Bechoros Chapter 8, Mishnah 2. In this mishnah we conclude the topic we began in the previous mishnah: an offspring who is not entitled to a double portion of the inheritance, and who is also not obligated in the laws of pidyon haben. The simple and obvious case is any child who is not a firstborn son, but the mishnah comes to teach us the laws of a 'yotzei dofen'.
What is a 'yotzei dofen'?
Its literal meaning is one who emerges from the side. In modern Hebrew, the expression is used to describe an exceptional or unusual person, but in the mishnah the intention is a sort of Caesarean section: an incision is made in the pregnant woman, she is opened, and the baby is removed from her abdomen and does not emerge from her in the usual way.
The mishnah rules: "Yotzei dofen vehaba acharav - shneihem einan bechor lo lanachalah velo lakohen" - A yotzei dofen and the one who comes after him, neither of them is a firstborn for inheritance or for the kohen. We are dealing with two sons: the first was born by Caesarean section and removed from his mother's side, and the second was born in the usual way. We will call the older brother Reuven and the second brother Shimon. Neither of them is entitled to a double portion, and neither of them is obligated in the laws of pidyon haben.
Reuven, the first son:
Reuven was removed from his mother's side and did not open her womb from below, and therefore he is not called a 'peter rechem', and so he is exempt from pidyon haben. As for the inheritance, logically there would be room to say that he is certainly entitled to a double portion, since he is the older brother and the firstborn son; however, in the passage dealing with the double portion of inheritance it is stated "veyaldu lo" - and they have borne him. The women bear for him, for the husband. The word "veyaldu" is extraneous, and from it they expounded that a birth is specifically required, a regular birth in the way babies are born, and not a yotzei dofen who is removed from the side. We find that the same Torah that established that the firstborn takes a double portion, is what established that a firstborn who was not born but rather removed from the side does not take a double portion.
Shimon, the second son:
Shimon is not entitled to a double portion, since he has an older brother. Even in pidyon haben he is not obligated: although he is the first to emerge from the womb from below in the way a baby is born, he is not the firstborn, since he has an older brother; and since he is not the first and the oldest, he too is exempt from pidyon haben. We find that neither of them is a firstborn, not for inheritance and not for the kohen.
The opinion of Rabbi Shimon:
Rabbi Shimon argues on this: "Rabbi Shimon omer: Harishon lanachalah vehasheni lechamesh sela'im" - Rabbi Shimon says: The first is for the inheritance and the second is for five sela'im. Rabbi Shimon argues on both things together:
The first is for the inheritance: Rabbi Shimon rejects the aforementioned exposition, and he has an additional exposition from a completely different passage. In Parashas Tazria, in the laws of tumah of birth (forty days or eighty days, for a male or for a female), the word "teiled" is stated, and it teaches that there is an additional type of birth besides a regular birth - birth from the side. Therefore, even a Caesarean section is included in the language of the verse, and the first son takes the double portion based on that derivation.
The second is for five sela'im: The bottom line is that Shimon is the peter rechem - he is the one who opened the mother's womb from below, since the offspring who emerged from the side is not considered as opening the womb, but rather it is a surgery. Because of this, Rabbi Shimon rejects the claim that he has an older brother: the one who opened the womb is the one who is obligated in pidyon haben, and the five sela'im to the kohen is a requirement.
However, the halachah does not follow Rabbi Shimon in either of the two cases. Therefore, in such a case, there is no double portion and no pidyon haben for either of the sons.