YEVAMOS 67 - Dedicated l'Iluy Nishmas Hershel Avraham ben Simcha Yosef z'l by his daughter and son in law.

1) THE STAKE OF A FETUS IN THE ESTATE OF HIS FATHER
QUESTION: The Beraisa states that if a Kohen dies and leaves behind sons and a wife who is pregnant, the Kohen's Avdei Tzon Barzel may not eat Terumah due to the portion of the Avadim in the possession of the fetus. RASHI (DH Avdei) explains that the Beraisa means that since the fetus owns part of the Avadim and it is unknown which of the Avadim eventually will be given to him, the Avadim may not eat Terumah.
Rashi's words are perplexing. Rashi explains that since the fetus might receive partial ownership of the Avadim after the estate is divided, none of the Avadim may eat Terumah. This implies that if the fetus does not receive any of the Avadim, but receives some other part of the estate instead, the Avadim may eat Terumah. Accordingly, Rashi's explanation follows the opinion which maintains "Yesh Bereirah." "Bereirah" refers to a situation in which a future event determines a retroactive change of status. According to those who maintain "Yesh Bereirah," brothers who divide an inherited estate have the status of absolute heirs ("ha'Achin she'Chalku, Yorshin Hen"). Hence, their apportionment of the property clarifies retroactively that each brother was the true heir to that share of the property from the time their father died. (This is in contrast to those who maintain "Ein Bereirah," who maintain that the brothers' division of the property is considered a "trade" or exchange of portions with each other.)
Why does Rashi explain the Beraisa according to the opinion which maintains "Yesh Bereirah"? With regard to any Torah matter (such as the Isur d'Oraisa that forbids a Zar from eating Terumah), the Halachah is in accordance with the opinion which maintains "Ein Bereirah." Rashi should have given a more basic explanation: since the fetus inherits a portion of the estate and right now the estate is not yet divided, the fetus owns a small part of each Eved. Since the fetus owns a small part of each Eved, none of the Avadim may eat Terumah. (RASHBA)
ANSWERS:
(a) The RASHBA suggests that perhaps Rashi rules "Yesh Bereirah" even in the case of a Torah matter, contrary to the conclusion of the Gemara in Beitzah (38a). (Alternatively, Rashi may intend to explain why the Eved may not eat even Terumah d'Rabanan.)
(b) The Rashba assumes that if the Halachah is "Ein Bereirah," the fetus owns a share of every part of the estate. However, the Gemara in Gitin (47b) discusses the case of a field owned jointly by a Jew and a Nochri. The Gemara says that the produce which grows in the field is a complete mix of Tevel and Chulin. TOSFOS there (DH Tevel) explains that even if one separates Terumah from one part of the field on behalf of another part of the field, his act is not effective because perhaps the part that he separates does not belong to the Jew but to the Nochri (in which case he has separated Terumah from fruit that was exempt on behalf of fruit that was obligated in Terumah, and such fruit cannot become Terumah).
Similarly, in the case of the Gemara here, perhaps the fetus does not own a share of every Eved. Rather, he owns an unspecified portion of the estate in general. Accordingly, Rashi means that since it is possible that the fetus owns a part of this Eved now, the Eved may not eat Terumah. Rashi does not mean that in the future the fetus might own this Eved, but rather perhaps the fetus owns this Eved now.
However, this approach does not fully answer the question. Rashi in Gitin disagrees with Tosfos and writes that one may separate Terumah from the fruit of one part of the field on behalf of the fruit of the other part of the field, because every individual stalk is divided between the owners and thus half of every stalk belongs to the Jew. That is, if the Halachah is "Ein Bereirah," each owner has partial ownership of each and every part of the property until the field is divided. Accordingly, Rashi here should have been consistent with his opinion in Gitin. He should have explained that the fetus owns part of each Eved, and not that it is unknown which portion the fetus will inherit later.
(c) Rashi, however, may be consistent with his own opinion expressed elsewhere with regard to the meaning of "Ein Bereirah." Most Rishonim explain that "Ein Bereirah" means that one cannot effect a Kinyan, or a change of status, now based on the outcome of an event in the future. If one attempts to do so, the Kinyan does not take effect at all. (See RAN to Nedarim 45b.)
Rashi understands "Ein Bereirah" differently. Rashi explains in many places (see Rashi to Chulin 14a, DH Osrin; Gitin 24b, DH l'Eizo; Gitin 73b, DH u'Meshani) that the change which the person wants to take effect does occur, but the way in which it transpires remains unclear. For example, when a person has two fruits of Tevel and says, "If it rains tomorrow, the one on the left will be Terumah for the one on the right, but if it does not rain tomorrow, the one on the right will be Terumah for the one on the left," according to Rashi one of the two fruits certainly becomes Terumah, but which one it is remains in doubt. According to the way most Rishonim understand "Ein Bereirah," neither fruit becomes Terumah because "Ein Bereirah" dictates that a present status cannot take effect based on a future event. According to Rashi, however, one of the fruits is Terumah, but exactly which fruit is Terumah remains in doubt. The change of status is effected, but the details that depended on the future event remain in doubt even after the future event occurs. In practice, a Kohen is permitted to eat both pomegranates, because one of them is Terumah and the other is Chulin, and neither one is Tevel.
Rashi understands that when one makes a Kinyan dependent on a future event, the Kinyan does not depend on what actually happens in the future (since the Kinyan must take place now). Rather, it depends on what is destined -- at this point in time -- to happen in the future. Even if it actually does rain tomorrow (in the example above), those who rule "Ein Bereirah" maintain that the Kinyan does not take effect because it was impossible to know on the previous day, when the condition was stipulated, that it was destined to rain the next day. (TOSFOS Eruvin 37b, DH Ela, cites a similar ruling in the name of MAHARI. See CHIDUSHEI REBBI AKIVA EIGER in Ma'arachah #4 to Eruvin 38a, DH v'Nir'eh d'Vein. See also Insights to Eruvin 37:1, Yevamos 67:1, Gitin 25:1, Gitin 73:2, Zevachim 3:1, and Chulin 14:3.)
Accordingly, Rashi here does not explain the Sugya according to the opinion that "Yesh Bereirah." Rather, Rashi follows the Halachic opinion that "Ein Bereirah." Since the Halachah is "Ein Bereirah," it is impossible to determine which of the Avadim was destined to belong to which of the heirs based on the way they divide the Avadim at a later time. This is the intent of Rashi when he writes that it is not known "which Eved will come into his possession."
(When Rashi in Gitin writes that each owner has an equal portion according to those who maintain "Ein Bereirah," he is discussing a field which was still owned in partnership and was not yet divided. According to Rashi (Gitin 47b, DH Shel Yisrael), when the owners eventually divide the field their division cannot determine retroactively which portion belonged to whom at the time the grain was grown, because "Ein Bereirah.")

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