How we interpret the science of centuries past cannot be separated from our view of modern science. The danger is that this view may be based on a stereotype. A common stereotype of a scientist is that of a rational professional that evaluates new ideas based only on an objective evaluation of data. This would leave the impression that, unlike early scientists, modern scientists proposing radical new ideas do not need to fear the reactions of those entrenched in the existing system. Alfred Wegener is one modern scientist amongst many that demonstrate that new ideas threaten the establishment, regardless of the century.
Alfred Wegener was the scientist who championed the
Continental Drift Theory through the first few decades of
the 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 by looking at any world map.
below shows the continents of Africa and South America
Clicking on the image will illustrate their drift to their current positions (thanks are due NASA for the original
Since his ideas challenged scientists in geology, geophysics, zoogeography and paleontology, it demonstrates the reactions of different communities of scientists. The reactions by the leading authorities in the different disciplines was so strong and so negative that serious discussion of the concept stopped. One noted scientist, the geologist Barry Willis, seemed to be speaking for the rest when he said:
further discussion of it merely incumbers the literature and befogs the mind of fellow students.Barry Willis's and the other scientists wishes were fulfilled. Discussion did stop in the larger scientific community and students' minds were not befogged. The world had to wait until the 1960's for a wide discussion of the Continental Drift Theory to be restarted.
Why did Alfred Wegener's work produce such a reaction? He was much more diplomatic in presenting his theory than Galileo. Although he believed himself to be right and that some of his arguments were compelling, he knew he would need more support to convince others. His immediate goal was to have the concept openly discussed. Wegener did not even present Continental Drift as a proven theory. These modest goals did not spare him. The fact that his work crossed disciplines exposed him to the territoriality of scientific disciplines. The authorities in the various disciplines attacked him as an interloper 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 established authorities in each of the disciplines.
One can't underestimate the effect of a radical new viewpoint on those established in a discipline. The authorities in these fields are authorities because of their knowledge of the current view of their discipline. A radical new view on their discipline could be a threat to their own authority. One of Alfred Wegener's critics, the geologist R. Thomas Chamberlain, could not have summarized this threat any better :
"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 the criticisms from several different disciplines 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 as a coincidence. 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.
Thus far the picture painted of Alfred Wegener's contemporaries is not flattering. But this might be unfair. One would expect some scientists to resist ideas that would invalidate their life's work. But it doesn't explain all criticism of Wegener's ideas. Wegener presented very compelling arguments for Continental Drift but there were alternate explanations for some of his observations. 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 donot always arrive with all the t's crossed and i's dotted. Wegener did not have an explanation for how continental drift could have occurred. He proposed two different mechanisms for this drift, one based on the centrifugal force caused by the rotation of the earth and a 'tidal argument' based on the tidal attraction of the sun and the moon. These explanations could easily be proven inadequate and 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. The scientists of the time disagreed. After Alfred Wegener died, the Continental Drift Theory was quietly swept under the rug. With the Continental Drift Theory out of the way, the existing theories of continent formation were able 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. Some argue that this failing justified the early reactions to his work and to its dismissal. But Charles Darwin was missing a mechanism for the inheritance of beneficial traits when he published the Origin of Species in 1859. Darwin had amassed a huge amount of evidence that supported some type of adaptive process that contributed to the evolution of new species, much like Wegener had for Continental Drift. 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. One major flaw in Darwin's theory was that he did not have a mechanism for how the traits could be preserved over the succeeding generations. At the time, the prevailing theory of inheritance was that the traits of the parents were blended in the offspring. But this would mean that any beneficial trait would be diluted out of the 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.
In spite of the lack of a mechanism for the preservation of traits, Darwin's theory quickly came to dominate. Within 5 years, Oxford University was using a biology textbook that discussed biology in the context of evolution by natural selection. The textbook stated, "Though evidence might be required to show that natural selection accounts for everything ascribed to it, yet no evidence is required to show that natural selection has always been going on, is going on now, and must ever continue to go on. Recognizing this is an a priori certainty, let us contemplate it under its two distinct aspects." At Oxford, evolution by natural selection had gone from hypothesis to a priori certainty in the space of 5 years. In this case the scientific community (excepting a minority of skeptics) chose to ignore the lack of mechanism. Wegener had no such luck with his Continental Drift Theory. [_2_] .
