1) VIOLATING A NEDER WITH A SECONDARY OBJECT
QUESTION: The Gemara says that according to Rebbi Akiva, when a person makes a Neder to prohibit a certain object to himself, that Neder also includes "secondary" objects. A secondary object is defined as one which a Shali'ach, who was appointed to buy the primary object for the sender but is unable to find it, would ask the sender if he should buy instead (based on the assumption that the name of the primary object includes the secondary object).
Abaye states that although Rebbi Akiva maintains that one's Neder includes any object which a Shali'ach would ask the sender if he should buy in place of the primary object, there is no Malkus if the Noder violates the Neder with that secondary object. This is the way most Rishonim rule.
The RAMBAM (Hilchos Nedarim 9:6), however, rules like Rebbi Akiva but makes no mention of the exemption from Malkus, implying that the Neder includes the secondary object for all purposes, even for Malkus. Why does the Rambam not cite the ruling of Abaye? (KESEF MISHNEH)
ANSWERS:
(a) The LECHEM MISHNEH (Hilchos Nedarim 9:10) answers that the Rambam understands that Abaye does not mean that any object which a Shali'ach asks the sender about is included in the Neder out of doubt. Rather, Abaye means that Rebbi Akiva was unsure whether or not a Shali'ach, when asked to buy Yerek (vegetables), asks about Dilu'in (gourds). If it would be known for certain that a Shali'ach does ask about Dilu'in, Malkus certainly would be administered according to Rebbi Akiva. When the Rambam writes that an object which a Shali'ach asks about is included in the Neder, he refers to an object which we know a Shali'ach asks about, and that is why he rules that there is Malkus.
This approach is problematic, however, because the wording of the Mishnah implies that a Shali'ach does ask about Dilu'in, and there is no Safek about it.
(b) The Gemara asks that the Mishnah in Me'ilah seems to contradict Rebbi Akiva's opinion. The Mishnah there teaches that when a Ba'al ha'Bayis tells his Shali'ach to give meat (which is Hekdesh) to guests and the Shali'ach instead gives them liver (which is Hekdesh), the Shali'ach is liable for Me'ilah since he did not carry out the will of the Ba'al ha'Bayis. The Gemara says that this Mishnah is not in accordance with the view of Rebbi Akiva, because liver is something which a Shali'ach asks his sender about when he is sent to buy meat. Hence, when he gave liver to the guests, the Shali'ach fulfilled the will of the Ba'al ha'Bayis and the Ba'al ha'Bayis should be liable for Me'ilah.
The Rishonim ask that Rebbi Akiva himself says that there is no Malkus for a person who makes a Neder to prohibit himself from meat (Basar) and then eats liver. The fact that he does not receive Malkus indicates that the secondary object prohibited by the Neder (as something which a Shali'ach asks about) is only Asur mid'Rabanan or Asur mi'Safek, and that is why there is no Malkus. However, this means that in the case of Me'ilah, mid'Oraisa the Shali'ach who gave the liver to the guests did not fulfill the will of the Ba'al ha'Bayis even according to Rebbi Akiva, and the Ba'al ha'Bayis should not be liable for Me'ilah even according to Rebbi Akiva! (See RAN and TOSFOS.)
Moreover, Abaye himself explains that the Mishnah in Me'ilah may also follow the view of Rebbi Akiva, because the word (meat) which the Ba'al ha'Bayis mentioned includes the secondary object (liver) only when the Shali'ach actually asks about it. In the case in Me'ilah, the Shali'ach did not ask about the liver, and thus it was not included in the Ba'al ha'Bayis' request. Consequently, the Shali'ach is liable for Me'ilah. Why, though, does Abaye not answer according to his own reasoning, that the secondary object is included in the person's Neder only mid'Rabanan, and the fact that a Shali'ach asks about it does not make it part of the primary object mid'Oraisa? (See TOSFOS.)
