What’s the difference? TB Pesakhim 92

 With today’s daf TB Pesakhim 92 we finish the eighth chapter of our massekhet and begin the ninth chapter. The Gemara concludes by citing three examples when a rabbinic ordinance is upheld even though one would violate a commandment with the punishment of karet (i.e. not offering up the korban Pesakh). Consequently, that person would have to bring his korban Pesakh on Pesakh sheni, a month later. Immediately afterwards, we learn of the three examples when a rabbinic ordinance is not upheld because violation of a commandment with the punishment of karet and the person should bring is Passover sacrifice on Passover.

“Rava said: With regard to an uncircumcised gentile who converted, sprinkling the purification waters to purify impurity imparted by a corpse (מי חטאת-mai khatat), and a circumcision scalpel [izmel]¹, the Sages upheld their statement even in a situation in which doing so would violate a prohibition that carries the punishment of karet. However, with regard to an acute mourner (ענינות-aneenut)², a leper, and a beit haperas, an area in which a doubt exists concerning the location of a grave or a corpse, they did not uphold their statement in a situation in which doing so would violate a prohibition that carries the punishment of karet.”³

^{(Sefaia.org translation)}

If you’re interested, the Gemara explains each one of these cases in detail to conclude our daf. What is the qualitative difference between the first three cases in the last three cases which decides whether the rabbinic decree is upheld or not? The Rishonim explained the cases where the rabbis upheld their decrees because of the fear of transgressing the Torah law. An male convert circumcised on erev Pesakh is forbidden to partake of the korban Pesakh that year for fear the next year he might become ritually unready and think all he has to do is go to the mikvah in order to eat the korban Pesakh.⁴ Concerning the scalpel and the purification waters of the red heifer, the rabbis were afraid the person would carry it in a Torah prohibited space. These fears do not apply at all to the latter three cases

Rambam explains the reason differently in two cases. Rarely does the convert undergo circumcision and immersion on the same day. Usually he waits a period of time after the surgery to heal before entering the mikvah. he would not be eligible to eat the korban Pesakh during this intermediate time. Concerning the sprinkling of the purification waters a person is violating the Shabbat for a future time which is prohibited.

1This case is talking about carrying the scalpel for the purpose of a brit milah in rabbinic prohibited spaces on Shabbat

2According to the Torah acute mourning is only during the day of death and not during the night. Only by rabbinic decree is acute mourning continues into the nighttime.

3In the latter three cases the person would be able to correct his situation by going through the specific process of becoming ritually ready in the daytime and then being able to eat his korban Pesakh.

4The rules of ritual on readiness do not apply to a Gentile. The Jew by choice may not realize that is status is changed and draw the wrong conclusion.