1) A FLOATING OR FLYING OBJECT OF TUM'AH
QUESTIONS: The Beraisa states that a case of a Safek Tum'ah Tzafah -- a case in which there is a doubt whether an item of Tum'ah that was floating in water touched a person or a utensil -- is treated leniently (even in Reshus ha'Yachid). Another Beraisa adds that if a person held the floating object with his hand or by way of a string, the Safek is treated stringently and the person is Tamei. If, however, the Safek Tum'ah was "Nizrak" ("thrown in the air"), the Safek is Tahor.
The Beraisa continues and says that this principle does not apply to a k'Zayis of flesh from a Mes, or to a person who is Ma'ahil over a Safek Tum'ah. When a Safek arises with regard to an object thrown over a k'Zayis of flesh from a Mes, the Safek is treated stringently and is Tamei. TOSFOS explains that the rule of Safek Tum'ah Tzafah applies only to Tum'as Maga but not to Tum'as Ohel.
Tosfos (end of 63b) writes that there is a doubt about whether the laws of Tum'ah Tzafah refer exclusively to an object of Tum'ah floating on water, or even to an object thrown through the air.
(a) Why does Tosfos have a doubt about whether Tum'ah Tzafah applies to a Tahor object that is thrown over Tum'ah, or to an object of Tum'ah that is thrown over a Tahor object? The Beraisa clearly states that in the case of an object thrown through the air, the Safek is Tahor.
Tosfos himself seems to address this question. He explains that when the Beraisa states that a Safek Tum'ah which is held by a string is Tamei, it refers to a Tum'ah held over water by a string. Hence, when the Beraisa states that a Safek Tum'ah that is thrown is Tahor, it must refer to Tum'ah that was thrown over (and touched) the surface of the water. Accordingly, Tosfos' doubt is not addressed by the Beraisa.
Why, though, does Tosfos interpret the Beraisa in a manner different from its simple meaning and explain that "Nizrak" means that the item was thrown along the surface of the water? Tosfos should explain that the Beraisa refers to an item that was thrown through the air, nowhere near water. Indeed, the Mishnah in Taharos (3:1) clearly rules that a Safek Tum'ah which involves an object that is thrown, and not just an object that is floating, is Tahor.
(The CHAZON ISH is so perplexed by this question that he suggests that perhaps there is a printing error in the words of Tosfos.)
(b) The Tosefta in Taharos (3:8, cited by the RASH to Taharos 3:3) is apparently the source of the Beraisa which the Gemara quotes. However, although the Tosefta concludes that Safek Ma'ahil is Tamei, the Tosefta adds that if a Tahor item was thrown over a k'Zayis of a Mes, it remains Tahor. This is a blatant contradiction to the way the Tosefta is quoted by the Gemara, which says that when something is Safek Ma'ahil over Tum'ah, it becomes Tamei.
Moreover, what logic justifies the Tosefta's distinction between the case of an object of Tum'ah thrown over a Tahor object (in which case the Tahor object becomes Tamei mi'Safek) and the case of a Tahor object thrown over Tum'ah (in which case the Tahor object remains Tahor mi'Safek)? In the case of Tum'ah which is thrown, the law should be more lenient since the Tum'ah itself is moving! (This indeed is the opinion of Rebbi Yehudah in Taharos 3:1 cited by the Rosh here.)
ANSWERS:
(a) Tosfos seems to be bothered by the wording of the Tosefta (and Mishnah) which discusses Safek Tum'ah Tzafah -- floating Tum'ah. Why does it specifically discuss floating Tum'ah, and not Tum'ah that is flying or moving?
Tosfos answers this question by saying that the Tosefta seeks to avoid Machlokes, and that is why it limits its Halachah to Tum'ah Tzafah and does not mention flying Tum'ah. Flying Tum'ah is the subject of a Machlokes, because there is an opinion which maintains that "Kelutah k'Mi she'Hunchah Dami" -- an item that is in the air is considered resting on the ground below. According to this opinion, flying Tum'ah is not considered like Tum'ah Tzafah, but rather like Tum'ah resting on the ground (as the MEFARESH mentions in DH Kol ha'Nitlin). The Mishnah in Taharos (3:1) which rules leniently in the case of a Safek Tum'ah thrown through the air follows the opinion that "Kelutah" is not "k'Mi she'Hunchah Dami."
