Question: What do they argue about?

Answer #1: They argue about Isur Kolel, according to R. Yosi;

R. Chiya holds that R. Yosi is Mechayev twice for an Isur Kolel; Bar Kapara holds that he is Mechayev only once.

Objection: What Isur Kolel is there here?

We understand the case of a Zar who served on Shabbos. He was permitted to do Melachah (before Shabbos) and forbidden to serve. When Shabbos came, he also became forbidden to do Melachah. The Isur applies to Avodah as well.

We understand the case of a Ba'al Mum who served b'Tum'ah. He was permitted to eat Kodshim and forbidden to serve. When he became Tamei, he became forbidden also to eat Kodshim; the Isur applies to Avodah as well.

However, when a Zar ate Melikah, the Isurim come together, but it cannot be a case of Isur Kolel!

Answer #2: Rather, they argue about Isur Bas Achas (Isurim that come simultaneously), according to R. Yosi;

R. Chiya holds that R. Yosi is Mechayev twice; Bar Kapara holds that he is Mechayev once.

Question: How can the first two cases be Isur Bas Achas?

Answer: Regarding a Zar who served on Shabbos, the case is that he brought two hairs (after 13 years, and became an adult) on Shabbos. (All Isurim, including) Avodas Zar and Melachah on Shabbos take effect on him when he becomes an adult.

Likewise, if a Kohen Ba'al Mum was Tamei when he became an adult, the Isurim of Avodas Ba'al Mum and Avodah b'Tum'ah both come the moment he becomes an adult.

Alternatively, his finger was cut off with a Tamei knife, making him Tamei and blemished at the same time.

Objection: Granted, R. Chiya learned from Rebbi how R. Yosi holds, and he can say that Rebbi taught Bar Kapara how R. Shimon holds (and Bar Kapara later got confused).

However, how will Bar Kapara explain that R. Chiya heard Rebbi says that he is liable twice? (Bar Kapara says that even R. Yosi is Mechayev only once.) Would he say that R. Chiya is lying?!

Answer #3: Rather, they argue according to R. Shimon about Isur Bas Achas.

Question: Granted, R. Chiya had to swear to show that R. Shimon holds unlike he usually does (he says Isur Chal Al Isur only regarding Isur Bas Achas).

However, why did Bar Kapara have to swear?

This is left difficult.

Question: Granted, Bar Kapara will say that Rebbi taught R. Chiya according to R. Yosi (and R. Chiya later got confused).

However, how will R. Chiya explain that Bar Kapara heard Rebbi Mechayev once (since R. Chiya says that even R. Shimon is Mechayev twice)? Would he say that Bar Kapara is lying?!

Answer: R. Chiya will say that Rebbi taught only two cases of Isur Kolel, in which one is liable only once, according to R. Shimon.

Bar Kapara thought that the case of a Zar who ate Melikah is similar, so he joined it to the two teachings he heard from Rebbi.

Later, (he thought that Rebbi taught him all three, and) he realized that the Isurim of Melikah always come together. He reasoned that the other two cases are also Isur Bas Achas, and all are liable only once.

Question (Beraisa - R. Yosi): If a Zar served on Shabbos, and a Ba'al Mum Kohen served when Tamei, the former is liable for Avodas Zar and Melachah on Shabbos; the latter is liable for Avodas Ba'al Mum and Avodah b'Tum'ah;

R. Shimon says, the former is liable only for Avodas Zar; the latter is liable only for Avodas Ba'al Mum.

The Beraisa omitted the case of Melikah.

Question: Due to which Tana was this case omitted (because it is inconsistent with his other teachings)?

Suggestion: It was due to R. Yosi.

Rejection: He is Mechayev twice for Isur Kolel, so all the more so for Isur Bas Achas!

Answer: It was due to R. Shimon. He is Mechayev only once for Isur Kolel, but agrees that one is liable twice for Bas Achas.

Bar Kapara is refuted.

Question: What Avodah did the Zar do on Shabbos?

It was not Shechitah, for a Zar is Kosher for Shechitah!

It was not Kabalah and carrying the blood to the Mizbe'ach, for this is not a Melachah!

It was not Haktarah (burning on the Mizbe'ach), for R. Yosi holds that burning (on Shabbos) is only a Lav!

Answer #1 (Rav Acha bar Yakov): He slaughtered Par Kohen Gadol (of Yom Kipur), according to the opinion that a Zar may not do this.

Question: If so, why do they discuss a Zar? Even a Kohen Hedyot may not do this!

Answer: Indeed, Zar refers to anyone who is foreign to (unqualified for) this.

Answer #2 (Rav Ashi): (Really, he was Maktir.) The Beraisa did not say how many Chata'os must be brought, or how many Lavin were transgressed, rather, how many Isurim were transgressed!

Question: What difference does it make?

Answer: If he transgressed two Isurim, he is buried among the utterly wicked.

(Mishnah): If two men were Mekadesh two women, and at the time of Chupah they switched wives, they are liable for Eshes Ish. If they are brothers, they are (also) liable for Eshes Ach. If the women are sisters, they are liable for Achos Ishto. If they were Nidos, they are liable for Nidah;

We separate each woman (from her husband) for three months, lest she is pregnant (from the other man. Without separation, we would not know who is the father of children born withing nine months). If the women are minors, who cannot give birth, they return to their husbands immediately;

If they are Kohanos, they are disqualified from eating Terumah.

(Gemara) Question #1: 'They switched' connotes intentionally. Do we discuss Resha'im?

Question #2: R. Chiya taught that they bring (all together) 16 Chata'os. If they intentionally sinned, they do not bring Korbanos!

Answer (Rav Yehudah): The Mishnah should read 'They were switched'.

Support #1 (Seifa): If they were minors who cannot give birth, they are returned immediately.

If they intentionally switched, they are forbidden to their husbands!

Rejection: This is no support. A minor who commits adultery is considered forced, so she is permitted to her husband (unless he is a Kohen).

Support #2 (Reisha): They separate for three months, in case they are pregnant. (We discuss adults.)

Inference: If not for this concern (or after three months) they are permitted.

Had they intentionally switched, they would be forbidden.