1) HALACHAH: MAY ONE PERSON EAT ALL THE FOOD IN WHICH A FORBIDDEN ITEM BECAME "BATEL B'ROV"
OPINIONS: The Gemara (end of 99b) asks that when the Gid ha'Nasheh becomes mixed with permitted Gidin, the entire mixture should be permitted because of Bitul b'Rov; the forbidden Gid should become Batel due to the majority of permitted Gidin. Similarly, the Gemara asks that a piece of Neveilah that falls into permitted pieces of meat should become permitted because of Bitul b'Rov. The Gemara answers that in the case of Gid ha'Nasheh, since the Gid ha'Nasheh is an independent, significant entity in itself ("Biryah"), it is not Batel b'Rov like other Isurim would be Batel. Similarly, in the case of a piece of Neveilah, the Gemara answers that such an Isur is different, because it is "Re'uyah l'Hiskabed" -- it is fit to be served to guests as a display of honor to them, and thus it does not become annulled in a mixture with a majority of permitted food.
The Gemara implies that if not for these unique features of the Gid ha'Nasheh and a piece of Neveilah, the Isur would be Batel b'Rov and one would be permitted to eat the mixture (in a case of a piece of a dry Isur that fell into two dry pieces of Heter).
Does this mean that in a case of Bitul b'Rov, where one Isur fell into two pieces of Heter, one person may eat all three pieces, or only that three different people may eat them?
(a) The TOSFOS RID in Bava Basra (31b, as cited by the KOVETZ SHI'URIM there, 128a) rules that Bitul b'Rov permits the three pieces to be eaten only by three different people; the Rov states that the piece that each person is eating is the permitted piece. If one person eats all three pieces (even at separate times), then he transgresses mid'Oraisa and he is Chayav to bring a Korban Chatas.
Similarly, TOSFOS here (DH Biryah) says that even though the Gemara implies that when an Isur is Batel b'Rov there is not even an Isur d'Rabanan to eat the mixture, perhaps one person still should not eat all three pieces.
(b) The RASHBA (cited by BEIS YOSEF YD 109) maintains that one person is permitted to eat all three pieces, one at a time. Every time he eats one piece, the Rov dictates that the piece that he is eating is a piece of Heter. In contrast, one person is not allowed to eat all three pieces at the same time. (See TAZ YD 109:1.)
(c) The ROSH here (7:37) rules that one person is permitted to eat all three pieces, even at the same time. His reasoning is that the principle of Bitul b'Rov dictates not merely that the piece in question is part of the Rov, but that the principle of Bitul b'Rov effectively transforms the Isur into Heter entirely. (This is the teaching of the Gezeiras ha'Kasuv in the verse, "Acharei Rabim l'Hatos"). Therefore, all three pieces are permitted, and one person may eat them all at one time.
HALACHAH: The SHULCHAN ARUCH (YD 109:1) rules like the RASHBA that one person should not eat all three pieces at the same time. Similarly, the Shulchan Aruch rules that if all of the pieces were cooked together in gravy (thereby becoming a mixture of liquid (and not dry) Min b'Mino), there must be sixty times more Heter in order to annul the Isur.
2) HALACHAH: "CHATICHAH HA'RE'UYAH L'HISKABED"
QUESTIONS: The Gemara teaches that a piece of forbidden food that is a "Chatichah ha'Re'uyah l'Hiskabed" -- a piece fit to be served to guests as a display of honor to them -- does not become annulled in a mixture with permitted food.
(a) How do we assess that a certain piece of food is the type given to guests to honor them?
(b) Does the principle of "Chatichah ha'Re'uyah l'Hiskabed" apply to all types of prohibited foods, or only to certain types?
ANSWERS:
(a) There are two basic opinions in the Rishonim with regard to what constitutes a food that is Re'uyah l'Hiskabed.
1. The ROSH quotes one opinion (that of the RASHBA in TORAS HA'BAYIS, RAN, and others) that a food is considered Re'uyah l'Hiskabed when it is common to honor guests with that food in its present form. A live animal, for example, is not fit to be given to guests to eat in its present form, and thus it is not Re'uyah l'Hiskabed. Therefore, when a live Tereifah animal becomes mixed with Kosher animals, it is Batel. A similar case involves a defeathered chicken, which is considered Re'uyah l'Hiskabed, while a chicken with its feathers is not Re'uyah l'Hiskabed, since it is not given to guests in its present form. (It was the manner to serve raw meat ("Umtza") to guests, as the Gemara mentions in Shabbos (128a). This does not apply today, according to the view of the Rema (see below) who maintains that "Re'uyah l'Hiskabed" is based on the common practice today.)
