פירוש על ברכות 67:3

HE SHOULD NOT RESPOND AMEN AFTER [THE BLESSING OF] THE PRIESTS, BECAUSE OF CONFUSION. The Mishna said that the congregational leader should not answer אמן after the b’rochos of the Kohanim, because he may become confused and not be able to return to his prayer. This is bewildering. The rule that he may not answer אמן should be known¹ תיפוק ליה literally means – let him take it out. In the context of our Gemara- let it be known to him. because it is an interruption of the prayer that the congregational leader is in middle of saying if he answers אמן.
And we can answer: that since the Gemara does not offer this reason for not answering אמן; we can learn from this, that answering אמן is not considered an interruption since it is a requirement of the prayer. Answering אמן to the b’rochos of the Kohanim is essentially accepting their b’rochoh and that is thought of as part of the prayer service and not as an interruption.
Tosfos will now discuss a related issue, calling the Kohanim to recite their b’rochoh. In most synagogues the common custom is that the congregational leader calls the Kohanim to say the Birchas Kohanim. We will see further in this Tosfos that immediately after concluding the b’rochoh of modim with the words הטוב שמך ולך נאה להודות the leader would call כהנים. Rabainu Tam says that this is wrong. It is not the function of the congregational leader who is in middle of praying. Rather, it is the function of the sexton. Tosfos will explain that during the days of the Mishna and Gemara, the sexton was called the chazon. Nowadays the chazon is the congregational leader of the prayers. This difference in names of the various functionaries can cause a bit of confusion.
But to call the Kohanim to the duchon,² דוכן – literally the platform where the Kohanim stood. says Rabainu Tam, that the congregational leader cannot call them, because it is considered an interruption of the prayers. Rather, one of the members of the congregation calls them.
And that which we say in Sotoh perek Ailu Nemorim (38a) that for two kohanim he calls Kohanim etc.³As opposed to when there is only one Kohain when he is not called at all. that is not referring to the congregational leader of the prayers, rather, it refers to the chazon, as we have learned in Sifray (Parshas Noso) the Torah says אמור להם, literally say to them the Kohanim, this teaches us that the chazon says to them, recite the b’rochoh.
Who is this chazon?
And the chazon is not the congregational leader of prayer, for the chazon is the one who is involved in the needs of the congregation. Tosfos offers further proof that the congregational leader does not call the Kohanim to the duchon. And so too, it appears from Sotoh (39b) that the word קורא does not refer to the congregational leader, for initially the Gemara said that the Kohanim may not begin to recite the b’rochoh until the utterance calling Kohanim ceases to reverberate from the mouth of the קורא. This means the קורא, who calls “Kohanim”. And afterwards the Gemara says, the congregational leader is not permitted to etc. Since the Gemara speaks of a קורא and a שליח צבור, a congregational leader, it appears that they are two distinct people. The קורא, who is not the congregational leader, calls the Kohanim to the duchon, while the שליח צבור remains silent.
There are those who take this concept of the congregational leader not being allowed to interrupt his prayer a step further. And there are those who want to say that just as the congregational leader is not allowed to call out “Kohanim”, the congregational leader is similarly not allowed to read יברכך before the Kohanim as the custom is that the leader reads each word and the Kohanim recite after him. For that too, is an interruption of his prayer.
However, Rabainu Yehudoh explained that it is openly found in the Midrosh of the reasons for words with extra or missing letters, that the word אמור להם with an extra ו, teaches that the congregational leader says to them, that they should recite the particular word for each and every word that the Kohanim say. We see that it is the שליח צבור who must do the reading before the Kohanim.
There are those who want to say that even calling out Kohanim is permitted for the congregational leader nowadays. And so too, there are those who want to permit the congregational leader himself to call “Kohanim” even according to Rabainu Tam’s explanation. For that which he explained that it is an interruption, that was specifically in their days when immediately upon finishing the b’rochoh of modim they did not say “Our G-d and the G-d of our fathers, bless us with the blessing etc. as is our custom today. This is evident from Sotoh (ibid.) where the Gemara says the קורא is not permitted to call “Kohanim” until the word אמן ceases to reverberate from the mouths of the congregation. Which אמן is the Gemara referring to? The explanation is the אמן that they answer at the conclusion of the b’rochoh of modim. We see that it is evident that they only said “Kohanim” immediately at the conclusion of the b’rochoh of modim and they did not say “Our G-d and the G-d of our fathers as we do. But now, that it became the custom to say “Our G-d” in the format of a b’rochoh and prayer, this is not an interruption of the prayers, for it is not worse than answering אמן for the b’rochos of the Kohanim, which is not considered an interruption as we have explained earlier.

See Singer, p. 238a (10th ed.) and above, p. 104 n. 3.

Without making a mistake in the prayers.