1) IS THE NAME OF A CITY AN ESSENTIAL PART OF A GET
OPINIONS: The Mishnah states that if the name of her city or his city was recorded incorrectly in the Get and the woman remarried on the basis of this Get, she must leave both her first and second husbands.
TOSFOS (DH Shinah) writes that the Mishnah does not mean literally that the name of a city was written incorrectly. Rather, the Mishnah refers to a case in which a city is known by two different names in two difference places. In such a case, the principal name of the place or person must be written in the Get, and one must mention that there is an additional, secondary name.
What is the Halachah when the name of the city of residence of the husband or wife is entirely omitted from the Get? Is the Get invalid?
(a) Many Rishonim rule that the name of the cities of the husband and wife are essential components of the Get. If mention of either city is omitted from the Get, the Get is invalid. This is the view of the RA'AVAD (quoted by the RAMBAN and NIMUKEI YOSEF in Bava Basra 167b), TESHUVOS HA'RASHBA (1:213), and others.
The Rashba cites support for this ruling from the Gemara earlier (19b). The Gemara states that if one gives a Sefer Torah to his wife and declares that this is her Get, she is not divorced. (That is, the passage in the Sefer Torah which teaches the Mitzvah to give a Get is not considered a valid Get.) One of the reasons the Gemara there gives for why such a Get is not valid is that it does not contain his name and her name, and the names of his and her places of residence. The Gemara there clearly implies that a Get is invalid when the name of his or her city is omitted.
(b) Although the Rishonim quoted above may maintain that the Get is invalid only mid'Rabanan, the SHILTEI GIBORIM quotes the RI'AZ who rules that a Get which does not contain his or her city is invalid according to Torah law. The Shiltei Giborim states that he agrees with the ruling of the Ri'az.
(c) The ROSH here (#9) writes that even if one does not write the name of the city of the man or woman, the Get is valid b'Di'eved. The Mishnah invalidates the Get only when the name of the city was written incorrectly, but not when it was entirely omitted.
The KORBAN NESANEL (#70) cites proof for the ruling of the Rosh from the Mishnah earlier (26a). The Mishnah states that a scribe who prepares Gitin in advance must leave blank the place where the name of the husband is written, the place where the name of the wife is written, and the place where the date is written. The fact that the Mishnah mentions only these three items suggests that the omission of only one of these three render the Get invalid. If the name of his or her city is omitted, the Get is still valid. The reason why the Get is invalid if the name of the city is written incorrectly is that the Get is considered "Mezuyaf mi'Tocho" (see above, 4a, and Insights to 11:2), which everyone agrees is invalid since incorrect details are written in it. In contrast, if the name of his or her city is omitted entirely, the Get does not appear to be false, and since only non-essential components are missing the Get is valid (b'Di'eved).
The Korban Nesanel refutes the proof of the Rashba (see (a) above) by stating that in some texts of the Gemara, the Gemara (20a) says only that both of their names are essential. It does not mention that the name of both of their cities is essential. This is in fact the text of the HAGAHOS HA'GRA. (See also BI'UR HA'GRA to SHULCHAN ARUCH EH 128:3, who writes that this is also the text of Rashi and Tosfos there.) (D. Bloom, Y. Montrose)

80b----------------------------------------80b

2) DO REBBI MEIR AND THE CHACHAMIM ARGUE ABOUT TORAH LAW
QUESTION: The Mishnah (79b) states that if the date in the Get was written in accordance with the year of the reign of a king who is not the present or local ruler, the Get is invalid. The Gemara (80a) explains that the reason for this decree is in order that the Jewish nation should always be on peaceful terms with the ruling power. If the name of the wrong king was written and the wife remarried on the basis of this Get, a child from the second marriage has the status of a Mamzer because the woman is still married to the first husband. This is according to Rebbi Meir's opinion that whenever one alters the "Matbe'a" (form) which the Chachamim instituted for the writing of a Get, the Get is disqualified and any child born from a second marriage based on this Get is a Mamzer.
The Gemara here quotes Rebbi Aba in the name of Rav that this ruling is only in accordance with Rebbi Meir's opinion. The Chachamim, in contrast, rule that b'Di'eved the child is not considered a Mamzer. The Chachamim agree with Rebbi Meir that if the name of the husband or wife, or the name of the husband's city or wife's city, is written in the Get incorrectly, a child born afterwards would be a Mamzer.
The simple reading of the Gemara here raises difficulties with the interpretation of TOSFOS (20a, DH Ha) of the Gemara. The Gemara earlier (19b) discusses a case in which a man gives a Sefer Torah to his wife as a Get. The Gemara (20a) says that even if the man paid the scribe in advance to write -- with the man's wife in mind -- the passage in the Torah that describes the Mitzvah of Get, there is no reason to be concerned that there is any validity to the Get. The Halachah requires that the scribe write the names of the husband and wife in the Get, and if he did not do so the Get is not valid.
The Gemara here explains that when the Mishnah says that the child from the second marriage is a Mamzer when the husband's or wife's name is written in the Get incorrectly, it is expressing the view of Rebbi Meir. Tosfos there (20a) writes that this implies that according to the Chachamim, if the names are written incorrectly the Get is invalid only mid'Rabanan. Accordingly, if the names are omitted entirely, according to the Chachamim the Get should be valid.
The words of Tosfos are very difficult to understand. The Gemara says explicitly in the name of Rav that the Chachamim agree with Rebbi Meir that if the names are written incorrectly, the child will be a Mamzer. How does Tosfos reconcile his understanding of the Mishnah with Rav's statement?
ANSWER: The MAHARAM (20a) answers that Tosfos understands that the dispute between Rebbi Meir and the Chachamim involves an incorrectly written rabbinically required term in the Get, such as the writing of the date according to the reign of the incorrect king. It must be that Rebbi Meir maintains that in such a case the Get is invalid according to rabbinic law, while the Chachamim argue that the Get is valid b'Di'eved. This is apparent from Rebbi Meir's reasoning that whenever one alters the "Matbe'a" of a Get causes any children born to his wife from her second husband to be Mamzerim. Tosfos therefore understands that when Rav says that the Chachamim agree with Rebbi Meir when the names are written incorrectly, it must be that they agree that this type of mistake is the same type of mistake as writing the name of the wrong king according to Rebbi Meir. After all, this is the context of their dispute. Accordingly, Tosfos maintains that the incorrect name of the husband or wife in a Get results in the Get's disqualification only according to Rabbinic law and not according to Torah law. Consequently, Tosfos infers that if the names are omitted entirely, the Get is valid, and thus Tosfos asks his question on the Gemara there: Why is the Sefer Torah which the husband gives to his wife as a Get not a valid Get even though their names are not written in it? (See also MAHARAM SHIF to 20a.) (D. Bloom)