Homeopathy and Its Kindred Delusions

Homeopathy and Its Kindred Delusions: Two Lectures Delivered Before the Boston Society for the Diffusion of Useful Knowledge is an essay by Oliver Wendell Holmes, Sr., the noted American author and poet, and father of Oliver Wendell Holmes, Jr., Associate Justice of the United States Supreme Court. Written in 1842, it is one of the earliest criticisms of homeopathy, which was widely popular at the time.

It is an epic takedown of not only homeopathy but all forms of quackery, and an eloquent and powerful exposition of the placebo effect and the dangers of anecdotal evidence. Today it remains one of Holmes’ best known essays and is considered a seminal work in the history of skepticism.

Elisha Perkins' cure-all tractors
One of the subjects discussed by Holmes is a 19th century doctor named Elisha Perkins, who promoted some instruments called "tractors". These "tractors" were a pair of metal rods, which Perkins claimed could cure virtually every condition merely by being waved over the affected spot "very lightly for about twenty minutes" because they were made of a "rare alloy". These rods for a while enjoyed immense popularity, though they were opposed by mainstream opinion, there being endorsements from many credentialed and distinguished individuals (doctors, priests, politicians, government officials, and others) as well as hundreds of anecdotes in their favor. A few of the conditions they could supposedly treat included "rheumatism, local pains, inflammations, and even tumors". Holmes describes one amusing case involving a treatment session:

A certain lady had the misfortune to have a spot as big as a silver penny at the corner of her eye, caused by a bruise, or some such injury. Another lady, who was a friend of hers, and a strong believer in Perkinism, was very anxious to try the effects of tractoration upon this unfortunate blemish. The patient consented; the lady "produced the instruments, and, after drawing them four or five times over the spot, declared that it changed to a paler color, and on repeating the use of them a few minutes longer, that it had almost vanished, and was scarcely visible, and departed in high triumph at her success." The lady who underwent the operation assured the narrator "that she looked in the glass immediately after, and that not the least visible alteration had taken place."

One doctor tried to debunk them by applying tractors of various substances ("wood; with nails, pieces of bone, slate pencil, and tobacco-pipe") to many patients and found that no matter what they were made of, they had exactly the same effect as the real metallic ones patented by Perkins. Clearly, this does not mean that waving an object, no matter what, can cure everything. Holmes describes a case of a patient treated by these "sham tractors":

Ann Hill had suffered for some months from pain in the right arm and shoulder. The Tractors (wooden ones) were applied, and in the space of five minutes she expressed herself relieved in the following apostrophe: "Bless me! why, who could have thought it, that them little things could pull the pain from one. Well, to be sure, the longer one lives, the more one sees; ah, dear!"

Eventually, for some reason or other, the tractors fell out of use. Holmes notes:

Of course a large number of apparent cures were due solely to nature; which is true under every form of treatment, orthodox or empirical. Of course many persons experienced at least temporary relief from the strong impression made upon their minds by this novel and marvellous method of treatment.

Many, again, influenced by the sanguine hopes of those about them, like dying people, who often say sincerely, from day to day, that they are getting better, cheated themselves into a false and short-lived belief that they were cured; and as happens in such cases, the public never knew more than the first half of the story.