In 1914, there was a consensus among geologists that the earth under our feet was permanently fixed, and that it was absurd to think it could be otherwise. But in 1915, Alfred Wegener fought an enormous battle to convince them of the relevance of plate tectonics.
In 1904, there was a consensus among physicists that Newtonian mechanics was, at last, the final word in explaining the workings of the world. All that was left to do was to mop up the details. But in 1905, Einstein and a few others soon convinced them that this view was false.
In 1544, there was a consensus among mathematicians that it was impossible to calculate the square root of negative one, and that to even consider the operation was absurd. But in 1545, Cardano proved that, if you wanted to solve polynomial equations, then complex numbers were a necessity.
In 1972, there was a consensus among psychiatrists that homosexuality was a psychological, treatable, sickness. But in 1973, the American Psychiatric Association held court and voted for a new consensus to say that it was not.
In 1979, there was a consensus among paleontologists that the dinosaurs’ demise was a long, drawn out affair, lasting millions of years. But in 1980, Alvarez, father and son, introduced evidence of a cataclysmic cometary impact 65 million years before.
In 1858, there was a consensus among biologists that the animal species that surround us were put there as God designed them. But in 1859, the book On the Origin of Species appeared.
In 1928, there was a consensus among astronomers that the heavens were static, the boundaries of the universe constant. But in 1929, Hubble observed his red shift among the stars.
In 1834, there was a consensus among physicians that human disease was spontaneously occurring, due to imbalanced humours. But in 1835, Bassi and later Pasteur, introduced doctors to the germ theory.
All these are, obviously, but a small fraction of the historical examples of consensus in science, though I have tried to pick the events that were the most jarring and radical upsets. Here are two modern cases.
In 2008, there is a consensus among climatologists that mankind has and will cause irrevocable and dangerous changes to the Earth’s temperature.
In 2008, there is a consensus among physicists that most of nature’s physical dimensions are hidden away and can only be discovered mathematically, by the mechanisms of string theory.
In addition to the historical list, there are, just as obviously, equally many examples of consensus that turned out to be true. And, to be sure, even when the consensus view was false, it was often rational to believe it.
So I use these specimens only to show two things: (1) from the existence of a consensus, it does not follow that the claims of the consensus are true. (2) The chance that the consensus view turns out to be false is much larger than you would have thought.
These are not news, but they are facts that are often forgotten.