The fourth perek of Massekhet Gittin begins on our daf and deals with a wide variety of rabbinic enactments that were made for the betterment of society: mipnei tikkun ha-olam.
As we have learned, a geṭ can be sent by a husband to his wife by means of a messenger. Since the geṭ is only meaningful if the husband desires that the divorce take place, in theory up until the time that the geṭ is actually delivered, the husband can choose to nullify the geṭ – even without the knowledge of the messenger and without notifying his wife. Thus, a situation could be created where the woman may enter unknowingly into an adulterous relationship, thinking that she can remarry, unaware that she is legally still her first husband’s wife. To avoid this situation, the Sages decreed that a person cannot nullify a geṭ unless he is in the presence of the messenger.
Having taught about the establishment of this enactment, the Mishnayot continue along a theme of tikkun ha-olam. These cases offer a broad range of public policy topics that the Talmudic sages felt needed clarification and strengthening in order to ensure that the mitzvot would be kept properly and to keep people from harming one another. The first such cases that are discussed are in the realm of divorce, but other topics are covered, as well.
As we have learned, the Mishna quotes Rabban Gamliel as forbidding a husband to nullify the geṭ unless he does so in the presence of the messenger. The Gemara asks how this nullification can be done and brings a disagreement between Rav Nahman, who permits it to be done in front of two people, and Rav Sheshet who requires a full beit din of three. Rashi explains this discussion as relating to the halakha as it existed prior to the establishment of Rabban Gamliel’s enactment, but most of the commentaries argue that the Gemara would not enter into a discussion of a law that was no longer applicable. Several explanations are given. Tosafot suggest that this discussion is based on Rabbeinu’s position that it was forbidden for a man to nullify the geṭ, but if he does it properly it will work. The Tiferet Ya’akov suggests that this is talking about a case where the husband wants to nullify the geṭ in the presence of the messenger, as is required, and the Gemara is teaching that it must be done in a formal manner before the court.