Question: We must expound to learn about all the Arayos!

Answer: Granted, we must expound to learn about Yibum (that they are exempt and that they exempt the Tzarah), but the Isur (even not in a situation of Yibum) of the other Arayos is explicit;

The Isur of Bito is known only through expounding.

(Rava): We learn the Isur of Bito through (Gezeirah Shavah,) "Henah-Henah" and "Zimah-Zimah".

Question: If the Tana prefers what is learned by expounding, the case of Achos Ishto (for which the law of Yibum is most explicit) should be taught last!

Answer: Once the Tana started listing sisters, he also taught Achos Ishto.

Objection: If so, let him teach sisters at the end!

Answer #2 (to question 3a, Daf 2b): Rather, we teach the closest relatives first.

First we teach about the Yavam's own relatives, i.e. Bito, his daughter's daughter and his son's daughter;

After teaching about three generations below him, we teach about three generations below his wife;

After three generations below his wife, we teach about three generations above his wife.

We then teach about his sister and maternal aunt, which are his own relatives.

Once we discuss sisters, we teach about Achos Ishto.

It would have been proper to teach about his daughter-in-law before Eshes Achiv she'Lo Hayah b'Olamo, since the latter is not forbidden because of her closeness to Shimon.

However, once we list fraternal Isurim, we include Eshes Achiv she'Lo Hayah b'Olamo.

Question: Why did the Tana say that she exempts her Tzaros from Yibum and Chalitzah? She forbids her Tzaros!

Answer #1: Had he said that she forbids Yibum, we would have thought that Chalitzah is required.

Objection: He could have said that she (also) forbids Chalitzah!

Question: Why should Chalitzah be forbidden (even if it is not needed)?

Answer: If we allow Chalitzah (when it is unnecessary and Yibum is permitted), perhaps people will come to do Yibum!

Answer #2: Since the Tzarah is forbidden only regarding Yibum, but is permitted when there is no Mitzvah, we taught 'she exempts'.

Question: Why must it say that she exempts from Chalitzah and Yibum? It suffices to say that she exempts from Yibum!

Answer: If so, we would have thought that she does Chalitzah.

Rather, it teaches that whoever is obligated to do Yibum may do Chalitzah (instead), and whoever may not do Yibum does not do Chalitzah.

Question: The Mishnah should (list the primary Mitzvah first and) say that she exempts from Yibum and Chalitzah. Alternatively, it should just say that she exempts from Chalitzah (and obviously, from Yibum)!

Answer: The Mishnah is like Aba Sha'ul, who says that Chalitzah is preferable to Yibum.

Question: Twice, the Mishnah says that there are 15 cases. What other possibilities does it come to exclude?

Answer #1: It excludes (a Sotah and Ailonis,) the cases of Rav and Rav Asi (Daf 11a and 12a. Our Tana agrees that they do not do Yibum, but he holds that they do not exempt their Tzaros.)

Question: According to Rav and Rav Asi (who say that they exempt their Tzaros), what two cases are excluded?

Answer #2: If each agrees to the law of his colleague, we exclude the Tzaros of Mema'enes (a Mema'enes) and of Machazir Gerushaso (a woman who transgressed and remarried her ex-husband after marrying someone else in between).

If Rav and Rav Asi disagree with each other, each excludes the case of his colleague and Tzaras Mema'enes or Tzaras Machazir Gerushaso.

Question: According to Rav and Rav Asi, why didn't the Mishnah list their cases?

Answer: This is because Tzaras Tzarah does not apply in their cases. (Sotah and Ailonis are forbidden to all the brothers, so their Tzaros cannot do Yibum with any brother.)

Question: What is the source of the law of the Mishnah?

Answer #1 (Beraisa) Question: What do we learn from "V'Ishah El Achosah Lo Sikach Litzror (to be a Tzarah) Legalos Ervasah Aleha b'Chayehah"?

Answer: It says "Yevamah Yavo Aleha". One might have thought that this applies to Arayos (i.e. if his brother's wife was related to him in an additional way, e.g. Bito);

A Gezeirah Shavah teaches just like "Yevamah Yavo Aleha" discusses Yibum, also the Isurim of Arayos apply even in a case of Yibum.

Question: This forbids Yibum with Arayos. How do we know that Yibum with Tzaras Ervah is also forbidden?

Answer: It says "Litzror" (to include Tzaros).

Question: How do we know that the Tzarah of the Tzarah is forbidden?

Answer: It says "Litzror" instead of 'Latzor' (the extra 'Reish' comes to include).

Question: This teaches about when the Yevamah is the sister of the Yavam's wife. How do we know that this applies to other Arayos?

Answer: Achos Ishto is Arayos punishable by Kares (b'Mezid) and Chatas (b'Shogeg) and she may not do Yibum. All such Arayos may not do Yibum.

Question: This forbids the Arayos to do Yibum. What is the source to forbid their Tzaros?

Answer: Achos Ishto is Ervah punishable by Kares and Chatas, and she and her Tzarah may not do Yibum. The same applies to all such Arayos.

This is the source that the 15 cases of the Mishnah exempt the Tzaros, Tzaros of the Tzaros, ad infinitum from Chalitzah and Yibum.

Suggestion: Perhaps the six Arayos (of the Mishnah 13A) which are more stringent should also exempt the Tzaros!

Rejection: No. Shimon's Achos Ishto was able to marry his brother. We do not learn to the six Arayos that cannot marry any (paternal) brother of Shimon!

This is because the law of a Tzarah applies only to co-wives of a brother.

Question: This forbids Yibum. Where do we know the punishment if they do Yibum?

Answer: "All that do any of these abominations... (will get Kares)".

Inference: Had the Torah not written "Aleha" to forbid Yibum with Achos Ishto, we would permit Yibum.

Question: What is the reason?

Answer #1: An Aseh is Docheh (overrides) a Lav. (Additional answers will be given starting on Daf 7a. Answers to Question #1 (below) begin on Daf 5b.)

Question #1: This applies only to a plain Lav, but not to a Lav punishable by Kares!

Question #2: What is the source that an Aseh overrides a plain Lav?