The mechanism necessary to explain the preservation of beneficial traits was published shortly after the Origin of Species. Unfortunately it was largely ignored. In 1865, an obscure Augustinian monk from Moldavia presented a paper to the Natural History Society of Brunn where he discussed the results of experiments on pea plants. The results presented by this monk, Gregor Mendel, pointed to traits being inherited 'whole' (also known as particulate inheritance), and that certain traits (recessive traits) that disappear in one generation can reappear in a following generation (see Mendel and Evolution). This would have gone a long way in plugging at least one hole in the Darwin's theory. Mendel's work was largely ignored until about 1900. Shortly afterward it was incorporated into our modern view of evolution by natural selection known as the 'modern synthesis'.
Darwins theory had another problem. His theory proposed a gradual evolution through successive generations. But the fossil record at the time didn't co-operate. There seemed to be a 'explosion' of different life-forms over a relatively short time span (in geologic terms) in the early Cambrian period. There also didn't seem to be any transitional forms of life preceding these species. This eventually became known as the Cambrian Explosion. Darwin himself recognized this as a serious issue with his theory and he discussed it in the Origin of Species. Darwin explained away the problem as a problem with the fossil record and not with his theory. Over the course of the twentieth century, a much better picture of the fossil record of both the Cambrian and Pre-Cambrian eras was developed. The new discoveries made the problem worse. Much worse. In the early twentieth century, the American paleontologist, Charles Walcott, discovered and excavated the Burgess Shale in British Columbia, Canada. He found 65,000 more specimens of early Cambrian life, many of which were complex multi-celled animals. At the time there still was no evidence of transitional forms in the pre-Cambrian. Only recently have they started discovering isolated examples of moderately complex multi-celled animals from the Pre-Cambrian. This still doesn't explain the step-change in the diversity of life-forms in the Cambrian.
Wegener also shares much in common with Galileo. Wegener probably had at least as strong a case for Continental Drift in 1929 as Galileo had for the Copernican model in 1633. The reason many do not realize this is that the controversy is usually presented as a controversy between Galileo and the Church and not Galileo and other scientists (see Galileo's Battle for the Heavens). As a result most discussions of the early Copernican Model do not even mention any problems associated with the Copernican model. But it was a scientific controversy and it had many of the same elements of the Continental Drift controversy.
Galileo had his own 'tidal argument' ; one that was even more embarassing than Wegener's. Galileo argued that the tides were caused by the sun. It is difficult to understand how a great scientist who had spent his youth less than 20 kilometres from the sea would present an argument for Copernicism based on there only being 1 tide per day and where the tides cycle over the year and not over a month. While it took a noted geologist to show that Wegener's tidal argument was ridiculous, Galileo's tidal argument could be challenged by any fisherman or coastal dweller.
The tidal argument wasn't the only or the major problem with Galileo's defense of Copernicism. Wegener's critics never presented strong arguments that Continental Drift couldn't have happened or that it wasn't happening. They did show that the mechanism that Wegener suggested was driving Continental Drift was inadequate. 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.
Another argument against Copernicism was very simple and in its own way, empirical. In 1551, only 8 years after Copernicus's death, the Prutenic tables were developed from the Copernican model to predict the positions of stars and planets. There was 80 years of experience in comparing the performance of Copernican-based tables (Prutenic) and Ptolemaic-based tables (Alphonsine). It didn't seem that one was much better than the other. A reasonable conclusion based on this experience is that if the Ptolemaic was wrong, then the Copernican was not right. These scientists did not have computers and advanced statistical techniques to meticulously compare the predictions of the two systems. When these tools arrived in the twentieth century their hunch was proven correct; there wasn't much separating the two systems [_3_] . Today, it is the Keplerian system of planetary motion that is taught in schools, not the Copernican or the Ptolemaic. Galileo knew of Kepler's model and had never accepted it during his lifetime.
