Makshirin, Chapter Two, Mishnah Seven
1) If one found [an abandoned] child there:
2) If the majority [of the inhabitants] were non-Jews, it is considered a non-Jew;
3) If the majority were Israelites, it is considered an Israelite;
4) If they were half and half, it is also considered an Israelite.
5) Rabbi Judah says: we must consider the majority of those who abandon their children.
Section one: The mishnah continues to deal with a city composed of both non-Jews and Jews. A child is found, abandoned by his parents and we need to know whether to assume that the child is Jewish or not.
Section two: If the majority were non-Jews then in certain ways the child is treated as if s/he were non-Jewish. According to mishnaic commentaries based on the Talmud, we treat the child as non-Jewish and we are allowed to feed him/her non-kosher food.
Section three: If the majority were Israelites, the child is treated like a Jew. According to commentaries this means that we are obligated to return lost objects to the child (when s/he grows up and owns things), which as we learned in Bava Metzia and we will see again in tomorrow’s mishnah, is obligatory only to fellow Jews.
Section three: If the town is evenly split, the child is considered Jewish. Again, the commentators limit this to a case of damages. If this child’s ox damages a fellow Jew’s ox, the child’s ox only pays half damages, if it is an attested danger.
Note that the ramifications of the child being considered Jewish were limited to monetary matters. The Talmud says that when it comes to matters of personal status, such as marital law, the child is considered to be a “doubtful Jew.” If he marries a Jewish woman, she is potentially married and would require a divorce document to marry someone else. He/she is not fully considered an Israelite until conversion.
Section four: Rabbi Judah says that it is not logical to simply follow the majority of people in the city. We need to look at who most likely abandoned their kids. So if the majority of abandoners are Jews, then the kid is considered a Jew, even if the majority of the town is non-Jews.