Home / Opinion / Benjamin Franklin’s guide to spotting pseudoscience

Scientists—especially those in fields plagued by irreproducible results—could learn a thing or two from Benjamin Franklin. In the late 18th century, humanity had yet to invent most of the statistical tools now considered essential for social science, yet Franklin conducted a top-rate psychology experiment yielding conclusions that stand to this day.

To do it, he had to invent some of the core principles of experimental science. Franklin’s contribution to social science often gets drowned out by his equally great strides in electricity and other forms of innovation. But now, with critics charging that most published social science can’t be replicated, Franklin’s foray into psychology deserves some attention.

The year was 1782. The place: Paris. King Louis XVI asked Franklin to investigate an allegedly science-based form of medicine known as Mesmerism. Named for its inventor—Viennese physician Franz Mesmer—treatments involved moving an alleged magnetic fluid through the body by means of waving hands or rods over a patient, or having them touch a “magnetized" object.

It was wildly popular and a little too good to be true—much like a lot of the claims behind today’s supplements, homoeopathic remedies and self-help books. Mesmer, whose name lives on in the word “mesmerize", had become fascinated with magnetism and wanted to harness its power to heal the sick. His treatments played out like performances, according to Stanford historian Jessica Riskin. There was music and elaborate rituals, after which some patients went into convulsions or fainted. Then, they reported they were cured of their ills, aches and pains.

There was, in other words, abundant evidence that mesmerism had an effect on people. Sceptics thought there was something fishy, but it wasn’t obvious what it was. That’s why the king commissioned an investigation. It was headed by Franklin, as well as the famed French chemist Antoine-Laurent Lavoisier.

After Franklin visited one of the salons where people were lining up for treatments, he realized there was too much going on, and this was not the right setting for research. So he brought trained mesmerists and volunteer patients to his home.

Franklin reasoned that if Mesmer’s magnetic interpretation was correct, the effects should be the same whether or not patients were blindfolded. The experiment that followed was a precursor to today’s double-blind controlled trials. What the investigators controlled were two specific variables—whether patients were told they were getting the treatment or not, and whether they really were treated.

The investigators found that patients reacted to the treatments only if they were told they were getting them. Others were not treated, and they reacted too—but only if told they were in fact getting mesmerized. (In a true double-blind study, researchers are also “blinded" as to whether patients are getting the treatment or not.)

Franklin’s report hurt Mesmer’s credibility, but his ideas didn’t completely die. In the 20th century, something like mesmerism returned in the form of “therapeutic touch"—a practice that involves no actual touching. Practitioners run their hands through the air, allegedly realigning patients’ energy fields.

In 1998, an 11-year-old girl named Emily Rosa did an experiment much in the spirit of Franklin’s to debunk therapeutic touch, and became the youngest person ever to be published in The Journal Of The American Medical Association. She used a blinding procedure to show that a practitioner couldn’t sense other people’s energy fields, as had been claimed.

Franklin’s experiment did something more than just debunk mesmerism. He discovered something new—what would come to be called the placebo effect. He also discovered the “nocebo" effect—the experience of side effects when people wrongly think they are getting a treatment. In the case of mesmerism, those included convulsions, “fits" and fainting. Backing for this idea continues. Recently in Science, researchers reported that subjects experienced worse side effects from an inert cream if told it was the more expensive of two brands.

Franklin produced an example of what philosophers of science call abductive reasoning—finding the best explanation that fits the available observations. It’s science in the spirit of Darwin, Newton and Einstein. The power of suggestion also explains why so many people felt better after bloodletting and other now-discredited mainstream practices of Franklin’s time.

Modern psychological experiments are less likely to go after explanations and more likely to chase weird “counterintuitive" behaviour patterns. Many of the most surprising have been called into question: A study showing that forcing a smile by putting a pencil between your teeth can make you happy or that seeing words associated with old age would make people walk more slowly.

While Franklin’s results were very clear, many of these questionable results are hard to distinguish from random variation in the way people behave. Many are reporting mere noise, dressed up as real phenomena through the misuse of statistical tools. At some point, a leading journal published a paper in which psychologists used bad math to allege that their subjects had demonstrated extrasensory perception. Franklin would have known something was fishy. Bloomberg View

Faye Flam is a Bloomberg view columnist.

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