From the descriptions above it would be difficult to explain why one of the theories was quickly accepted by the scientific communities, another was quickly dismissed even as a hypothesis, and the other was accepted by some and challenged by others. Interpreting these events from a strictly scientific basis won't help. All of the theories had some compelling advantages and all had some very serious failings when they were first presented. We might have to look beyond the world of ideas to the world of people, events and things to help answer the question.
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 noted statistician who was considered the father of eugenics. Being part of the Wedgewood-Darwin clan meant having no worries about money and established connections in the scientific world. When evolution by natural selection was under attack, Darwin could enlist the efforts of a Who's Who of mid-nineteenth century English science. 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 also tremendously attractive to those supporting 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, appropriated elements of evolution by natural selection to justify the ruthless business practices of his time.
Alfred Wegener came from much more modest lineage than Darwin. He had to earn all his allies. Although he had a few notable allies for his theory (duToit and Holmes) his theory was generally met with skepticism, especially in the English-speaking world. Although it is difficult to assess what part anti-German bias played in the initial reactions to Continental Drift, it is known that anti-German bias was very strong in the 1910's and 1920's. In English-speaking countries such as Australia, Canada, the UK, and the USA it reached the stage where German-based names for cities, streets, foods and animal breeds were often being renamed 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. Given that his training was as an astronomer, and much of his work revolved around metereology, he was considered an outsider.
The early history of the Copernican model provides examples where the same outside force influenced both the acceptance and rejection of a hypothesis. When Copernicus' book de Revolutionibus was first published it drew very little criticism from the Catholic countries. The most serious early criticisms came from the Protestant countries in Europe. This situation was reversed in the seventeenth century. The easy ride that was given de Revolutionibus in Catholic countries may have been influenced by the knowledge of the Vatican's involvement in the publication of the book. In 1533, a series of lectures on Copernicus's work was given to Pope Clement VII and senior Vatican officials by an Albert Widmannstetter. After the lectures, it was decided that serious efforts should be made to ensure that Copernicus's work would be published. The church dispatched a letter to Copernicus asking him to share his ideas with other scholars. The local bishop, who was one of Copernicus' closest friends, tried repeatedly to get Copernicus to release his work for publication. Eventually the coercion worked, with the help of the Austrian professor, Rheticus. With the publication of de Revolutionibus, little doubt was left about the church's involvement. 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 heart-felt thank you from Copernicus to the local bishop, Bishop Giese. The heavy involvement of the church in the original publication of Copernicus' work may have muted criticism from academics in the Catholic countries of Europe and perhaps 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 true but only as a hypothesis. He was placed under house arrest in his villa in the Tuscan hills just outside Florence. Some clerical orders, such as the Jesuits, became important critics of the Copernican model. At the time, the Copernican model did not perform any better than the Ptolemaic, and there were still very serious theoretical problems with the theory (stellar parallax), but many Jesuits continued to be doubters even after Kepler had corrected many of the problems with the original Copernican model.
Science depends on facts. It also depends on reason. But fact and reason alone cannot explain the different reactions to new hypotheses and theories we see in the examples above. They all had some compelling support and some 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 the shortcomings in the initial theories. With Darwin's theory, the community of scientists were willing to accept the theory based on a faith that the problems with inheritance and the Cambrian Explosion would be dealt with by future scientists. With Wegener, the community of scientists simply did not have the faith that a mechanism would be found to explain the movement of land masses. With Galileo, some had faith that discovering stellar parallax was only a matter of time and others did not. But it is not only the community that requires faith, the champions of these new theories require faith in their ideas, even when facts sometimes 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 deter them. Paul Feyerabend, a modern philosopher of science, presents a similar view, where he argues that science sometimes is required to work "against the facts". One of his key examples, was how the heliocentric universe made less sense than a geocentric universe during Galileo's day given the facts that were available at the time. Given the current controversy over science versus religion, it is amusing that in the early stages of the development of many theories, science is dependent on faith much like religion.