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Who Will Debunk The Debunkers?

In 2012, network scientist and data theorist Samuel Arbesman published a disturbing thesis: What we think of as established knowledge decays over time. According to his book “The Half-Life of Facts,” certain kinds of propositions that may seem bulletproof today will be forgotten by next Tuesday; one’s reality can end up out of date. Take, for example, the story of Popeye and his spinach.

Popeye loved his leafy greens and used them to obtain his super strength, Arbesman’s book explained, because the cartoon’s creators knew that spinach has a lot of iron. Indeed, the character would be a major evangelist for spinach in the 1930s, and it’s said he helped increase the green’s consumption in the U.S. by one-third. But this “fact” about the iron content of spinach was already on the verge of being obsolete, Arbesman said: In 1937, scientists realized that the original measurement of the iron in 100 grams of spinach — 35 milligrams — was off by a factor of 10. That’s because a German chemist named Erich von Wolff had misplaced a decimal point in his notebook back in 1870, and the goof persisted in the literature for more than half a century.

By the time nutritionists caught up with this mistake, the damage had been done. The spinach-iron myth stuck around in spite of new and better knowledge, wrote Arbesman, because “it’s a lot easier to spread the first thing you find, or the fact that sounds correct, than to delve deeply into the literature in search of the correct fact.”

Arbesman was not the first to tell the cautionary tale of the missing decimal point. The same parable of sloppy science, and its dire implications, appeared in a book called “Follies and Fallacies in Medicine,” a classic work of evidence-based skepticism first published in 1989.1 It also appeared in a volume of “Magnificent Mistakes in Mathematics,” a guide to “The Practice of Statistics in the Life Sciences” and an article in an academic journal called “The Consequence of Errors.” And that’s just to name a few.

All these tellings and retellings miss one important fact: The story of the spinach myth is itself apocryphal. It’s true that spinach isn’t really all that useful as a source of iron, and it’s true that people used to think it was. But all the rest is false: No one moved a decimal point in 1870; no mistake in data entry spurred Popeye to devote himself to spinach; no misguided rules of eating were implanted by the sailor strip. The story of the decimal point manages to recapitulate the very error that it means to highlight: a fake fact, but repeated so often (and with such sanctimony) that it takes on the sheen of truth.

In that sense, the story of the lost decimal point represents a special type of viral anecdote or urban legend, one that finds its willing hosts among the doubters, not the credulous. It’s a rumor passed around by skeptics — a myth about myth-busting. Like other Russian dolls of distorted facts, it shows us that, sometimes, the harder that we try to be clear-headed, the deeper we are drawn into the fog.


No one knows this lesson better than Mike Sutton. He must be the world’s leading meta-skeptic: a 56-year-old master sleuth who first identified the myth about the spinach myth in 2010 and has since been working to debunk what he sees as other false debunkings. Sutton, a criminology professor at Nottingham Trent University, started his career of doubting very young: He remembers being told when he was still a boy that all his favorite rock stars on BBC’s “Top of the Pops” were lip-synching and that some weren’t even playing their guitars. Soon he began to wonder at the depths of this deception. Could the members of Led Zeppelin be in on this conspiracy? Was Jimmy Page a lie? Since then, Sutton told me via email, “I have always been concerned with establishing the veracity of what is presented as true, and what is something else.”

As a law student, Sutton was drawn to stories like that of Popeye and the inflated iron count in spinach, which to him demonstrated both the perils of “accepted knowledge” and the importance of maintaining data quality. He was so enamored of the story, in fact, that he meant to put it in an academic paper. But in digging for the story’s source, he began to wonder if it was true. “It drew me in like a problem-solving ferret to a rabbit hole,” he said.

Soon he’d gone through every single Popeye strip ever drawn by its creator, E.C. Segar, and found that certain aspects of the classic story were clearly false. Popeye first ate spinach for his super power in 1931, Sutton found, and in the summer of 1932 the strip offered this iron-free explanation: “Spinach is full of vitamin ‘A,’” Popeye said, “an’ tha’s what makes hoomans strong an’ helty.” Sutton also gathered data on spinach production from the U.S. Department of Agriculture and learned that it was on the rise before Segar’s sailor-man ever starting eating it.

It seems plausible that the tellers of these tales are getting blinkered by their own feelings of superiority — that the mere act of busting myths makes them more susceptible to spreading them.

