In 1907, American physician Duncan MacDougall claimed to have weighed the human soul by placing dying people on a set of industrial measuring scales. He claimed that a half to a full ounce of weight was lost upon death, and that the only explanation for this discrepancy was a soul. Scientifically, this (for lack of a better phrase) is absolute cack. In response to Sophie’s article last week, I’ll take the role of Devil’s advocate.
There is no evidence for the existence of a human soul, and MacDougall only proved that he was a terrible scientist. The most basic principle of any scientific experiment, often taught as early as primary school, is to control your variables. You can’t say ice cream sales are linked to shark attacks, as they’re just both related to activities typically done in the summer, and maybe there was a coincidental ice cream sale. The lost ounce MacDougall’s recorded could not have conclusively been a soul, as we lose an awful lot of things when we die. His experiment volunteers may have been sweating, which evaporates; and air in our lungs is expelled. Also, the area of the brain responsible for controlling involuntary reactions shuts down, and certain sphincters relax, occasionally leading to post-mortem defecation and urination.
Another vital principle to any experiment is sampling. You’re more likely to find a link between ice cream sales and shark attacks on the Australian coast than in Blackpool or Brighton. You need to use a lot of beaches to make such claims, and similarly, MacDougall used very few people in his study. Upon reading The New York Times’ report on MacDougall’s experiment, it can be seen that the loss of weight didn’t always happen at the same point after death. MacDougall makes the outlandish claim that the the soul took longer to leave the body, due to the corpse once being “a phlegmatic man, slow of thought and action”. This is classic confirmation bias and selective sampling. The former involves explaining away and making excuses for discrepancies in data, so that it makes sense for the scientist’s desired results. Likewise, selective sampling involves inclining to trust the data you want, and disregarding data that doesn’t suit you. They are distinct ideas, but may be used in conjunction in bogus studies, such as MacDougall’s.
A more modern example of this is the infamous Wakefield paper, which linked the MMR vaccine to autism. In a manner not dissimilar to MacDougall, Wakefield and co. picked their data to suit their ends, in addition to outright falsifying some facts. The Lancet rapidly retracted Wakefield’s paper when it was exposed for its fraud, but we still see the ripples of the publication to this day in Trump’s America. Incidentally, there is a popular conception that the soul weighs 21 grams as a misinterpretation of MacDougall’s experiments from as long ago as 1907. Believing in a soul is certainly not nearly as dangerous as believing vaccines cause autism. But, both ideas are founded in fraudulent scientific practices, having influenced popular beliefs in varying degrees from quaint to fatal, which the general public must remain wary of.
Mentioned today in Headcandy:
Duncan MacDougall’s Experiment:
(Now retracted and disproved) Wakefield et al on the MMR Vaccine and developmental disorders:
A brief but comprehensive discussion of Wakefield’s exposure (with links to further reading) by
Sathyanarayana Rao and Andrade: