Question: Perhaps "Bas Eshes Avicha" comes to exclude a sister from Chayavei Lavin!

Answer (Rav Papa): Kidushin takes effect on Chayavei Lavin:

Question: "Ki Sihyena l'Ish Shtei Nashim ha'Achas Ahuvah veha'Achas Senu'ah" - would one really think that this affects inheritance?!

Answer: Rather, the wives are "beloved" and "hated" in their marriages (the latter is forbidden), and it says Sihyena (there is Kidushin)!

Question: Perhaps "Bas Eshes Avicha" comes to exclude a sister from Chayavei Kerisos!

Answer (Rava): "Ervas Achoscha Vas Avicha O Vas Imecha Moledes Bayis O Moledes Chutz" - the Torah calls her your sister, whether or not your father may keep her mother.

Suggestion: Perhaps it comes to include a sister from a Shifchah or Nochris!

Rejection: "Bas Eshes Avicha" teaches that her mother could be married to your father.

Question: (The verses do not specify what to include and exclude.) Why do we include sisters from Chayavei Kerisos and exclude sisters from a Shifchah or Nochris, and not vice-versa?

Answer: It is more reasonable to include children from Chayavei Kerisos, since they can be married to others.

Objection: To the contrary! A Shifchah or Nochris, if she converts, can marry your father!

Answer: When she converts, she is a new entity.

Chachamim exclude a sister from a Shifchah or Nochris from "The woman and her children will be to her master" (they are slaves. At this point we are thinking that we learn both from the verse.)

R. Yosi b'Rebbi Yehudah uses one verse to teach about a Shifchah, and one for a Nochris. Both are needed:

If there was a verse only about a Shifchah, we would have thought that this is because slaves have no lineage, but since a Nochris has lineage, her daughter is considered a sister!

If there was a verse only about a Nochris, we would have thought that this is because she is not commanded in Mitzvos; but since a Shifchah is commanded in Mitzvos, her daughter is considered a sister!

Question: We showed how Chachamim learn about a Shifchah. What is their source regarding a Nochris?

Suggestion: We learn from a Shifchah.

Rejection: We showed that one cannot learn from a Shifchah!

Answer (R. Yochanan): "(...Do not marry your daughter to a Nochri.) For He will veer your son away from Me" - your son from a Yisraelis is called your son, but your son from a Nochris is called her son. (Rashi - He, your Nochri son-in-law, will veer your son, i.e. grandson. Since this grandson is from a Yisraelis (your daughter), he is called your son (he is a Yisrael). It does not say (about the Reisha of the previous verse, "Do not marry your son to a Nochris") that she (your Nochris daughter-in-law) will veer your son, for your grandson from a Nochris is not called your son (he is a Nochri). Tosfos (17a) says that "He will veer your son" refers to the Reisha. He, your son's Nochri father-in-law, will veer your son (from your Yisraelis wife) from Me. The Torah is not concerned about your grandson from a Nochris, for he is a Nochri.)

(Ravina): We learn that your daughter's son fathered by a Nochri is called your son. (Tosfos - here the Torah did not express concern (only) about your daughter, for here we are concerned also about the grandson. He is a Yisrael, like his mother.)

(Version #1) Suggestion: Ravina holds that the child of a slave or Nochri from a Yisraelis has proper lineage.

(Version #2) Suggestion: Ravina holds that the child of a slave or Nochri from a Yisraelis is a Mamzer. (Since the child is a Yisrael, Mamzerus applies!) (end of Version #2)

Rejection: The child is not a Mamzer, nor is his lineage proper. He is called a Yisrael Pasul (to Kehunah).

Question: "Do not intermarry with them" discusses the seven Kena'ani nations! (What is the source for other nations?)

Answer: "He will veer" includes anyone that makes veer (i.e. all Nochrim).

Question: This is like R. Shimon, who derives laws based on (our understanding of) the purpose of Mitzvos. What is Chachamim's source?

Answer: The Chachamim who disagree with R. Yosi bar Yehudah hold like R. Shimon.

(Mishnah): If a man was Mekadesh one of two sisters and does not know which, he divorces both;

If he died leaving one brother, he does Chalitzah to both. If he left two brothers, one does Chalitzah and the other Yibum. If both did Yibum, they may keep their wives.

If Reuven and David were Mekadesh Rachel and Leah (sisters) and each is unsure whom he was Mekadesh, each divorces both;

If each died leaving one brother, each brother does Chalitzah to both. If Reuven left one brother and David left two, Reuven's brother does Chalitzah to both. One of David's brothers does Chalitzah and one does Yibum. If both did Yibum, they may keep their wives.

If Reuven and David have two brothers each, one brother of Reuven does Chalitzah with (e.g. Leah) and one brother of David does Chalitzah with Rachel. Reuven's other brother does Yibum with Rachel and David's other brother does Yibum with Leah;

If both of Reuven's brothers did Chalitzah, Shimon's brothers may not both do Yibum. One must do Chalitzah and the other may do Yibum. If both did Yibum, they may keep their wives.

(Gemara) Suggestion: This teaches that Kidushin she'Ein Mesurin l'Vi'ah (Tosfos - the Kidushin itself forbids Bi'ah with her, e.g. because we are unsure if he was Mekadesh her sister) takes effect!

Rejection: No. At the time of Kidushin, he knew which he was Mekadesh. Later, he became unsure.

The wording of the Mishnah proves this. It says 'he does not know', and not 'it is not known'.

Question: If so, what is the Chidush?

Answer: When he dies leaving two brothers, one must do Chalitzah before the other does Yibum. If not, (perhaps) he has Bi'ah with the sister of his (true) Yevamah.

(Mishnah): If two men were Mekadesh two sisters...

Suggestion: This teaches that Kidushin she'Ein Mesurin l'Vi'ah takes effect!

Rejection: No. At the time, each knew which he was Mekadesh. Later, they became mixed up.

Support: It says 'he does not know', and not 'it is not known.'

Question: If so, what is the Chidush?

Answer: If one left one brother and the other left two, the lone brother does Chalitzah to both.

Objection: We learned this already!

Answer: We would have thought that we forbid in this case due to the case when each has only one brother.

The lone brother must do Chalitzah before the Yibum, for perhaps the woman doing Yibum is the Yevamah of the lone brother.

(Mishnah): If each left two brothers...

Question: What does this teach that we have not already learned?

Answer: One might have thought that we decree not to do Yibum, lest they do Yibum before Chalitzah.