Science and the Talmud

The Talmudic approach to the sciences, from astronomy to botany.

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The rabbis of the Talmud molded Jewish law and practice, but they also took note of scientific ideas and the world around them. They made observations, tested their hypotheses, and classified their results. This was, in large part, because it helped them know how to perform the mitzvot most accurately. In order to apply the mitzvot of the Torah to the world--the chief project of the Talmud--the rabbis had to know the world.

A survey of the Talmud turns up frequent discussions of botany, anatomy, biology, zoology, astronomy, medicine, magic, astrology (which would have been regarded as "science"), and even rudimentary chemistry. Although they were not engaged in sophisticated scientific calculations, the rabbis demonstrated a remarkable awareness of various branches of scientific study.

Religion and science are often seen as being in conflict. In general, the former makes claims based on faith; the latter on reason and method. But because the religion of the Talmud is concerned with practice more than dogma, this dichotomy is rarely addressed.

Driven by practicality and their own curiosity, there were times that the rabbis did what would be called science for its own sake, as a means to understand the way the world operated. This may have helped them do mitzvot more accurately, but that was not always their chief concern.


One of the most important endeavors for the rabbis in talmudic times was setting the calendar and the holidays. This depended on a significant understanding of astronomy, and many of the talmudic sages became experts in this field. Using observations of the new moon, Samuel bar Abba was able to calculate and determine the calendar and the dates of holidays many years in advance, and even accounted for leap years (Rosh Hashana 20b).


Judaism is often described as an embodied religion--the practices depend on the physical performance of the commandments. The rabbis tried to become intimately aware of the ways that the body works, in order to more fully understand how to observe the commandments.

Many commandments assume a properly functioning and classifiable body, and so the rabbis also had to account for human anomalies--blindness, deafness, muteness, late development, and double or no sex-organs. For example, they considered whether a deaf person could blow the shofar for a hearing person to discharge their obligation on Rosh Hashanah (Rosh Hashanah 29a).

The rabbis' extensive concern with purity led them to carefully study labor, menstruation, miscarriage, and male procreative functions. This familiarity allowed the rabbis to fit people into categories and determine which obligations applied to which types of people. The rabbis thus concluded the ways in which an intersex person was similar and dissimilar to a man. Could an intersex person marry? Were they obligated to fulfill the commandments? Were their mothers in a state of impurity after their birth as they are with a boy or with a girl? (Mishna Bikkurim 4:1-2).

The commandment of pikuah nefesh (saving a life), is taken very seriously, and the science of medicine permeates the pages of the Talmud. Yevamot 64b prohibits circumcising a child with hemophilia, for example. Medicine was also practiced in order to return "quality of life," as when the rabbis describe the performance of cranial surgery on an affliction called Ra'atan (Ketubot 77b), which  prevented a man from fulfilling his marital duties.

Still, it would be an overstatement to suggest that the rabbis' anatomical curiosity was only related to performing the commandments. The Talmud reports that the students of Rabbi Yishmael dissected a deceased prostitute, causing them to reconsider the belief that the body had 248 joints and limbs (Bekhorot 45a). In another similar incident Rabbi Haviva and Ravina dissected an ewe to decide whether it was suffering from a hip disease or a severed spinal chord (Hullin 51a). What is remarkable about these instances is that they seem to have been undertaken independent of any desire to perform the mitzvot more accurately.

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Rabbi Micah Kelber

Micah Kelber received his rabbinical ordination from the Jewish Theological Seminary in 2004 and his Masters of Education from The William Davidson School at JTS in 2005. He served for three years as the rabbi at the Bay Ridge Jewish Center and is now building his freelance writing and freelance rabbi practice in Park Slope, Brooklyn.