We are taught that modern scientists are driven only by reason and facts. It was only early scientists like Galileo who needed to fear the reaction to their radical views. Neither of these beliefs is true. The reaction to Alfred Wegener's Continental Drift Theory demonstrates that new ideas threaten the establishment, regardless of the century.
Alfred Wegener was the scientist who proposed the Continental Drift Theory in the early twentieth century. Simply put, his hypothesis proposed that the continents had once been joined, and over time had drifted apart. The jigsaw fit that the continents make with each other can be seen looking at the map of soil types below (derived from University of Idaho). South America can be dragged and rotated (rotating is tricky by touch) so you can try to see how well it joins with Africa.
Since his ideas challenged scientists in geology, geophysics, zoogeography and paleontology, it demonstrates the reactions of different communities of scientists. These reactions eventually shut down serious discussion of the concept. The geologist Barry Willis summed it up best:
further discussion of it merely incumbers the literature and befogs the mind of fellow students.The students' minds would not be befogged. The world had to wait until the 1960's for a wide discussion of the Continental Drift Theory to be restarted.
Why the extreme reaction? Alfred Wegener did not even present Continental Drift as a proven theory. He knew he would need more support to convince others. His immediate goal was to have the concept openly discussed. These modest goals did not spare him. His work crossed disciplines. The authorities in the various disciplines attacked him as an amateur that did not fully grasp their own subject. More importantly however, was that even the possibility of Continental Drift was a huge threat to the authorities in each of the disciplines.
Radical viewpoints threaten the authorities in a discipline. Authorities are expert in the current view of their discipline. A radical view could even force experts to start over again. One of Alfred Wegener's critics, the geologist R. Thomas Chamberlain, suggested just that :
"If we are to believe in Wegener's hypothesis we must forget everything which has been learned in the past 70 years and start all over again."
He was right.
In spite of all the criticism, Wegener was able to keep Continental Drift part of the discussion until his death. He knew that any argument based simply on the jigsaw fit of the continents could easily be explained away. To strengthen his case he drew from the fields of geology, geography, biology and paleontology. Wegener questioned why coal deposits, commonly associated with tropical climates, would be found near the North Pole and why the plains of Africa would show evidence of glaciation. Wegener also presented examples where fossils of exactly the same prehistoric species were distributed where you would expect them to be if there had been Continental Drift (e.g. one species occurred in western Africa and South America, and another in Antartica, India and central Africa) [_1_] . The graphic below shows the striking distribution of fossils on the different continents.
Wegener used an Alexander duToit graphic to demonstrate the uncanny match of geology between eastern South America and western Africa.
The picture painted of Alfred Wegener's contemporaries might not be fair. One would expect scientists to resist ideas that challenged their life's work. It doesn't explain all of the criticism. There were alternatives. To explain the unusual distribution of fossils in the Southern Hemisphere some scientists proposed there may once have been a network of land bridges between the different continents. To explain the existence of fossils of temperate species being found in arctic regions, the existence of warm water currents was proposed. Modern scientists would look at these explanations as even less credible than those proposed by Wegener, but they did help to preserve the steady state theory.
New theories often have rough edges. Alfred Wegener did not have an explanation for how continental drift could have occurred. He proposed two different mechanisms for this drift. One was based on the centrifugal force caused by the rotation of the earth and another a 'tidal argument' based on the tidal attraction of the sun and the moon. These explanations could easily be proven inadequate. They opened Wegener to ridicule because they were orders of magnitude too weak. Wegener really did not believe that he had the explanation for the mechanism, but that this should not stop discussion of a hypothesis. Wegener's contemporaries disagreed. A major conference was held by the American Association of Petroleum Geologists in 1926 that was critical of the theory. Alfred Wegener died a few years later. With his death, the Continental Drift Theory was quietly swept under the rug. The existing theories of continent formation were allowed to survive, with little challenge until the 1960's.
The main problem with Wegener's hypothesis of Continental Drift was the lack of a mechanism. He did not have an explanation for how the continents moved. His attempt to explain it using tides only made things worse. But both Galileo and Darwin had serious flaws in their theories when they were first presented. Galileo had a tidal theory that was more embarassing than Wegener's and Darwin was missing a mechanism for his theory. History treats the three men differently in spite of the fact that their theories arrived with pretty big holes.
Charles Darwin was missing an important mechanism for evolution when he published the Origin of Species in 1859 (see Mendel and Darwin). He argued that with the natural variations that occur in populations, any trait that is beneficial would make that individual more likely to survive and pass on the trait to the next generation. If enough of these selections occured on different beneficial traits you could end up with completely new species. He did not have a mechanism for how the traits could be preserved over the succeeding generations. At the time it was thought that the traits of the parents were blended in the offspring. Unfortunately, blending would dilute any beneficial trait out of a population within a few generations. This is because most of the blending over the next generations would be with individuals that did not have the trait. This gaping hole in the theory didn't stop universities such as Oxford from teaching Evolution as fact shortly after the publication of the Origin of Species. This hole in Darwin's theory was plugged about 50 years later using the work of a Roman Catholic monk, Gregor Mendel. His theory provided an alternative to blending where traits were inherited whole.
