Talmud - Ketubot 15b כתובות ט״ו ב׳

If there is a city in which both Jews and gentiles reside, and one found an unidentified, abandoned baby in the city, if there is a majority of gentiles in the city the baby is deemed a gentile; if there is a majority of Jews in the city the baby is deemed a Jew. If half the population is gentile and half Jewish, the baby is deemed a Jew.

And Rav said with regard to this mishna: The Sages taught that if there is a majority of Jews in the city the baby is deemed a Jew only with regard to sustaining him; however, with regard to lineage, e.g., marrying him to a Jewish woman, no, he is not deemed a Jew based on the majority and would require conversion. And Shmuel said: It was taught that he is deemed a Jew in order to create an opening in a heap of debris on his behalf on Shabbat, i.e., desecrating Shabbat in order to save his life. Apparently, contrary to the ruling of Rav Ḥiyya bar Ashi, Rav holds that a single majority is insufficient to deem him Jewish in matters of lineage.

The Gemara answers: Rav Yirmeya overlooked that which Rav Yehuda said that Rav said with regard to the mishna: The incident of the rape of the young girl transpired among the wagons in the marketplace of Tzippori, and there were two majorities; the majority of the inhabitants of the city and the majority of the passing contingent. Therefore, when Rav Ḥiyya bar Ashi ruled that the halakha is in accordance with the opinion of Rabbi Yosei, i.e., that the young girl may marry a priest, it was in a case of two majorities.

The Gemara asks: And if the case in the mishna is one of two majorities, according to Rav Ḥanan bar Rava who said in the name of Rav: That was a provisional edict issued in exigent circumstances, meaning that two majorities were required in that case but typically one majority is sufficient, it is difficult. Didn’t Rav say that in matters of lineage one majority is insufficient? The Gemara answers: That is not difficult. The one who teaches this, that the ruling in our mishna was a provisional edict, does not teach that statement that Rav Yehuda said that Rav said that the incident took place among the wagons in the marketplace of Tzippori. Rather, he holds that there was a single majority and nevertheless, due to exigent circumstances, the girl was permitted to marry into the priesthood, although generally two majorities are required in cases of lineage.

§ Apropos the case of the abandoned baby, the Gemara analyzes the matter itself: If there is a city in which both Jews and gentiles reside, and one found an unidentified, abandoned baby in the city, if there is a majority of gentiles in the city the baby is deemed a gentile. If there is a majority of Jews in the city the baby is deemed a Jew. If half the population is gentile and half Jewish, the baby is deemed a Jew. Rav said: The Sages taught that the baby is deemed a Jew only with regard to sustaining him; however, with regard to lineage, no. And Shmuel said: It was taught that he is deemed a Jew in order to create an opening in a heap of debris on his behalf on Shabbat.

The Gemara asks: And did Shmuel say that? But didn’t Rav Yosef say that Rav Yehuda said that Shmuel said: One does not follow the majority in matters involving saving a life? Even if there is the slightest concern that the life of a Jew may be in danger, one takes all steps necessary to save him, even on Shabbat. Rather, when the statement of Shmuel was stated with regard to saving a life it was stated concerning the first clause of the mishna: If there is a majority of gentiles in the city the baby is deemed a gentile. Shmuel said: And with regard to creating an opening in a heap of debris on his behalf [lefake’aḥ alav et hagal] on Shabbat, that is not so. Even if there is a gentile majority in the city, one does not follow the majority in cases involving the saving of a life.

The mishna continues: If there is a majority of gentiles the baby is deemed a gentile. The Gemara asks: With regard to what halakha was this stated? Rav Pappa said: It was stated in order to feed the baby animal carcasses, i.e., non-kosher food.

And it is taught in the mishna: If there is a majority of Jews the baby is deemed a Jew. The Gemara asks: With regard to what halakha was this stated? Rav Pappa said: It was stated in order to return lost property to him, as one is required to return lost property to a Jew.

And it is taught in the mishna: If half the population is gentile and half Jewish, the baby is deemed a Jew. The Gemara asks: With regard to what halakha was this stated? Reish Lakish said: It was stated with regard to damages. In terms of payment of damages, the courts judge him as a Jew. The Gemara asks: What are the circumstances? If we say that our ox, one belonging to a Jew, gored his ox, one belonging to a person of uncertain status, and he claims that he should be compensated for the damages as a Jew, let the owner of the ox that gored say to him: Bring proof that you are a Jew, and take payment. Due to the uncertainty surrounding his status, he is unable to produce any proof.

Rather, this halakha is necessary only in a case where his ox gored our ox, one belonging to a Jew. In that case, there is no question that he pays half the damage, which is the payment when an innocuous ox belonging to a Jew gores an ox belonging to a Jew. And with regard to the other half, which the owner of the gored ox is claiming, asserting that this person of uncertain status is a gentile and therefore liable to pay full damages, the owner of the ox that gored can say to the claimants: Bring proof that I am not a Jew and I will give you payment of the other half of the damages. It is with regard to that case that Reish Lakish ruled that in a case of uncertainty, the baby has the presumptive status of a Jew, and it is incumbent upon the claimant to prove otherwise.

May we return to you “A virgin is wedded.”

MISHNA: With regard to a woman who was widowed or divorced, and is now claiming payment of her marriage contract that is not before the court, and she says: You married me as a virgin, who is entitled to two hundred dinars, and he says: No; rather, I married you as a widow, who is entitled to one hundred dinars, then, if there are witnesses that she went out of her father’s house to her wedding with a hinnuma or with her hair uncovered, in a manner typical of virgins, payment of her marriage contract is two hundred dinars. Rabbi Yoḥanan ben Beroka says: Even testimony that there was distribution of roasted grain, which was customary at weddings of virgins, constitutes proof that she is a virgin.

Several disputes between Rabban Gamliel and Rabbi Yehoshua were cited previously with regard to the credibility accorded to the respective claims of parties to a dispute. Based on one of those disputes, the tanna adds: And Rabbi Yehoshua concedes in a case where one says to another: This field, which is currently in my possession, belonged to your father and I purchased it from him, that he is deemed credible, and his entire claim is accepted. The court accepts not only his admission that it once belonged to the other’s father, but also his statement that he purchased it.

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Ketuvot 15b explores determining an abandoned baby's Jewish status by population majority, plus debate over lineage rulings and Shabbat desecration to save a life.