Gemara

Question: It says "Shok ha'Terumah va'Chaze ha'Tenufah Al Ishei ha'Chalavim", "Es ha'Chelev Asher Al he'Chazeh", and "va'Yasimu Es ha'Chalavim Al he'Chazos"!

Answer: One Kohen brings them from the place of Shechitah, and flips them over into the hands of another Kohen, and he flips them over into the hands of a third Kohen. The verses teach that three Kohanim are used. The Avodah is more honorable this way - "b'Rav Am Hadras Melech."

Berachos 39a: Two Talmidim were in front of Bar Kapara. Vegetables and meat were brought in front of him. He gave permission to one to bless.

42a (Mishnah): If people were sitting (at a meal), everyone blesses for himself. If they reclined, one blesses for everyone.

If wine was brought during the meal, everyone blesses for himself. After the meal, one blesses for everyone;

42b: Rav's Talmidim said "let's eat bread at the river." They were unsure if this is as good as Hasivah (reclining) to allow one to bless for everyone.

Rav Ada bar Ahavah: Rav died, and we do not even know the laws of Birkas ha'Mazon!

Contradiction (Beraisa): If 10 were travelling, even if all eat from the same loaf, everyone blesses for himself. If they sat to eat, even if everyone eats from his own loaf, one blesses for everyone. (They need not recline!)

Answer (Rav Nachman bar Yitzchak): The case is, they said 'let us go eat bread in the place Ploni.'

43a - Version #1 (Rav): Only bread requires Hasivah (for one to bless for everyone). Wine does not require Hasivah.

(R. Yochanan): Even wine requires Hasivah.

Version #2 (Rav): Hasivah helps only for bread (for one to bless for everyone). It does not help for wine;

(R. Yochanan): It helps even for wine. (End of Version #2)

(Beraisa) Question: Why must everyone bless for himself on wine during the meal, but one blesses for everyone on wine after the meal?

Answer (Ben Zoma): During the meal, people have food in their mouths when the leader blesses.

53a (Beraisa - Beis Shamai): If fire was brought to people in a Beis Medrash (on Motza'ei Shabbos), everyone blesses for himself;

Beis Hillel says, one blesses for everyone -- "b'Rov Am Hadras Melech."

Beis Shamai disagree, for it is Bitul Torah for everyone to stop learning to listen to the Berachah and answer Amen.

Chulin 106a - Rabah bar bar Chanah: Peros were brought in front of R. Ami and R. Asi. They did not give to me, and each blessed by himself.

Inference: When people eat Peros together, they do not Mezamen (one does not bless afterwards to exempt the others), and when two ate fruit, the Mitzvah is for each to bless by himself.

Rishonim

Rambam (Hilchos Berachos 5:15): If two ate together, everyone blesses for himself. If one knows how to bless and the other doesn't, the former blesses aloud and the latter answers Amen to each Berachah, and he is Yotzei.

Rosh (Berachos 6:33): Our Mishnah (42a) applies to a Berachah Rishonah and Berachah Acharonah. When there are two, one may say a Berachah Rishonah for the other if they reclined. If not, even though Shome'a k'Oneh and he answered Amen, he was not Yotzei. When there are three, one blesses Birkas ha'Mazon for them if they reclined on beds. Nowadays we do not recline, so our sitting is Kevi'us (being fixed together) like their Hasivah. R. Chananel explains that they were sitting for another reason, and they happened to eat, so everyone blesses for himself. If they reclined to eat and not for another reason, one blesses for everyone. Some say that they were sitting in different places, unlike the way people eat (together). Hasivah is when they sat around a table. Rashi's (the first) Perush is primary. The case of Rav's Talmidim is difficult for all other Perushim. In the Yerushalmi, R. Yehoshua ben Levi says that the Mishnah discusses guests. A man's household is drawn after him, so they need not recline.

