Shabbat Parashat Vayigash | 5770

Hemdat HaDaf HaYomi: Determining the Firstborn (127b)

  Tevet 3-9, Baba Batra 121-127

This week in the Daf Yomi the Gemara (127b) quotes a dispute between Rabbi Yehudah and the Chachamim regarding the power of the father to determine the status of his sons. According to Rabbi Yehudah, the father can state which of his sons is the firstborn, even if another son was presumed to be the firstborn. So too, he can state that his son is a mamzer (born from a strictly prohibited relationship) or a chalal (born from a cohen and a woman prohibited to a cohen). In contrast, the Chachamim claim that a father can state who the firstborn is only when it was not previously known who the firstborn was. Most Rishonim rule like Rabbi Yehudah.

The Rishonim dispute how extensive the power given to the father is. According to the Bahag (Hilchot Milah page 154), the power of the father is limited to a case where he is determining who is the firstborn. For example, if he says that his younger son is his firstborn, and it can thus be inferred that his elder son is not his own, but rather is a mamzer, then he is believed. However, if he simply states that one of his sons is a mamzer, without any implication as to who is the firstborn, then he is not believed.

However, many of the Rishonim (Tosafot d"h kach, Rosh 8, 21, and others) disagree with the Bahag and claim that in any case the father is believed, whether it is to determine who the firstborn is or whether it is to determine that a son is a mamzer.

The Rid (in his response, 92) has a unique opinion regarding the power of the father. He claims that a father can state that his son is a mamzer only if he claims that he is indeed his son, but was born from a relationship with a woman who is strictly prohibited to him (issurei arayot). However, regarding a son that was born from his wife, he is not believed to say that the son is not his, and that his wife betrayed him. His reasoning is that the Torah only believed the father regarding his sons, but since here, he claims that this is not his son, he is therefore no longer believed. According to this opinion, if we know who the older son is and who is the younger, the father cannot state that the younger is his firstborn, thereby turning the elder into a mamzer. Only in a situation where we are not certain as to the ages of the children, but we assume that one is older, then the father is believed to say that the other one is actually older.

Summary and Ruling:

The Shulchan Aruch (Even Ha'ezer 4, 29) rules like the Rishonim who claim that the father is always believed to state which of his sons is the firstborn, and whether his son is a mamzer, or not his son at all. However, even according to this opinion, there are many qualifications and details regarding when the father is believed. A book on this issue was recently published, summarizing this issue from the original sources until recent rulings by the Israeli Rabbinical Courts. It is called "Vayeker Yehudah" and was written by Rav Yehudah Fris. 

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