ABSTRACTThere has been much debate surrounding the way in which Ptolemy handled the observations that are behind his planetary models. This article aims at presenting an interesting case of manipulation of observational data within the epistemological frame of what we may call Ptolemy’s philosophy of knowledge. It deals with an interesting case from the Almagest, that of the determination of the longitudes of the apogee and perigee of Venus’s deferent, and shows that the selections and adjustments Ptolemy carried out in (...) order to obtain the needed results are nothing but an analogous application of the epistemological doctrines expressed in his On the Kriterion and in his Harmonics. (shrink)

: In earlier work, Bernard R. Goldstein and the present author have introduced a procedural rule for historical inquiry, which requires that one take pains to establish the credibility of any citation of ancient thought by later writers in antiquity through a process of verification. In this paper, I shall apply what I call the Rule of Ancient Citations to Simplicius' interpretation of Aristotle's remarks in Meta L. 8, which is the primary point of departure for the modern understanding of (...) Greek planetary theory. I first sketch several lines of argument that lead me to conclude that Simplicius' interpretation should not be accepted because it assumes a concern with planetary phenomena unknown to the Greeks before the late 2nd and early 1st centuries BC. Then, after showing that there is a fairly well defined range of readings of Aristotle's remarks more in keeping with what we actually know of astronomy in the 5th and 4th centuries BC, I conclude that neither Aristotle's report about the Eudoxan and Callippan accounts of the celestial motions nor Simplicius' interpretation of this report is a good starting point for our understanding of early Greek planetary theory. (shrink)