IS EXECUTION PERMITTED ON SHABBOS?
Answer (Rav Simi bar Ashi): The Tana did not think that execution overrides Shabbos because an Aseh overrides a Lav. Rather, a Kal va'Chomer suggested this.
Avodah (in the Mikdash) is severe, it overrides Shabbos. Execution overrides Avodah - "From My Mizbe'ach you will take him to die".
If Avodah overrides Shabbos, all the more so execution does!
Question: Why did the Tana say (Suggestion #2) 'Perhaps it does not override'?
Answer: Burial of a Mes Mitzvah (a Mes with no one else to bury it) disproves the Kal va'Chomer. It overrides Avodah, but it is not Docheh Shabbos!
The Tana reconsidered and suggested (Suggestion #3) that burial of a Mes Mitzvah should override Shabbos from a Kal va'Chomer:
Avodah overrides Shabbos, and we learn from "Ul'Achoso" that burial of a Mes Mitzvah overrides Avodah (someone heading to offer Korban Pesach may not interrupt to bury his sister, but he interrupts to bury a Mes Mitzvah, even though he will not be able to offer Pesach afterwards)!
Therefore, "Do not burn..." is needed to teach that execution is not Docheh Shabbos.
Question: First, the Tana thought that execution overrides Shabbos just like an Aseh overrides a Lav. Why did he think that execution might not override Shabbos?
Answer: We find that an Aseh overrides a simple Lav, but not one that has Kares.
He later thought that an Aseh overrides a Lav even though a Lav is more severe. If so, even if it is much more severe (i.e. Kares)!
Therefore, we need "Do not kindle..." to forbid execution on Shabbos.
Answer #2 (to question 5:b Daf 3b): If not for "Aleha", one might have thought that the Isur of Eshes Ach was part of a Klal (the category of Arayos), and the special law taught about it (it is permitted for Yibum) applies to the entire Klal.
(Beraisa): An example of something that was part of a Klal, and a special law was taught about it is "A Tamei person who will eat Shelamim"
Shelamim is in the Klal of Kodshim. The Torah specified (Kares for a Tamei person who eats) Shelamim to equate all Kodshim to it. It is Kodshei Mizbe'ach, so too (Kares for eating b'Tum'ah is only for) all Kodshei Mizbe'ach, but not Bedek ha'Bayis.
Here, also, Eshes Ach is in the Klal of Arayos. It was singled out to be permitted (for Yibum. If not for Aleha,) one would think that all Arayos are permitted (for Yibum).
Objection: The comparison is improper! In the Beraisa, the Klal and Perat (specific case) are both forbidden. Here, the Klal is forbidden, and the Perat is permitted!
Correction: Rather, our case is a law that was part of a Klal, and was given a new law. It does not retain the other laws of the Klal unless the Torah specifically says so:
(Beraisa): If a law was part of a Klal, and was given a new law, it does not retain the other laws of the Klal unless the Torah specifically says so.
Question: "He will slaughter (Asham) where Chatas and Olah are slaughtered... Asham is like Chatas" - why is this needed? (It already says that they are slaughtered in the same place!)
Answer: Since the Asham of a Metzora has a new law, some of its blood is put on the right thumb and toe (and ear of the Metzora), one might have thought that its blood and Chelev need not be put on the Mizbe'ach;
Therefore, "Asham is like Chatas" obligates putting the blood and Emurim of Asham on the Mizbe'ach, like Chatas.
If not for this verse, one would say that the laws of other Korbanos do not apply to Asham, only what the Torah specified regarding Asham.
Also in our case, Eshes Ach was permitted, not other relatives (so "Aleha" is not needed)!
Answer #3 (to question 5:b, 3b): Rather, we would have thought to learn from a Mah Matzinu (precedent) from Eshes Ach.
Just like Eshes Ach does Yibum, also Achos Ishto (his sister's wife).
Question: These are different. Regarding Eshes Ach, there is only one Isur. Regarding Achos Ishto, there are two!
Answer: One might have thought that once there is permission, even more Isurim are permitted.
ONE LENIENCY CAUSES ANOTHER
Question: What is the source to allow additional things?
Answer (Beraisa): Normally, a Tevul Yom (one who was Tovel today, he is still slightly Tamei until nightfall) may not enter Har ha'Bayis. However, if Erev Pesach was the eighth day (of Taharah) of a Metzora, and he saw an emission that day and immersed, he may enter (to have Dam ha'Asham put on him to complete his Taharah so he can offer Korban Pesach). It is better that an Aseh (Korban Peach) punishable by Kares override an Aseh without Kares (Temei'im must leave the Mikdash).
(R. Yochanan): There is not even an Aseh of the Torah (for a Tevul Yom to leave)!
"Yehoshafat stood up... in front of the new courtyard."
(R. Yochanan): It is called this because they made new laws. They said that a Tevul Yom may not enter Machaneh Levi until nightfall.
Question (Ula): (A Metzora must enter his ear, thumb and toe into the Azarah to receive the blood. Mid'Oraisa, a Tevul Yom may not enter the Azarah.) Why is this permitted for this Tevul Yom?!
Answer (Ula): Since the Torah allows him to partially enter even though some Tum'ah remains from his Tzara'as, it is permitted even if some Tum'ah also remains from his emission.