1) THE REASON NOT TO RETURN A GET THAT WAS FOUND
QUESTION: The Mishnah states that if one finds a lost Get, he may not give it to the woman whose name is written in it, because perhaps the husband wrote the Get but then decided not to give it, and thus it never took effect.
Why does the Mishnah give this as the reason for not returning a Get that was found? Even if the husband did not change his mind and intended to give the Get to his wife, the finder may not give it to her because the husband did not designate the finder as his Shali'ach to give the Get to his wife. In order for a Get to take effect, either the husband or his appointed agent must give the Get to the woman. (PNEI YEHOSHUA)
ANSWER: The PNEI YEHOSHUA answers that the Mishnah implies that in the case of a Get that is found, the woman herself claims that she already received the Get from her husband and then lost it. It is necessary for the Mishnah to teach that the Get is not returned to the woman because one might have thought that it should be returned to her since there is a greater likelihood that a Get that was found was lost by the wife than by the husband.
There are two reasons why it is more likely that the Get was lost by the woman after she had received it, and not by the man before he gave it:
1. There is no urgent need for a woman to keep her Get once she has received it and has become divorced. Hence, a woman is not careful to guard her Get punctiliously, and she easily could have lost it. In contrast, if the Get had been in the possession of the husband, it would have been very unlikely that he would have lost it, since he has a reason to be very careful about guarding the Get and preventing its loss, lest it come into the hands of his wife without his consent. Therefore, it is more likely that the Get was lost by the woman.
2. There is a general rule that a person does not hurry to bring upon himself misfortune. Hence, it is unusual for a man to write a Get and to hold on to it for a long time. Rather, a man waits to write a Get until the moment before he plans to give it to his wife. Since the Get can be assumed to have been in the husband's possession for only a very short time, it is reasonable to assume that it was lost by the wife after she received it..
The Mishnah therefore must teach that although it is more likely that the Get was lost by the woman, the finder should not give her the Get, because there is still reason to fear that it was lost by the husband. The Mishnah mentions the concern that the husband "decided not to give it" to explain how it is logical to assume that the husband might have lost it: perhaps he was not careful to guard it because he decided not to give it, or perhaps he placed it among his other possessions because he decided not to give it.

18b----------------------------------------18b

2) APPLYING THE RULE OF "KAROV" TO A GET THAT WAS FOUND
QUESTION: The Gemara relates that a Get was found in the court of Rav Huna. The name of the place written in the Get was "Sheviri." Rav Huna suggested that it not be returned to the Shali'ach who claimed that he lost it, because there might be two cities called "Sheviri." RASHI explains that since there might be another city "Sheviri," Rav Huna was concerned that there might be a couple in the other city of Sheviri with the same names as the couple for whom the Shali'ach was supposed to deliver the Get, and the Get that was found may have been written for the other husband with this name and lost by him. Hence, the Get cannot be given, for it might have been written for someone else.
There is a rule that states that in cases of a doubt, the doubt may be resolved (where applicable) by following "Karov." This means that the item in doubt is assumed to have come from the nearest place. In this case, Rav Huna knew that there was at least one Sheviri -- the city from which the Shali'ach brought the Get. Even though there might have been another Sheviri somewhere else, farther away, Rav Huna should have assumed that this Get came from the Sheviri that was closer, because of the rule of "Karov." Why, then, did Rav Huna suggest that the Get not be returned out of concern that it may have been written for someone else by the same name in a city farther away? (CHASAM SOFER, EH 2:12, TORAS GITIN EH #132)
ANSWERS:
(a) The SEFER NEFESH CHAYAH answers that mid'Oraisa the rule of "Karov" would resolve the concern that the Get was lost by someone with the same name, and the Get should be returned to the Shali'ach who claims that he lost it. Rav Huna, however, suggested that the Chachamim may have decreed that the Get may not be given back anyway. The Chachamim may have been concerned that other people might cast aspersions on the validity of the Get (see TOSFOS to 20b, DH Isura) and suspect that it was written for someone else with the same name, in the other city of the same name. Such aspersions would cause the woman's children from her second marriage to be rumored to be Mamzerim, and therefore the Chachamim decreed that a Get that was found may not be given to the woman.
(b) The SEFER MAYANEI HA'CHOCHMAH answers that Rav Huna was not concerned merely that two cities with the same name might exist. The rule of "Karov" would apply to such a case. Rather, Rav Huna was concerned that there might be many cities of the same name, in which live many people with the same names as those written in the Get. Hence, there would be a "Rov" which counters the "Karov," and the Gemara in Bava Basra (24a) teaches that the Rov overrides the Karov in such a situation.
(c) The CHASAM SOFER answers that the Gemara in Beitzah (10b; see RASHI there) teaches that when many people from different parts of the world gather in a single place, the principle of "Karov" does not apply. Since many people from many places converge on this place frequently, all of the places are considered "Karov."
Here, too, the Get was found in the Beis Din of Rav Huna. Rashi writes that everyone was accustomed to coming to him for judgment, and thus his Beis Din was considered a place frequented by caravans (Shayaros Metzuyos). Since many people came to his Beis Din from all parts of the land, he could not rule in accordance with the principle of "Karov," for in that place people from nearby and from far away frequently gathered. (I. Alsheich)