Gemara

(Beraisa #1): Reuven came before R. Tarfon for Edus Ishah.

R. Tarfon: How do you know that the man died?

Reuven: We were travelling together; a troop chased us. He broke off an olive branch and chased them away. I said 'Aryeh (lion), your strength should be increased!'

Aryeh: How did you know my name? In my city, they call me Yochanan b'Rebbi Yonason Aryeh, of the village Shichya.

Reuven: Later, he fell sick and died.

R. Tarfon permitted Aryeh's wife to remarry.

Contradiction: R. Tarfon requires Drishah v'Chakirah (interrogation of witnesses)!

(Beraisa #2): R. Tarfon asked a witness how he knew that the man died.

Reuven: We were travelling... he chased a troop away...

Aryeh: You guessed my name! In my city, they call me Yochanan b'Rebbi Yonason Aryeh, of the village Shichya.

Reuven: Later, he fell sick and died.

R. Tarfon: Didn't you say Yochanan b'Rebbi Yonason of the village Shichya Aryeh?

Reuven: No, I said Yochanan b'Rebbi Yonason Aryeh, of the village Shichya.

R. Tarfon tested Reuven two or three times. When he saw that his story was consistent, he permitted Aryeh's wife to remarry.

Resolution: Tana'im argue about whether or not interrogation is required (and about R. Tarfon's opinion):

(Beraisa): We do not interrogate witnesses testifying to permit a woman to remarry;

R. Akiva and R. Tarfon say, we interrogate them. (The Meforshim have this text. Our text attributes the first opinion to R. Akiva.)

Tana'im argue about R. Chanina's law:

(R. Chanina): Mid'Oraisa, both monetary and capital cases require interrogation - "You will have one law";

Chachamim exempted monetary cases from interrogation, lest people be afraid to lend money (lest the witnesses be disqualified).

The first Tana (in the Beraisa) considers Edus Ishah to be a monetary case, since she receives her Kesuvah (if we allow her to remarry);

R. Akiva and R. Tarfon hold, since we permit a married woman to remarry, it is like a capital case.

Rishonim

Rif and Rosh (16:13): We do not require Drishah v'Chakirah for Edus Ishah.

Nimukei Yosef (DH Garsinan): Drishah is questions about what happened. Chakirah is asking what day and hour (etc.) The Ge'onim rule that Edus Ishah does not require Drishah v'Chakirah. The concern lest we discourage loans does not apply to the Kesuvah, for women want to marry more than men do. Nevertheless, we do not require Drishah v'Chakirah regarding the Kesuvah, for in many places Chachamim were concerned for Chen (encouraging women to marry). This is why she may collect a Kesuvah from orphaned minors, sell property outside of Beis Din, and other leniencies.

Question: The lenient opinion does not require Drishah v'Chakirah for Edus Ishah because she receives her Kesuvah, so it is like monetary cases. Edus Ishah is primarily to permit marriage, a capital case. Only afterwards she receives her Kesuvah. We should say that without Drishah v'Chakirah she may not remarry, and she will not get her Kesuvah!

Answer (Nimukei Yosef citing Ramban): Nowadays, Edus Ishah is more like a monetary case than a capital case. Most women have a Kesuvah. Therefore, we always treat it like a monetary case, even for an Arusah who has no Kesuvah.

Rambam (Hilchos Gerushin 13:15): Even if a witness says that he heard that Ploni died from a woman who heard from a slave, he is Kosher. Ploni's widow may remarry based on this. If the witness or woman says that he saw Ploni dead, we ask how he saw and how he knows that he was dead. If he testified about something that usually causes death, she may not remarry. He must have seen that he was Vadai dead, without any doubt.

Magid Mishneh: When the witness heard from someone else, we cannot ask about the death. When he says that he himself saw, we do. Even the first Tana exempts only from Drishah v'Chakirah, but he agrees that we ask about how he died. If not, he should have said 'we do not check Edei Ishah at all'. Also, we can be lenient only where Chachamim explicitly permitted. Perhaps the witnesses err about situations that Chachamim do not consider to be death.