What about the fabled decimal point? According to Sutton’s research, a German chemist did overestimate the quantity of iron in spinach, but the mistake arose from faulty methods, not from poor transcription of the data.2 By the 1890s, a different German researcher had concluded that the earlier estimate was many times too high. Subsequent analyses arrived at something closer to the correct, still substantial value — now estimated to be 2.71 milligrams of iron per 100 grams of raw spinach, according to the USDA. By chance, the new figure was indeed about one-tenth of the original, but the difference stemmed not from misplaced punctuation but from the switch to better methodology. In any case, it wasn’t long before Columbia University analytical chemist Henry Clapp Sherman laid out the problems with the original result. By the 1930s, Sutton argues, researchers knew the true amount of iron in spinach, but they also understood that not all of it could be absorbed by the human body.3

The decimal-point story only came about much later. According to Sutton’s research, it seems to have been invented by the nutritionist and self-styled myth-buster Arnold Bender, who floated the idea with some uncertainty in a 1972 lecture. Then in 1981, a doctor named Terence Hamblin wrote up a version of the story without citation for a whimsical, holiday-time column in the British Medical Journal. The Hamblin article, unscholarly and unsourced, would become the ultimate authority for all the citations that followed. (Hamblin graciously acknowledged his mistake after Sutton published his research, as did Arbesman.)

In 2014, a Norwegian anthropologist named Ole Bjorn Rekdal published an examination of how the decimal-point myth had propagated through the academic literature. He found that bad citations were the vector. Instead of looking for its source, those who told the story merely plagiarized a solid-sounding reference: “(Hamblin, BMJ, 1981).” Or they cited someone in between — someone who, in turn, had cited Hamblin. This loose behavior, Rekdal wrote, made the transposed decimal point into something like an “academic urban legend,” its nested sourcing more or less equivalent to the familiar “friend of a friend” of schoolyard mythology.

Emerging from the rabbit hole, Sutton began to puzzle over what he’d found. This wasn’t just any sort of myth, he decided, but something he would term a “supermyth”: A story concocted by respected scholars and then credulously disseminated in order to promote skeptical thinking and “to help us overcome our tendency towards credulous bias.” The convolution of this scenario inspired him to look for more examples. “I’m rather a sucker for such complexity,” he told me.


Complicated and ironic tales of poor citation “help draw attention to a deadly serious, but somewhat boring topic,” Rekdal told me. They’re grabby, and they’re entertaining. But I suspect they’re more than merely that: Perhaps the ironies themselves can help explain the propagation of the errors.

It seems plausible to me, at least, that the tellers of these tales are getting blinkered by their own feelings of superiority — that the mere act of busting myths makes them more susceptible to spreading them. It lowers their defenses, in the same way that the act of remembering sometimes seems to make us more likely to forget. Could it be that the more credulous we become, the more convinced we are of our own debunker bona fides? Does skepticism self-destruct?

Sutton told me over email that he, too, worries that contrarianism can run amok, citing conspiracy theorists and anti-vaxxers as examples of those who “refuse to accept the weight of argument” and suffer the result. He also noted the “paradox” by which a skeptic’s obsessive devotion to his research — and to proving others wrong — can “take a great personal toll.” A person can get lost, he suggested, in the subterranean “Wonderland of myths and fallacies.”


In the last few years, Sutton has himself embarked on another journey to the depths, this one far more treacherous than the ones he’s made before. The stakes were low when he was hunting something trivial, the supermyth of Popeye’s spinach; now Sutton has been digging in more sacred ground: the legacy of the great scientific hero and champion of the skeptics, Charles Darwin. In 2014, after spending a year working 18-hour days, seven days a week, Sutton published his most extensive work to date, a 600-page broadside on a cherished story of discovery. He called it “Nullius in Verba: Darwin’s Greatest Secret.”

Sutton’s allegations are explosive. He claims to have found irrefutable proof that neither Darwin nor Alfred Russel Wallace deserves the credit for the theory of natural selection, but rather that they stole the idea — consciously or not — from a wealthy Scotsman and forest-management expert named Patrick Matthew. “I think both Darwin and Wallace were at the very least sloppy,” he told me. Elsewhere he’s been somewhat less diplomatic: “In my opinion Charles Darwin committed the greatest known science fraud in history by plagiarizing Matthew’s” hypothesis, he told the Telegraph. “Let’s face the painful facts,” Sutton also wrote. “Darwin was a liar. Plain and simple.”

Some context: The Patrick Matthew story isn’t new. Matthew produced a volume in the early 1830s, “On Naval Timber and Arboriculture,” that indeed contained an outline of the famous theory in a slim appendix. In a contemporary review, the noted naturalist John Loudon seemed ill-prepared to accept the forward-thinking theory. He called it a “puzzling” account of the “origin of species and varieties” that may or may not be original. In 1860, several months after publication of “On the Origin of Species,” Matthew would surface to complain that Darwin — now quite famous for what was described as a discovery born of “20 years’ investigation and reflection” — had stolen his ideas.

Darwin, in reply, conceded that “Mr. Matthew has anticipated by many years the explanation which I have offered of the origin of species, under the name of natural selection.” But then he added, “I think that no one will feel surprised that neither I, nor apparently any other naturalist, had heard of Mr. Matthew’s views.”

That statement, suggesting that Matthew’s theory was ignored — and hinting that its importance may not even have been quite understood by Matthew himself — has gone unchallenged, Sutton says. It has, in fact, become a supermyth, cited to explain that even big ideas amount to nothing when they aren’t framed by proper genius.

