Rambam - 1 Chapter a Day

When he has no sons, and his brothers will inherit his estate, he may identify another person as his brother and give him a share of the estate.

When he has neither sons nor brothers, and his uncles will inherit his estate.

See Bava Batra 134a and commentaries, where it is explained that the rationale is based on the principle of miggo. Since he could give this person his property as a present, his word is accepted when he identifies him as an heir.
The commentaries debate whether the person’s word is accepted with regard to property that he acquires in the midst of his death throes (i.e., a person whose estate he inherits dies shortly before he does). The rationale is that when a person is in his death throes, he is not capable of giving his property away. Hence, the miggo mentioned above no longer applies. The Ramah (Choshen Mishpat 279:1), however, maintains that the dying man’s word is accepted even in this situation.

The Rambam’s wording here is significant, because from his wording in Hilchot Gerushin 2:15, the Kessef Mishneh deduced that when a person can write intelligibly, there is no need to test his powers of comprehension. Writing alone is proof that he is in command of his faculties. Here the Rambam’s wording clarifies that that is not the case. For a person can write without comprehending a matter.

See the notes on Chapter 2, Halachah 15.

As mentioned in the notes on Chapter 2, Halachah 14, Bava Batra121b derives this concept from Deuteronomy 21:17: “he shall recognize,” which is interpreted to mean that he shall cause others to recognize. The identification of a person’s sons is dependent on him (the father). This right applies, however, only with regard to a person’s sons, and not with regard to his other heirs.

This expression refers to a conclusion based on the Rambam's deductive reasoning, which does not have an explicit source in prior Rabbinic literature.

See Hilchot Issurei Bi’ah 15:15 and Bava Batra 127b. In principle, the father’s word should be accepted with regard to his son, even when he has already fathered children, based on the exegesis of the verse mentioned above. Nevertheless, since it would appear ridiculous for the person’s grandson to be considered of acceptable lineage, but his son not, once the son has become a father, his own father’s word is not accepted.

The Rambam’s rationale is that since it is only for the sake of appearance (see the previous note) that the son’s lineage is accepted, that argument applies only with regard to the lineage itself, but not with regard to the inheritance. Alternatively, the Rambam’s conclusion appears to be an extension of the principle of miggo. Since the father could give his property to a person other than his son, his word is accepted when he claims that his son is not his heir (Maggid Mishneh).
The Maggid Mishneh also states that if a person’s son fathered children and then died during the lifetime of his father, his father may not disqualify his deceased son’s children as his heirs. The Shulchan Aruch (Choshen Mishpat 279:2) accepts the Rambam’s deduction as law. The Ramah adds the thesis of the Maggid Mishneh.

I.e., the statement that he originally gave is considered binding. For once significant testimony is given, it cannot be retracted.

Sefer Me’irat Einayim 279:7 quotes the Tur, whose statements imply that if the “son” performs the functions of a servant, the deceased’s word is not accepted.

Thus, the person’s new statement is not considered to be a retraction of his previous statement (which would not be acceptable), but a clarification of its intent. We accept this interpretation because of the principle of miggo. Had the person desired merely to endow this person with his estate, he could have freed him and given him the estate as a present.

As mentioned by the Kessef Mishneh, the Rambam’s version of Bava Batra 127b (which conforms to the standard printed text of the tractate) differs slightly from the version quoted by the Tur and the Shulchan Aruch (Choshen Mishpat 279:3).

In this situation, the miggo mentioned above no longer applies, for it is considered as if it is public knowledge that the person is a servant. The principle of miggo is not effective when there is public knowledge to the contrary.

Where a charge was imposed on a person for bringing in servants.

Sefer Me’irat Einayim 279:9 states that this applies only in a situation where we are unaware of the person’s lineage. If, however, it is assumed that the person is a free man, the fact that the individual who passed through customs called him a servant is not significant.

Hence, his first statement is not considered to be significant.

For if he had not been his servant, there would not have been any reason to identify him as such, especially when doing so would lead to a financial charge.
The Shulchan Aruch (Choshen Mishpat 279:4) states that this applies only when the identity of the person’s mother is not a matter of public knowledge. If, however, the woman reputed to be his mother is Jewish, the fact that the individual who passed through customs called him a servant is not sufficient to have him placed in that category. He may be considered a mamzer because of that person’s testimony, but not a servant.

We have chosen the names Joe and Sarah instead of the term "so-and-so" used by the Rambam.

I.e., a person might think that the servant the person referred to with the term Papa or Mama is in fact his parent. See Sefer Me’irat Einayim 279:14.

This term is used to refer to the head of the Torah academy, who serves as the leader of the Jewish community in Eretz Yisrael. Berachot 16b relates that Rabban Gamliel's children would refer to the servants of his household in this manner.

When a Jew engages in relations with a maidservant, any offspring conceived are servants and are not considered to have any connection to their natural father. Even if they [or the mother after conception occurs] were freed, they are not considered to be the person's sons.

I.e., we assume that before engaging in relations with the maidservant, the father freed her, so that her offspring is considered to be his son. As evident from the continuation of the text, the scope of this assumption is limited.

This son is not considered to have any connection to his natural father, unless his mother was freed before he was conceived. Nevertheless, if she was freed between his conception and birth, he is considered to have been born a Jew and need not be freed independently. There is no difficulty in his marrying a Jewess.

