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Calendars in Antiquity and the Middle Ages


ERC Research Project


The Jewish calendar dispute

The Jewish calendar dispute of 921-2 CE

In 921/2 CE, a major dispute erupted between the Jews of Palestine and Iraq about how the calendar should be calculated. This resulted in both communities, followed by other Jews in the Near East, observing the festivals of Passover and the New Year, in 922, on different dates. It has long been assumed that this was the last dispute of this kind within rabbinic Judaism, and that the triumph of the Iraqi side led to the finalization of the rabbinic Jewish calendar; but this present project will challenge this consensus.

Bornstein, haMahloqet front page

The dispute of 921/2 vanished from historical memory after the 11th century, until a trove of letters and memoranda by the main protagonists of the dispute was re-discovered in the late 19th century in the Cairo Genizah. These documents, in Hebrew and Judeo-Arabic, also provided the earliest evidence we have of the Iraqi calendar computation, which has become the present-day rabbinic calendar. The texts were nearly all published around the turn of the 20th century, and brought together in a monograph of H. Y. Bornstein (1904), although further documents were subsequently published in that and the next decade. These early editions, however, were rushed and very faulty; pages were often pieced together in disorder, leading to a faulty reconstruction of the original works. Very few scholars examined at the time, or have examined since, the original manuscripts; and no one has investigated the history of the transmission of the texts.

Our researcher in this area is Prof. Sacha Stern, in collaboration with Prof. Marina Rustow (Johns Hopkins University).

Our aim is to produce a revised edition and analysis of all the documents. This will open the way for a revised interpretation of the texts and their significance, and to a completely new understanding of the dispute, its aftermath, and its impact in the following century. The study of this dispute and its resolution will shed important light, more generally, on the social and cultural processes that brought about the standardization and fixation of the Jewish calendar in the medieval world.

Besides the editorial work, our research questions are:

· How much importance was attached by Palestinians and Iraqis to their disagreement about the dates of the festivals, and why? To what extent was their goal to institute a standard calendar, rather than just to prevail in this particular dispute?

· How did the dispute come to an end? Did one of the sides prevail, or did they just lose interest in arguing? Did a standard calendar emerge, in fact, from this dispute?

· How did both sides attempt to extend their authority over other Jewish communities in the region?

· What impact did the dispute have on later generations? What large-scale and long-term effect did it have on the standardization of the Jewish calendar?