Sutton thinks that story has it wrong, that natural selection wasn’t an idea in need of a “great man” to propagate it. After all his months of research, Sutton says he found clear evidence that Matthew’s work did not go unread. No fewer than seven naturalists cited the book, including three in what Sutton calls Darwin’s “inner circle.” He also claims to have discovered particular turns of phrase — “Matthewisms” — that recur suspiciously in Darwin’s writing.

In light of these discoveries, Sutton considers the case all but closed. He’s challenged Darwin scholars to debates, picked fights with famous skeptics such as Michael Shermer and Richard Dawkins, and even written letters to the Royal Society, demanding that Matthew be given priority over Darwin.

But if his paper on the spinach myth convinced everyone who read it — even winning an apology from Terence Hamblin, one of the myth’s major sources — the work on Darwin barely registered. Many scholars ignored it altogether. A few, such as Michael Weale of King’s College, simply found it unconvincing. Weale, who has written his own book on Patrick Matthew, argued that Sutton’s evidence was somewhat weak and circumstantial. “There is no ‘smoking gun’ here,” he wrote, pointing out that at one point even Matthew admitted that he’d done little to spread his theory of natural selection. “For more than thirty years,” Matthew wrote in 1862, he “never, either by the press or in private conversation, alluded to the original ideas … knowing that the age was not suited for such.”


When Sutton is faced with the implication that he’s taken his debunking too far — that he’s tipped from skepticism to crankery — he lashes out. “The findings are so enormous that people refuse to take them in,” he told me via email. “The enormity of what has, in actual fact, been newly discovered is too great for people to comprehend. Too big to face. Too great to care to come to terms with — so surely it can’t be true. Only, it’s not a dream. It is true.” In effect, he suggested, he’s been confronted with a classic version of the “Semmelweis reflex,” whereby dangerous, new ideas are rejected out of hand.

Could Sutton be a modern-day version of Ignaz Semmelweis, the Hungarian physician who noticed in the 1840s that doctors were themselves the source of childbed fever in his hospital’s obstetric ward? Semmelweis had reduced disease mortality by a factor of 10 — a fully displaced decimal point — simply by having doctors wash their hands in a solution of chlorinated lime. But according to the famous tale, his innovations were too radical for the time. Ignored and ridiculed for his outlandish thinking, Semmelweis eventually went insane and died in an asylum. Arbesman, author of “The Half-Life of Facts,” has written about the moral of this story too. “Even if we are confronted with facts that should cause us to update our understanding of the way the world works,” he wrote, “we often neglect to do so.”

Of course, there’s always one more twist: Sutton doesn’t believe this story about Semmelweis. That’s another myth, he says — another tall tale, favored by academics, that ironically demonstrates the very point that it pretends to make. Citing the work of Sherwin Nuland, Sutton argues that Semmelweis didn’t go mad from being ostracized, and further that other physicians had already recommended hand-washing in chlorinated lime. The myth of Semmelweis, says Sutton, may have originated in the late 19th century, when a “massive nationally funded Hungarian public relations machine” placed biased articles into the scientific literature. Semmelweis scholar Kay Codell Carter concurs, at least insofar as Semmelweis was not, in fact, ignored by the medical establishment: From 1863 through 1883, he was cited dozens of times, Carter writes, “more frequently than almost anyone else.”

Yet despite all this complicating evidence, scholars still tell the simple version of the Semmelweis story and use it as an example of how other people — never them, of course — tend to reject information that conflicts with their beliefs. That is to say, the scholars reject conflicting information about Semmelweis, evincing the Semmelweis reflex, even as they tell the story of that reflex. It’s a classic supermyth!

And so it goes, a whirligig of irony spinning around and around, down into the depths. Is there any way to escape this endless, maddening recursion? How might a skeptic keep his sanity? I had to know what Sutton thought. “I think the solution is to stay out of rabbit holes,” he told me. Then he added, “Which is not particularly helpful advice.”


  1. Its authors cite the story of the misplaced decimal point as an example of the “Bellman’s Fallacy” — a reference to a character from Lewis Carroll who says, “What I tell you three times is true.” Such mistakes, they wrote, illustrate “the ways in which truth may be obscured, twisted, or mangled beyond recognition, without any overt intention to do it harm.”

  2. Another scholar with an interest in the spinach tale has found that in Germany, at least, the link between spinach and iron was being cited as conventional wisdom as early as 1853. This confusion may have been compounded by research that elided differences between dried and fresh spinach, Sutton says.

  3. It’s long been suggested that high levels of oxalic acid — which are present in spinach — might serve to block absorption of iron, as they do for calcium, magnesium and zinc. Other studies find that oxalic acid has no effect on iron in the diet, though, and hint that some other chemical in spinach might be getting in the way.

Daniel Engber writes about science and culture.