The Tiff Over Two Tefillin
By Rabbi Avrohom Sebrow • 12/8/2025
Many people wear two pairs of
tefillin — Rashi and Rabbeinu
Tam. The question arises
whether one may wear both pairs at the
same time. The Shulchan Aruch rules that
one may. However, this seems problematic:
doesn’t this constitute baal toseif, adding
to a mitzvah? Hashem commanded us
to wear one pair of tefillin; by wearing two,
isn’t one adding to the commandment?
This is unlike tzitzis, where any
four-cornered garment one wears is obligated
in tzitzis. A person could theoretically
wear fifty such garments, each
with tzitzis, without any concern of baal
toseif. Indeed, Rav Scheinberg, zt”l, wore
many garments with tzitzis. Married
men wear both a tallis katan and a tallis
gadol during Shacharis.
The Chofetz Chaim, in his Biur Halacha,
explains that there is no violation of
baal toseif when wearing both Rashi and
Rabbeinu Tam tefillin, because one of the
pairs is certainly invalid. The order of the
parshiyos is essential (me’akeiv). According
to Rabbeinu Tam, Rashi’s tefillin are
invalid, and according to Rashi, Rabbeinu
Tam’s tefillin are invalid. Therefore, one is
effectively wearing only one valid pair of
tefillin, not two.
Still, the Chofetz Chaim concedes that it
may appear as if one is transgressing baal
toseif. To address this, he explains that the
Shulchan Aruch’s advice is for the person to
stipulate: if Rabbeinu Tam’s tefillin are the
kosher ones, he only intends to fulfill the
mitzvah with those; and if Rashi’s are the
kosher ones, he only intends to fulfill the
mitzvah with those. Since he does not intend
to fulfill the mitzvah with both pairs,
it does not even fall under the rabbinic concern
of looking like baal toseif.
Interestingly, standard Rabbeinu Tam
tefillin are not fully Rabbeinu Tam at all.
There is more than one dispute between
Rashi and Rabbeinu Tam. The two pairs
of tefillin generally address only the order
of the parshiyos. However, there is another
dispute regarding the orientation of the
parshiyos: according to Rashi, they are
placed vertically, while according to Rabbeinu
Tam, they should be placed horizontally.
In practice, most Rabbeinu Tam tefillin
only change the order of the parshiyos
but keep them vertical. They are therefore
a hybrid of Rashi and Rabbeinu Tam. This
is one of the arguments advanced by those
who choose not to wear Rabbeinu Tam tefillin.
In fact, to truly account for all permutations
of opinions, one would theoretically
need to wear at least 64 pairs of tefillin.
This dispute extends to mezuzah as
well. Should a mezuzah be affixed vertically
(Rashi) or horizontally (Rabbeinu Tam)?
The common custom is to place it on an
angle, which is often said to compromise
between the t wo opinions. However, this
is not so simple. The Steipler Gaon maintained
that a 45-degree angle may not fulfill
either opinion — as if there is no mezuzah
at all. The Minchas Elazar disagreed and
argued that the mezuzah should indeed be
placed on a 45-degree angle to satisfy both
views. The Steipler maintained that since
the halacha follows Rashi, one should make
it primarily vertical, with only a slight tilt.
That way, Rashi is certainly fulfilled and
Rabbeinu Tam potentially as well.
Seemingly, the simplest solution would
be to install two mezuzos on each doorpost
— one vertical and one horizontal. Mezuzah
merchants would certainly welcome this!
Indeed, t he B irur H alacha s uggests t hat
this is comparable to wearing both Rashi
and Rabbeinu Tam tefillin, since one mezuzah
would certainly be invalid. However,
the Mezuzos Melachim argues that it is not
absolutely clear that Rashi would consider
a horizontal mezuzah invalid. As a result,
placing two mezuzos on one doorpost, one
vertical and one horizontal, may indeed
constitute baal toseif.
It is clear that placing two otherwise-
valid mezuzos on one doorpost definitely
poses a problem of baal toseif. But
what if one is unsure whether the existing
mezuzah is kosher — may he simply add
a second one? Rav Moshe Feinstein ruled
that he may not. The Minchas Elazar, however,
reportedly rented a bungalow that already
had a mezuzah and simply added a
second one. The Shut Betzeil HaChochmah
(4:165) explains that he knew that most, if
not all, of the mezuzos in that establishment
were invalid.
The Yad HaKetanah suggests a situation
where one might have no choice but
to affix t wo mezuzos on one doorpost. If
the doorpost is straight for ten tefachim
and then curves into an arch, the Rambam
maintains that the mezuzah must
be placed on the straight section, whereas
Rashi holds that even the arched section is
considered part of the doorpost. According
to Rashi, the mezuzah would be placed at
the bottom of the top third including the
arch; according to the Rambam, at the bottom
of the top third of the straight portion.
To fulfill both opinions, one would have no
choice but to affix two mezuzos. Still, this
isn’t one hundred percent clear because it is
possible that both mezuzos may be kosher
according to Rashi.
Generally, a mezuzah is placed on the
right side when entering a room. But what
if two rooms are connected and it is unclear
which direction is considered “entering”?
In such a case, one might argue that
a mezuzah should be placed on both doorposts.
Since only one is actually required,
the other would be meaningless. This is
the ruling of the Binyan Tzion. The Maharam
Schick, however, rules that even in
this situation, placing two mezuzos could
still constitute baal toseif.
The Pischei Teshuvah (286:11) cites the
Chamudei Daniel, who maintains that a
storage room within a larger house requires
a mezuzah even if it is smaller than sixteen
square a mos. A ccording t o t his v iew, a
walk-in closet or balcony would be obligated
in mezuzah regardless of size, since it is
considered a functional space.
Rebbi Akiva Eiger does not accept the
Chamudei Daniel’s ruling. However, he
suggests that a mezuzah may be required
on the doorway of a walk-in closet specifically
because that doorway is significant: it
leads into a larger room.
The practical difference between the
Chamudei Daniel and Rebbi Akiva Eiger
lies in which side of the doorway receives
the mezuzah. According to the Chamudei
Daniel, it would be placed on the right side
when entering the closet. According to Rebbi
Akiva Eiger, it would be placed on the
right side when entering the larger room
from the closet. Whether one could place
a mezuzah on both sides depends on the
earlier debate between the Binyan Tzion
and the Maharam Schick.
Rav Moshe’s opinion was that no mezuzah
should be installed in such a situation,
since the halacha does not follow
either the Chamudei Daniel or Rebbi Akiva
Eiger on this matter. The Chazon Ish,
however, disagreed.
Rabbi