the brachos before donning tefillin

My son's bar mitzvah is in a few months and we have begun thinking about tefillin, which is a good excuse for some review of the halachos. The gemara (menachos 36) writes that the bracha on tefillin shel yad is l'haniach tefillin; the bracha on tefillin shel rosh is al mitzvas tefillin. The gemara continues: if one speaks between the tefillin shel yad and tefillin shel rosh one must recite two brachos, otherwise one only recites a single bracha. Taken alone, the implication of the first statement is that there is a single bracha recited on tefillin shel yad and a single bracha on tefillin shel rosh. However, the implication of the second statement is that in reality one bracha suffices for both unless an interruption occurs.

Given the gemara’s ambiguity, it is not surprising that this issue is debated in the rishonim. Rashi holds that under normal circumstances only one bracha need be recited on tefillin. If an interruption occurs between donning the tefillin shel yad and shel rosh, only then is a bracha of al mitzvas tefillin added before the shel rosh in addition to the l'haniach bracha already recited. Rabeinu Tam, however, holds that both brachos of l’haniach and al mitzvas are always recited – l’haniach before the tefillin shel yad, al mitzvas before the tefillin shel rosh. If one has an interruption between the shel yad and shel rosh, both brachos together must be recited before donning the shel rosh.

It seems clear from the position of Rabeinu Tam that the bracha of l’haniach applies to the shel rosh, and therefore there must ideally be no interruption between donning the tefillin shel yad and shel rosh. Somewhat less clear is whether the bracha of al mitzvas retroactively applies to the tefillin shel yad. If one has only tefillin shel yad and not shel rosh (the mitzvos are not dependent upon each other and in cases of need one can be fulfilled without the other), according to Rabeinu Tam would one recite just a bracha of l’haniach, or both brachos? Tosfos in Brachos writes that the bracha of l’haniach is on the beginning of the mitzvah; the bracha of al mitzvas is on the gmar hamitzvah, the conclusion of the act – the implication is that both brachos are needed as one unit. Halacha l’ma’aseh only one bracha is recited in this case, but that is out of deference to Rashi's opinion that only one bracha is normally ever recited.

Though these opinions sound mutually exclusive (either one says one bracha like Rashi or two like Rabeinu Ram), R’ Akiva Eiger offers a suggestion by which both opinions can be fulfilled - one can don tefillin shel yad and recite the bracha of l’haniach with the intent that if the halacha is in accordance with Rashi one does not wish to be yotzei saying the bracha on tefillin shel rosh yet. This in effect artificially creates an interruption, in which case even Rashi agrees that a bracha is needed on the shel rosh. This is not a bracha sh’aina tzericha because one is forced into this situation to avoid a safeik bracha. The Biur Halacha notes R’ Akiva Eiger’s opinion but writes that others disagree, perhaps because this innovation runs contrary to minhag yisrael.

The minhag recorded by the Rama is to recite two brachos, but to add “baruch shem kvod malchuso” after the bracha of al mitzvas, as if one recited an unnecessary bracha. The Aruch haShulchan poses the obvious question: if we rely on Rabeinu Tam, then we have every justification to recite the bracha and do not need to add “baruch shem”; if there is a doubt, then based on the rule of safeik brachos l’hakeil no bracha at all should be recited. What is this strange compromise the Rama suggests of reciting a bracha, but adding baruch shem?
Bli neder, to be continued...