The Philosophical Justification for the Equant in Ptolemy’s Almagest

@article{Zainaldin2017ThePJ,
  title={The Philosophical Justification for the Equant in Ptolemy’s Almagest},
  author={James Lockwood Zainaldin},
  journal={Phronesis},
  year={2017},
  volume={62},
  pages={417-442}
}
In this paper I offer a close reading of Ptolemy’s philosophical defense of the equant in Almagest 9.2. I identify the challenge to the equant that his defense is supposed to meet, characterizing it as a dispute concerning the origin and authority of the astronomer’s first principles (ἀρχαί). I argue that the equant could be taken to violate a principle fundamental to the Almagest’s astronomical project, namely, that the heavenly bodies move only in uniform circular motions. I show that Ptolemy… 

References

SHOWING 1-10 OF 23 REFERENCES

The Empirical Foundations of Ptolemy's Planetary Theory

In beginning his consideration of the theory of the planets in Almagest 9.2, Ptolemy states that, just as he has already done for the Sun and Moon, he wishes now to show that the apparent, irregular

AL-SHĪRĀZĪ AND THE EMPIRICAL ORIGIN OF PTOLEMY'S EQUANT IN HIS MODEL OF THE SUPERIOR PLANETS

Abstract Ptolemy presents only one argument for the eccentricity in his models of the superior planets, while each one of them has two eccentricities: one for center of the uniform motion, the other

The Demarcation of Physical Theory and Astronomy by Geminus and Ptolemy

The Hellenistic reception of Babylonian horoscopic astrology gave rise to the question of what the planets really do and whether astrology is a science. This question in turn became one of defining

Plato and Eudoxus on the Planetary Motions

According to an ancient tradition, it was Plato who posed to Eudoxus and the other mathematicians the project of devising hypotheses of uniform circular motion for "saving the phenomena" of planetary

Simplicius and the Early History of Greek Planetary Theory

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

On the function and the probable origin of Ptolemy's equant

We examine the roles of the equant point and the eccentric deferent circle in Ptolemy’s planetary theory. The necessity of these features of the model is demonstrated empirically by a study of the

PHYSICS AND ASTRONOMY: ARISTOTLE'S PHYSICS II.2.193b22–194a12

In the first part of chapter 2 of book II of the Physics Aristotle addresses the issue of the difference between mathematics and physics. In the course of his discussion he says some things about

A Re-examination of Aristotle's Philosophy of Science

There have recently appeared some studies in which Aristotle's views on science are related to modern philosophical issues and distinctions, some articles in which a return to at least some of his

Mathematical method and philosophical truth

PLATO'S ACADEMY AND THE SCIENCES At some time between the early 380s and the middle 360s Plato founded what came to be known as the Academy. Our information about the early Academy is very scant. We

Remarks on Physics and Mathematical Astronomy and Optics in Epicurus, Sextus Empiricus, and Some Stoics

In Plato's Republic (VII 528e-30c) astronomy (αστρονομία) is included as one of the five mathematical disciplines (μαθήματα) to be studied by potential philosopher-kings. In Physics II 2 Aristotle