I'm still reading Michael Polanyi's "Personal Knowledge" - it's a deep book, with lots of interesting digressions. The latest that caught my attention was an off-hand remark he makes in his chapter on "Intellectual Passions" in the section on "The Tacit Component":
But there is, unfortunately, no rule by which to avoid the risk of occasionally disregarding [...] true evidence which conflicts (or seems to conflict) with the current teachings of science. During the eighteenth century the French Academy of Sciences stubbornly denied the evidence for the fall of meteorites, which seemed massively obvious to everybody else. Their opposition to the superstitious beliefs which a popular tradition attached to such heavenly intervention blinded them to the facts in question.
with a further footnote:
"Scientists in other countries were anxious not to be considered as backward compared with their famous colleagues in Paris", writes F. Paneth ("Science and Miracles", Durham University Journal, vol. 10 (1948-9), p. 49). "... many public museums threw away whatever they possessed of these precious meteorites; it happened in Germany, Denmark, Switzerland, Italy and Austria."
There's a fascinating more-detailed account of the background of the meteorite question and how it was resolved in this recent account of Ernst Chladni's work, by Matt Salusbury. Essentially, going all the way back to Aristotle, the learned folk had declared that outer space contained only the known large celestial bodies (by the 18th century one had to make exceptions for the moons of Jupiter and Saturn which could be seen through telescopes, the newly discovered Uranus, and the comets, which Tycho Brahe showed were further away than the Moon; the first asteroid was not found until January 1, 1801). What people claimed as rocks falling from the sky were variously declared to be the output of volcanoes, the product of lightning strikes, or some rock version of rain.
Salusbury's account of Lavoisier's role provides an example of the mindset of the time:
One contemporary scientist was Antoine Laurent Lavoisier, who in his earlier career with France’s Académie Royale des Sciences gained a reputation as a tenacious superstition-buster. He demolished contemporary claims about water-dowsing and of a boy who could see water through strata of earth and rock. Lavoisier was part of the team called in to evaluate Franz Anton Mesmer’s claims around “animal magnetism”, for which he found no evidence.
Lavoisier’s report on “a stone which it is claimed fell from the sky during a storm” was the first known chemical analysis of a piece of a meteorite, which fell in 1768 in Luce, France. He read his report to the Academy the following year, and it was written up in 1772. Lavoisier, the junior partner in the committee that wrote the report, found iron pyrites in the stone, and concluded that “thunder struck preferentially on pyritiferous rock”, which peasants had misidentified. He speculated that the iron pyrites in the rock somehow attracted lightning. On the subject of meteors, he added that “true physicists” had always been sceptical.
Salusbury goes on to write about Ernst Chladni's investigations starting in 1793 in Göttingen, leading to a book on the subject in 1794 which asserted the veracity of the eyewitness accounts, with chapter headings declaring "fireballs are cosmic bodies”, “most shooting stars are no different”, that shooting stars are “not of volcanic origin… They are not smelted by lightning." This didn't quite convince everybody. In April 1803 The French Academy sent physicist Jean-Baptiste Biot to look into the L'Aigle Meteorite fall, which produced thousands of fragments over a 40 square km area. Biot was convinced by both the eyewitness accounts and the material evidence that the origin had to be cosmic, not terrestrial, and his science was finally convincing enough for the French Academy.
As to museums actually throwing out their meteorite collections, this investigation tracked the claim down to the book “Cosmic Debris: Meteorites in History”, by John G. Burke which in turn quotes Chladni:
“Chladni, in his Uber Feuer-Meteore (1819), decried the fact that some meteorites in collections were discarded in the eighteenth century, terming their removal “Enlightenment vandalism.” These acts, he wrote, occurred at five places: Dresden, Vienna, Copenhagen, Bern and Verone; and they involved meteorites from two sixteenth-century and four seventeenth century falls”
Meteorite falls are the sort of thing that happen rarely enough that only a small fraction of people are likely to observe one directly in their lifetime. Clearly 18th century scientists didn't have a lot of faith in such observations by ordinary people. With systematic gathering of evidence, even without direct observation of the phenomenon by scientists, the truth did eventually prevail.
Does this episode tell us anything about the possibilities for similar problems in modern science? Certainly, for phenomena at the scientific fringe - things which recur only rarely under special circumstances, things which are intrinsically hard to reproduce, or matters in subject areas where scientific theory is necessarily hard to test - I think it's likely the scientific community will, as Polanyi puts it, "occasionally disregard[...] true evidence which conflicts (or seems to conflict) with the current teachings".
But the scientific community is vastly bigger now than the 18th century French Academy, with many more eyeballs out there to spot such "true evidence" if it's actually available, and many more brains to consider alternatives to "current teachings". On the other hand, the scope of science is vastly greater now too, so perhaps correction would be no faster now than then. There are probably some examples in medical science of recent episodes of this sort - the role of infection in ulcers, for example? I can't think of any recent examples in physics where "true evidence" was disregarded in this sort of way, at least that have been satisfactorily resolved. Anybody else?