When Albert Einstein proposed his Theory of Relativity it was not accepted immediately but eventually over time and after some debate it became a replacement for the idea of physical mechanics formulated by Isaac Newton to explain the motion of large bodies in the presence of gravity. Relativity did not totally discredit Newtonian Mechanics but it did raise new questions and could prove certain things that Newton could not. There were questions, critics, and proponents of the new idea but it came in time and after much debate. Shifting from one theory to another after the original idea has existed and been accepted for so long never sits well with scientists. This same shift of ideas is true for Alfred Wegener and his theory of Pangaea and plate tectonics. Wegener?s theories gave a plausible explanation for the presence of the same species of fossils found on two different continents. His theory refuted the current theory of huge land bridges that connected the continents. This shift from one idea to another, according to Thomas Kuhn, is considered a paradigm shift. Kuhn said, a paradigm is term that relates closely to ?Normal Science?. Normal science being ?research firmly based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice? (Kuhn p.159). In the sense of scientific discoveries a paradigm is considered an example of a model formed by the theories presented by a scientist. Wegener?s theory of plate tectonics and continental drift is an example of a Kuhn paradigm shift because it took an original idea that was believed to be true and expanded on it to form a new theory and model that is still followed today.
The current theory on plate tectonics is the theory that Earth’s outer layer is made up of plates, which have moved throughout Earth’s history. The theory explains the how and why behind mountains, volcanoes, and earthquakes, as well as how, long ago, similar animals could have lived at the same time on what are now widely separated continents. Perhaps initiated by heat building up underneath the vast continent, Pangaea began to rift, or split apart, around 200 million years ago. Oceans filled the areas between these new sub-continents. The landmasses continued to move apart, riding on separate plates, until they reached the positions they currently occupy. One theory is that convection within the Earth’s mantle pushes the plates causing them to rift moving the continents and hitting other plates causing mountains to form and earthquakes to occur. Exploration of the ocean floor was the proof Wegener needed to prove his theory about plate tectonics and how it affected the movement of the continents.
The original theory for the presence of organisms on two separate continents was huge land bridges that connected one continent to the other. These bridges disappeared after huge amounts of ice melted and filled the ocean with more water. The land bridges sunk under the water and the higher elevated areas are what can be seen today. Wegener concluded that the land bridges were not the cause for organisms to be present on two continents separated by an ocean. He believed that the Earth and all its continents were one large land mass at one time and he called it Pangaea. He concluded that the continents were all connected and that explained how fossilized organisms are present in Africa and South America. He explained the position of the continents current location from Pangaea with his theory of continental drift. Continental drift theory says the continents moved and the moving plates under the Earth folding up and causing cracks in the Earth?s crust formed mountains. Wegener knew his ideas were more believable than land bridges but he could not find proof to make his theory believable. Wegener displayed his content for the scientists who did not want to accept his new theory in his book, The Origins of Continents and Oceans (4th edition) when he said:
“Scientists still do not appear to understand sufficiently that all earth sciences must contribute evidence toward unveiling the state of our planet in earlier times, and that the truth of the matter can only be reached by combing all this evidence. . . It is only by combing the information furnished by all the earth sciences that we can hope to determine ‘truth’ here, that is to say, to find the picture that sets out all the known facts in the best arrangement and that therefore has the highest degree of probability. Further, we have to be prepared always for the possibility that each new discovery, no matter what science furnishes it, may modify the conclusions we draw.”
Thomas Kuhn presents a theory about the formation of a paradigm and how there can be a shift from one paradigm to another with the emergence of a new theory. Kuhn says that science revolves around a paradigm that is formed by the ideas and theories of a scientist. Kuhn?s idea of a paradigm is like a circle whose center is the question and perimeter are the answers. When a theory is proposed and accepted the circle is complete and all other questions and answers form around the circle. A shift occurs when an answer does not seem correct or when a question exists that cannot be answered and a new circle forms around it. There is an overlap of circles but the new focus is centered on the new idea. When this new idea can be answered and more information is gathered in explaining it better than the previous circle the paradigms shifts and the new theory is accepted. The new paradigm is not accepted right away. It is argued and accepted by many people especially when it replaces something that was believed to be the standard for so long. In the case of Wegener and his theory of plate tectonics and continental drift replacing the land bridge theory; Wegener used theories from the land bridge to come up with his own theory that accounted for the continents and went further to explain formation of mountains, volcanoes and earthquakes. This paradigms shift does not prove or disprove anything because what it is explaining is only a theory. The shift is only a shift in the belief of the theory held within a paradigm. Because of ocean exploration can Wegener?s theory be accepted more enthusiastically over the land bridge theory. There is nobody alive today to prove either theory thus the land bridge theory and the plate tectonic theory are both valid. One theory just expands and explains more than the other and can be more believable.
After careful consideration of both theories and the explanation of Kuhn?s notion of a paradigm shift I believe that Wegener?s theory of plate tectonics from the land bridge theory was a paradigm shift. The land bridge theory explained the presence of fossils on different continents with the knowledge of the time; there was no overhead picture of how South America looked when fit next to Africa. Wegener saw mountains, knew what the continents looked like from above, and felt earthquakes to know that there could possibly be something more the Earth. Since he could not prove the tectonic theory without going underwater he fell short but after some underwater discoveries it was found he was right. Because of new information and technology a theory can be discredited and a new one can replace it causing a paradigm shift in thought. It is up to the individual to accept or refute the specific paradigm but everyone must know that there is more than one explanation for things that occur in nature. Alfred Wegener theory of plate tectonics clearly represents Thomas Kuhn?s idea of paradigm shift of a theory.