TB Bekhorot Buying and selling futures

This past Monday we began massekhet Bekhorot which discusses the laws concerning firstborn animals and children. The Art Scroll’s introduction to our massekhet reads: “There are three basic criteria that qualify it firstborn for bechor status: It must be a male, it must be the firstborn of his mother, and it must be the offspring that ‘opens his mother’s womb’ {פטר רחם} (Exodus 13:2), i.e. it must emerge naturally rather than by cesarean section. These criteria apply to every animal bechor, whether a donkey or a kosher animal. They also apply to human bechoros, inasmuch as the requirement to redeem a firstborn son pertains only to one who ‘opened the womb’.” (Page 1 of the general introduction)

These rules apply only to animal who was completely owned by a Jew. If a non-Jew owns even an ear of the animal, it is exempt from the laws of the firstborn. The first Mishna discusses what happens when the transaction between the Jew and non-Jew is a fetus.

“MISHNA: With regard to one who purchases the fetus of a donkey that belongs to a gentile, and one who sells the fetus of his donkey to a gentile although he is not permitted to sell a large animal to a gentile, and one who enters into a partnership with a gentile in ownership of a donkey or its fetus, and one who receives a donkey from a gentile in order to care for it in exchange for partnership in its offspring, and one who gives his donkey to a gentile in receivership, in all of these cases the donkeys are exempt from the obligations of firstborn status, i.e., they do not have firstborn status and are not redeemed, as it is stated: “I sanctified to Me all the firstborn in Israel, both man and animal” (Numbers 3:13), indicating that the mitzva is incumbent upon the Jewish people, but not upon others. If the firstborn belongs even partially to a gentile, it does not have firstborn status.” (Sefaria.org translation)

In American law people are allowed to buy and sell futures; however, selling futures is forbidden by Jewish law. “A person cannot transfer ownership of an object that has not yet come into the world (אֵין אָדָם מַקְנֶה דָּבָר שֶׁלֹּא בָּא לָעוֹלָם!).” If this is the case, how can a person sell or share a fetus that certainly yet hasn’t come into the world?!

Tosefot ד"ה דַיְקָא נָמֵי דְקָתָנֵי is troubled by this problem. Rebbeinu Tam solves this problem by saying that the acquisition, the kinyan-קנין, was on the cow and not on the fetus for the sake of the ear. This is not unprecedented. One may buy the futures of the dates of the tree by making a kinyan on the tree. Since you own the tree, the fruit becomes yours. The same thing happens here in our case. The non-Jew makes a kinyan on the cow and he will get whatever he purchased e.g. the ear of the fetus as the “fruit” of the cow.

Not making a kinyan on his flock as described above, Rebbeinu Tam teaches that this was Rav Mari fatal flaw in the following story. Rav Mari made the kinyan on the fetuses and not the mother animals.

“Rav Mari bar Raḥel had a certain flock of animals. He would transfer ownership of the ears of the firstborn fetuses to a gentile in order to exempt them from the obligations of firstborn status. But nevertheless he prohibited them from being sheared and used for labor, and gave them to the priests, halakhot that apply to a standard firstborn animal. And ultimately, the animals of Rav Mari bar Raḥel died.

“The Gemara asks: But since he prohibited them from being sheared and used for labor and also gave them to the priests, why did he initially transfer ownership of their ears to the gentile, abrogating their firstborn status? The Gemara answers that he did so lest the priests come to experience a mishap with them, improperly shearing them or using them for labor. The Gemara asks: If so, what is the reason that the animals of Rav Mari died as a punishment? The Gemara answers: It was because he abrogated their sanctity by selling their ears.” (Sefaria.org translation)