Rosh (ibid.): In Version #1, something important requires Hasivah. R. Yochanan holds that even wine is important. Other things do not need Hasivah. Since the Berachah is mid'Rabanan, we follow the lenient opinion, i.e. Version #1. A proof is 39a, in which a Talmid was allowed to bless for others.

Rosh (8:3): Blessing on fire is unlike bread. We said that when people sat together, everyone blesses on bread for himself. This is because they needed Hasivah. Since they did not, they were not fixed together for one to be Yotzei through another's Berachah. Here, this is like wine, according to Rav, who does not require Hasivah for wine. R. Yochanan requires Hasivah, for people normally recline together for wine. He agrees that for other Berachos, it is as if they reclined.

Tosfos (106a DH u'Shma): Since there is no Zimun for Peros, obviously the Mitzvah is to split up! Rather, there is no Chiyuv to be Mezamen even when there are three. If there were a Chiyuv, they would have given to Rabah to eat! Rather, for Peros, two are like three. One might have thought that when two ate bread or even three ate Peros, one may bless for the others. Since they blessed separately, this shows that one may not. If it were permitted, they would have done so, in order to say 'let us bless the One from Whom we ate', to add to His praise. Why is there no Zimun for Peros for a Berachah Acharonah, but one may bless for everyone a Berachah Rishonah? Everyone benefits through a Berachah Rishonah, for it permits eating. Therefore, people join. Afterwards, they do not join. Nowadays, one blesses beforehand to exempt others only on bread, for we do not fix to recline for wine or Peros.

Rashi (43a DH Ho'il): If one hears a Berachah while food is in his mouth, he is occupied with swallowing, and does not listen to the Berachah.

R. Yonah (Berachos 30b DH Ba): Even if one has food is in his mouth, he can listen! Some say that the mouth must be empty to answer Amen - "Yemalei Pi Tehilasecha." Really, one can say one word with food in his mouth. However, it is dangerous (lest they choke). The Yerushalmi supports this.

Poskim

Shulchan Aruch (OC 298:14): If fire was brought to people in a Beis Medrash, one blesses for everyone.

Magen Avraham (18): Even though all must be quiet and listen and there is Bitul Torah, this is better, due to b'Rav Am. See 213:1 (below).

Chayei Adam (68:11): If a Mitzvah can be done with a group, it is better to do so, due to b'Rav Am. Many doing a Mitzvah is unlike a few doing a Mitzvah. Menachos 62 connotes that three are considered b'Rav Am.

Kaf ha'Chayim (70): Ri'az rules that everyone blesses for himself, due to Bitul Torah.

Mishnah Berurah (35): This is when they already made Havdalah and they did not have fire, and now they obtained fire, or they know that they will not have wine tonight. If they expect to have wine tonight, it is better to delay the Berachah on fire and say it (with Havdalah) over the wine.

Shulchan Aruch (213:1): For all Peros and other things, except for bread and wine, if two or more people were eating, one exempts the other even without Hasivah. However, they must sit together. Only bread and wine require Hasivah. Our sitting is like their Hasivah, so for us, bread and wine are like other things.

Beis Yosef (DH Al): Most say that the Halachah follows Version #1.

Gra (DH Al): The Halachah follows R. Yochanan, in Version #1.

Beis Yosef (DH u'Mah she'Chosav ul'Didan): We do not require Hasivah, and perhaps not even sitting. Bread requires Kevi'us, so it requires sitting. However, in some editions of the Tur, in Siman 174 he says that other things require sitting. Kevi'us is not needed, but we need a proof that they intend to be Yotzei. Tosfos in Chulin and R. Yerucham require Kevi'us for a Berachah Rishonah or Berachah Acharonah.

Gra (DH u'Mihu): There is no proof from Tosfos, for he holds that all Peros are like wine. Just like R. Yochanan argues about wine, he argues about all Peros!

Mishnah Berurah (3): It is better that one exempt the others, for b'Rav Am Hadras Melech.

Magen Avraham (1): Tosfos says that incense does not require Hasivah, for everyone benefits together. I.e. it does not require even sitting. OC 298:14 supports this, for there they were not sitting with Kevi'us. They were learning! Even so, one may bless on fire for everyone.

