by Paul Braterman
Science, it is often said, is restricted in principle to the search for natural causes. Is this a fundamental rule for doing science? Or merely a useful procedural guide, derived from experience? Is it even true? Or meaningful? Does it matter? These questions are addressed in an important series of papers in 2010, 2012, and 2014, by Maarten Boudry at the University of Ghent and his colleagues. They conclude that it matters a great deal, that the alleged restriction does not in fact exist, and that appealing to such a principle in argument is harmful to the cause of science. I agree.
I will deal with the first four questions in reverse order. Can we make a meaningful distinction between the natural and the supernatural? I was initially inclined to say no. If something occurs, it's part of nature. It is a law of nature that water doesn't turn into wine, but if you believe that the miracle of the wedding feast of Cana really happened, then you need to modify the law to say “Water doesn't turn into wine, except when Jesus tells it to.” Maarten persuaded me that this was not a helpful line to take. Like all attempts to define a problem out of existence, it is logically unassailable, but useless. It denies us access to the very distinction that we should be clarifying.
The question, however, is more difficult than it seems. After all, we do not know everything that there is to be known about nature. We readily apply the label “supernatural” to purported phenomena such as telekinesis or telepathy, in which mind is regarded as operating on matteror on other minds without material agency, but we do not have a satisfactory account of mind-matter relationships anyway. Other prime candidates for supernatural status, such as precognition and remote viewing, would if real involve transcending the usual space-time framework, but space and time are much less rigidly defined now than they seemed to be before Einstein. The limits of natural explanation have been extended in the past, by invoking action at a distance (gravity, then other forces), intrinsic randomness (quantum mechanics), and more recently particle entanglement (quantum mechanics again). Presumably they will be in the future, in ways yet undreamt of. So the fact that something cannot be explained by today's science need not force us to invoke the supernatural. What would, then? Boudry and Taner Edis suggest a test for what they call unphysical causation, but it is highly technical, with their criterion based on demonstrated access to uncomputable numbers (I will not attempt to reproduce their argument). However, they suggest some examples. What, for instance, if Lourdes started producing undeniable miracles in large numbers, including the regrowth of amputated limbs, but only for devout Catholics? What if all organisms were found to contain an identical section of DNA, whose diffraction pattern spelt out the message “© Yahweh 4004 BC”? What, I might add, if we really did start receiving messages from the dead?
Searching for messages is not a new idea. There are cottage industries within both Christianity and Islam, producing evidence that the authors of the Bible or the Qur'an are referring to scientific facts unknown by mere mortals when these books were first written. For instance, does the reference to the “circle of the earth” in Isaiah 40:22 imply that the author knew that the earth goes round the sun? Do the numerous biblical references to God stretching out the heavens show an awareness of the expanding universe? Mohammed is said to have “split the moon”; is this a reference to its formation by accretion? Few of us would find these examples convincing.
Or, to take a much more sophisticated (and lucrative) example, what of the “Bible code” claim that computer searching of the Hebrew text according to certain counting rules reveals messages about post-biblical, including recent, history, placed there on purpose so that, when computers became available, we would be able to read these messages? The claim was taken seriously by enough people to put three successive volumes on the best-seller list. But that tells us nothing about its truth. This is testable, in at least two different ways, and fails both tests miserably.
Firstly, is the text special? Test: take some other, undoubtedly secular, text, apply the same methodology, and see what happens. Many people have done this with remarkable results. My favourite is an analysis, by the geophysicist Dave Thomas, of the Amazon website excerpt from the third book in the series, from which he unearthed the messages that the Bible Code was a “vain hoax” and “megalomania”. Well, that's English, not Hebrew, but Hebrew should be even easier since it is written with consonants only.
Secondly, are the predictions correct? Take this example: Bible Code II predicted that Yasser Arafat would be shot by Hamas gunmen. In fact, he died of an infection, and Hamas had nothing to do with it. Again, the same book predicted Libya acquiring weapons of mass destruction; in fact, Libya renounced its plans in that direction, opening up a brief honeymoon between Gaddafi and the West. There were also predictions of an end-times nuclear war, and had any policy makers been paying attention to these (not inconceivable when millions of Americans await the Rapture) the consequences could have been serious indeed.
