Scientists love to point out fallacies about science which are accepted as fact by a sizable portion of the general public. More interesting to me are the fallacies that are accepted by scientists themselves. Such fallacies should be rare in the 21st century, given the sophistication of modern science. Nevertheless, if we were to put them on the spot, most scientists would admit there could be a few fallacies kicking around, though more likely in other branches of science than in their own.
Of course, an acknowledged fallacy is always a thing of the past because as soon as it is proven to be fallacious, no serious scientist would continue to accept it as fact. Except, perhaps, when the proof leaves room for doubt, in which case it may be necessary to wait until the champion of a fallacious theory retires or dies.
Those present day fallacies which are accepted as fact by members of the scientific community cannot be identified with any certainty because if there was clear proof of error, they would no longer be accepted. In looking for candidates, it helps to consider fallacies which were once widely accepted by scientists.
This is the classic scientific fallacy. The geocentric model of the movement of heavenly bodies survived for many centuries. Men of science recognised that planets were different than stars. But it wasn't until astronomers started to describe the paths of the planets mathematically that a few of them realised that an elegant description of the paths of the planets was possible if the sun were considered to be the body around which the earth and planets revolved. Copernicus was not the first to propose a heliocentric model but he made a pretty good case and it only took another 100 years for his model to be accepted.
It is easy to see how the geocentric fallacy got started. It still looks as though the sun and stars rotate around the earth. Many fallacies persist because the fallacy has the look of truth to a casual observer. On the other side of this coin, a lack of opportunity to observe may contribute to the durability of a fallacy.
Lemmings are furry little mice of the far north. My 1937 edition of the Standard American Encyclopedia has the following to say about lemmings: “The lemming is remarkable for migrating at certain periods in immense multitudes. They move in parallel columns and nothing will induce them to deviate from the straight line, the migration always terminating in the sea and ending in the drowning of all that have survived the journey.”
In 1958 Disney released White Wilderness which had a 12 minute segment on lemmings. The general belief that lemmings are suicidal was reinforced by the Disney film. But paradoxically that same film may have stimulated closer observations of lemmings which, in turn, dispelled the suicide myth. Word leaked out that in order to show lemmings going over a cliff to their death, the filmmakers had to throw lemmings over the edge. The lemmings were apparently very reluctant participants in this scene.
Biologists now believe that while lemmings do migrate from time to time (when the home turf gets crowded) they are not suicidal. They do not voluntarily jump off cliffs. They are pretty good swimmers so when the come to a river they dive right in, but with the intention of crossing to the other side.
This fallacy had a remarkable life despite the naysayers. From the time Sir Walter Raleigh got Queen Elizabeth to try smoking in 1600, there have been those who spoke out against tobacco. In 1601 Samuel Rowlands wrote,
But this same poyson, steeped India weede
In head, hart, lunges, do the soote and cobwebs breede
With that he gasp'd, and breath'd out such a smoke
That all the standers by were like to choke.
In the middle of the 20th century, 350 years after Rowlands’ warning, modern science was still having trouble proving harm. Now, in 2008, it is clear that smoking was causing a variety of ailments for all of those 350 years and for many years before. The difficulty in proving harm was two fold:
While there was good reason to suspect that tobacco was harmful (nicotine is a poison; smoke blackens the lungs), there was no positive proof. Even after the tide had all but turned, many heavy smoking medical professionals behaved as though the lack of positive proof of harm meant it was safe.
Since everybody reacts differently to tobacco smoke, a cause and effect relationship was hard to prove. Researchers had to try to demonstrate that in a set of smokers there was more cancer, heart disease, lung problems than in a similar set of non-smokers. And there was. But they also had to show that the difference was too large have occurred by chance. Most studies fell short in that respect. The rare study that seemed to clearly demonstrate harm was balanced by studies which demonstrated no effect.
This may be where the tobacco industry came in. They were doing their own studies. Probably many such studies were discarded for every one that was actually published. It wouldn’t be necessary to cook results. Just be selective in which studies saw the light of day.
The influence of special interests on scientific proof is even more of a problem now than it was 50 years ago. More and more research institutions and scholarly journals get part of their funding from private industry. If a respectable journal receives a paper with good solid research, they will publish the paper even if they know it could annoy one of their financial supporters. But what about a flawed paper? Most research projects have minor flaws of one sort or another. I’m guessing that a flawed paper which makes a supporter unhappy is sure to be rejected. On the other hand, a flawed paper which benefits a supporter will be published.
An example of inappropriate pressure by financial supporters was clearly evident a few years ago in Scotland where administrators of a public institution tried to silence a scientist who had done an experiment that cast doubt on what is probably a fallacy.
Transgenic researchers are fighting an image created many years ago by Mary Shelley’s Frankenstein, an image kept fresh in this century by the movie industry. There is a great deal of pressure on researchers to maintain a clean record. When Dr. Arpad Pusztai (working for the publicly funded Rowett Research Institute in Aberdeen, Scotland) reported that his rats were doing poorly (negative effects on brain, liver and immune system) on a diet of transgenic potatoes, he was told to keep quiet about it.
Pusztai had not done a large enough feeding trial to prove harm. He wanted to repeat his experiment to confirm his tentative results. He was told to drop it. His feeding trial wasn’t legally required – it was just something he had done on his own hook as a responsible scientist. He went public and was fired.