Bi'ur Halachah (DH Al): The Pri Megadim said that we cannot learn about incense, a Berachah of praise, from a Berachah on fire, which is like a Mitzvah. Even fire is not so clear. Shitah Mekubetzes requires sitting for it! Even if initially they were learning, if now they want to be Yotzei, Kevi'us helps! Nowadays people are Yotzei Borei Me'orei ha'Esh while standing, for it is with Havdalah. Since Kevi'us helps for Havdalah, it helps also for Borei Me'orei ha'Esh. One should not be lenient if it is said by itself, and surely not for incense. This requires investigation.

Kaf ha'Chayim (3): Also Berachos of praise and Mitzvos do not require Hasivah. The Birkei Yosef says the same about Birkas ha'Mazon; Aruch ha'Shulchan disagrees.

Magen Avraham (2): Sitting must be at one table.

Kaf ha'Chayim (2): If they were not at one table or eating on one cloth, Kevi'us does not help.

Mishnah Berurah (5): L'Chatchilah they must sit. B'Di'eved, as long as both intended that he be Yotzei through the other's Berachah, he was Yotzei.

Shulchan Aruch (ibid.): Except for bread, one may bless for others only the Berachah Rishonah. Everyone blesses for himself the Berachah Acharonah, for we do not make a Zimun for Peros.

Beis Yosef (DH v'Hani): Ohel Mo'ed says that some say that the Rambam discusses only food and drink, but not other Berachos. Others say that Shome'a k'Oneh applies to all Berachos, even l'Chatchilah. The Ro'oh says that Hasivah helps for a Berachah Rishonah, but not for a Berachah Acharonah, except for Birkas ha'Mazon. The Rashba says that Shome'a k'Oneh always works, but l'Chatchilah we do not do so for Peros. Hagahos Maimoniyos (11:4) says that if 10 do a Mitzvah, one blesses for everyone.

Mishnah Berurah (9): If one does not know how to bless, l'Chatchilah he may be Yotzei through another even without any Kevi'us. The Taz says that nowadays many disgrace the Berachah Acharonah, so one should rely on the Rashba, and one blesses aloud, and the others are Yotzei through him, either of they know how to bless. This is especially for me'Ein Shalosh, which not everyone knows by heart. It is best if those listening say it word for word with the Mevarech.

Kaf ha'Chayim (7): Where people bless properly, everyone should bless for himself.

Kaf ha'Chayim (8): If Reuven is unsure if he ate a Shi'ur to obligate Al ha'Michyah, and Ploni is about to bless after cake and dates, Reuven may be Yotzei, even though Ploni will include 'Al ha'Peros', which Reuven did not need to say.

Kaf ha'Chayim (10): One who is Yotzei through another's Berachah should not say Baruch Hu u'Varuch Shmo. We do not protest against one who says it.

Kaf ha'Chayim (12): Ri'az explicitly says that when there are three, one blesses for everyone also a Berachah Acharonah, due to b'Rav Am. The Rambam connotes like this, and the Kesef Mishneh says so in the name of Ramach. However, many Rishonim and the Shulchan Aruch disagree. We follow them.

Rema: Some say that Hasivah helps only for bread and wine, and the same applies to our sitting. Therefore, nowadays the custom is that everyone blesses for himself on Peros.

Gra (DH v'Yesh): This is like Version #2.

Magen Avraham (5): For things that come during the meal, one blesses for everyone. Since Hasivah helps for bread, it helps for other things. `

Taz (2): Nowadays, beer and mead are like bread and wine; our sitting helps for them. Most hold that sitting helps for everything, and even the Rema says that it depends on the custom. The custom is that when people sit to drink, one blesses for everyone.

Mishnah Berurah (12): Nowadays the custom is that one is not Motzi another in almost any food, even though this is unlike the Halachah. Perhaps it is because not everyone knows to intend to be Yotzei and to be Motzi properly.