1) DESIGNATING BIRDS BEFORE YOM TOV
QUESTIONS: The Gemara discusses one who selects birds before Yom Tov in order to slaughter them on Yom Tov. The Gemara cites the Mishnah later (on 10a) in which Beis Shamai says that one who selects the birds must pick them up and shake them; it does not suffice merely to name them verbally. Beis Hillel permits one to designate the birds for use on Yom Tov merely by naming them verbally.
RASHI explains that Beis Shamai does not permit one to designate the birds merely by naming them, because perhaps he will pick up a bird on Yom Tov, inspect it, and then decide not to use it, in which case he will have handled the bird for no reason on Yom Tov.
Rashi adds that by changing his mind about this bird, he retroactively annuls the declaration of Hachanah with which he verbally prepared the bird for use before Yom Tov (and thus when he handled the bird on Yom Tov, he transgressed the prohibition against handling Muktzah).
Rashi's words are difficult to understand for several reasons.
First, Rashi seems to contradict himself. On the one hand, he says that the problem, according to Beis Shamai, is that the person will perform an unnecessary act of "Tircha" (exertion) by handling the bird for no reason on Yom Tov. But then he writes that the problem is on of moving an object which was retroactively Muktzah. The reason of "Muktzah" is not the same as the reason of "Tircha!"
Second, why does the person's choice not to use the bird annul his Hachanah retroactively? Since he said, "I intend to take this bird and that bird," those birds should remain designated for use even if he does not take them on Yom Tov. His decision on Yom Tov not to use them should not make them un-prepared and Muktzah. (This point is clear from the Gemara later which differentiates between a case of "Zeh v'Zeh Ani Notel" and a situation of Bereirah, retroactive determination.)
Third, when Rashi explains the Mishnah later (DH Gazrinan), he says that according to Beis Shamai the problem is "Tiltul she'Lo l'Tzorech" -- unnecessary exertion on Yom Tov. Rashi there makes no mention of the problem of annulling one's preparation of the bird retroactively and handling Muktzah as a result. (TAL TORAH, BIGDEI YOM TOV, CHIDUSHIM U'VI'URIM)
ANSWER: It seems that the two statements in Rashi reflect two differing approaches to understanding Beis Shamai's reasoning. That is, they are indeed two approaches, and not a single approach, and inferences to both of these approaches can be found in other comments of Rashi on this Daf. (See our Introduction to Maseches Eruvin, I:b, where we noted and discussed this phenomenon.)
To understand why Rashi shifted between these two explanations, we must analyze a section of Gemara later on this page.
(a) The Gemara implies, later on the Daf, why Beis Shamai did not accept the reasoning of Beis Hillel. The Gemara there explains why Beis Hillel did not allow a person to rely on retroactive choice (Bereirah), stating before Yom Tov "whichever bird I choose to eat on Yom Tov shall hereby be prepared for slaughter, and not Muktzah." The reason this cannot be done, the Gemara asserts, is because we are afraid that on Yom Tov, the person will pick up a bird, find it unacceptable for eating, and replace it, picking another bird instead. By doing so, he will be abusing Yom Tov since he has "moved an object that is not fit for his Yom Tov use" (Midei d'Lo Chazi Lei).
The Gemara then asks, if that is so, then even if one pronounces "Zeh va'Zeh Ani Notel" - I will eat this and this bird on Yom Tov - we should have the same concern. Perhaps the person will pick up on Yom Tov the birds that he chose, find them unacceptable for eating, and replace them, thus abusing Yom Tov and moving an object that is not fit for Yom Tov use.
Although the Gemara answers its question and explains Beis Hillel's reasoning for allowing a statement of "Zeh va'Zeh Ani Notel," nonetheless it follows to reason that Beis Shamai did not accept Beis Hillel's answer. They required that one actually handle the birds prior to Yom Tov, in order that one should not come to abuse Yom Tov by moving an object that is not fit for Yom Tov use.
