Saving the phenomena was a central motivation for mathematical astronomy during the ancient and medieval era. It was assessed by Pierre Duhem who based the report on the findings of Simplicius who had attributed his work to Plato, of the fourth century B.C.E. Duhem claimed that Ptolemy had the intention of saving the phenomena. The Ptolemy’s Almagest was composed in 150 A.D. History regards the text as the oldest in the field of astronomy. The parameters used to derive this piece were geometrical techniques though they lacked a trace of the Almagest of the Babylonian schemes, which were used to compute the positions of the planets (Goldstein, 2).
Ptolemy based his presentation of the models to tables, which did not go handy with the Babylonians arithmetic schemes. He based all his arguments on dated observations conducted by his predecessors. Goldstein, however, criticized Duhem’s assessment by arguing that the Ptolemy’s claims that the observations were made over a long time was simply a claim based on probably few and isolated observers. Also, the Babylonian tablets did not display any interest in preserving schemes as they were in the form of procedural texts or tables. There was also no prove that the Romans and the Greek understood how the schemes related to each other and when they were to be applied.
Ptolemy, as Duhem described, discussed how to use mathematical astronomy to consider the length of the seasons, the time of the equinoxes and solstices, the position of the lunar parallax and moon, the elongation of the sun to the outer planets among other things. Goldstein, however, believed that it was impossible to determine the distance from the sun to the outer planets. Goldstein also views Ptolemy’s argument, that the shells that make up the planets are conjoined in such a way that the outer surface coincides with the inner surface of the nest planet as plausible since “it is not conceivable that there be in nature a vacuum or any meaningless and useless thing” (8).
In conclusion, the findings of Ptolemy as assessed by Duhem are full of assumptions. He assumes that the sun and the moon are planets and that the size of his models did not matter regarding the predictive directions. In contemporary science, this is not applicable since the sun and moon are not planets and the sizes of the models do matter in predicting the direction and in determining the mean motion. The reader would, therefore, be convinced with Goldstein’s critic on Duhem’s assessment, that most of his findings were pure assumptions that had no basis. It is, however, important to accredit Ptolemy for he invented the theory on which astronomy mathematics was built to what is used today.
Works Cited
Goldstein, Bernard R. Saving the Phenomena: The Background to Ptolemy's Planetary Theory. Pittsburgh, PA: University of Pittsburgh, 1997. Print.