Similarly, a item is Re'uyah l'Hiskabed only when it is of a size that is normally given to guests. An entire lamb, for example, is not Re'uyah l'Hiskabed, since one does not give an entire lamb to a guest to eat.
2. The Rosh argues with this opinion and asserts that the term "Re'uyah l'Hiskabed" refers only to the size of the food item. In order not to be annulled in a mixture, the food item must be large enough that one would give it to guests as a show of honor. It does not matter whether the item is fit to be given to guests in its present form or not. As long as it will be fit once it is defeathered or cooked, it is considered Re'uyah l'Hiskabed if its size is fit to honor guests. Hence, a live animal is considered Re'uyah l'Hiskabed.
Both opinions are recorded by the SHULCHAN ARUCH (YD 101:3). The REMA writes that the practice follows the second opinion, except in the case of a Tereifah chicken with its feathers. Since the chicken is lacking a significant act before it can become fit for giving honor to guests, it is not considered Re'uyah l'Hiskabed.
The Rema adds that "in these regions," the hooves of small domesticated animals are not considered Re'uyah l'Hiskabed and are Batel. The words of the Rema imply that when determining whether a food is Re'uyah l'Hiskabed, one must take into account the practices of the place and time. This is also written explicitly by the PRI MEGADIM (Mishbetzos Zahav 101:8).
(The PISCHEI TESHUVAH (YD 101:4) cites the NODA B'YEHUDAH who discusses the question of whether a forbidden food is considered Re'uyah l'Hiskabed when it is given only by a Nochri host to his guests (such as frog legs). The Noda b'Yehudah asserts that only a food normally given by a Jew to his guests is considered Re'uyah l'Hiskabed. However, he does not rule conclusively on the matter.)
(b) The RASHBA quotes the RA'AVAD who says that a food is considered a Chatichah ha'Re'uyah l'Hiskabed only when it is inherently prohibited. In contrast, a food that became prohibited by acquiring the taste of a prohibited food (such as by being cooked with it) does not have the status of a Chatichah ha'Re'uyah l'Hiskabed, because the absorbed taste alone is not Re'uyah l'Hiskabed. This is also the view of the ROSH (7:36), RAN (36b of the pages of the Rif), in contrast to the view of the ISUR V'HEITER HA'ARUCH (25:5), as the DARCHEI MOSHE (YD 101:1) points out.
This is the Halachah as recorded by the SHULCHAN ARUCH (YD 101:2).
3) HALACHAH: "CHATICHAH NA'ASAH NEVEILAH"
QUESTION: Rabah bar bar Chanah teaches that a piece of Neveilah or a piece of a non-Kosher fish that fell into a pot of permitted food does not make the contents forbidden unless it is large enough to spread its taste to all of the contents of the pot, including the gravy, sediments, and other pieces of food in the pot.
Rav disagrees and teaches that once the Neveilah gives its taste to another piece of meat in the mixture (that is, the two pieces of meat were first cooked together, and then they fell into a pot with more permitted food), the other piece itself becomes like Neveilah ("Chatichah Atzmah Na'ases Neveilah"). Since the second piece of meat is like a piece of Neveilah, it forbids the entire mixture; it is not Batel, because it is a mixture of Min b'Mino.
The Gemara explains that Rav follows the view of Rebbi Yehudah, who rules that in a mixture of Min b'Mino, the forbidden food is not Batel even if it is very small.
The Gemara asks that if Rav follows the view of Rebbi Yehudah, then why does Rav say that the mixture is forbidden only when the first piece of meat (the Neveilah) imparts its taste to the second piece of meat? Even if it does not impart its taste to the mixture, the presence of the Neveilah should forbid the entire mixture, because the Neveilah is not Batel (because it is Min b'Mino)!
Abaye answers that Rav is discussing a case in which the original piece of Neveilah was removed from the mixture. Since the Neveilah is no longer present, the mixture will be prohibited only if the taste of the Neveilah entered another piece of meat, thereby making that piece of meat into a piece of Neveilah.
If Rav follows the view of Rebbi Yehudah, then why does he need to say that when the piece of Neveilah gives its taste to the neighboring piece, it makes that piece into Neveilah which then prohibits the entire mixture? According to Rebbi Yehudah, even without a transfer of taste from the Neveilah to the second piece of meat, the second piece becomes Asur! Once the two pieces of meat are cooked together, the piece of Neveilah prohibits the other piece of meat because any amount of Isur in a mixture of Min b'Mino prohibits the entire mixture, even without giving its taste to the permitted food!
