has some interesting stuff of his own to say.


Steve Zara said...

I have a great problem with the concept of supernaturalism. But then I also have a problem with naturalism. They both seem to be outdated descriptions of a reality whose true "nature" looks increasingly beyond anything we can easily understand. I wrote an article at RD.net recently that was referred to by PZ and Coyne on this subject, and seemed to kick off this Gnu Atheist discussion, expressing position of refusal to accept the possibility of evidence for God/supernaturalism. I'm probably a bit too fundamentalist for you about this, but I think a new approach is needed rather than conceding that terms like "supernatural" are meaningful. I really don't think that they are. They express a desire for what reality should be like rather than a coherent position on what reality could be like.

Alex SL said...

Of course, science cannot investigate the supernatural if we define "the supernatural" as "whatever cannot be investigated by science"!

That seems to be the trick. Massimo Pigliucci and Eugenie Scott simply define "supernatural" as a synonym of "capricious". And when you point out that claims of capriciousness could be made for all other phenomena (cryptozoology, quack medicine, etc.), the answer is that you are not allowed to do that in these cases. But for god, you are. And so help me, but that special privilege seems to be granted to the faithful for the sole purpose of being able to say that science cannot examine the supernatural. Kinda frustrating.

Others make the much more interesting point that there is no coherent definition of supernatural. To your example of disembodied intelligence, they would in essence reply that we know that this is impossible. But how do we know that it is (very likely) impossible? Only because of scientific evidence that we have accumulated! QED, I would say, but it does not seem to convince the majority of commenters over at WEIT...

Alex SL said...

Steve, our comments must have been made at the same time. You write, "nature looks increasingly, etc." So my question is (and I would ask PZ Myers the same): Do you want to say that what we know now, from our scientific discoveries, makes any assumption of the supernatural existing nonsensical, or that any definition of supernatural whatsoever was incoherent from the get-go, even 6000 years ago, and science could thus never have found evidence for it to start with?

If it is the first, then there does not seem any basis for disagreement, but it also does not seem to be the point. I do not think that Jerry Coyne, Russell Blackford or any other reasonable person expects science still to be able to find evidence for the supernatural now, with all that we already know making it extremely unlikely. The claim is that it could have turned out differently, that we could not have known 6000 years ago that we find ourselves in a universe where disembodied intelligence is very likely impossible, that was very likely not created fully formed just a few years earlier, or where we were very likely not bestowed with immortal, immaterial souls that survive the death of our bodies and can be spoken to through a shamanic trance.

Don't get me wrong: I would also call all these phenomena part of nature, if they existed. But that is not very helpful. The question then simply becomes: if we call ghosts, souls and faith healing fuzzlegarb instead of supernatural, could science have found evidence for the fuzzlegarb?

Richard Wein said...

At the risk of beating my own drum, I'm another one who's been saying this for years, though not as eloquently as Russell or the three Bs. The recognition that there are two meanings of "methodological naturalism" in use is important. I've referred to these in the past as a priori MN and rule-of-thumb MN (IMN and PMN respectively).

It seems to me that supporters of IMN like it for two reasons. They see it as useful for keeping religion out of science (as an argument against ID) and for keeping science out of religion (its role in "accommodationism").

As an argument against ID it can be counterproductive (as well as fallacious).
1. It distracts from all the good arguments against ID, the scientific arguments. ID advocates can focus on the argument from IMN and give the impression that ID critics have nothing else.
2. It undermines the argument from authority against ID. ID advocates can claim that scientists have have an a priori rule that prevents them from accepting ID regardless of the scientific evidence, so their knowledge of science is irrelevant.
3. There may be people who haven't considered the science in detail but can see that the argument from IMN is fallacious. They are liable to think, "I've seen the ID critics make one fallacious argument, so I'm going to be a lot more skeptical about everything else they say".

Steve Zara said...


I think it's more helpful to consider why the term "supernatural" is used rather than what it is supposed to mean. I think it's fair to say that these days it's used to describe supposed phenomena that mustn't be explained by science: once a miracle is explained, it's no longer a miracle.

I think we can have all kinds of arguments about meanings, but they aren't of any use unless we look at motives, and the motivation for what seems to me to be a pointless division of the world into natural and supernatural seems clear: to define ideas that aren't vulnerable to destruction by science and reason. The point of the supernatural is that there should be a "behind the scenes" of the universe, which humans have access to, so we can avoid the consequences of a vast and unfeeling universe.

AskWhy! Blogger said...