It must be that Abaye changed his mind and decided that Rebbi Akiva maintains that liver is included in "meat" mid'Oraisa, and Malkus is administered for one who transgresses his Neder by eating liver as well. This is why Abaye gives a different answer for the Mishnah in Me'ilah when he explains how it can follow the view of Rebbi Akiva, and he does not say simply that its inclusion in the Neder is mid'Rabanan.
This may also explain why Rava announced afterwards that "Abaye's answer is a good answer." Why does the Gemara need to relate that Rava approved of Abaye's answer? If the Gemara means that Rava said same answer, the Gemara should say simply that "Rava and Abaye both say...." Rather, Rava's intention was to say that he expected Abaye to give a different answer and to say that the secondary object is included in the Neder only mid'Rabanan (according to Abaye's own reasoning), with which Rava would have disagreed (since he maintains that something which a Shali'ach asks about is included in the Neder mid'Oraisa). However, now that Abaye gave a different answer, Rava declared that he agrees with it. This explains why the Rambam rules that the secondary object is included in the Neder mid'Oraisa, in accordance with the conclusion of Abaye and Rava.

54b----------------------------------------54b

2) WHAT IS INCLUDED IN "BASAR"?
QUESTION: The Gemara explains that Rebbi Akiva and Raban Shimon ben Gamliel disagree about whether one who makes a Neder to prohibit meat ("Basar") also includes in his Neder chicken, liver, and other secondary forms of meat. They also disagree about whether a Neder to prohibit vegetables ("Yerek") also includes Dilu'in, gourds. Raban Shimon ben Gamliel maintains these objects are not included in the Neder; liver and chicken are not called "Basar," and a gourd is not an actual Yerek. Rebbi Akiva maintains that they are included in the Neder, because when a person asks a Shali'ach to buy "Basar" (or "Yerek") for him and the Shali'ach finds no meat (or vegetables), the Shali'ach will return to the sender and ask him if he should buy chicken (or gourds) instead.
The Rishonim rule in accordance with Rebbi Akiva, who says that chicken and liver are included in a Neder which prohibits Basar, and gourds are included in a Neder which prohibits Yerek. The Gemara explains that according to Rebbi Akiva, fish are also included in a Neder which prohibits Basar, unless circumstances indicate that the person clearly did not intend to prohibit fish (for example, in a situation in which he would not have eaten fish anyway). The meat of Chagavim (grasshoppers) is not included in a Neder which prohibits Basar.
The RAMBAM's ruling in this matter (Hilchos Nedarim 9:6, and as cited by the Ran here), however, is difficult to understand. The Rambam rules like Rebbi Akiva and writes that Chagavim are not included in a Neder which prohibits Basar. Fish are included in the Neder in a place where a Shali'ach would return to the sender to ask if he should buy fish when he was sent to buy Basar. With regard to chicken and liver, however, the Rambam writes that chicken and liver are always included in the Neder. Why does the Rambam rule this way? The Gemara clearly equates fish with chicken and states that a Shali'ach returns to ask about both. Why does the Rambam differentiate between the two? (Many Acharonim discuss this question.)
ANSWER: Perhaps the clearest answer to this question is that of the KESEF MISHNEH (based on the RADBAZ). The Kesef Mishneh points out that that the Gemara seems unnecessarily wordy when it compares chicken to fish. The Gemara asks why the Tana includes chicken in a Neder which prohibits Basar, and it answers that a Shali'ach sent to buy Basar asks if he should buy chicken when he cannot find any meat. The Gemara then asks that if chicken is included in "Basar" for that reason, then "fish, too -- it is normal for a Shali'ach, if he does not find meat, to ask about it, saying, 'If I do not find meat, shall I bring fish?'"
Why does the Gemara not say simply that "fish, too -- it is normal for a Shali'ach who does not find meat to ask about it"? Why does the Gemara repeat at length the actual words of the Shali'ach? (See SHALMEI NEDARIM in the name of TESHUVOS MAHARIK.)
