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January 23, 2009
How Radical was Copernicus?
Many people think of Copernicus as a radical scientist who shocked the world by claiming that the sun was the center of the universe. Although Copernicus rejected some of the traditional beliefs of Aristotelian natural philosophy and Ptolemaic astronomy, he was still strongly rooted in these schools of thought and they were extremely important to his work. Copernicus rejected certain ideas of Ptolemaic astronomy in order to strengthen and improve the central principles, not to revolutionize them. Copernicus attempted to continue, preserve, and build upon the classical work of Ptolemy, not destroy it. Copernicus was in many ways more radical than many members of the academia, but he was not one of the true radicals of the Scientific Renaissance.
Just like all scholars of his time, Copernicus was taught and studied the classics.
The classics were mainly collections of the ancient writings of Greek philosophers, including Aristotle, who was one of the central classical thinkers and philosophers of the time. Aristotle and his followers created a way of thinking and studying based on observation, which was known as natural philosophy. This natural philosophy was not based on experimentation, and was more concerned with the "why" and not the "how" of things. That is to say that Aristotle was more interested that all of the planets rotated around earth because earth was the center of the universe, and did not care so much about the mechanisms which made the planets rotate.
One way in which Copernicus can be viewed as radical compared to the natural philosophers of the time was in his way of going about his studies. Aristotelian natural philosophers based their beliefs on observations and their knowledge of common truths. One of the common truths was that the earth was the center of the universe and everything orbited around the earth with uniform circular motion (Dear, Revolutionizing the Sciences, 19). Since many astronomers of the time used this form of study, no one thought to change the belief in geocentricism or uniform circular motion. However, Copernicus rejected this way of thinking and started to use a system more similar to our modern system of the scientific method. Copernicus states, "This certainly would never have happened to them if they had followed fixed principles; for if the hypotheses they assumed were not false, all that resulted there from would be verified indubitably" (Matthews, Scientific Background, 42). This clearly shows that Copernicus did not believe in the Aristotelian form of natural philosophy and that he attempted to create a planetary model based on truth, not ancient beliefs.
Another influential classical thinker was Ptolemy. Copernicus and all astronomers before him based their systems on Ptolemy's astronomy. Ptolemy laid down several sacred laws of astronomy consisting of uniform circular motion, uniform speed, and geocentricism. The most revolutionary of Copernicus' theories was that of a heliocentric planetary system, and not a geocentric system. This was viewed as a radical rejection of Ptolemaic thought because the geocentric system was one of the most important and basic beliefs held by astronomers of the time. However, in Copernicus' mind this was not a rejection of Ptolemy, but rather a way of preserving and building upon Ptolemy (Dear 35). By eliminating the geocentric system Copernicus was able to preserve Ptolemy's other laws of uniform circular motion and uniform speed. Copernicus believed that uniform circular motion was one of the basic laws of astronomy, and by moving the center of the universe to the sun he was able to increase the ability of predicting planetary motion (Dear 36). The accepted use of equants by other astronomers was already a step away from Ptolemy's geocentric system and, although Copernicus' heliocentric theory eliminated the use of equants, it was not really that radical to move on from equants to a heliocentric system. Copernicus' intention was to increase the accuracy of Ptolemy's model and to improve it, not to remake it (Dear 34).
Copernicus was not the only thinker who went against the established Aristotelian thought and challenged or rejected the work of predecessors; he was part of a large Scientific Renaissance. Others such as Vesalius or ViÃÂ¨te continued the work of ancient writers and built upon them as Copernicus did with Ptolemy (Dear 37-41), and Copernicus and other thinkers viewed his model as an "imitation of Ptolemy" not a rejection (Dear 35), thus showing that Copernicus was not truly radically different. Furthermore, the writings of Kepler and Galileo were far more radical than those of Copernicus. Kepler went so far as to completely throw out the entire idea of uniform circular motion and uniform speed, which Copernicus would never have dreamed of doing, due to the fact that Copernicus was attempting to preserve and improve those laws (Koestler, The Watershed: A Biography of Johannes Kepler, 122). In many ways Copernicus' ideas were reasonably tame, and therefore less radical, compared to those of Kepler and Galileo.
History remembers Copernicus as a radical who rejected many of the beliefs of his time and shocked the world by claiming that the sun, not the earth, was the center of the universe. Although Copernicus was more revolutionary than many members of the academia and rejected Aristotelian natural philosophy, he was not as radical as history remembers him. Copernicus attempted to improve the classical work of Ptolemy, not to destroy it. Also, as part of the larger Scientific Renaissance, Copernicus was not nearly as radical as other scientists such as Kepler or Galileo. Therefore, Copernicus should not be remembered as a radical, but rather as he was: a scientific thinker who continued, preserved, and built upon the work of the greats who came before him.
Arthur Koestler, The Watershed: A Biography of Johannes Kepler (1960), 122-159
Copernicus, excerpts from Commentariolus (1512) and preface of On the Revolutions of the Heavenly Spheres (1543) (Matthews, Scientific Background, 36-44)
Dear, Peter. Revolutionizing the Sciences. Princeton: Princeton University Press, 2001.