The problem was not that Geologists could not see the match up, it was that there was no known scientific explanation.
Because it was known that stress and diet did cause ulcer flare-ups.
You are mostly correct. Small details only differ,
Luminiferous aether was the general consensus of what filled space, as it was thought light waves could not possibly travel through a vacuum.
Wiki has a whole article about these-
You are mixing up correlation with causality.
No, I am not - they did. They observed that stress and diet did cause ulcer flare-ups, so they assumed that was the cause.
Whoa, this is fascinating! I’ve never heard of this and couldn’t understand the Wikipedia article (and there’s no Simple English version). But I had AI explain it with some visualizations, and it’s quite the marvelous mindfuck 
Thanks for sharing! Super cool stuff.
Yes. Exactly
I thought the links in my earlier mention of peptic ulers shows that there was not a scientific consensus on this:
There may have been a consensus among people who were NOT doing peptic ulcer research that stress was the cause. My memory is that there was such a consensus on television. In gastroenterology journals, I’m finding no consensus.
This sounds to me, based on the Wikipedia article, a good candidate.
What this thread is making me realize is that each proposed candidate has its own complex scientific history and that carefully studying it, I’d be unsure how strong the mistaken consensus really was.
A simple example is the patterns produced by Penrose tiles (which are one of the examples that produces fivefold diffraction patterns). Searching for those will produce some pretty illustrations.
Perhaps the once accepted notion that humans did not grow new neurons which was overturned by The Plastic Brain proof
…
Published: January 27, 2026 11.32pm AEDT
For much of the 20th century, scientists believed that the adult human brain was largely fixed. According to this view, the brain developed during childhood, settled into a stable form in early adulthood, and then resisted meaningful change for the rest of life.
Today, the concept of neuroplasticity, the brain’s ability to change its structure and function in response to experience, is a central principle of brain science. The brain can change throughout life, but not without limits, not instantly and not effortlessly.
Two-time Nobel prize winner Linus Pauling came up with one of the all-time great insults:
“There are no quasicrystals, only quasi-scientists.”
Of course, he was wrong. But, it’s still a great quip.
Well, the first link is just the first page, and the second-
The search for the cause or causes of peptic ulcers has been a long one. It was recognised as early as the 19th Century that damage to the stomach or duodenal bulb was likely to result if the resistance of their mucosae to luminal acid was for some reason impaired. An early theory suggested microscopic vascular occlusion leading to local infarction could be the initiating event but evidence was lacking. Excessive acid secretion is seen in some patients but not in many so is implausible as the main factor in most ulcers. Cigarette smoking is a risk factor and chronic life difficulties has been shown to sometimes play a part, but we would now think that they play only minor roles to possibly tip the balance when a major etiologic factor is already present. The overwhelming evidence now is that the major etiologic factors in chronic peptic ulcer are ingestion of nonsteroidal anti-inflammatory drugs (NSAIDs) and infection with Helicobacter pylori.
So, perhaps not a consensus , but stress and diet was commonly thought to be a cause- since the cause was unknown.
Stomach ulcers were previously thought to be due to stress or lifestyle factors, and when Marshall & Warren discussed their findings with the medical community, they were met with scepticism and criticism. They struggled to make their case and their attempts to infect animals with the bacteria hadn’t worked.
At that time when Warren and Marshall announced their findings, it was a long-standing belief in medical teaching and practice that stress and lifestyle factors were the major causes of peptic ulcer disease.
That the Coelacanth was could only be known by the fossil record.
they were thought to have become extinct in the Late Cretaceous, around 66 million years ago.
I still recall being astonished when I read in National Geo they caught one.
It took 14 years before a second one turned up.
The way that the appearance of dinosaurs was constructed over the past two centuries or so, along with their ecology and behaviour, represents a bunch of consensus positions tangled up together, playing off each other, which probably have different histories of being unravelled. Simply, the shift from dinosaurs as seen in 1950s kids book as lumbering, scaly eating machines into properly formed animals was probably as much a social and palaeoart consensus as a scientific one.
While there were palaeontologists and palaeoartists who mooted a more modern perspective from time to time, the view only changed as new fossils and re-examination of old material began with the ‘Dinosaur Renaissance’ of the late 1960s (good overview). This itself was triggered by changes in how biologists thought and explained the living world as well.
Arguably, if you were a believer in the consensus prior to the dinosaur revolution and had the resources to review the evidence, you may have changed your interpretation to something more modern. However, your ability to think about these possibilities was also tempered by a view of how evolution worked as a progressive, advancing and always improving mechanism, where extinct things were always expected to be clunkier and less perfect than those extant today. Again, not a scientific consensus but a social one, but strong enough to constrain science’s idea of the possible past.
I would throw in the miasma theory of illness, still present in words like malaria (literally: bad air), a word that remains despite new knowledge that it is caused by a parasite (Plasmodium faciparum). The theory goes back further than 1900, but not by much.
And some people still believe it!
Miasma theory was pretty generally accepted up until the late 19th century.
That’s not accurate - other mechanisms were proposed before plate tectonics - expanding Earth and crustal displacement, to name a couple that had some currency once. Now they only live on in woo.
Indeed, that is what I wanted to write. It was debunked just before the cutting point set by the OP, but not by much, and the “or so” in the OP made me think I could mention it. I also wanted to write falciparum, with an l. It went missing, sorry.
“Bleeding” had a lot of adherents in the medical community. Or some anyway. There was also a school of thought that anytime someone came down with anything, the best thing to do was prescribe a combination of emetic or purgative and laxative. Get a feller to puking and crapping his guts out, why he’ll be much better by morning for sure. “Dr. Rush’s Celebrated Thunderclaps!”.
That’s a better example than most. Until 1880 or so, the humoral and then miasma theories were the theories that explained disease, and there was scientific (such that it was) consensus that they were the best explanations.
Then with the advent of the germ theory of disease in the late 1800s, they fell out of favor.
But I think the OP is trying to get a feel for what scientific consensus means, and if it can be trusted/relied upon.
The answer as I see it, is that yes, it can be relied on as far as the evidence we currently have shows. So something like FTL communication is supported by the evidence we currently have, but the way science works is that if something is discovered and proven via the usual scientific mechanisms, then the scientific world will shift its consensus. That’s what happened with ulcers and H. Pylori; you really don’t have anyone saying they’re due to stress anymore. You get an ulcer, they give you antibiotics and PPIs, and you get better.
I think there’s also maybe a latent question there about the utility and worth of researching things that are outside the scientific consensus, such as FTL travel or communication. I don’t know the answer to that- part of me says it’s kind of silly, but part of me says we don’t know conclusively, so why not?
I think the overall point is Science is most definitely not “Consensus”, simply because consensus is not necessarily equal to correct by any stretch. Observations and theories have to be proven and/or disproven. And has been seen countless times, the “consensus” can be awfully stubborn about recognizing when its wrong.