Rabbi Gershom

In at least one thread, I’ve seen Rabbi Gershom mentioned as the individual who outlawed polygamy for one segment of the Jewish population. How did he get the authority to change the marriage laws?

Rabbi Gershom ben Judah founded a Talmudic academy at Mainz, which got recognized as preeminent in the Ashkanazi world. Rabbi Gershom issued four major Takanot…that a man can only have one wife, a man can’t divorce his wife without her consent, that it’s sinful to open someone else’s mail, and that it’s forbidden to remind a Jew who was forced to convert to Christianity that he was forced to convert.

A Takanah (singular of Takanot) is a Rabbinic law, touching on something not directly addressed in the Torah, kind of similar to an Islamic fatah, and it’s binding on those individuals and communities that accept it. In Rabbi Gershom’s case, because he was so respected, the entire Ashkanazic world accepted his takanot, and so they’ve become binding law.

I’m not familiar with the case, but we can assume he didn’t change the laws - he published a very well-respected ruling that re-interperted the laws. That’s how Rabbinical Judaism works.

Thanks, both Captain Amaizing and Alessan. So, in other words, he didn’t change anything but merely issued a more restrictive interpretation of law than that which was accepted to that point.