Being right, being early, and being unbearable
In 1847 Ignaz Semmelweis cut maternal deaths in a Vienna obstetric clinic from around 18% to near 2% by requiring doctors to wash their hands in chlorinated lime. He was dismissed, ridiculed for two decades, and died in an asylum in 1865 from an infected wound.
He had a natural experiment: two clinics, one staffed by doctors who also performed autopsies, one by midwives who did not, with mortality differing several-fold. Germ theory did not exist. His proposed mechanism — “cadaverous particles” — persuaded nobody, his evidence was statistical at a time when medicine trusted pathology, and he took to accusing colleagues in writing of being murderers.
The story is told as a parable about closed minds. It is at least as much about what evidence without a mechanism can and cannot do, and about what it costs to be correct in a form your field has no way to absorb.
Semmelweis was sitting on close to an ideal comparison: two wards, alternating admission, one variable that plausibly differed. He reported the result but never designed a further test, and he refused for years to publish in a form his opponents could examine. The tragedy is not only that he was disbelieved; it is that he made being believed harder than it needed to be.
“Semmelweis reflex” now names the reflexive rejection of a finding that contradicts a paradigm. The term is most often invoked by people who are simply wrong, which has made it nearly useless. A parable about a rare event became a licence for a common one.
The parable is used to license any rejected claim whatsoever.
The asymmetry that matters is not that Semmelweis was rejected — most rejected claims are rejected correctly. It is that he had a controlled comparison and a large measured effect. Invocations of his name almost never come with either.
Nothing about the history; the useful question is about the inference drawn from it, not the facts.