The potatoes in question had been genetically altered to produce lectins, carbohydrate-binding proteins, which increase insect resistance. The ability to produce lectin came from genes transplanted from snowdrop and jackbean. Nobody knew how the lectin would affect the eating quality of these potatoes (the hope would be that the lectins would appear in the leaves but not the tubers as do the potato’s own poisonous alkaloids). This project was discontinued after Pusztai went public. It is not clear what would have happened if he had kept quiet.
What is clear is that a private company, through a modest financial contribution, had an undue influence on a public institution.
There is no such problem with the next fallacy which like the geocentric fallacy has the look of truth. In this case experimental evidence has exposed the fallacy but there are still scientists in horticulture who believe the fallacy. Until they retire, this will be a fallacy in transition.
When horticulturists started using sheets of plastic for soil warming in cool climates, the natural assumption was that black plastic would be best because black is the colour of heat absorption. In fact black plastic does warm the soil, so professionals began using it themselves and they recommended it to home gardeners. In the meantime, university researchers did trials with various kinds of plastic and discovered that clear plastic always warms the soil more than black plastic. This has been tried in different climates and the further north you go (where soil warming is really needed) the greater the advantage of clear over black plastic. What happens is that black plastic gets very hot in the bright sun but only a fraction of that heat transfers to the soil. With clear plastic the greenhouse effect kicks in and over 90% of the heat of the sun is captured.
Presumably, new graduates from horticultural programs will know about the superiority of clear plastic for soil warming but there are still older professionals who recommend black plastic.
This may or may not be a fallacy. It is accepted as fact by nutritionists even though it has never been proven in a scientific experiment. Such an experiment would be very difficult to design and control. Factors to be taken into account would include:
Then there would have to be some agreement about how to measure optimum health.
If there is no scientific proof, then where did such a specific recommendation come from? It would appear that somebody made a guess at what would be an optimum water intake and that guess had such a lovely symmetry that it was enshrined.
Even if eight by eight were proven to be a fallacy, it is unlikely that it will have done much harm. This is unlike tobacco which has done a great deal of harm and continues to do so albeit on a smaller scale now that it is generally accepted to be harmful.
Despite many claims to the contrary, amalgam fillings and the preservative thimerosal are officially considered to be safe. If this should turn out to be untrue, the harm from low level mercury (in the worst case scenario) could exceed that from tobacco.
Mercury is a potent neuropoison but like all poisons, there is a threshold amount below which it is not harmful. Some poisons are even beneficial at very low levels. Not so mercury. While mercury has been used medicinally to kill what ails you, no claim has ever been made for a positive biological effect from mercury at any level. Nevertheless, there is a lot of evidence that the average human is not harmed by the small amount of mercury absorbed from amalgam fillings or from the vaccine preservative called thimerosal.
Of course, sensitivity to a poison like mercury is going to vary from person. There has been little research on what fraction of the human race is especially sensitive to mercury and at what level of mercury exposure the most sensitive among us are affected.
The possibility of a heightened sensitivity to mercury is not even acknowledged by many researchers. Given that many of us have problems with normal foods (as in diabetes, lactose intolerance and celiac disease), what should we expect from a poison? It would be remarkable if mercury sensitivity did not exist.
There are indications that as many as 10% of us are sufficiently sensitive to mercury to be affected by the mercury absorbed from amalgam fillings. This is not easy to prove and any attempt at proof is going to run into resistance from institutions with very deep pockets. The result is that even if the safety of amalgam is a fallacy, it is one that will be with us for a while.
The situation with thimerosal is complex. Vaccinations save lives. If a few babies get autism, that is better than many babies dying. On the other hand if vaccinations were conceded to have an occasional side effect like autism, then some parents would refuse the vaccinations, the profits of vaccine makers would decline and more babies would die. It is in the financial interest of vaccine manufacturers to disprove the connection with autism. Also, health officials with the greater good in mind may also want to disprove the autism connection. This dual pressure can lead to scientific distortion. There was an example of this in early 2008.
A paper was published in the journal Pediatrics on the time it takes for mercury, from the preservative thimerosal, to clear the blood stream. The study’s author, Michael Pichichero, was interviewed by a science writer and he reported that the mercury was pumped out of a baby’s body too fast for it to be a cause of autism. Turning to the Pediatrics paper, “Mercury Levels in Newborns and Infants After Receipt of Thimerosal-Containing Vaccines,” the language is more restrained than in the public announcement and the autism connection is a stretch at best.
The study does a good job of measuring the half life of mercury in the bloodstream of an average baby. But autistic babies are not average. Only a few babies in a thousand get autism. In order to say something about a possible autism connection, the study would have to look at mercury sensitive babies. Most, if not all, such babies were eliminated from this trial in the following ways:
If thimerosal is causing autism, it is probably happening in cases of mercury sensitivity coupled with a genetic susceptibility to autism. This study does a good job of determining the half-life of mercury (from thimerosal) in the blood of an average baby but has nothing to say about mercury sensitive babies, and hence nothing of any substance to say, one way or the other, about thimerosal as a cause of autism.
Some fallacies are harmless – it doesn’t matter to most of us whether lemmings are suicidal or not. Some fallacies have done a great deal of harm. Before the 20th century religion was the major factor in preventing the correction of a fallacy. Now it is big money. If the results of a scientific experiment coincide with the interests of a large corporation, we should be sceptical. If the results stand up to scrutiny, then good for them. If not, keep an open mind. We may be dealing with a modern day scientific fallacy.