[Avodah] tefillin RT

[Eli Turkel]

RET

http://www.tzemachdovid.org/thepracticaltorah/bo.shtml

among those who agree with Rabbeinu Tam are
Rabbeinu Chananel, Rav Sherira Gaon,
Rav Hai Gaon,
 and the Rif;
the Rashba (Sheilos
V'Teshuvos HaRashba attributed to the Ramban Siman 234) cites Rav
Saadyah Gaon as concurring as well.

On the other side, the Rashba himself (Ibid.) concludes that Rashi 's
order is correct, adding that
Rabbeinu Yonah and the Ramban held that way too;
the Sefer HaChinuch
(Mitzvah 421) also accepts this position, ..."

This question is somewhat rhetorical

Given this how can we make a bracha on any given sheeta of Tefillin?

OR
IOW via what mechanics can we defitively settle this post-Tallmudic
dispute decisively enough to overcome "s'feiq brachos lehaqeil"?

KT
RRW