According to the derivation of Ulla, that if someone was a "baal keri" and was a metzorah, we allow him to enter the beis hamikdash with his thumbs. We derive from this that without the Pasuk of "Aleha" we would have thought that since the torah threw of the Averia of Aishes Ach, it would also throw off the aveirah of Achos Ishto. My question is the following:
What is the simillirity? in the case of the Tuma, we could say that as there is only one prohibition of enetring the bais Hamikdash, once we throw away one reason ("Metzorah") so we throw away another reason ("Baal Keri"). However, in the case of Yibum, there are two independant prohibitions, one of Aishes Ach and one of Achos Ishto. So how could Ulla say that we hold of Hoyil Deshterey Ishterey?
Jack Smith, LA, USA
Your question is so good that Tosfos (DH Rava Amar) uses it as an explanation for the logic of Rava, who does not accept Ula's proof.
However, in order to understand the logic of Ula, Rebbi Akiva Eiger suggests that in essence, all the Isurei Ervah are like a single Isur. This is evident from the fact that we need a Pasuk to tell us that a woman who is Asur due to two Isurei Ervah, must bring two Chata'os. This is why Ula held that Ho'il v'Ishteri applies by two Isurei Ervah.
D. Zupnik
I Understand the Hava Amina to see the Isurei Bia as all one isur. However, according to the torah's Maskana, that it is two aveiros, then what would Ulla say?
Jack Smith, LA, USA
As I mentioned, Rav Akiva Eiger writes that although if the Isurim were unrelated we surely would not apply "Ho'il v'Ishteri" when it comes to Arayos, nevertheless, according to Ula we consider the Arayos all as one Isur, since there is one Kares in the Pasuk for all of them. We treat the verse from which we learn "L'chalek" (see Kerisus 2b) similarly to the verse which teaches "l'Chalek" by the Melachos of Shabbos. That is, although it teaches that there is a separate Kerisus for each, they are still all parts of the same Isur.
D. Zupnik