The debate within science, heretics and scientific consensus
Science, Skepticism June 12th, 2009
There will be quite a few posts in the near future on the subject of the scientific process, but the recent article from the Scientific Alliance on how scientific consensuses form and how they can impede scientific progress for years is a good primer:
The scientific method is a valuable way to advance objective knowledge. By testing a hypothesis against observation, it can either be falsified or supported. Not proved, of course, but nevertheless over time sufficient evidence can accumulate for a hypothesis to be generally accepted as the best available explanation. It is then known as a theory. Hence, although the vast majority of scientists and citizens (at least in Europe) accept Darwin’s description of evolution, this is still regarded as a theory rather than fact. This is important, because as our understanding develops, apparently satisfactory theories may be replaced by others.
For simple things such as the effect of the Earth’s gravity on objects we are familiar with, collecting the evidence is straightforward and no experiments have been done which contradict the theory of gravity. But over the last century, it has been accepted that classical Newtonian mechanics is actually only valid at a certain scale (which encompasses everything in our normal Earthbound existence). At the atomic scale, we enter the abstruse realm of quantum mechanics, and on a cosmic scale Einstein’s theory of relativity is currently the best description of what goes on across the observable universe.
The most interesting thing and the cause of much excitement in physics is the really large problem that Einstein’s General Theory of Relativity and Quantum Mechanics are incompatible with each other even though in their realm of measurement (the cosmological scale for Relativity, the atomic scale for QM) the ability of those theories to predict phenomena is one of the most battle-tested areas of scientific knowledge.
The SA article mentions a fairly recent example of a scientific consensus which was destroyed by the work of two Australian scientists:
A classic recent example which is often quoted is of the cause of stomach and duodenal ulcers. Many readers will remember that stress and spicy foods were considered the primary causes of peptic ulcers, until the Australian scientists Robin Warren and Barry Marshall discovered the bacterium Helicobacter pylori in 1982 and proposed that colonisation by this micro-organism was the main factor. Warren took the rather extreme step of deliberately infecting himself (and inducing symptoms of gastritis) and publishing the results before the theory began to gain acceptance.
In this case, doctors and scientists “knew” that stress and diet were the main causative factors for ulcers because that was what they had been taught and that was the basis on which patients were treated. It is human nature to accept facts rather than continually question them: indeed, society would probably not function if we did not behave like this. To overturn received wisdom requires either unexplained observation (as for the behaviour of the universe) or one or more awkward individuals who are sufficiently motivated to do their own experiments.
So non-evidenced based beliefs can be just as pernicious amongst scientists as other forms of faith-based reasoning amongst the general population.
Oh and by the way, Warren and Marshall won the Nobel Prize for Medicine in 2005 for their consensus-busting evidence-based theory on gastric disorders.
This year’s Nobel Prize in Physiology or Medicine goes to Barry Marshall and Robin Warren, who with tenacity and a prepared mind challenged prevailing dogmas. By using technologies generally available (fibre endoscopy, silver staining of histological sections and culture techniques for microaerophilic bacteria), they made an irrefutable case that the bacterium Helicobacter pylori is causing disease. By culturing the bacteria they made them amenable to scientific study.
In 1982, when this bacterium was discovered by Marshall and Warren, stress and lifestyle were considered the major causes of peptic ulcer disease. It is now firmly established that Helicobacter pylori causes more than 90% of duodenal ulcers and up to 80% of gastric ulcers. The link between Helicobacter pylori infection and subsequent gastritis and peptic ulcer disease has been established through studies of human volunteers, antibiotic treatment studies and epidemiological studies.
But at the time, Warren and Marshall were villified by specialists in the field of gastric disorders who believed these Australians were crazy.
Barry Marshall and Robin Warren, for example, are contemporary former heretics — we say “former” not because they recanted their beliefs but because they provided evidence to prove their strange hypothesis correct. In the 1970s, the medical consensus was that stomach ulcers were caused by excess acid, stress or a poor diet. Marshall and Warren, however, had a different idea: they thought that the condition might be triggered by bacteria.
At first, their hypothesis met with ridicule because it flew in the face of many years of medical insight. The origins of ulcers, it was argued, were well understood; besides, the stomach was too acidic for bacteria to survive. Warren’s claim to have observed bacteria was dismissed as a delusion. “When I said they were there, no one believed it,” he said.
And so the pair gathered observation after observation, fact after fact. When Warren identified curved bacteria in the stomach biopsies of patients with peptic ulcers, he knew that a handful of intriguing observations would be insufficient to carry the day. He and Marshall examined hundreds of biopsies and established that when a duodenal or stomach ulcer was present, so, too, was an organism called Helicobacter pylori.
This correlation, however, was not sufficient to prove causation: the ulcers and the infections could have been the result of a third factor. Marshall decided an unorthodox experiment was needed. He drank a flask of the bacteria and was rewarded with an ulcer. He promptly cured himself with antibiotics, a cure that would be effective only if the bacteria was indeed the culprit. Before long, the Helicobacter heresy had won the day.
So what happened to the original consensus? It died. Alone.