Explanation #1 (Rashi): This itself is a decree (that she may not do Yibum), due to an orphan in her father's lifetime.

Objection (Ri): Rav Ashi gave this reason, and not Rava!

Explanation #2: Rather, this itself is a decree, lest people say that one did Yibum to his brother's divorcee, for everyone knows about the divorce, but not everyone knows that he remarried her, like Rava said above.

Observation: He does not literally mean a decree due to a decree, for this does not apply here. (For the same reason that she may not do Yibum, also her Tzarah may not. This is not a second decree!) Rather, it is only an Isur mid'Rabanan.

Explanation: Above (107b), R. Chananel explained in the name of a Gaon that one should not be Mekadesh an orphan until they bring a proof that she is a Bogeres, in order to distance from Mi'un.

Note: The Maharshal says that "Bogeres" is not precise. Once she is an adult (Na'arah) she cannot do Mi'un. Aruch l'Ner suggests that Tosfos is stringent like opinions that permit Mi'un after bringing two hairs (Nidah 52b). I do not understand this. That is when there was no Bi'ah since bringing hairs. Here, if he is Mekadesh an orphaned Na'arah, it is Kidushin mid'Oraisa!

Implied question: Rabanan enacted Nisu'in for an orphan, like it says below (112b)!

Answer: According to the Gaon, we must say that this is only when there is concern lest people conduct with her like Hefker.

However, there is no proof from here [that one should not marry a minor orphan], only that one should not persuade her to do Mi'un.

Implied question: Why can't we learn from what is written above, "Mi ha'Ish ha'Chafetz Chayim..." [that one should pursue Shalom]?

Answer #1: We could not learn from there. Perhaps it refers to the entire Parshah "guard your tongue from evil, veer from evil and do good...", i.e. the entire Torah.

Answer #2: There it says Tzedakah, life and honor, which are not written here;

In Kidushin (40a), we derive from that verse ("Rodef Tzedakah...") that one eats their Peros (of certain Mitzvos) in this world, and the principal is intact for him in the world to come.

Explanation: Some explain that we learn from a Gezeirah Shavah "Chidlah- Chidlah." It says here "v'Chi Sechdal Lindor", and it says there "Chidlu Lachem Min ha'Adam Asher Neshamah b'Apo Ki va'Meh Nechshav";

It says in Berachos (14a) 'do not read this "va'Meh", rather, "Bamah".

In Nedarim (22a), we expound the Gezeirah Shavah "Chidlah-Chidlah" [differently]. Shmuel taught that one who vows, even if he fulfills it, he is called a Rasha;

Citation (22a - R. Avahu): What is his source? It says here says "v'Chi Sechdal Lindor", and it says there "Sham Resha'im Chadlu Rogez."

Explanation (Ri): This is when they persuade him to convert, or accept him immediately.

Distinction: However, if they strive to convert, we should accept them, for we find that Avraham, Yitzchak and Yakov were punished for not accepting Timna, who came to convert;

She went and became a concubine to Elifaz ben Esav, and Amalek came from her, who afflicted Yisrael, like it says in Sanhedrin (99b).

Support: Also Yehoshua accepted Rachav the Zonah, and [Yisrael accepted] Na'amah and Rus the Mo'abite.

Implied question: In Shabbos (31a), it says that Hillel converted the man who said "convert me on condition that you will make me Kohen Gadol", and the man who said "[convert me] on condition that you teach me the entire Torah [while I stand on one foot]", even though they were not striving to convert!

Answer: He knew that in the end they would be total (sincere) converts, like happened in the end.

Question #1: It says in Yuma (87a) that anyone who brings merit to the Rabim, he will not come to sin;

It explains the reason there, lest people say that the Rebbi is in Gehinom, and the Talmid is in Gan Eden!

Question #2 (Ri): R. Meir learned from Acher, and even so Acher sinned!

Answer: Perhaps when he was evil from the beginning, before he taught others, this reason does not apply;

However, when he was good from the beginning, surely sin will not come through him.

Acher was evil from the beginning, like it says in Chagigah (15b) that musical instruments did not cease from his house, and books of Tzedukim would fall from his lap.

Explanation #1 (Rashi): Rashi explained here and in Sanhedrin (7a) that this refers to [the Sanhedrin in] Lishkas ha'Gazis.

Objection: It should have said 70 or 71!

Explanation #2: Rather, it refers to the 60 Ribo (10,000's) of Yisrael.

Inference: They are armed in judgment, like we expound in Sanhedrin (36a) from "va'Yachgor David Charbo" - he judged Naval in a Sanhedrin.

Even though regarding Torah it says Chagor Charbecha Al Yarech Gibor" [there, it refers to judgment].

Explanation: Even if we hold that one who is Mekadesh Achos Yevamah does not exempt the Yevamah, in any case when the Kidushin comes automatically, the Yevamah is exempted automatically.

Explanation: He can expel me through a Get against my will. I am better (stronger than) him, for I can do Mi'un until he does Bi'ah [after maturity];

Only mid'Oraisa she can do Mi'un. Mid'Rabanan, she cannot do Mi'un after bringing two hairs;

Citation (Nidah 52a - Mishnah): Until when can a girl do Mi'un? Until she brings two hairs.

This is even if he did not do Bi'ah. If he did Bi'ah, R. Yehudah would not argue [and permit] until there is more black (hair) than white;

This is like it says in the Gemara, that R. Yehudah agrees if he did Bi'ah.