Tosfos explains that the Beraisa here as well refers only to Tum'ah dragged over water in order to avoid the question of "Kelutah." (It seems that Tosfos' text did not include the word "veha'Nizrakin" in the Beraisa, but rather the word "veha'Tzafin.")
(b) The words of the Tosefta are difficult to reconcile. The RASH in Taharos suggests that the Tosefta maintains that an object cannot be Mekabel Tum'ah while it flies through the air. (The Rash implies the contrary in Ohalos 8:5.) The Beraisa quoted by the Gemara here might disagree with the Tosefta in this regard.
It is possible that there is a printing error in the Tosefta and it should read "Tamei" in both cases. Alternatively, the end of the Tosefta does not refer to Safek Tum'as Ohel, but rather to Safek Tum'as Maga that comes from a k'Zayis of a Mes. (However, the RAMBAM cited by the VILNA GA'ON here writes that even Safek Maga of a k'Zayis of a Mes is Tamei.)
However, the comments of the VILNA GA'ON on the Tosefta provide two possible answers to the question.
1. It is possible that the Tosefta argues with the Gemara and rules more stringently in the case of a k'Zayis from a Mes thrown over a Tahor object than in the case of a Tahor object thrown over a k'Zayis from a Mes. The Tosefta's stringency is based on the underlying reason for why Tum'ah Tzafah does not apply to Tum'as Ohel.
The Vilna Ga'on suggests that there is a clear logical basis for this exception to the rule of Tum'ah Tzafah (at least according to the Tosefta). The logic is that even when a k'Zayis from a Mes is thrown, it is as if it is resting on the ground because of the principle that Tum'as Mes is "Boka'as v'Yoredes." This principle states that wherever a source of Tum'as Mes is located, it "pierces" straight down to the depths of the ground. Consequently, any object that lies under a k'Zayis of a Mes considered as though it is touching the k'Zayis. Similarly, the principle of "Boka'as v'Yoredes" makes the k'Zayis from a Mes considered as though it is touching the ground and being dragged along the ground rather than flying through the air! In contrast, when a Tahor object is thrown over a k'Zayis from a Mes, it unquestionably is "in the air" and not being dragged along the ground. Consequently, any Safek is judged leniently, like all cases of Tum'ah Tzafah. (The Vilna Ga'on's approach is based on the view of most Rishonim that only Ohel of Tum'as Mes is an exception to the rule of Tum'ah Tzafah, in contrast to the view of the Rambam cited by the Vilna Ga'on here.)
This approach explains the distinction of the Tosefta. The Beraisa cited by the Gemara apparently does not accept this distinction. Rather, the Beraisa maintains that it is simply a Gezeiras ha'Kasuv that the rule of Tum'ah Tzafah does not apply to Tum'as Mes b'Ohel, whether the Tum'as Mes is thrown over the Tahor object or the Tahor object is thrown over the Tum'as Mes.
2. The Vilna Ga'on suggests that the Tosefta's scenario assumes that the person is holding the Tahor object but not the Tamei object. Accordingly, when Tum'as Mes is thrown above a Tahor object, the object below (in the person's hand) is judged Tamei mi'Safek, since the rule of Tum'ah Tzafah does not apply to Tum'as Ohel (or, according to the Rambam, to Tum'as Mes in general). However, if the Tahor object is thrown above the Tum'ah, the Tahor object is no longer in the person's hand at the time the Safek arises. As mentioned above, the Tum'as Mes is also not in the person's hand. Since neither the Tahor object nor the Tamei object is in the person's hand, the Tahor object remains Tahor mi'Safek for another reason: it is a Safek in the case of an object which is "Ein Bo Da'as li'Sha'el." The Tosefta is teaching that although a person threw the Tahor object and thereby provided the force that propelled it above the Tum'as Mes, since the Tahor object is not actually in the person's hand at the time it flies through the air, it is considered "Ein Bo Da'as li'Sha'el."
The Beraisa, on the other hand, may refer to a situation in which the person is holding the Tum'as Mes as the Tahor object flies above it. Therefore, it is deemed a Safek Tum'ah in the case of a person who is "Yesh Bo Da'as li'Sha'el." The Safek Tum'ah in such a case is judged stringently since it arises in Reshus ha'Yachid (as the entire Sugya deals with a Safek that arises in Reshus ha'Yachid).