Wednesday, 10 July 2002 at www.askwhy.co.uk:
"Eugenie Scott... made a distinction between methodological and philosophical naturalism to leave a scientific gap for God. She says science adopts naturalism simply as a methodological tool for doing research, but this methodological tool does not dismiss God. The naturalist who denies the existence of God is a naturalist in a philosophical sense -- the physical world is all there is. She is saying that Christians who wants to practice science can pretend that Nature is all there is in the lab, and then they can resume their belief that God is all important instead when they leave it. For Scott, naturalism is not a scientific conclusion, but an assumption of the scientific method, and so science cannot inform us as to the existence of God. Since Scott admits that religion has nothing to say about anything natural, then NOMA must be true.

"What is ignored is that the scientific method could not work unless naturalism was true in practice. If the finger of God waggled incessantly in everyday affairs according to His whims and the prayers of individual Christians, then science would notice it because effects that are uncaused would be commonplace. Gould admits that a personal God would contradict the scientific evidence. If the God behind the universe works in subtle ways, and entirely through natural laws, as some theistic scientists say, it is impossible to infer His presence. It is therefore more parsimonious to assume His absence. The best that can be had from Scott’s argument seems to be that God is absent in practice! If God is what most people think of as God, NOMA is invalid."

Alex SL said...

And here is me thinking that getting definitions sorted out is the very first thing you have to do to have any meaningful discussion at all - otherwise, we might be talking past each other without even realizing it.

And that seems to happen at the moment. You draw a direct line from your position to these posts from PZ Myers. Now please read them again with an outsider's eye, with the eye of one who is maybe not even an atheist.

I guess (and you have not really answered my related question above) that what you both mean is that science can examine all that exists, and thus demonstrate things commonly called supernatural to exist (in which case they aren't supernatural) or not to exist. And if that is it, I agree completely. But here and here we have a philosopher who would call that position scientism, and he apparently read PZ's post as an admission that science cannot say anything about the supernatural at all. Which at least to me, does not seem to be the idea, I guess? He is also an atheist, but he likes to bash atheist scientists for daring to reject god based on lack of evidence, and thinks that only philosophers are qualified to comment on the issue.

Even worse, if you read PZ's posts with a believers eye, you will find it very hard not to understand them as an open admission that atheism is just another blind faith. He does not say: science might well have found gods to exist, given the right evidence, but it is just not there. He says: no evidence whatsoever could convince me that a god exists. What is his intention, to come back to your question? The way the posts are written, it may well be to provide the faithful with arguments that allow them to dismiss him as a fundamentalist.

Roedy said...

We study animals that are elusive (capricious) with cameras, droppings, hair, traps or by studying other effects they have on the environment.

If a supernatural thing can be claimed to exist, it must have some observable effect, otherwise it is imaginary, by definition.

Alex SL said...
This comment has been removed by the author.
Russell Blackford said...

Alex, your most recent comment is addressed to Steve - yes?

Alex SL said...

Yes. And sorry for the double post. My browser crashed and I was assuming it had not transmitted the information.

bad Jim said...

I like the IMN/PMN distinction. I am however confused by the notion that the alleged capriciousness of supernatural entities is merely an attempt to avoid falsifiability. The excuse that ghosts refuse to reveal themselves to skeptics is less than convincing, of course, but the gods of myth were nothing if not capricious.

If heretics were routinely struck by lightning or holy men drawn up to heaven in a whirlwinds it would be worthy of investigation. The scarcity of observable miracles suggests above all the weakness or the laziness of the gods; at the least we can set a very low bound to the extent of their influence.

Preeti said...

Only science can explain super natural and will be agreed by all for its authenticity, else difference in opinion will always prevail. Whether true or untrue.

Maarten Boudry said...

Even worse, if you read PZ's posts with a believers eye, you will find it very hard not to understand them as an open admission that atheism is just another blind faith. He does not say: science might well have found gods to exist, given the right evidence, but it is just not there. He says: no evidence whatsoever could convince me that a god exists. What is his intention, to come back to your question? The way the posts are written, it may well be to provide the faithful with arguments that allow them to dismiss him as a fundamentalist.

Exactly, Alex! Ironically, there seem to be two very different kinds of people who hold that there could never be scientific evidence for the 'supernatural'
- atheists like PZ Myers ans Steve Zara, who want to make clear that believers don't even stand a chance of convincing them, because they will never budge
- accomodationist and theologians like Eugenie Scott, John Haught & Robert Pennock, who want to make sure that science has no (negative) bearing on the supernatural, so that religion is safeguarded.
(I'm not sure where Massimo Pigliucci fits in here!)
Both positions are counterproductive, because they come off as dogmatic and closed-minded. I would say especially for the accomodationists: if they explicitly leave open the possibility of supernatural intervention, why do they exclude it a priori as a matter of methodology? Now all the ID pundits are whining that God is already “disqualified at the outset”. How unfair!

Yair said...

I would suggest that as naturalists, it is far better to start by defining what "naturalism" means and work our what "supernatural" means by contrast. It is more productive to formulate a positive doctrine that we could then contemplate and justify or amend than to adopt the definitions and discourse of another worldview.

