The Chain of Reason vs. the Chain of Thumbs

Brad Roth
3 min readJan 14, 2022


Bully for Brontosaurus, by Stephen Jay Gould.

I have written previously in this blog about my admiration for evolutionary biologist Stephen Jay Gould and his essays published in his monthly column “This View of Life” in the magazine Natural History. Today, I focus on one of these essays, “The Chain of Reason vs. the Chain of Thumbs,” that is related to a topic in Intermediate Physics for Medicine and Biology. You can find this essay reprinted in Gould’s book Bully for Brontosaurus.

IPMB has a chapter on biomagnetism (the production of magnetic fields by the body) and a section on the possible effects if weak external electric and magnetic fields. Much nonsense has been written about using magnetic fields to treat diseases, including to relieve pain. When did all this silliness begin? Over two hundred years ago.

Gould’s essay describes the fascinating story of the Franz Mesmer, who operated a clinic in Paris in the seventeenth century to treat various illnesses using “ animal magnetism.” Gould writes

Franz Anton Mesmer was a German physician who had acquired wealth through marriage to a well endowed widow; connections by assiduous cultivation;… and renown with a bizarre, if fascinating, theory of “animal magnetism” and its role in human health.

Mesmer, insofar as one can find coherence in his ideas at all, claimed that a single (and subtle) fluid pervaded the universe, uniting and connecting all bodies. We give different names to this fluid according to its various manifestations: gravity when we consider planets in their courses; electricity when we contemplate a thunderstorm; magnetism when we navigate by compass. The fluid also flows through organisms and may be called animal magnetism. Disease results from a blockage of this flow, and cure of disease requires a reestablishment of the flux and a restoration of equilibrium.

Cure of illness requires the aid of an “adept,” a person with unusually strong magnetism who can locate the “poles” of magnetic flow on the exterior of a human body and, by massaging these areas, break the blockage within and reestablish the normal flux…

Mesmer’s treatments were quite dramatic.

Within a few minutes of mesmerizing, sensitive patients would fall into the characteristic “crisis” taken by Mesmer as proof of his method. Bodies would begin to shake, arms and legs move violently and involuntarily, teeth chatter loudly. Patients would grimace, groan, babble, scream, faint, and fall unconscious.

Gould then tells the story of a Royal Commission established in 1784 by French king Louis XVI to investigate Mesmer’s claims. The commission was headed by American Benjamin Franklin, and included chemist Antoine Lavoisier and medical doctor Joseph Guillotin.

In a clever series of experiments, designed mainly by Lavoisier and carried out at Franklin’s home in Passy, the commissioners made the necessary separations and achieved a result as clear as any in the history of debunking: crises are caused by suggestion; not a shred of evidence exists for any fluid, and animal magnetism, as a physical force, must be firmly rejected.

Gould was impressed by the quality of the commission’s work.

Never in history has such an extraordinary and luminous group been gathered together in the service of rational inquiry by the methods of experimental science. For this reason alone, the Rapport des commissaires chargés par le roi de l’examen du magnétisme animal (Report of the Commissioners Charged by the King to Examine Animal Magnetism) is a key document in the history of human reason. It should be rescued from its current obscurity, translated into all languages, and reprinted by organizations dedicated to the unmasking of quackery and the defense of rational thought.

Nowadays we see a lot of ridiculous claims that magnetic fields can alleviate pain and have other health effects. Julian Whitaker and Brenda Adderly, in their book The Pain Relief Breakthrough, assert that magnets can cure backaches, arthritis, menstrual cramps, carpal tunnel syndrome, sports injuries, and more. Mexican surgeon Isaac Goiz Duran says that his “biomagnetic therapy” can cure diabetes, AIDS, cancer, and Covid-19. All these therapies are based on static magnetic fields, a type of 21st century animal magnetism.

I highly recommend all of Gould’s essays, including this one. Remember the efforts of Franklin, Lavoisier, and Guillotin before you start believing that static magnetic fields can improve your health.

Originally published at



Brad Roth

Professor of Physics at Oakland University and coauthor of the textbook Intermediate Physics for Medicine and Biology.