Feke, Jacqueline. Ptolemy’s Philosophy: Mathematics as a Way of Life

Abstract

Jacqueline Feke's book presents the results of her efforts to elucidate Claudius Ptolemy's philosophical system. That Ptolemy conceived his mathematical studies as forming part of a broader investigation is especially clear in the elaborate preface of the Almagest, in which he defends the thesis that mathematics is the only non-conjectural part of philosophy. For Ptolemy, only with mathematics can we advance in physics and theology, the two other branches of theoretical philosophy in the classification of knowledge that he proposes; and, furthermore, only mathematics helps us approach the divine. Thus, even if at the beginning of this preface he posits that ethics is independent of theoretical philosophy, Ptolemy ends up making it dependent upon it. As Feke notes [78], this is typical of several philosophical passages in Ptolemy's works, in which his writing takes the form of a serious, ongoing philosophical investigation, as in his discussion of the constitution of body and soul in On the Criterion and the Commanding Faculty. We would perhaps expect that short philosophical excursions by a mathematician adopt a more expositional, handbook tone; but they turn out to be original and valuable records that are worth studying for his thinking process, the vivid style of which (I dare propose) demonstrates Ptolemy's admiration for Plato's dialogues and of Aristotle's treatises. 1