1) A BIRD SENT AWAY IN FULFILLMENT OF "SHILU'ACH HA'KEN"
QUESTION: Rav Ashi teaches that the source for the prohibition against eating meat and milk that were cooked together is the verse, "Lo Sochal Kol To'evah" -- "Do not eat any abominable thing" (Devarim 14:3). Rav Ashi understands that the verse is saying that we may not eat anything that Hash-m has made abominable to us.
The Gemara questions Rav Ashi's teaching from a number of sources, including the law of Shilu'ach ha'Ken. The Gemara asks that according to Rav Ashi, if one takes the mother bird from her nest (in violation of the Mitzvah of Shilu'ach ha'Ken), and then is told by Beis Din to fulfill the Mitzvah and send the mother bird away (and thereby avoid being punished with Malkus, as the Mishnah later (141a) teaches), then he should be forbidden to eat the mother bird itself. Since a "To'evah" -- an Aveirah -- was done by taking the mother bird, the bird should be prohibited to eat. (This is the first way that RASHI (DH Shilu'ach) explains the Gemara. Rashi later (DH Lo Amrah) gives a second, and more preferred, explanation.)
The Gemara answers that when the Torah says, "Shale'ach Teshalach Es ha'Em" -- You shall surely send away the mother" (Devarim 22:7), it cannot be commanding us to send away a bird that is forbidden to be eaten, because the Torah does not tell us to do something that will cause another person (who later catches this bird) to sin. Therefore, in the case of Shilu'ach ha'Ken, Rav Ashi's principle does not apply because there is a verse that specifically permits the bird.
Why, though, would prohibiting the mother bird cause another person to sin? Since the majority of birds in the world are permitted, and in a case of doubt we follow the Rov (majority) according to Torah law, the person who catches the released bird should be permitted to eat the bird based on the principle of Rov.
(a) The CHIDUSHEI CHASAM SOFER answers that although the finder is permitted to take the bird, the sender still would have been forbidden from sending away the bird in the first place if not for the verse of "Shale'ach Teshalach," which explicitly permits the bird. The Chasam Sofer cites TOSFOS (95a, DH uv'Nimtza) who writes that an item of clothing that contains Sha'atnez may not be sold to a Nochri, because he might resell it to a Jew. Even though the principle of Rov should permit selling it to a Nochri, because in the majority of cases it will not be resold to a Jew, one is not permitted l'Chatchilah to put a forbidden item into the world and then rely on the Rov to permit it. The Chasam Sofer asserts that such an act is prohibited mid'Oraisa.
The verse "Shale'ach Teshalach" is necessary to teach that the bird is not forbidden at all, and thus one is permitted to send away such a bird even l'Chatchilah.
(b) RAV ELCHANAN WASSERMAN Hy'd in KOVETZ SHEMU'OS (printed in Kovetz Shi'urim, vol. 2, #55) answers based on the Yerushalmi cited by the RASH (in Orlah). The Yerushalmi teaches that, in general, Bitul is effective only after it is known that there is an Isur in the mixture, but it is not known where the Isur is. Before it is known that an Isur is present, the Torah does not say that the majority of permitted items annuls the Isur. The reason for this, as explained in KOVETZ HE'OROS (Yevamos 58:2), is that the Torah permits a mixture that contains a majority of Heter because of the doubt that exists. However, when there is no doubt (because it is not known to the person who found the bird that there was a forbidden bird flying around somewhere), the Torah does not say that one may follow the majority, and thus the bird should remain forbidden (if not for the verse that specifically permits it). (D. BLOOM)
2) THE "TWO TYPES" OF ANIMALS
OPINIONS: Rebbi Yochanan quotes the teaching of Rebbi who said that the extra verse, "Do not eat it" (Devarim 12:25), written with regard to blood, teaches that one is forbidden to eat a mixture of meat and milk. The Gemara asks that perhaps that verse is forbidding something else. The Gemara answers that the intent of the verse may be derived from the context. The rest of the verse discusses two types of animals, and thus the prohibition must be forbidding two different types of food (i.e. a mixture of meat and milk).
What "two types" of animals is the verse discussing? The Torah there is teaching that the Jewish people may eat unconsecrated meat when they enter Eretz Yisrael from the Midbar. The first verse that says, "Do not eat it" (12:24), clearly refers to the blood of animals, and the second verse, "Do not eat it" (12:25), makes no mention of two types of animals.
(a) RASHI (DH bi'Shnei Minin) explains that the "two types" of animals which the Gemara asserts the verse is discussing refers to the earlier verses there (12:15-16) that teach that one is permitted to eat an animal of Pesulei ha'Mukdashin -- a blemished Korban that was redeemed. "Two types" actually refer to a single animal, the blemished Korban that was redeemed. It is called "two types" because it is like an animal of Chulin in some ways (it may be eaten), while it is like an animal of Kodshim in other ways (it is forbidden to shear its wool and to make the animal work).
(b) TOSFOS (DH bi'Shnei Minin) rejects Rashi's explanation, because it is not logical to call a single animal "two types." Tosfos instead explains that the "two types" of animals refer to the "Tzvi" and "Ayal" mentioned in an earlier verse which says that an animal of Pesulei ha'Mukdashin may be eaten just as "a Tzvi and Ayal" may be eaten" (12:15). The verse gives each animal of Pesulei ha'Mukdashin the status of two distinct species. Accordingly, it is prohibited to have such an animal pull a wagon alone, because doing so is considered as though one is working two different types of animals together, as the Gemara in Makos (22a) teaches. (See also Rashi and Tosfos in Makos there, DH she'Harei.) (Z. Wainstein)
3) AN OBJECT WITH WHICH AN "AVEIRAH" WAS DONE
QUESTION: The Gemara explains that no proof can be adduced from Orlah that any object used to transgress an Aveirah becomes prohibited to be eaten, because the Torah permits the produce that results from a transgression of the Isur of plowing with an ox and a donkey, or placing a muzzle on a cow while it threshes grain.
Why does the Gemara not prove that the object does not become prohibited from the case of "Ma'aseh Shabbos"? The Gemara earlier (115a) proves from the fact that an object brought about as a result of a Melachah performed by a Jew on Shabbos is not Asur mid'Oraisa, even though an Aveirah was committed. Moreover, the very source that the produce is not prohibited when one plows with an ox and donkey is the verse that permits Ma'aseh Shabbos!
(a) The ROSH YOSEF suggests that the Gemara's proof indeed is from Ma'aseh Shabbos. The Gemara mentions plowing with an ox and a donkey only because it is a corollary of Ma'aseh Shabbos.
(b) The TIFERES YAKOV suggests that the Gemara's intention here is to attempt to prove -- based on logical grounds -- that an object used for a transgression is prohibited. Accordingly, perhaps it was obvious to the Gemara that Ma'aseh Shabbos could not be prohibited on logical grounds. It cannot be compared to Orlah or Kil'ayim because, with regard to a Melachah performed on Shabbos, it is the day that causes the prohibition ("Yoma Hu d'Ka Garim") and not solely the action that was done.