Nicole Oresme analyzed the apparent diurnal motion of the heavens in his Livre du ciel et du monde. His considered the current arguments for the earth remaining still and logically refuted them, showing that there was no philosophical reason to believe that the earth was still or that it rotated diurnally. Nevertheless, he concluded that the earth was motionless, based on Scripture, and indicated that this work was simply an exercise showing the inconsequence of philosophical studies of such matters.
Nicole Oresme was one of the preeminent thinkers of the 14 th century. He lived from about 1320 to 1382. He was of Norman extraction, born in Allemagne, Normandy, and lived most of his life in Rouen or Paris. He studied the arts and theology at the University of Paris, receiving his master of theology degree in 1355. By 1360 he had published a number of Latin treatises, and had already become a noted scholar. In 1359 he became secretary du roi to the dauphine, Charles V, and remained an advisor and friend of Charles throughout his reign. Oresme had a number of scholastic and ecclesiastical positions, including grand master of the College of Navarre in the University of Paris, and dean of the Cathedral of Rouen. Charles asked him to translate a number of Aristotle’s works and had him write several works in French (Taschow). One of these was the work here considered, his Livre du ciel et du monde, or Book of the Heavens and the Earth. Nicole Oresme contributed innovative ideas and excellent work to nearly every discipline studied at the time.
The section of Livre du ciel et du monde that is here considered is from Book II, Chapter 25. The section discusses whether the apparent diurnal motion of the heavens is due to the earth spinning on its axis, or the heavens moving around a stationary earth. Oresme provides an excellent analysis of this problem.
His paper begins with the problem: “And some say the earth is at the center of the universe and revolves and moves circularly about the pole established for this” (Oresme). He notes that Heraclides of Pontus supported this view, and that it was written in Plato’s Timaeus. Oresme adopts an analytical approach to the problem, stating that he will first show that one could not demonstrate the contrary by experience, that one cannot prove contrary by reason, and finally will present arguments in favor of this diurnal rotation.
Oresme first presents the arguments commonly exhibited in favor of the earth remaining stationary. The first argument proceeds thus: we see with our senses the heavenly bodies rising and setting daily; the obvious conclusion is that they do rise and set daily, moving around the earth. The next argument is that if the earth is rotating daily, the objects on the ground are moving very quickly to the east, and the air and wind should blow continuously from the east, which is not the case. Finally, Ptolemy gives the following experiment: if one is on a ship moving rapidly and fires an arrow upward, it should fall well behind the ship. Likewise, if the earth is rotating rapidly, a stone thrown directly upward should fall well to the west. But that is not the case in reality.
Oresme next proceeds to logically dismantle the three arguments against the earth rotating. He first differentiates between relative motion and actual motion, noting that our senses perceive only relative motion. We cannot tell the difference between our ship staying still and another moving and our ship moving and the other staying still. Thus we cannot tell whether the heavens are moving or the earth is moving. Next, he notes that the air in an enclosed ship that is moving does not move; the air moves along with the ship, but to the observer inside the ship, the air does not appear to move. Finally, he notes that to an observer on the ship a hand moved up and down simply appears to move in rectilinear motion, while in fact it does not, as the whole ship is moving as well. These arguments show that one can not prove the earth is standing still from experience.
Next, Oresme addresses proofs by reason, presenting the proofs first. One states that all astronomy would be false if there is no diurnal movement of the heavens. Another refers to scriptures that mention the sun rising, going down, or otherwise moving; those state that these would be in error if the earth were to be rotating instead of the heavens, and this cannot be the case.
Oresme refutes the first argument by stating that the astronomy is still completely correct, from our view, whether it is the earth spinning or the heavens rotating that contributes the diurnal motion. To the latter argument, he notes that the Bible is written from the point of view of man, whether or not that view is what happens in actuality. As an example, he cites the place where the scriptures say “Who covereth the heavens with clouds” (Psalm 146:8) when actually the heavens are still above the clouds, covering them. It just looks like the clouds cover the heavens from our point of view. Thus, the writings that mention the sun rising and setting do not preclude the possibility that that is not what happens in actuality.
Finally, Oresme puts forward reasons for believing the earth is moving. The primary argument is for the economy of motion: it is much less motion for earth to rotate than for the whole of the heavens to hurtle around the earth daily. Indeed, due to their vast circumference, the speed at which they would have to travel would be excessive.
After concluding this section, showing that there is no philosophical reason to believe either case is true, he states that he still believes the earth is stationary, based on a single scripture: “God created the orb of the earth, which will not be moved” (Ps. 92:1). This scripture decides the question for him, based on the inerrancy of the Bible. He then states that he has philosophically shown that it is reasonable to believe that the earth rotates, but that this seems more against common sense than much of the Christian faith. Therefore, this argument can be used to counter those that would attack the Christian faith through philosophical reasoning; this example shows the unreliability of reason.
Oresme discusses all of the different reasons for believing the earth is stationary, based on both philosophy and religion. He refutes all philosophical arguments and all but one of the scriptural ones. However, because of that scripture, Oresme concludes that the earth is stationary. This indicates Nicole Oresme’s view: scripture is the absolute authority. As a theologian, this view is to be expected. Indeed, even if he had considered that this scripture also could be explained away, there is no explicit reason to believe the earth rotates, and it would have been expedient to agree with the views of the establishment, especially those of the Catholic Church. Oresme was willing to explore this argument to the point where there was no longer any support for the Bible from the philosophical argument. Nevertheless, his unwavering belief in the accuracy of the Bible in the end decided the question.
Nicole Oresme was an excellent example of a late medieval scholar, willing to look into topics hitherto considered decided. His analysis of the diurnal motion of the heavens is a work constructed on superb logic and concluding based upon solid considerations. His use of theological arguments in addition to philosophical ones is natural for a scholar of that time and does not diminish the skill he shows in this argument. Indeed, it should increase our respect for the conclusion, for theological concerns should be weighed in addition to philosophical ones.
References
Lindberg, David C. The Beginnings of Western Science: The European Scientific Tradition in Philosophical, Religions, and Institutional Context, 600 B.C. to A.D. 1450. Chicago: University of Chicago Press, 1992.
O’Connor, J. J., and E. F. Robertson. “Nicole d’Oresme.” MacTutor History of Mathematics Archive. Accessed October 18, 2005 < http://www-groups.dcs.st-and.ac.uk/%7Ehistory/Mathematicians/Oresme.html>
Oresme, Nicole. “Book II Chapter 25.” Livre du ciel et du monde. Quoted in History of Science Study Guide, by Dr. Robert Hatch. Accessed October 18, 2005 < http://web.clas.ufl.edu/users/rhatch/pages/02-TeachingResources/HIS-SCI-STUDY-GUIDE/0040_nicoleOresme.html>
Taschow, Ulrich. “Biography of Nicole Oresme.” Nicole Oresme and the Spring of Modern Age. Accessed October 18, 2005 <http://www.nicole-oresme.com/seiten/oresme-biography.html>