Questions: The Magid Mishneh could have brought a better proof! We established Beraisa #1 like the opinion that does not require Drishah v'Chakirah, nevertheless R. Tarfon asked how the man died! Also, we exempt from Drishah v'Chakirah because we made Edus Ishah like monetary cases. In monetary cases we ask the witness how he knows that Ploni owes!

Answer (Lechem Mishneh): In Beraisa #1, perhaps the widow brought the witness and the witness was silent, therefore R. Tarfon needed to ask him. The Rambam (Halachos 28,29) holds that the primary reason we exempt from Drishah v'Chakirah is not because it is like monetary cases.

Rambam (28): We do not interrogate Edei Ishah with Drishah v'Chakirah. Chachamim were not stringent about this. They were lenient in order to permit Agunos.

Rivash (266 DH v'Chen Ein, cited in Mishneh l'Melech): No one requires Drishah v'Chakirah for Gitin and Kidushin. These are common, so we are concerned for Ne'ilas Deles (discouraging marriage). Edus Ishah is uncommon, therefore one opinion requires Drishah v'Chakirah without concern for Ne'ilas Deles.

Rambam (29): Do not be troubled by why Chachamim were so lenient to permit Ervah through Pasul witness, Ed mi'Pi Ed, written testimony and without Drishah v'Chakirah. The Torah was particular about two witnesses and laws of testimony only regarding something that can be known only through witnesses, e.g. Ploni lent to or killed Almoni. The Torah was particular about something that can be known without the witness that he will be unable to deny if he lied, e.g. when he says that Ploni died. It is far-fetched that someone would lie about such a matter. Therefore, Chachamim were lenient so Benos Yisrael will not be Agunos.

Ra'avad: Alternatively, it is because she will check carefully before remarrying.

Question (Lechem Mishneh): The Rambam says that because it is Avid l'Igluyei, Chachamim could be lenient to permit Agunos. This implies that when it is not Avid l'Igluyei, we are not lenient. The Gemara says that they were lenient about Drishah v'Chakirah because it is like monetary cases! It seems that this applies to all cases of Gitin and Kidushin, for they pertain to Kesuvos, like the Nimukei Yosef says. Perhaps the Rambam holds that the Gemara did not give the primary reason. We are not concerned for discouraging marriage. Because women want to marry more than men do, Chachamim said that a Kesuvah is collected from lowest quality land. Therefore, when it is not Avid l'Igluyei, Drishah v'Chakirah is required. This requires investigation.

Answer (Gra EH 17:81): The Rambam teaches that we are not stringent (to interrogate) when we can be lenient, due to Agunah.

Poskim

Shulchan Aruch (EH 17:21): We do not interrogate witnesses for Edus Ishah with Drishah v'Chakirah. Even if they contradicted each other in Bedikos (questions about the death), they are Kesherim.

Source (Teshuvas ha'Ran 47, cited in Beis Yosef DH v'Chosav ha'Ran): If Edei Ishah contradicted each other in Bedikos, presumably they are Kesherim, just like in monetary cases. If David testified about the death of Avraham, Leah's Yevamah, and Moshe testified about the death of Shmuel, Leah's Yevamah, and we know that her husband had only one brother, she is permitted.

Chelkas Mechokek (39): As long as the contradiction was not about Chakiros (the precise time and place), on which Hazamah depends, the testimony is Kosher.

Beis Shmuel (63): We require Drishah v'Chakirah to forbid a woman to her husband (due to Zenus - 11:4). Even if she is permitted and has a Kesuvah, she does not get it now, so it is not a monetary case. Permitting a widow is a capital case, but nowadays there is no Misas Beis Din, so it is considered monetary due to the Kesuvah.

Rema: It is forbidden to interrogate much unless there is suspicion for fraud. Then, we require interrogation.