Rabbeinu Tam - Halakhic Disputes

Halakhic Disputes

Legend has it that when Rashi was holding his infant grandson, the baby touched the tefillin that were on Rashi's head. Rashi predicted that this grandson would later disagree with him about the order of the scripts that are put in the head tefillin. Regardless of the episode's veracity, Rabbeinu Tam did disagree with the opinion of his antecedent. Today, both "Rashi tefillin" and "Rabbeinu Tam tefillin" are produced: the Shulchan Aruch requires wearing Rashi's version and recommends that God-fearing Jews wear both in order to satisfy both halakhic opinions. However:

"It is worth noting that the Shulchan Aruch ... rules that Rabbeinu Tam Tefillin should be worn only by one who is known to be a very pious person; the Mishnah Berurah ... explains that it is a sign of haughtiness for anyone else to do this because the accepted practice is to wear Rashi Tefillin."

However, many Sephardim and chasidic Jews wear Rabbeinu Tam's Tefillin (in addition to wearing Rashi's) per opinions presented in the Shulchan Aruch and its extensive commentaries authored throughout the early-modern and modern era. The rise and articulation of chasidic philosophy has conflated the kabbalistic and halakhic aspects of Rabbeinu Tam's position, popularizing the custom to wear both pairs every day. Wearing Rabbeinu Tam tefillin is an almost universal custom among the many and diverse communities that follow the teachings of the Baal Shem Tov and his students.

Another halakhic disagreement between Rabbeinu Tam and Rashi concerns the placement of the mezuzah. Rashi rules that it should be mounted on the doorpost in a vertical position; Rabbeinu Tam holds that it should be mounted horizontally. To satisfy both opinions, Ashkenazi Jews place the mezuzah on the door in a slanted position/ Sephardi Jews mount the mezuzah vertically, per the opinions of Rashi, Maimonides, and the Shulchan Aruch.