It is well known that the Tractatus of Peter of Spain (later Pope John XXI) was one of the most popular logic textbooks in the Middle Ages and early Renaissance. Less known is the Tractatus's considerable reputation and diffusion among the Jews, as evidenced by five translations, two commentaries, and what appears to be an abbreviatio — if not of the Tractatus itself, then of a similar work. The present article attempts to understand the phenomenon of the Tractatus's popularity and offers an analysis of the three translations whose authors are known — those by Shemaryah ha-Ikriti (Greece, early to mid-fourteenth century), Abraham Abigdor (late fourteenth century), and Judah b. Samuel Shalom (either Italy or Spain, mid-fifteenth century) — and their subsequent fate. The more popular versions of Abraham Abidgor and Judah Shalom provided Jewish students, many of whom would likely become physicians, with a grounding in logic comparable to that of their Christian counterparts.

The major part of the mathematical “classics” in Hebrew were translated from Arabic between the second third of the thirteenth century and the first third of the fourteenth century, within the northern littoral of the western Mediterranean. This movement occurred after the original works by Abraham bar Hiyya and Abraham ibn Ezra became available to a wide readership. The translations were intended for a restricted audience — the scholarly readership involved in and dealing with the theoretical sciences. In some cases the translators themselves were professional scientists (e.g., Jacob ben Makhir); in other cases they were, so to speak, professional translators, dealing as well with philosophy, medicine, and other works in Arabic.

In aketshing this portrait of the beginning of Herbrew scholarly mathematics, my aim has been to contribute to a better understanding of mathematical activity as such among Jewish communities during this period.

It was commonly accepted in the middle ages that void within or outside the world is impossible. The paper presents a quite unusual conception of void, which is described in Yeda'aya ha-Penini's commentary on Ibn Rushd's epitome on Aristotle's Physics. According to this conception there is a thin layer of void between the water and the inner surface of the container. Ha-Penini describes two versions of this conception. According to one version this void layer is three-dimensional but thin, according to the other it is two-dimensional. The first part of the paper shows how ha-Penini “corrects” the text of Ibn Rushd, putting into it ideas which were unknown to Ibn Rushd. It is argued that, though the two views are rejected by Ibn Rushd, ha-Penini himself partly accepts (his version of) these views. The second part of the paper argues that ha-Penini could not have found these views in the Arabic-Hebrew tradition, and it seems that he relied on Christian sources. If this is indeed so, the paper presents an example of acquaintance of Hebrew scholars in southern France with Scholastic science in the first half of the fourteenth century.

Levi ben Gerson, also known as Gersonides or Leo de Balneolis, was one of the most original Jewish thinkers of the Middle Ages, and he wrote on logic, philosophy, biblical exegesis, mathematics, and astronomy. During the last years of his life he maintained relations with the papal court of Clement VI (1342–52) at Avignon, and collaborated in the translation into Latin of his Sefer Tekhuna (Book of Astronomy). The object of this paper is to establish the main stages of the redaction of the Hebrew and Latin extant versions of his astronomical work. Although Levi declares that the work was finished in 1328,1 argue that this text was the preliminary draft of the preserved one, most of which was composed after 1338. A thorough revision of the work was undertaken at an indeterminate date before 1344. It is also argued that the final form of the work was probably due to the request of solar and lunar tables made to Levi by “great and noble Christians” around 1332.

Yehuda Halevi's Kuzari was written in response to the challenge posed to Judaism by a highly spiritual, nondenominational philosophy. Science, especially that embodied in the Hellenistic heritage, was a major component of philosophy; thus, if for no other reason than to make Judaism a serious competitor, Halevi had to show that the Jewish tradition as well possessed a body of scientific knowledge. The superiority of the Jewish teachings was demonstrated chiefly by appeal to the criteria of tradition, consensus, and authority, which, in Halevi's judgement, were in practice the criteria most influential in deciding scientific opinion. Despite the rather unique setting for the book, and the wide range of stances Halevi develops, the Kuzari was rather quickly and smoothly absorbed into the mainstream of Jewish religious thought.