ANSWERS:
(a) TOSFOS (DH b'she'Kadam) cites RABEINU TAM who answers that even though the second piece of meat, which is the same Min as the Neveilah, would become forbidden even if the Neveilah did not impart its taste to it, nevertheless we would not say that the second piece itself becomes a piece of Neveilah with the ability to forbid all of the other pieces when it becomes mixed with them. The second piece of meat can forbid the rest of the mixture only when it has absorbed the taste of the original Neveilah, thereby becoming a piece of Neveilah itself.
(b) Tosfos writes that RABEINU EFRAIM has a different approach. Even when the Neveilah imparts its taste to the second piece of meat, the second piece does not become Neveilah itself to require sixty times more Heter than the entire piece itself in order to become Batel. Rather, the Isur of the second piece is Batel as long as the Heter is sixty times greater than the amount of the taste of Isur absorbed in the piece. Rav's ruling of "Chatichah Na'asah Neveilah" means that the second piece has the ability to transfer to the mixture whatever taste it absorbed from the original piece, but not that the whole piece itself becomes Asur like a piece of Neveilah.
According to Rav, who maintains that "Min b'Mino" is not Batel, when the permitted piece receives taste from the forbidden piece the Isur is considered "b'Ein," recognizable, and it will make an unlimited number of pieces forbidden. However, if the first piece would not impart its taste to the second piece, then the Isur would not be considered recognizable and its taste would not spread to the other pieces. (The RASHBA explains that since it does not give taste, it is considered to have no Shi'ur (size) and therefore it cannot spread.)
There are two important differences between the opinion of Rabeinu Tam and the opinion of Rabeinu Efraim. The first difference is that according to Rabeinu Tam, in order for the second piece of meat (that has "become Neveilah") to be annulled in the mixture, there must be sixty times more Heter than the entire piece of meat. According to Rabeinu Efraim, it suffices to have sixty times more Heter than the taste absorbed in the second piece of meat.
The second difference is that according to Rabeinu Tam, the principle of "Chatichah Na'asah Neveilah" applies to all Isurim, and not only to the Isur of meat and milk (where the entire mixture becomes Asur as "Basar b'Chalav"). (Most Poskim maintain that even according to Rabeinu Tam, the principle of "Chatichah Na'asah Neveilah" applies only mid'Rabanan to other forms of Isur, while it applies mid'Oraisa to Basar b'Chalav.) According to Rabeinu Efraim, "Chatichah Na'asah Neveilah" applies only when a drop of milk falls onto meat. Since both milk and meat are permitted by themselves, they became forbidden only as a result of mixing with each other. Therefore, the entire piece of meat becomes forbidden as "Basar b'Chalav." "Chatichah Na'asah Neveilah" does not apply to other Isurim, such as the Isur of Neveilah.
HALACHAH: The SHULCHAN ARUCH (YD 92:4, 106:1) rules like Rabeinu Efraim that "Chatichah Na'asah Neveilah" applies only to a mixture of meat and milk. Therefore, with regard to all other Isurim, when a food became prohibited because of a forbidden taste that it absorbed, and it then fell into a pot of permitted food, it suffices to have sixty times more than the taste absorbed in it in order to annul it, and it is not necessary to have sixty times more than the entire piece.
The REMA states that our practice is that "Chatichah Na'asah Neveilah" applies to all Isurim. Therefore, sixty times more than the entire piece is necessary in order for the contents of the pot to be permitted. (D. BLOOM, Y. SHAW)

100b----------------------------------------100b

4) MITZVOS GIVEN BEFORE AND AFTER SINAI
QUESTION: In the Mishnah, Rebbi Yehudah and the Chachamim disagree about whether the Isur of Gid ha'Nasheh was given to Bnei Noach at the time of Yakov Avinu, or whether it was given only at the time the Torah was given at Sinai.
The RAMBAM (in Perush ha'Mishnayos) explains that we perform the Mitzvos because Hash-m gave them to us and commanded us to fulfill them at Har Sinai, but not because Hash-m told the Mitzvos to the earlier prophets (such as the Avos, or Noach). The prohibition against eating the Gid ha'Nasheh is not based on the command that Hash-m gave to the sons of Yakov, but because Hash-m commanded us at Har Sinai not to eat it. Similarly, we do not perform the Mitzvah of Bris Milah because Avraham was commanded to perform Bris Milah, but because Hash-m commanded us at Har Sinai to perform Bris Milah.
What practical difference does it make whether we are obligated to fulfill a Mitzvah because it was given at Sinai, or because it was given to the Avos or to Noach?
