The consensus was wrong
In an article in the Guardian, Richard Tol wrote that “There are plenty of examples in history where everyone agreed and everyone was wrong”. He didn’t give examples there – perhaps he thought this was so well known that it wasn’t worth commenting on, or perhaps space was too limited.
Here are a few examples of where the consensus has turned out to be wrong (thanks to @Fastcom, @intrepidwanders, @DerrickByford, @nmrqip and @Beautyon for suggesting many of these).
Yes, I know, these stories are all greatly oversimplified.
Copernicus, Galileo and the Sun. For some time after Copernicus wrote his book saying that the Earth goes round the Sun, most scientists continued to believe the opposite.
Ernst Chladni and meteorites. The consensus was that meteorites came from the earth, perhaps from volcanoes, until, around 1800, some nutter suggested they might come from outer space.
Cholera and John Snow. The consensus was that cholera was caused by ‘miasma’ – bad air, until John Snow identified a link with a contaminated water pump in the 1850s.
Semmelweis, hand-washing and puerperal fever. His results were rejected because they conflicted with the consensus of scientific opinion.
Evolution. The consensus was that God created species in a few days. Darwin was so worried about the consequences of what he’d found that he sat on it for many years.
The Aether and the speed of light. It used to be thought that light travelled at a certain speed relative to a background known as ‘aether’. Experiments and then Einstein’s theory of relativity showed that this was wrong.
Wegener and continental drift. Wegener was attacked and ridiculed for this theory.
George Zweig and quarks. The consensus was that protons and neutrons were fundamental elementary particles until Zweig and Gell-Man came up with quarks.
Barry Marshall and stomach ulcers. The consensus was that gastritis and ulcers were related to poor diet and stress. in 1984, Marshall had to ingest the bacteria, helicobacter pylori, to show he was right that this was the cause, and eventually won the Nobel Prize.
Stanley Prusiner and prions The consensus was that disease agents needed nucleic acids. Prusiner’s theory of prions in the 1980s led to incredulity, personal attacks and then a Nobel Prize.
Barbara McClintlock and “jumping genes”. Another Nobel Prize winner whose work wasn’t accepted at first because it went against received wisdom.
Maybe all those people insisting on how important it is to convince the public that there’s a consensus on climate change need to take a basic course in the history of science.