(Mishnah): All (may) slaughter, and the Shechitah is Kosher, except for a Cheresh (Rambam, Rosh - deaf-mute; Tosfos Chagigah 2b, Or Zaru'a - anyone deaf, even if he can speak), lunatic or minor, lest he slaughter improperly;

If any of them that slaughtered while others looked on, the Shechitah is Kosher.

(Gemara) Question: 'All (may) slaughter' connotes, l'Chatchilah. 'And the Shechitah is Kosher' connotes b'Di'eved!

Question #1 (Rav Acha brei d'Rava): 'All' does not always connote l'Chatchilah!

(Mishnah): All make Temurah (declare a Chulin animal to be in place of a Korban), both men and women.

This is not l'Chatchilah - "he will not switch it"!

Answer (Rav Ashi): There, the Mishnah clarifies itself, 'not that one may make Temurah, but that if one did, the Chulin animal becomes Hekdesh, and the person gets 40 lashes'.

Question #2 (Rav Acha brei d'Rava - Mishnah): All (may) pledge one's Erech (a value based on his age and gender) to Hekdesh, and others (may) pledge them. All pledge one's value (as a slave) to Hekdesh, and others pledge them.

This is not l'Chatchilah - "if you will refrain from vowing, you will not bear sin"!

(Beraisa - R. Meir): "It is better that you should not vow, than to vow and not fulfill" - better than either (vowing and not fulfilling, or vowing and fulfilling) is not to vow at all;

R. Yehudah says, the best is to vow and fulfill.

Even R. Yehudah allows only declaring an animal Hekdesh, but not to obligate oneself (to bring an animal, or to pledge to Hekdesh, due to concern lest he be unable to fulfill)!

Counter-question #1 (Rav Ashi): Can you say that whenever the Mishnah says 'all', it is b'Di'eved?

(Mishnah): 'All are obligated in the Mitzvah of Sukah.'

(Mishnah): 'All are obligated in the Mitzvah of Tzitzis.'

Answer (Rav Acha): I agree that when it says 'all are obligated', it is l'Chatchilah. However, otherwise, 'all' connotes b'Di'eved.

Counter-question #2 (Rav Ashi - Mishnah): All do Semichah (lean on the neck of their Korban), both men and women.

This is l'Chatchilah - "he will lean his hand, and the Korban will be acceptable"!

Answer (and clarification of Question #2 - Rav Acha): I agree that 'all' applies to l'Chatchilah, but it applies also to b'Di'eved.

I asked why we assume that in our Mishnah, it means l'Chatchilah, in order to ask a question. Perhaps it means b'Di'eved, and there is no difficulty!

Answer (to Question #2 - Rav Ashi): The Mishnah continues 'and the Shechitah is Kosher', i.e. b'Di'eved. If 'all slaughter' also means b'Di'eved, why does the Mishnah use a second expression of b'Di'eved?

Answer #1 (to Question (c) - Rabah bar Ula): The Mishnah teaches 'all may slaughter.' Even a Tamei person may slaughter Chulin...

Interjection: This is obvious!

Answer: He may slaughter Chulin Al Taharas Kodesh (treated as Kodshim). Rabah bar Ula holds that Chulin Al Taharas Kodesh is like Kodshim;

He uses a long knife, to avoid touching the animal (after the Shechitah, for then it can become Tamei).

(Continuation of Answer #1): A Tamei person should not slaughter Kodshim, lest he touch the animal. If he slaughtered, and he is sure that he did not touch, the Shechitah is Kosher';

The Mishnah says 'except for a Cheresh, lunatic or minor.' If they slaughtered even a Chulin animal, it is forbidden, lest they pause during the Shechitah, press (the knife, instead of cutting), or do Chaladah (Shechitah when the knife is covered).

Question: The Mishnah says 'any of them who slaughtered while others looked on, the Shechitah is Kosher.' To whom does this refer?

Suggestion: It refers to a Cheresh, lunatic or minor.

Rejection: (They were just mentioned.) If so, the Mishnah should have said 'if they', and not 'any of them'!

Answer #1: Rather, it refers to a Tamei (person) who slaughtered a Chulin animal.

Objection: The Reisha permits that l'Chatchilah!

Answer #2: Rather, it refers to a Tamei who slaughtered Kodshim.

Question: Why must others look on? We said that it suffices that he is sure that he did not touch!

Answer: The case is, he is not here to ask him whether he touched.

Question: A different Mishnah teaches that if a Tamei slaughtered Kodshim, it is Kosher!

(Mishnah): If a Pasul (anyone disqualified from Avodah) slaughtered a Korban, it is Kosher, since Shechitah may be done by a Zar (non-Kohen), woman, slave, or Tamei;

This applies even to Kodshei Kodoshim, on condition that (if he is Tamei) he did not touch the animal.

Answer #1: Primarily, our Mishnah teaches this law. That Mishnah teaches all Pesulim for Avodah, so it repeated the law of a Tamei who slaughtered a Korban.

Answer #2: Primarily, that Mishnah teaches this law. Since our Mishnah teaches about a Tamei who slaughters Chulin, it teaches also about when he slaughters Kodshim.