Sources on Rabbis Changing Their Minds

I've been interested in this problem - at a time when the British parliament (and society?) is at loggerheads.

The 'standard' Talmudic sugya opens with alternate positions taken by two sages and several pages later preserves the alternate positions as being 'correct' for the disputants. i.e. Talmudic 'success' results in a principled and tolerant disagreement. I get that.

But I've been trying to think of examples of sages changing their opinion, admitting their mistake, being persuaded by argument etc. and ... I'm struggling.

The first two cases aren't really examples. 

But there are examples. And interesting ones at that. And a great joke.

Mishnah Rosh Hashanah 2:8-9

Rabban Gamaliel had diagrams of the moon on a tablet [hung] on the wall of his upper chamber, and he used to show them to the unlearned and say, “Did it look like this or this?” It happened that two witnesses came and said, “We saw it at a certain time, but on the night which should have been the new moon it was not seen,” and Rabban Gamaliel accepted their evidence. Rabbi Dosa ben Harkinas said: they are lying witnesses. How can they testify that a woman has given birth when on the next day she’s still heavily pregnant? Rabbi Joshua to him: I see your argument.

Rabban Gamaliel sent to him: I order you to appear before me with your staff and your money on the day which according to your count should be Yom Hakippurim. Rabbi Akiva went and found him in distress. He said to him: I can teach that whatever Rabban Gamaliel has done is valid, because it says, “These are the appointed seasons of the Lord, holy convocations, which you shall proclaim at their appointed times” (Leviticus 23:4), whether they are [proclaimed] at their proper time or not at their proper time, I have no other appointed times save these. Rabbi Joshua went to Rabbi Dosa ben Harkinas [who also said Joshua would have to accept the opinion of Rabban Gamliel]. So he took his staff and money and went to Rabban Gamaliel on the day which according to his count should be Yom Hakippurim. Rabban Gamaliel rose and kissed him on his head and said to him: Come in peace, my teacher and my student my teacher in wisdom and my student because you have accepted my decision.

Nazir 52b

Rabbi Yehuda HaNasi said to Bar Kappara: Do not teach Rabbi Akiva changed his mind about whether a Nazir can be in a room with a quarter-log of blood, as Rabbi Akiva held onto his opinion in this regard. And furthermore, the verse supports his opinion, as it states: “Neither shall [the Nazir] go in to any dead bodies” (Leviticus 21:11).[1] Rabbi Shimon says: “All his days, Rabbi Akiva would deem a quarter-log of blood from two corpses ritually impure. Whether he retracted his opinion after he died, I do not know.” A Sage taught: Rabbi Shimon’s teeth blackened due to his fasts.[2]

Rosh Hashanah 13b

Rabbi Yirmeya said to Rabbi Zeira: How can the Sages possibly discern precisely between produce that reached one-third of its growth and produce that reached less than one-third of its growth!? Rabbi Zeira said to him: Don’t I always tell you must not take yourself out of the bounds of the halakha? All the measures of the Sages are like this; precise and exact. One who immerses himself in a ritual bath containing forty se’a of water is rendered pure, but in forty se’a less the tiny amount cannot immerse and become pure in them. Similarly, an egg-bulk of impure food can render other food ritually impure, but an egg-bulk less even the tiny amount of a sesame seed does not render food ritually impure.

Rabbi Yirmeya said: What I said is nothing.

Baba Batra 23b
Mishnah: If a fledgling bird is found within fifty cubits of a dovecote, it belongs to the owner of the dovecote. If it is found outside the limit of fifty cubits, it belongs to the person who finds it…
Gemara: Rabbi Yeremiah asked: “What if one foot of the bird is within fifty cubits, and one foot is outside it?” It was for this question that Rabbi Yeremiah was thrown out of the Beit Midrash.

Mishnah Eduyot 1:12

These are subjects concerning which Bet Hillel changed their mind and taught according to the opinion of Bet Shammai:[3]

A woman who came from overseas and said: “My husband died” may be married again; Bet Hillel says: “We have heard so only in the case of one who came from the harvesting grain.” Bet Shammai said to them: “It is the same thing in the case of one who came from harvesting grain, or olives or from overseas; they mentioned harvesting only because that is how it happened in the original case.” Then Bet Hillel changed their mind and taught according to Bet Shammai.

Bet Shammai says: “She may be married again and take her kethubah payment.” But Bet Hillel says: “She may be married again but may not take her kethubah payment.” Bet Shammai said to them: “You have permitted the graver matter of a forbidden marriage, should you not permit the lighter matter of property?” [there is another round of argument]. Then Bet Hillel changed their mind and taught according to the opinion of Bet Shammai.

Chagigah 2a-b

Everyone should make an appearance in Jerusalem at the festivals apart from [a list including] slaves.

You might say the use of the word ‘everyone’ means even one who is half-slave and half-freeman needs to make an appearance, as the Mishnah (Pesaḥim 88a) teaches: One who is half-slave half-freeman serves his master one day and works for himself one day. This is the statement of Beit Hillel.

Beit Shammai said to them: You have remedied things for his master, but not for him, for he is unable to marry a slave (as half of him is free), and unable to marry a free Jew (as half of him is still a slave). And if you say he should not marry, surely the world was created for the sake of procreation. Rather we force his master to make him wholly free, and he writes a bill to his master accepting his responsibility to pay half his value to him. And Beit Hillel retracted their opinion, to rule in accordance with the statement of Beit Shammai.

Eruvin 13b

Rabbi Abba said that Shmuel said: For three years Beit Shammai and Beit Hillel disagreed. These said: The halakha is in accordance with our opinion, and these said: The halakha is in accordance with our opinion. A Divine Voice emerged and proclaimed: “Both these and those are the words of the living God. However, the halakha is in accordance with the opinion of Beit Hillel.” The Gemara asks: Since both these and those are the words of the living God, why were Beit Hillel privileged to have the halakha established in accordance with their opinion? They were agreeable and forbearing, they would teach their own statements and the statements of Beit Shammai. Moreover, they prioritized the statements of Beit Shammai to their own statements.

A Final Thought

In 1920s Soviet Russia, in the middle of the jockeying for power following Lenin’s death, Stalin emerges to address an expectant crowd. “Comrades! I have in my hand a telegram from Comrade Trotsky, which I think will resolve our current differences of opinion. Let me read it to you: ‘You were right and I was wrong. You are the true heir of Lenin. I should apologize. Signed, Leon Trotsky.'”

The crowd goes wild! But wait, there’s one man in the crowd signalling to get Stalin’s attention. “Yes, comrade?” Stalin asks. “Comrade Stalin, I think you know Comrade Trotsky is Jewish.” “Yes, I do.” “Well, I’m Jewish, too, and I thought I might have an extra insight on what Comrade Trotsky was trying to say. May I read the telegram myself?” “Of course, comrade.” The man gets up and starts reading: “You were right and I was wrong? You are the true heir of Lenin? I should apologize? Signed, Leon Trotsky.”

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[1] The plural form “bodies” understood to include blood, even blood that could have come from more than one body.

[2] Which he undertook for uttering this irreverent comment about Rabbi Akiva.

[3] There follow three examples, of which the second is the same as recorded in Mishnah Chagigah – below.