Disambiguations of Rishonim
Often times, two contradictory statements of a Rishon will baffle the Poskim, and all it takes is a little history to know that there were actually two or more people with the same name, each of which said one of the contradictory statements.
It's important to be aware that there are three individuals known as the Ra'avad:
"ריב"א" can stand for a couple of different names, or even two people of the same name, as such, it's beneficial to specify who is who.
- R' Yitzchak HaLevi Bar Asher, probably one of Rashi's teachers.
- R' Yitzchak Bar Asher, a student of Rashi who was named after the former and was one of the Baalei HaTosafot, also known as Riva.
- R' Yitzchak Bar Avraham of Shantz, also known as Ritzba (ריצב"א), or Ri HaBachur, brother of the Rash MiShantz, and was killed Al Kiddush Hashem. Some say he's also the same person as the Ri HaLavan
- R' Yitzchak Bar Abba Mari, who wrote Sefer HaIttur.
There were at least four Rabbeinu Yonahs:
- R' Yonah Gerondi (HeChassid), whom we know as Rabbeinu Yonah, cousin of the Ramban, and Rebbe of the Rashba. His grandson, son of his daughter and the Ramban's son Shlomo, was named R' Yonah after him. He had grandson who was also named R' Yonah, whose daughter married the Rashbetz and was thereby the grandfather of the Rashbash.
- R' Yonah שניין, a cousin of the R' Yonah Gerondi, who overlapped in his lifetime.
- R' Yonah author of the Sefer Issur veHetter and Talmid of the Terumat HaDeshen. Printers and Poskim mistakenly labeled his Sefer as a product of R' Yonah Gerondi, but it's clearly impossible.
Of course, Rabbeinu Tam is well known as Rashi's grandson, R' Yaakov ben Meir, but some Rishonim do refer to R' Yaakov author of Shu"t Min HaShamayim as "Rabbeinu Tam," as well.
- There were two Ri Baalei HaTosafots, one of whom was the Ri, Rav Yitzchak Bar Shmuel HaZaken, nephew of Rabbeinu Tam through his sister. The other is the Ri HaLavan or Ri HaBachur mentioned above (see Riva).
R' Asher (Rosh)
"ריא"ז" can stand for a number of names:
There were a number of people named Rabbeinu Moshe ben Maimon throughout the generations, as it was a common name.
Rabbeinu Bechaye (Bachya)
- R' Bechaye ibn Pakuda was the author of the Chovot HaLevavot.
- R' Bechaye ben Asher was a student of the Rashba and author of the well known commentary on the Torah.
They both lived in Zaragoza, but the latter was born two centuries after the former.
There were two Rishonim known as the "Tashbetz"
- Yad Malachi (Klalei HaRif 20)
- Shem HaGedolim (Gedolim, Aleph 9-11). See Shach Choshen Mishpat 39:2
- Shem HaGedolim (Gedolim, Yud 291)
- See Shem HaGedolim (Gedolim, Yud 325) regarding the various teachers of Rashi and their similar names.
- Shem HaGedolim (Gedolim, Yud 368)
- Hagahot Menachem Tzion ad loc citing Shu"t Maharam Semachot 78 and Moredechai Moed Kattan 904. He also points out how it's questionable if this is the same Ri HaLavan, student of Rabbenu Tam, as
- Shu"t HaRashbash Siman 291
- Yad Malachi (Klalei Shear Mechabrim 14), Hagahat R' Tzvi Hirsch Berlin ad loc based on Beit Yosef Choshen Mishpat 388. See Shem HaGedolim, Gedolim, Yud 98)
- Pri Megadim (Orach Chaim Klalim 10, Yoreh Deah Klalim BeHoraat Issur veHetter 11), Shem HaGedolim (Gedolim, Mem 161), HaRav Hershel Schachter (Vayakhel-Pekudei 5778, Tetzaveh 5777), Rav Meir Mazuz (Ohr Torah Iyyar 5777 Siman 86)
- Yad Malachi (Klalei Shear Mechabrim 12), Shem HaGedolim (Gedolim, Bet 46). See Chaim She'al 1:69, Matnat Yado ad loc. and Moriah Kovetz 143 page 3
- Yad Malachi (Klalei Shear Mechabrim 13)
- Shem HaGedolim (Gedolim, Zayin 13)
- Shem HaGedolim (Yud 224)
- Yad Malachi (Klalei Shear Mechabrim 15), Shem HaGedolim (Gedolim, Yud 368). Note Haga Menachem Tzion ad loc. cites the Rama (Even HaEzer 61:3), who refers to the Ri as "Rivash."
- Yad Malachi (Klalei Shaar HaMechabrim 1), Matnat Yado fn. 1-2, Shem HaGedolim (Gedolim, Aleph 237). See Shach (Choshen Mishpat 107, Yoreh Deah 105:2) and Sdei Chemed Klalei HaPoskim 15:25
- Shem HaGedolim (Gedolim, Yud 304)
- Shem HaGedolim (Gedolim, Samech 5)
- Shem HaGedolim (Gedolim, Mem 150, 153). See YUTorah
- Shem HaGedolim (Gedolim, Mem 152)
- Shem HaGedolim (Gedolim, Mem 151; Sefarim, Heh 55)
- Shem HaGedolim (Gedolim, Nun 36)
- Shem HaGedolim (Gedolim, Bet 1)
- Shem HaGedolim (Gedolim, Bet 2)
- See the relevant Wikipedia articles.
- Shem HaGedlim (Gedolim, Shin 187; Sefarim, Taf 100)