Why do we wear Rabbeinu Tam Tefillin if the halacha follows Rashi?

Tefillin contain four parshiyos, and the Gemara’s description of their required order is open to various interpretations. Rashi explains they must be written according to their order in the Torah, while Rabbeinu Tam holds that the two ‘vehaya’s are in the middle.¹

Although the views are known as those of Rashi and his grandson, Rabbeinu Tam, the disagreement dates back much earlier. In most areas of halacha, one view is followed exclusively, but the order of the tefillin parshiyos remained an ongoing debate. The Shaalos Uteshuvos Min Hashamayim writes that both are “divrei Elokim Chayim,” and it is disagreed upon above — between Hashem and the Beis Din shel Maalah — just as it is below.²

The Arizal revealed that from the days of Moshe Rabbeinu through the period of the geonim, people would wear both types, even simultaneously. Each pair draws down a different spiritual light, and one should therefore wear both.³

Shulchan Aruch rules that the general practice follows Rashi, yet a yerei shamayim should put on both, either simultaneously or one after the other. Yet only an especially pious person may do so in public, as for others, it is perceived as arrogance.⁴ The Alter Rebbe writes in his Siddur that whoever feels any Yiras Shamayim in his heart should put on Rabbeinu Tam tefillin after davening, and if he is concerned about haughtiness, he could don them privately at home.⁵

Considering the extra purity required for putting on an additional pair of tefillin, the accepted practice in Chabad was to wait at least until age 18, or marriage, and only begin with the Rebbe’s approval, often with certain stipulations (e.g., mikveh, chassidus).⁶

However, on Purim 5736, the Rebbe announced that the time had come for everyone to start putting on Rabbeinu Tam at bar mitzva,⁷ and in 5749, the Rebbe extended the directive to begin already from hanachas tefillin.⁸ The Rebbe explained that this is necessary as we come closer to Moshiach, and to combat the ever-increasing darkness of golus.⁹

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