What is the criterion of "relevance" in matters of Torah study?

This issue arises in our gemara when the Sage Rav is quoted as ruling on a halachic issue concerning what sort of death penalty the Torah stipulates for the married daughter of a kohen guilty of adultery. It is clear from the passage (Vayikra 21:9) that her infidelity is deemed more serious than that of a married daughter of a non-kohen because she "profanes her father" by disgracing his holy status. There is a difference of opinion, however, between Rabbi Simon and the other Sages as to whether the penalty mentioned in that passage also applies to such a woman if she is only an "arusa" betrothed through an act of kiddushin and forbidden to other men but not yet a "nesua" whose marriage is consummated with a Chupa. Ravs ruling in favor of the Sages raised a challenge from Rabbi Yosef as to why we need a ruling for something which will only be relevant in the time of Mashiach when the Sanhedrin will once again be empowered to inflict capital punishment.

Rabbi Yosefs disciple, the Sage Abaye, countered with the argument that it is important to study Torah matters even if they are not relevant today just as we study the laws of Temple sacrifices although they will not be relevant until Mashiachs arrival and the rebuilding of the Beit Hamikdash. But it is the challenge of the master which invited the analysis of the leading commentaries.

The same challenge is found in Mesechta Zevachim (44a- 45b) in regard to a ruling concerning the disqualification of a sacrifice because of an improper intention of the kohen performing the service. (Our texts identity the challenger there as the Sage Rava but Tosefot identifies him as the same Rabbi Yosef as in our gemara.) Tosefot here and elsewhere raises the question why the same challenge is not presented in regard to other halachic discussions in the Talmud which are not relevant to the present. Among the resolutions offered by Tosefot to this problem is that of Rabbi Chaim Kohen. There is no basis for challenging the need for a halachic ruling, he explains, even if it is not relevant today. The two above mentioned challengers, however, both deal with cases of sin adultery of the kohens daughter and disqualification of a sacrifice. The application of the halachic ruling in such cases will only be in the time of Mashiach and then everyone will be righteous so that there will be virtually no need to apply them. This is why Rabbi Yosef felt that rulings in these cases were and would remain irrelevant as opposed to other halachic matters which would regain their relevance in Messianic times.

Sanhedrin 51b

We are all familiar with the seven Noachide commandments which G-d legislated for all of mankind. But why are they referred to as commandments given to the descendants of Noach rather than to the descendants of Adam since he was the first to receive all seven of them?

This problem is based on the statement of Rabbi Yochanan in our gemara that in addition to six others Adam was also commanded to refrain from eating flesh cut from a live animal. This is deduced from the text of the passage (Bereishet 2:16) which ends with the words "eat, you shall eat" which limited his right to eat only things which were intended to serve as food, to the exclusion of a live animal whose function is to reproduce (Rashi).

This view, however, seems to be disputed by the Sage Rav (Sanhedrin 59b) who states that Adam was not permitted to eat any meat, even after the animal was slaughtered. This ban was in effect on all of Adams descendants until Noach who was told that all living things were permitted to him for consumption in the same manner as vegetation had always been but that he could not eat from the animals while they were still alive (Bereishet 9:3-4).

Rambam indeed saw this as a clash of opinions and recorded (Hilchot Melachim 9:1) the latter opinion that Adam received only six mitzvot with the seventh one given to Noach along with his permission to eat meat. This explains why the seven commandments incumbent on all Mankind are referred to as Noachide rather than Adamide.

Tosefot, however, attempts to reconcile the two views. The ban on Adam's eating meat, he writes, related only to slaying an animal in order to eat its flesh. If the animal otherwise died its flesh was permissible but if part of it fell off from its body while it was still alive it was forbidden because Adam was bound by that seventh mitzvah as well.

Some commentaries raise a question regarding this approach. When the gemara challenged the aforementioned view of Rav by citing a statement of Rabbi Yehuda ben Taima that angels broiled meat for Adam to eat, the response was that it was not earthly meat forbidden to Adam but meat which had descended from heaven. According to Tosafots approach the gemara could simply have answered that it was not Adam who slaughtered the animals but the angels. In defense of Tosefot it has been suggested that it is unlikely that the angels would do something in his behalf which was prohibited to him.

Sanhedrin 56b