ANSWER: HAGA'ON RAV YISRAEL ZEV GUSTMAN zt'l (in Kuntresei Shi'urim, Bava Metzia 12:6) explains that according to the Rambam, when we fulfill the seven Mitzvos that were also commanded to Bnei Noach, we do not fulfill the same Mitzvos that the Nochrim are commanded to fulfill. Their seven Mitzvos were given through Noach's prophecy; we observe them as part of a new set of Mitzvos given at Sinai.
Rav Gustman points out that according to this understanding, the suggestion of the MINCHAS CHINUCH is not accurate. The Minchas Chinuch suggests that even according to the opinion that a blind person is exempt from performing Mitzvos, he should be required to observe the basic seven Mitzvos of Bnei Noach. Rav Gustman disagrees based on the words of the Rambam. Since a blind person is not a Ben Noach but a Jew, the Mitzvos given to Bnei Noach do not apply to him.
We may add that the Rambam elsewhere (Hilchos Melachim 10:7) rules that "all of the descendants of Avraham are obligated to perform Bris Milah." On the other hand, the Rambam rules that when a person vows not to accept any benefit from a circumcised person, he may benefit from Bnei Noach who are circumcised! The Rambam in Perush ha'Mishnayos to Nedarim (3:11) explains that this is because Bnei Noach are not commanded to perform Bris Milah, and therefore they cannot be considered "Mahul" ("circumcised"). Since the Rambam writes that all of the descendants of Avraham are obligated to perform Bris Milah, why does he write that a person who vows not to derive any benefit from a "Mahul" is permitted to derive benefit from a circumcised Nochri? He should write that one is prohibited to derive benefit from all of Bnei Yishmael (descendants of Avraham) who are circumcised!
According to the approach that the set of Mitzvos given to Jews does not include the set of Mitzvos given to Bnei Noach, it is clear that even though the Bnei Yishmael are obligated to circumcise themselves, they are not commanded to perform the same Mitzvah of Bris Milah as the Jews, and therefore they are not considered "Mahul." (Z. Wainstein)
5) A NOCHRI'S OBLIGATION WITH REGARD TO THE PROHIBITION OF "GID HA'NASHEH"
QUESTION: Rebbi Yehudah maintains that the prohibition of Gid ha'Nasheh applies to the Gid of a non-Kosher animal. Since the Gid ha'Nasheh was forbidden from the time of Yakov's children, and non-Kosher animals were permitted to eat at that time, it must be that the prohibition of Gid ha'Nasheh applies to the Gid of non-Kosher animals as well.
The Gemara explains that the Isur of Gid ha'Nasheh can take effect on a non-Kosher animal, even though the animal is already forbidden (and there is a rule that "Ein Isur Chal Al Isur"), because the Isur of Gid ha'Nasheh is more severe ("Chamur") than the Isur of eating a non-Kosher animal. The Isur of Gid ha'Nasheh applies to Nochrim, while the Isur of eating a non-Kosher animal applies only to Jews (see RASHI DH u'Meshani Af Al Gav).
Why does Rebbi Yehudah answer that the Isur of Gid ha'Nasheh is an "Isur Chamur"? He should answer that it is an "Isur Kolel" -- an Isur that makes the object forbidden to more people, since the Isur of eating a non-Kosher animal makes the animal forbidden to Jews, while the Isur of Gid ha'Nasheh makes it forbidden to Nochrim as well.
ANSWERS:
(a) TOSFOS (90a, DH Kodshim) suggests two answers. In his first answer, he says that Rebbi Yehudah does not mean that the Gid ha'Nasheh was prohibited to all Nochrim at the time of Yakov Avinu. Rather, he means only that it was prohibited to the children of Yakov before the Torah was given. Accordingly, it is not an Isur Kolel at all. (This is also the opinion of RASHI to Sanhedrin 59a, DH v'Aliba.)
(b) In his second answer, Tosfos explains that even if the Gid ha'Nasheh indeed was prohibited to all Nochrim before Matan Torah, after Matan Torah it remained prohibited only to the Jewish people. Since it no longer includes Nochrim, it is not an Isur Kolel.
(However, TOSFOS in Pesachim (22a, DH v'Rebbi Shimon) quotes RABEINU YAKOV of Orleans who implies that even today Bnei Noach may not eat the Gid ha'Nasheh. This opinion requires further explanation, because the Gemara in Sanhedrin (59a) clearly implies that the Gid ha'Nasheh is permitted to Bnei Noach today. See also Insights to Chulin 91:2-3.)

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