The Kesef Mishneh answers that it is evident from the apparent repetitiveness that there are two different inquiries which a Shali'ach might pose to his sender about what he is supposed to buy. In the case of chicken (or liver), as soon as the Shali'ach is appointed to buy meat for the sender, the Shali'ach asks, "Do you want animal meat or chicken meat (or liver)?" When it comes to fish, however, the Shali'ach does not ask as soon as he is appointed, "Do you want fish-meat," because he assumes that the sender does not want fish-meat. Only in the event that he finds no meat in the market will he return to ask the sender if fish will suffice.
Raban Shimon ben Gamliel maintains that in both cases of the different inquiries of the Shali'ach, the word "Basar" does not include the secondary type of meat (chicken or fish). Neither type of food is included in "Basar." Rebbi Akiva, on the other hand, maintains that even in the latter inquiry, where the secondary food is bought only when there is no other meat in the market, the secondary food is also included in "Basar," as is evident from the words of the Mishnah.
(The Kesef Mishneh does not explain why Raban Shimon ben Gamliel disagrees with the first category of inquiry. If the Shali'ach normally asks, "Do you want animal meat or chicken meat (or liver)," because both may be called "meat," why should Raban Shimon ben Gamliel say that the word "Basar" means only animal meat? The answer might be that animal meat is more desirable and important to people, and thus they mean animal meat when they say "Basar." Raban Shimon ben Gamliel maintains that the word "Basar" includes only the more desirable type of Basar and not the less desirable type of Basar such as chicken or liver. See KEREN ORAH.)
This is why the Rambam rules that whether or not fish is included in "Basar" depends on the place; it depends on whether a Shali'ach in that place normally asks the sender if fish will suffice when he is sent to buy meat, as the Gemara says. However, the Rambam says that chicken and liver are included in the word "Basar" in all places (according to Rebbi Akiva), because they are considered to be types of meat (even though animal meat is generally more desirable).
Strong support for this approach may be found in the wording of the Gemara. Earlier (54a), when the Gemara explains the dispute between the Rabanan and Rebbi Akiva, it says that the Rabanan maintain that an item which a Shali'ach must ("d'Tzarich") ask about is not included in the object of the Neder, while Rebbi Akiva maintains that anything which a Shali'ach asks about is the same as the object in the Neder. Later (54b), when the Gemara compares fish with chicken, it says that according to Rebbi Akiva fish are included in the Neder because it is normal for a Shali'ach ("d'Avid Shelicha") to ask about it. Why does the Gemara use three different phrases to express the same idea?
According to the Kesef Mishneh's approach in the Rambam, the Gemara is clear. The first type of food -- a food which is called "Basar" and may have been included in the command of the sender (such as chicken and liver) -- is a food which a Shali'ach needs to ask about immediately. It is called something which a Shali'ach "must" ask about; since the term "Basar" includes both meat and chicken, the Shali'ach must ask what the sender wants. The Rabanan maintain that even those items are not included in the Neder which prohibits "Basar." Rebbi Akiva, on the other hand, maintains that even when the Shali'ach does not need to ask, but it is merely normal for him to ask, such as when he does not find any Basar and returns to ask if the sender wants fish instead, that item is included in the Neder. Since Rebbi Akiva maintains that both (chicken or liver, and fish) are included in "Basar," the Gemara does not say that the Shali'ach "must" ask ("d'Tzarich") or that it is "normal" for him to ask ("d'Avid"), but rather merely that he "asks" about it.
When the Gemara (54b) attempts to show that fish should be included in a Neder of "Basar" just as chicken is included (according to Rebbi Akiva), it refers only to the second type of inquiry, where the Shali'ach asks if he should buy fish if he cannot find any Basar. Therefore, the Gemara uses the appropriate term and says that it is "normal" ("d'Avid") for a Shali'ach to ask! (The Gemara uses the term "d'Avid" also with regard to chicken only because it must use that term with regard to fish.)