Why have I spent so much time on this silly example? Because it gives the answer to all but one of my original five questions. Despite the problem of definition, we would all agree that if the Bible Code claims had been correct, they would have been evidence of supernatural agency. So yes, the distinction (Question 4) between natural and supernatural is meaningful. More importantly, this example shows that we do in fact investigate supernaturalist claims using the methods of science (Question 3; science is not restricted to the search for natural causes; so the initial assertion is not true). It follows at once that when occasion demands we cheerfully violate the purported restriction on how we do science, which therefore cannot be a fundamental rule (Question 1).
It is only after the Bible Code claims have been convincingly shredded that we can decide that claims of this kind are not worth our time and trouble. It was only after exhaustive card-guessing experiments had failed to reveal any evidence for ESP (and after the published evidence for its reality was found to be faulty if not fraudulent) that people decided it was just not worth while continuing in that direction. It was only after spiritualists had repeatedly been exposed as fakes that scientists more or less stopped investigating them. For a while, even such distinguished scientists as Alfred Russel Wallace took their pretensions seriously. However, nowadays such investigations are undertaken more to unmask fraud and protect the public than in the hope of new discoveries. (In this endeavour, scientists have been joined by professional magicians, from Houdini to James “the amazing” Randi, illustrating to my mind the artificiality of separating off “science” from other kinds of factual enquiry.) Much the same, but with less emphasis on fraud, can be said about hunting for ghosts. In this century, there have been several studies of the effects of intercessory prayer on recovery from illness. No effect (or in one case, a small negative effect, tentatively attributed to the added stress of the situation), and a recommendation from Cochrane Reviews, which collate data from clinical trials, that no further work of this kind be undertaken. In each of these cases, the scientific search has been abandoned, not because of some overarching principle about the nature of science, but because plain experience showed it to be pointless. A priori rejection of the supernatural had nothing to do with these decisions, which were based purely on experience. Experience that would never have been attained if scientists really were debarred from submitting the supernatural to investigation.
Science, as P. J. Medawar pointed out in his devastating critique of Koestler’s Act of Creation, is an extremely practical activity, and it is commonplace for lines of enquiry to be abandoned because they were getting nowhere (I can confirm this from bitter experience, as a sometime experimental chemist). Thus, as Boudry and colleagues remind us (2010), the Royal Academy of Sciences in Paris decided in 1775 to have nothing more to do with proposals to build a perpetual motion machine. This was many years ahead of the development of the laws of thermodynamics, which tell us that such a machine is impossible, but so much effort had been spent to so little effect that the Academy decided no more was warranted. Not because (as we might now be tempted to say) such a machine would require a supernatural mechanism, but because they didn't think there was any chance of it working. The suggestion made in Question 2 is correct, and can be extended beyond the supernatural to futile questions in general; when, as often happens, we turn aside from investigating this or that incredible claim, we do not do so on principle but because experience warns us that we would be wasting our time.
Now for the final question, does it matter? Yes, obviously, as an intellectual question. Also, I think, from the point of view of the individual researcher. We all of us carry philosophical baggage, but scientists to my mind should do their best to travel light, so unnecessary principles should be deliberately discarded. But, most importantly, as part of the ever-necessary strategy of defending science from its enemies. As I shall argue in my next post, the principle that science is only allowed to look for natural causes is widely seen as a bastion against obscurantist encroachment. But this is a strategic error. It is an unnecessary and inaccurate metaphysical add-on to science, an easy target for its enemies, and should be abandoned.
I thank Maarten Boudry for helpful suggestions. Illustrations: Book cover from Amazon; “Vain Hoax” from Dave Thomas at New Mexicans for Science and Reason here (see also here)
 This discussion refers to Michael Drosnin's Bible Code books, rather than to the original statistical puzzle posed by Eliyahu Rips, who has dissociated himself from them.
 New Statesman, 19 June 1964, reprinted in Pluto’s Republic, OUP 1984