Darwin's theory had another problem. His theory proposed a gradual evolution through successive generations. The fossil record of the time contradicted this. There seemed to be an 'explosion' of different life-forms over a relatively short time span in the early Cambrian period ( the Cambrian Explosion). There also didn't seem to be any transitional forms of life preceding these species. New discoveries made the problem worse. Much worse. In 1909, a massive find of 65,000 more specimens of early Cambrian life was discovered in the Burgess Shale in British Columbia, Canada. Many were complex multi-celled animals with no evidence of preceding transitional forms.
Alfred Wegener also shares much in common with Galileo. Galileo had his own 'tidal argument' ; one that was even more embarassing than Wegener's. To defend his belief that the sun was the center of the solar system, Galileo argued that the tides were caused by the sun. His argument was based on there only being 1 tide per day and where the tides cycle over the year and not over a month. It didn't take a scientist to realize that the argument was ridiculous.
There were other problems with Galileo's defense of Copernicism. The scientists of Galileo's day did have scientifically valid reasons to doubt a moving earth. A moving earth required that a phenomenon known as stellar parallax (see Copernicism and Stellar Parallax) would be observed . No one in Galileo's day or for two centuries after his death was able to observe this phenomenon. Neither did the current data support Galileo's favoured Copernican Model. Modern statistical analyses don't either [_2_] . Galileo wasn't proposing the Keplerian model that works so well; he was proposing the Copernican Model against the Keplerian and other models. More info on the Galileo Affair can be found at Galileo's Battle for the Heavens and The Galileo Myths.
Why was one theory quickly accepted, another quickly dismissed, and the other a cause of controversy. All of the theories had serious flaws. The answer might lie with the social background to these events and not science.
Darwin was the ultimate insider in English scientific circles. His grandfather, Erasmus, was an early student of evolution and his half-cousin, Francis Galton, was a famous statistician. Being part of the Wedgewood-Darwin clan meant he would never have to worry about money. His connections meant that he could enlist the elite of mid-nineteenth century English science if needed. The most famous of the early defenses of Darwinism was not by Darwin himself but by the famous biologist, Thomas Huxley and the social philosopher, Herbert Spencer. Darwin's ideas were adopted by supporters of laissez-faire capitalism. "Survival of the fittest" gave an ethical dimension to the no-holds barred capitalism of the late nineteenth century. Andrew Carnegie, the fabulously rich robber baron, used elements of evolution by natural selection to justify his own ruthless business practices.
Alfred Wegener wasn't an insider. He had to earn all his allies. His few allies (duToit and Holmes) were no match for his many skeptics. His place of birth may have played a role. Anti-German bias was very strong in the 1910's and 1920's in English-speaking countries. This resulted in German-based names for cities, streets, foods and animal breeds being changed to names that were more 'patriotic'. Being German wasn't Wegener's only problem; the arguments he used to support his hypothesis crossed into disciplines that were not his specialty. He was trained as an astronomer and worked as a meterologist. He was considered an outsider for a reason.
The early history of the Copernican model is an example of the effect of outside forces. The publication of Copernicus' de Revolutionibus drew very little criticism from the Catholic countries. The most serious early criticisms came from the Protestant countries in Europe. The Vatican's interest began 10 years before the publication of de Revolutionibus, after a series of lectures given to Pope Clement VII on Copernicus's work. The church's support for Copernicus' work was well known since the original publication included a copy of the letter from the Vatican urging him to share his work, a dedication to the pope, and a thank you to a bishop who was an important supporter of his work. The involvement of the church may have muted criticism from academics in the Catholic countries of Europe and encouraged criticism in the Protestant countries. The reverse happened after Galileo's trial in 1633. Galileo was tried for not obeying an order from 1616 to not teach the Copernican theory as a proven theory but only as a hypothesis. (more on this at Galileo's Battle for the Heavens).
Science depends on facts. It also depends on reason. But fact and reason alone cannot explain how science works. The examples chosen all had some compelling support and serious shortcomings. Part of the answer may lie in the sociology of groups. Another part lies in simple faith: faith that future scientists will address a theory's shortcomings. Darwin needed an explanation for the Cambrian Explosion and a mechanism for the preservation of traits (see Mendel and Darwin) . Wegener needed a mechanism for Continental Drift. Galileo needed an explanation for the lack of stellar parallax and the poor performance of his model (see Galileo's Battle for the Heavens) . It is not only the community that requires faith. The champions of these new theories require faith in their ideas, even when facts contradict their hypotheses. In each case above, there were facts which when combined with the current assumptions of the time clearly contradicted their hypotheses. None of these scientists let those facts get in the way. Paul Feyerabend, a modern philosopher of science, presents a similar view, where he argues that science is sometimes required to work "against the facts". His key example was how the heliocentric system made less sense than a geocentric system during Galileo's time. One irony missed by discussions of science and religion is how much both depend on faith.