For myself, I believe the fundamental doctrine of naturalism is the Principle of the Uniformity of Nature that Hume so long ago identified as the unjustified assumption underlying empiricism. Naturalistic universes are ones that are highly uniform, especially in some specific ways (such as causality). This makes them easily amenable to scientific inquiry. Current physics indicates that our universe is uniform to almost absurd levels (e.g. all types of fundamental particles exist everywhere, just in varying degrees).

This leads by contrast to the idea that "supernatural" worlds are ones that are non-uniform. This does not necessarily imply that scientific investigation is precluded. If the non-uniformity is itself regular (e.g. prayer works, in defiance of the laws of physics), then the supernatural can be investigated scientifically. If the non-uniformity is taken to the extreme, a world with no uniformity at all would not allow science to work - but then again, it would not allow sentient creatures to exist, either, as that too is a uniformity. So from the weak anthropic principle, it arises that the type of non-uniformities that we could expect in our world if it is supernatural are probably amenable to scientific investigation. "Capricious" phenomena may, however, make such investigations impractically difficult.

This is of course but one way to define the "supernatural". But it appears to me that this is a good way for a naturalist to do so.

Alex SL said...

I do not doubt that an unclear or even incoherent definition of "supernatural" is a big problem. And really, I also believe that the best definition of supernatural would be an empty set: nature is everything that exists, even if it includes gods or souls.

But the problem is, Massimo Pigliucci and Eugenie Scott apparently define supernatural as capricious - in one of the discussions over at his blog, MP went as far as saying "if it follows clear rules, why would you call it supernatural?"

But what I have tried to point out over and over again is that many people do not use that definition. They will quite happily call magic or faith healing supernatural even if they expect it to work reproducibly and reliably (that seems to be the entire point of magic, no?). If you then go on and say, as the NCSE and MP do, that science cannot examine the supernatural, these believers will not understand this to mean that science cannot test claims that are nothing but goal post moving, which is trivially true anyway, but simply that science is forbidden from saying that faith healing does not work!

Richard Wein said...

Like most words in natural language, the meaning of "supernatural" is given by a cluster of associations that the word has for us. We have a pretty good idea of which entities get labelled "supernatural" in common parlance, even if it's difficult to say just what these entities have in common and there are questionable cases. There's no need for us to come up with a definition unless we are using the word in a way that makes such a definition necessary. IMN supporters do use the word in such a way. Since they are claiming that a certain type of hypothesis is necessarily excluded from scientific consideration, they need to say what type of hypothesis that is. So the onus is on them to say what _they_ mean by "supernatural". They usually fail to do so until challenged, and then come up with a wide variety of different definitions.

I don't think PMN requires a definition, because it's only a vague guideline or attitude, not a definite rule. So the vague everyday usage of "supernatural" is sufficient. Scientists tend to ignore the sorts of hypotheses that might get labelled "supernatural" in everyday parlance. It doesn't matter if there's uncertainty about whether to label some hypothesis "supernatural", because scientists are not really interested in the label. If there's a questionable case, they should consider that case on its own merits, without regard to labels.

There are plenty of other hypotheses that scientists routinely exclude, besides "supernatural" ones. Scientists don't keep asking themselves, "should I consider the hypothesis that an unknown extraterrestrial got into my laboratory and interfered with my experiment?". I would say that PMN is just a particular case of the more general principle that "extraordinary claims require extraordinary evidence".

So in my view there was no need for Maarten et al to give their own definition of "supernatural".

Maarten Boudry said...

That's right, the burden of proof is on those who exclude the supernatural a priori to provide a clear and consistent definition, I hadn't thought of it that way!

Anonymous said...


PZ's first comment in full is:

"The nature of this god is always vague and undefined and most annoyingly, plastic — suggest a test and it is always redefined safely away from the risk. Furthermore, any evidence of a deity will be natural, repeatable, measurable, and even observable…properties which god is exempted from by the believers' own definitions, so there can be no evidence for it. And any being who did suddenly manifest in some way — a 900 foot tall Jesus, for instance — would not fit any existing theology, so such a creature would not fit the claims of any religion, but the existence of any phenomenon that science cannot explain would not discomfit science at all, since we know there is much we don't understand already, and adding one more mystery to the multitude will not faze us in the slightest.

So yes, I agree. There is no valid god hypothesis, so there can be no god evidence, so let's stop pretending the believers have a shot at persuading us."

AFAICT it is consistent with what you have written. The only difference would be that you may have examples of theistic claims that are not "vague and undefined" or "plastic". ID'ists sometimes make this claim -- but do they really hold to it in the face of discomfirming evidence, or does it get plastic in the end?