Senior Fellow: April–August 2021
Research Project: Cosmology, Probabilistic Astrology, and Rationality in the Thought of Rabbi Levi ben Gerson (1288–1344)
This project will focus on Rabbi Levi ben Gershom, or Gersonides (1288–1344), who is undoubtedly the medieval European Jewish scholar who can best qualify as a philosopher-scientist. To put it in a nutshell: notwithstanding his commitment to rationalism and Aristotelian natural philosophy in its Averroean formulation, Gersonides substantially drew on the astrological body of knowledge. This project will ask how Gersonides reconciled his thorough empiricism and rationalism with his explicit vindication of astrology and his reliance on it as a resource for trustworthy knowledge. The working hypothesis is that at least part of the answer is to be found in Gersonides’s original use of the notions of (statistical) probability and probable truth.
Gersonides repeatedly and approvingly corroborates his statements by referring to the observations of the “masters of judicial astrology” (ḥakhmei ha-mišpaṭ), thereby evincing that he regarded the information gathered via judicial astrology as trustworthy empirical evidence. How did Gersonides reconcile his endorsement of astrology with his commitment to rationality, empiricism, Aristotelian natural philosophy, and the religious postulate of free choice? I have begun to probe into Gersonides’s thinking on this issue and at present it seems that one theoretical tool used by Gersonides was the notion of (frequentist) probability, which in turn provides a basis for the idea of statements that are only probably, but not certainly, true.
Gad Freudenthal is a senior research fellow emeritus of the National Center for Scientific Research (CNRS) in Paris.