The Way of Science
Continental Drift and Plate Tectonics
Unit II, Part 1 |
Unit II, Part 2 |
Unit II, Part 3 |
Unit II, Part 4
5. Resistance: Why was Wegener's hypothesis rejected for so long?
Wegener presented his full hypothesis in 1912; at that time, opinion was certainly divided, but the idea was treated as possibly worthwhile, and it was examined without rancor. By 1928 (two years before his death), the "continental displacement" hypothesis had become neglected at best, and very much reviled at worst, particularly by North American geologists. Many professionals treated Wegener as a crank, and the whole idea of massive lateral movement as a fantasy. It's interesting to note that, by 1928, most geologists had abandoned land bridges (because of the isostasy problem), but other (paleontologists and biologists) were still using them extensively to "explain" distributions of both fossils and their living counterparts. Why was this hypothesis subjected to such antagonism? What does this fifty-year rejection have to say about the nature of scientific inquiry?
In class, we will examine these questions. As background for this discussion, many items that may - or may not - have been causes and/or contributing factors are described below. Read them carefully, and think about their wider significance. Remember the big bonus question on the last exam? Hint, hint...
- Wegener's credentials
Wegener obtained his doctorate in astronomy, and did original work in that discipline. He then became very much interested in the then-new science of meteorology, and proceeded to establish additional credentials in that area. For example, he was part of a Danish expedition to Greenland to study atmospheric dynamics, and then went on to additional accomplishments as an Arctic explorer. He was awarded the position of chairman of the department of meteorology and geophysics at the University of Graz, Austria. Many modern commentators on his life have noted that, like Darwin, he was a "synthesizer," moving into disciplines that were not only outside his primary training, but that were rather isolated from each other in terms of free flow of ideas and data. Wegener died in 1930.
- Mechanism for continental drift
One of the major objections to his hypothesis was presented at that 1928 meeting of geologists, along with other aggressive opposition.
According to H. Jeffreys, of prestigious Cambridge University, the mechanism that was proposed by Wegener to explain how continents could plow their way around the globe was dead wrong and impossible. In fact, it was wrong: "tides in the Earth's crust" were far too weak to possibly account for extensive lateral displacement. If they were strong enough to do that, the Earth would have shown massive additional effects. Note that until quite recently, no generally accepted mechanism was available to account for the Earth's magnetic reversals, yet the fact of reversals has been accepted for at least 40 years. Think about that, in terms of Jeffreys's objections.
Soon after Wegener's death, some geologists (Holmes and duToit) proposed convection currents in the mantle as a mechanism. Although their version was not quite the modern model, it certainly was close, and very much anticipatory. It was essentially ignored by Jeffreys and most other geologists.
At this same (1928) meeting, Wegener's empirical evidence was attacked or ignored, as the case may be. The fit of continents was not good enough, and thus coincidental; land bridges could account for fossils; the glacial evidence was ambiguous, as was the evidence for tropical coals, and so on. One piece of direct evidence presented earlier by Wegener (an apparently measurable movement of Greenland) was dismissed (rightly so, as we now know) as ambiguous and probably incorrect.
- Premature ideas
Gunther Stent and Michael Polanyi have proposed two closely related ideas about the nature of science that need describing here. Stent's proposal is that in any area of science, an extraordinary new idea must have some logical way of connecting to the body of facts and explanations commonly accepted by the discipline involved. If the leap is large enough that it is very difficult to link the old and the new by small logical steps, the new ideas will be "premature" and likely to be rejected. In the same vein, Polanyi proposed that a major characteristic of the sciences is the idea that there is a "standard" body of knowledge and explanations against which all new concepts must be weighed. The burden of evidence, in the views of both Stent and Polanyi, is placed very heavily on the new ideas. If true, this very conservative approach significantly delayed the acceptance of a major synthetic theory. Is this conservative approach good, bad, or neither? What would Asimov's Corollary have to say about it?
- Progress in science
"Science is a self-correcting discipline." Based on the whole semester so far (not just Wegener), what do you think of that oft-repeated phrase? Is it accurate? Are the sciences alone in being "self-correcting?" How about religion? How about all those other areas of inquiry wherein humans try to understand and describe their world? If you think that we are trying to make you start on the big bonus question, you are correct.
Unit II, Part 5 |
Unit II, Part 6 |
Unit II, Part 7 |
Unit II, Part 8 |
Unit II, Part 9 |
Unit II, Part 10 |
Unit II, Exam
© copyright 2001, Michael Wirth and Sachiko Howard, New England College