The Rule of All or Nothing
“Until Rabbi Akiva came and taught: A neder that is partially permitted is completely permitted.”
This teaching, in the first mishna on our daf, changed the way that earlier authorities taught and ruled. Previously, if a person made a neder to forbid something, he would be asked if he would have still made the neder if he had known that sorrow was forbidden on Shabbat and Yom Tov, which would lead to permitting his neder on those days but not on the rest of the days of the week. Rabbi Akiva came along and ruled that “since the neder was partially permitted, it was totally permitted.” (Shulchan Aruch Yoreh De’ah 129:1)
One explanation for Rabbi Akiva’s rule is that it is logical that the person who made the neder wanted it to be valid only if all aspects of it would be valid. (Rabbeinu Asher) The Yerushalmi Talmud derives the rule in our mishna from the verse, “as all that goes out from his mouth (his neder that he spoke) he will do.” (Bamidbar 30:3) This implies that the neder exists only if all of the neder exists. (Rabbeinu Nissim)
An Agent of a Person
“But he (the husband) didn’t hear the vow!”
The gemara asks this question regarding a scenario where the husband appointed a guardian agent to annul his wife’s vows. However, this question seems difficult to understand since the agent did, in fact, hear the vow, and there is an accepted rule that “the agent of a person is like the person.” Therefore, it would seem to be clear that the agent’s hearing should suffice. So, why is it a question in our sugya?
One approach to understanding the question is that it is not logical that the agent should have the ability to do something that that husband who appointed him cannot do. If this were true, the agent would be “greater” than the one who appointed him and not merely “like” that person. (Harav Rav Yossi in Tosefot as cited by Rabbeinu Nissim)