The Rambam’s rulings here are dependent on the principles and the logic that he stated in Hilchot Gerushin 10:17-19:
When a man divorces his wife and then engages in relations with her... we assume that since she was [originally] his wife, he remarried her and engaged in relations with the intent of consecrating her, and not as a licentious act.... For it is an accepted presumption that a person will not enter into sexual relations with his wife with a licentious intent, when he has the opportunity of having these relations considered a mitzvah....
Several of the Geonim have ruled that any woman with whom a man engaged in sexual relations in the presence of witnesses requires a divorce. [The rationale for their ruling is that] a person will not carry out sexual relations with a licentious intent.
The Rambam continues to mention and dispute the more lenient opinions mentioned in this halachah, stating:
I consider these opinions far from the path of [the Torah’s] judgments, and it is not fit to rely on them. Our Sages made such statements only with regard to [a man’s] wife whom he divorced, or to a person who consecrated a woman conditionally.... In these instances, the woman is the man’s wife, and with regard to a man’s wife we assume that he will not enter into sexual relations with a licentious intent.... With regard to other women, however, [we do not follow this assumption]. Instead, whenever [a man engages in relations with] a wanton woman, we assume that he had a licentious intent unless he explicitly states that he intends to consecrate her. Needless to say, this applies with regard to a maidservant.
To apply the above concepts to the case at hand: If the person involved is a Torah scholar, we assume that he desired to minimize the prohibition involved in engaging in relations with her, and hence, freed the mother. (He still would be committing a transgression, for a man is forbidden to engage in relations with any woman unless he is married to her. That prohibition is, however, less severe than that involved in relations with a maid-servant.) Accordingly, the offspring may be considered to be the person’s son. And then we follow the principles mentioned above (Halachah 1) and give “the son” the right to share in the inheritance.
This leniency applies only with regard to monetary law. With regard to the Torah’s prohibitions, we rule more stringently. Hence, since if the mother had not been freed, her offspring would have been a servant and forbidden to marry a Jewess, we require that offspring to supply proof that his mother was freed before his birth.
The Shulchan Aruch (Choshen Mishpat 279:6) quotes the Rambam’s ruling. The Ramah states that with regard to the inheritance, the burden of proof is on the “son.” Since he desires to collect a share of the estate, he must demonstrate his right to it. See the first law of the following halachah which appears to support this contention.

I.e., we do not consider that the father desired to avoid committing a transgression. This decision reflects the Rambam’s ruling in Hilchot Avadim 9:1: “When a Jew has relations with a Canaanite maid-servant - even if she is his own maidservant - the offspring is considered to be a Canaanite slave with regard to all matters.”

Or the other heirs to his father's estate.

I.e., he is their property and they may do with him as they desire.

When a man dies childless, his widow must marry one of his brothers to perpetuate his name. See Deuteronomy, Chapter 25. Since we consider this offspring a servant, he has no connection with his natural father, and it is as if his natural father had never fathered children. See Hilchot Yibbum VaChalitzah 1:4.
The Shulchan Aruch (loc. cit.) quotes the Rambam’s ruling. The Ramah states that the woman should undergo the rite of chalitzah - where she releases her deceased husband’s brothers from the obligation to marry her - rather than yibbum. Since there is a doubt involved, this is a more desired option.

The Ra’avad questions the Rambam’s ruling and maintains that the father has the right to determine the identity of his son. If the father states that the mother was freed before the son was conceived, the son is considered to be his son.
The Maggid Mishneh disputes the Ra’avad’s contention, stating that the right the Torah gives a father to recognize his son involves only the question of whether he fathered him, and not whether the son’s lineage is acceptable or not.

I.e., they deny the "son" a right to the inheritance unless he supplies proof that his mother was freed before his conception. They do not, however, consider the "son" to be the property of the other sons unless those sons can prove that the woman was not freed. This is the perspective followed by the Ramah, as mentioned above.

I.e., we do not say that certain Jews are bound by one set of laws and others by another.

I.e., they do not have to bring witnesses who testify regarding their lineage. Instead, we rely on the popular conception of the matter.

I.e., while he did not accept the contention, he did not contest it either.

For he did not acknowledge Levi as an heir. As far as Shimon is concerned, Levi is required to prove his claim to the inheritance before it is given to him.

I.e., the portion deducted from Reuven’s share.

For it was taken from his share of the estate.
The Tur and the Ramah (Choshen Mishpat 280:2) clarify that this applies only when the property inherited or property that was acquired in its stead remained in Levi’s possession. If, however, those assets were no longer definable, Reuven does not receive a greater share of Levi’s estate.

I.e., according to Reuven, they both are Levi’s heirs. Hence, his estate should be divided between them.

I.e., without Levi’s investing anything to cause this increase in value.

Our translation is not literal; the Rambam’s words mean “an increase that [will soon be carried away] on a person’s shoulders” (Maggid Mishneh). Alternatively, “crops that have grown to shoulder height” (Sefer Me’irat Einayim 280:5) Thus, it is almost ready to be reaped. Although such crops still need the land, they are - in several halachic contexts (Bava Kama 95b, Bava Metzia 15b, Bava Batra 42b, et al) - considered to be movable property, and hence, a separate entity from the land itself.

For the crops are considered to be part of the land itself, and the land belongs to Reuven.

For in contrast to the previous instances, where the matter was left open, here he explicitly stated that he shares no connection to Levi.