(b) If so, in order to understand
We asked (in our second question), why does Beis Shamai prohibit the bird prepared before Yom Tov just because "he might change his mind (and not slaughter it)," as the Gemara says? Since the bird was prepared for use before Yom Tov, one's decision not to eat it should not make it Muktzah on Yom Tov. Why, then, may one not handle the bird?
Rashi (DH Gazrinan) seems to answer this question by asserting that by doing so, the person will "unnecessarily exert himself" when he handles the bird on Yom Tov. However, this answer is not completely satisfactory. What significant degree of exertion is involved when one picks up a bird and places it back in its coop?
Other Rishonim suggest different reasons for why Beis Shamai prohibits the bird on Yom Tov.
1. The RE'AH explains that Beis Shamai maintains that the declaration, "I intend to take this bird and that bird," does not constitute a Hachanah Gemurah, a full designation. The declaration does not fully prepare the bird for use because it is common for a person to change his mind about what bird to eat. One's verbal declaration is not a real Hachanah until he actually picks up and shakes the bird before Yom Tov and thereby shows that he really intends to use it.
2. The RAMBAM (in Perush ha'Mishnayos) explains that Beis Shamai is concerned that a person might change his mind before Yom Tov, designate other birds instead, and then change his mind again on Yom Tov and decide to use the birds he designated originally. When he takes those birds on Yom Tov, however, he will be handling Muktzah (because he revoked their designation before Yom Tov).
3. RABEINU CHANANEL explains that Beis Shamai is concerned that on Yom Tov the person will find the birds unfit for a Yom Tov meal. Since he prepared no other birds, he will have no meal on Yom Tov and his Simchas Yom Tov will be diminished.
(b) Perhaps Rashi learns like the Re'ah, that since it is common for a person to change his mind, his verbal Hachanah of the birds is not a complete Hachanah. If, however, his statement explicitly designated the birds for use on Yom Tov, why is it not a complete Hachanah? While he may be uncertain in his heart, the principle of "Devarim sheb'Lev Einam Devarim" teaches that the words that one speaks override the thoughts in his heart. Why are the birds not considered designated for use on Yom Tov if he declared them as designated?
To answer this question, Rashi explains that when one says, "I intend to take this bird and that bird," he includes a condition in his words. He is actually saying, "These birds are designated for use because I am going to take them." If, on Yom Tov, he decides not to take one, then that bird was never prepared in the first place because his condition (that he takes it on Yom Tov) was not fulfilled.
This is what Rashi means when he says that the bird becomes Muktzah retroactively. It becomes Muktzah as a result of the lack of fulfillment of his condition. This is also what Rashi means when he says that he moves the bird "for nothing"; he moves the bird not in a permitted manner, as he originally intended to do before Yom Tov, but rather he moves it wrongfully. Since he did not fulfill the condition of using it on Yom Tov, its Hachanah was annulled retroactively.
(c) Why, though, does Rashi later explain that Beis Shamai prohibits handling the bird because it is "Tiltul she'Lo l'Tzorech," unnecessary exertion?
The Gemara at that point assumes that Beis Shamai maintains that Bereirah does not work, as the Gemara itself explains. Therefore, Rashi has no choice but to give another explanation which is not based on Bereirah. The first explanation utilizes the principle of Bereirah, in that one is able to determine retroactively that the birds are not designated for use.
However, the Gemara concludes that there is no proof whether or not Beis Shamai maintains that Bereirah works (because the Mishnah which the Gemara cites as a proof does not actually discuss a case of Bereirah). Since Beis Shamai may accept the principle of Bereirah, therefore Rashi's earlier explanation of Beis Shamai, which is based on the principle of Bereirah, remains the more acceptable explanation for why Beis Shamai prohibits moving the birds. (M. KORNFELD; see also BIGDEI YOM TOV for a similar approach.)

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