The “Semmelweis effect” or “Semmelweis reflex” refers to the tendency to reject offhand any new scientific evidence, discovery, knowledge, or analysis that contradicts the dominant paradigm or perceived scientific consensus (I write “perceived” because in reality there is never a full consensus in any field of science, despite what the media or politicians may insist). In Robert Anton Wilson’s book, The Game of Life, Timothy Leary defines this reflex as “Mob behavior found among primates and larval hominids on undeveloped planets, in which a discovery of important scientific fact is punished.” Thomas Szasz referred to it as “the invincible social power of false truths.”
Ignaz Philipp Semmelweis was a Hungarian physician who discovered that mortality rates could be drastically lowered by simply requiring doctors to disinfect their hands when moving between different patients, and particularly after performing an autopsy.* Twenty years before Pasteur’s discovery of the germ theory of disease and its universal acceptance, Semmelweis’s premature finding, and subsequent recommendation of hand-washing to eliminate the transmission of what he called “cadaverous particles,” was met with derision and summarily rejected by his fellow doctors. The idea that they the healthcare providers could actually be the angels of death spreading disease to their own patients was unconscionable and beyond the pale. Some simply refused to believe that disease could be transmitted by a gentleman’s hand.
As the chief resident of obstetrics at the Vienna General Hospital, Semmelweis noticed a rather obvious discrepancy between two clinics running side-by-side. One clinic trained midwives to deliver babies and had a mortality rate of about 4 percent. The second clinic trained medical students to do the same but had a mortality rate of 10 percent. What was even more perplexing was that for women who chose to give birth outside of either clinic, that is in the open fields and streets of Vienna, the death rate was even lower.
Then by happenstance one day, a friend and fellow doctor was accidentally pricked by a clumsy student’s scalpel during an autopsy. The doctor became ill and died days later. His illness, puerperal fever, was the same as that of the mothers who died. So Semmelweis came up with a hypothesis that trainee doctors performing autopsies were being exposed to “cadaverous particles” (they knew nothing of bacteria at this time) of which they transferred to the mothers giving birth. The midwives’ clinic did not have this problem because midwives did not concern themselves with performing autopsies, only with births. “Semmelweis proposed, for the first time in medical history, a connection between touching cadavers and a risk of infection."*
Semmelweis then mandated a new protocol of hand-washing, required after being in contact with a cadaver and before assisting in any birth. But he found this to be insufficient. “Ordinary washing with soap is not sufficient to remove all adhering cadaverous particles,” he wrote. “This is proven by the cadaverous smell the hands retain.”* So in addition to hand-washing, he introduced a chlorinated lime solution† that removed the smell of the dead and hopefully the “cadaverous particles” as well.
It worked. Within three months, death rates in the medical students' clinic went from an average of one in ten to one in a hundred.
Yet, the medical establishment completely rejected his arguments, citing his lack of any strong theoretical foundation that would coincide with the conventional medical wisdom of the period. Maybe he did reduce the death rates, but that was either just dumb luck, or part of the normal fluctuations of mortality rates, or perhaps some other variable that had yet to be discovered. If he was right he was only right for the wrong reasons, they reasoned. They postulated that perhaps it was bad air coming in through the windows. Danish physician Carl Edvard Marius Levy, head of the Danish Maternity institution in Copenhagen, wrote that it was absurd that something so small, indeed invisible, could possibly cause death: “With due respect for the cleanliness of the Viennese students, it seems improbable that enough infective matter or vapor could be secluded around the fingernails to kill a patient.”*
Semmelweis was criticized for his methods, for not running a simpler experiment. Why make hospital staff disinfect their hands after working on a cadaver rather than just keeping people who work on cadavers away from those giving birth? He also thought that it was only “cadaverous particles” that caused the fever that lead to death, and he couldn’t explain why some mothers in the midwives clinic also became feverish and died (though certainly not as many as had died in the medical students’ clinic). None of them knew what bacteria or viruses were, or that germs could be classified into different species, or that there was something call germs to begin with. Semmelweis thought the particles that caused death only came from the already dead.
Yet he was closer to the truth than were any of his contemporary critics. But what really got him in trouble within his profession was the underlining implication of his argument. As Leah Ginnivan wrote, “perhaps most importantly, his theories presented a behavioral conundrum for his fellow physicians: testing his hypothesis further could implicate them as dealers of death. Accusing doctors of haplessly causing disease was a slur on the gentlemanly art of medical practice.”*
Semmelweis was not an agreeable man. He could be very confrontational. And he took his colleagues’ rejections personally. And he publicly castigated them, directly calling them killers: “I declare before God that you are a murderer and [history] would not be too unfair if it remembers you as a medical Nero.”* His colleagues eventually had enough of him.
While on vacation with his wife and child, he was unexpectedly met at a train station by an old friend who said he wanted to show him his sanitarium. What Semmelweis did not know was that three obstetricians had already signed referrals for him to be committed to a mental asylum. At age 47, Semmelweis was tricked into being driven to an asylum where guards were awaiting his arrival. Once there and upon realization, he resisted. The guards severely beat him. Two weeks later he was dead of an infection.
In one of his last recorded thoughts, Ignaz Semmelweis, in the midst of depression, surmised on a future hope:
When I look back upon the past, I can only dispel the sadness which falls upon me by gazing into that happy future when the infection will be banished . . . The conviction that such a time must inevitably sooner or later arrive will cheer my dying hour.
Though an enemy of the medical establishment of his time—and arguably driven mad by them—he is today remembered as the “savior of mothers.” He is also remembered in the context of the “Semmelweis reflex”: “the kneejerk reflex to reject new evidence contradicting established norms.”*
Yes he was a disagreeable man, but it is disagreeable people, the honest troublemakers, who are capable of telling everyone else that they are wrong, sometimes deadly wrong, when no one else can or will see it.
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* Most of the quotations in this post are from Leah Ginnivan's article, “The Dirty History of Doctor’s Hands,” National Infectious Disease Prevention Initiative, Ohio State University, Nov. 25, 2016
Also see the EconTalk Podcast, “Megan McArdle on the Oedipus Trap,” March 20, 2023. Her take on the Semmelweis Reflex starts around 53:30
† “Carbolic acid” says Megan McArdle