THE FINAL RULING
Answer: Rather, both Rav and R. Nasan follow estimation. We understand the one who said that the Halachah follows R. Elazar ben Azaryah;
The other says that the Halachah does not follow him because here, we assess that he gave Tosefes due to the feeling of closeness, which already came (before Nisu'in).
(Rav Chanina): The Halachah follows R. Elazar (ben Azaryah).
R. Yanai: Do not teach this in the Beis Medrash! The Halachah follows Chachamim.
(Rav Yitzchak bar Avdimi): The Halachah follows R. Elazar.
(Rav Nachman citing Shmuel): The Halachah follows R. Elazar.
(Rav Nachman himself): The Halachah does not follow R. Elazar.
Chachamim of Neharda'a: Rav Nachman says, the Halachah follows R. Elazar;
Even though Rav Nachman cursed any judge who will rule like R. Elazar, the Halachah follows R. Elazar.
In practice, the Halachah follows R. Elazar.
WHEN IS THE ADDITION TO THE KESUVAH ACQUIRED?
Question (Ravin): If there was Chupah but no Bi'ah, does she receive the Tosefes?
Does the dearness of Chupah acquire?
Or, does the dearness of Bi'ah acquire?
Answer (Rav Yosef's Beraisa): He wrote the Tosefes only for the dearness of the first night.
Granted, if the dearness of Chupah acquires, this is only the first night.
Question: If the dearness of Bi'ah acquires, this is not only the first night!
Question: (You learn from here that the dearness of Chupah acquires.) Chupah is not only at night!
Counter-question: Do you say that Bi'ah is only at night?!
(Rava): One may have Bi'ah during the day in a dark house.
Answer: The Beraisa teaches that it is normal to have Bi'ah only at night.
Answer: Since Chupah is for Bi'ah, it is normal to do it at night.
Question (Rav Ashi): If she entered Chupah and became Nidah, what is the law?
If the dearness of Chupah acquires, is this only a Chupah fitting for Bi'ah?
Or, perhaps we do not distinguish!
The question is unsettled.
WRITING A RECEIPT
(Mishnah - R. Yehudah): He may write to a virgin... (and she writes that she received half).
Question: R. Yehudah holds that we do not write receipts!
(Mishnah - R. Yehudah): If one paid part of his debt, we destroy the first document and write a new one for the remaining debt;
R. Yosi says, we write a receipt.
Answer #1 (R. Yirmiyah): The receipt is written in the Kesuvah itself (so there is no concern lest he lose the receipt and she will collect the entire amount).
Answer #2 (Abaye): The receipt need not be written in the Kesuvah itself!
Regarding a borrower who paid; if he takes a receipt he might lose it and have to pay again;
Here, the husband did not pay anything. She merely said that she received part. If he guards the receipt, fine; if not, he caused his own loss!
Question: Granted, Abaye did not answer like R. Yirmiyah because the Mishnah does not say that the receipt is in the Kesuvah;
Why didn't R. Yirmiyah learn like Abaye?
Answer: We decree not to write a receipt here lest people do so regarding a loan.
STIPULATIONS CONTRARY TO TORAH
R. Yehudah implies that she must write that she received 100. It is not enough for her to say so.
Question: This is a monetary matter, and R. Yehudah holds that such stipulations work!
(Beraisa - R. Meir): If a man was Mekadesh a woman on condition that he is exempt from giving to her food, clothing or Onah (the proper frequency of Bi'ah), the Kidushin takes effect and his stipulation is void;
R. Yehudah says, in monetary matters the stipulation is valid.
Answer: R. Yehudah holds that Kesuvah is an enactment mid'Rabanan, and Chachamim strengthened their words more than Torah laws.
Question: An enactment mid'Rabanan allows a husband to eat the Peiros of his wife's land, yet this was not strengthened!
(Mishnah - R. Yehudah): A man may always eat the Peiros of his wife's land unless he writes that he has no rights to her property, its Peiros, and the Peiros of its Peiros ad infinitum.
We hold that here, 'writes' really means 'says'.
Answer (Abaye): All wives have a Kesuvah, but not all have Peiros; Chachamim strengthened their enactment regarding Kesuvah, which is common, but not regarding Peiros, which are uncommon.
Question: Merchants are common, yet (R. Yehudah holds that) Chachamim did not strengthen their enactment (of Demai, to suspect that merchants scheme to lie for each other)!
(Mishnah): If two merchants entered a city, and one said 'My produce is Chadash (new), and my friend's is old. Mine is untithed, and my friend's is tithed', they are not believed;
R. Yehudah says, they are believed.
Answer #1 (Abaye): A Vadai enactment mid'Rabanan was strengthened, but not one that is based on Safek.
Answer #2 (Rava): Chachamim were lenient about Demai (because most Amei ha'Aretz tithe).
STIPULATIONS TO REDUCE THE KESUVAH
(Mishnah - R. Meir): Anyone who reduces the Kesuvah from 200...
Inference: Anyone connotes that even if he stipulated, the stipulation is void and the Kesuvah really is 200, but since she thinks that it is not 200, the Bi'ah is Znus.
Question: R. Meir holds that a stipulation contrary to Torah is void. This implies that a stipulation contrary to a mid'Rabanan law is valid!
Answer: R. Meir holds that the Kesuvah is mid'Oraisa.
(Beraisa - R. Meir): If anyone reduces the Kesuvah of a virgin from 200, or of a non-virgin from 100, the Bi'ah is Znus;
R. Yosi says, he is permitted;
R. Yehudah says, he may write 200 to a virgin or 100 to a non-virgin, and she writes that she received half.
Question: R. Yosi forbids!
Contradiction (Beraisa): We do not designate Metaltelim (to be the sole source of payment) for a Kesuvah. This is an enactment to fix matters.
Objection (R. Yosi): How does this fix things? Their value is not fixed, and they depreciate!
Question: Also the first Tana does not allow designating Metaltelim!
Answer: Rather, the first Tana distinguishes: Metaltelim may be used only if he accepted Acharayos (responsibility to pay from other property if they will be lost);
R. Yosi forbids even if he accepted Acharayos. Their value is not fixed, and they depreciate!
Summation of contradiction: R. Yosi is concerned lest they depreciate. All the more so he forbids stipulating to definitely decrease the Kesuvah!
Answer: This is not difficult! She does not know that Metaltelim will depreciate, and does not intend to pardon the loss. Here, she knowingly pardoned the decrease!