The Gemara says the priestly blessing is said daily. The Sephardic do so. The Ashkenaz do not. My Rabbi told me something to the effect that the RAMA was going to and a fire broke out. He tried again and another fire. Thus, the Ashkenaz don't. The difficulty with this answer is that it explains TODAY but doesn't answer why the Ashkenaz didn't BEFORE the fire. Please elaborate as to why the Ashkenaz don't do duchining on a daily basis.
Barry Epstein, Dallas, USA
Here are some comments that the Kollel wrote about your question elsewhere.
Kollel Iyun Hadaf
I have some kohanim questions:
1) what is the basis for kohanim not duchanim on a daily basis outside Israel?
2) What is the basis that some have for duchanim on a daily basis only in Yerushalayim and not in other parts of israel?
(a) The Poskim write that the reason for the practice not to recite Birkas Kohanim in Chutz la'Aretz is because Birkas Kohanim requires Simchah and the fact that they are in Chutz la'Aretz lessens the Simchah, except on Yom Tov when Simchas Yom Tov compensates and enables the Kohanim to say Birkas Kohanim.
(b) The original settlers of Yerushalayim of the modern age were the Talmidim of the VILNA GA'ON. The Ga'on maintained that Birkas Kohanim is a Chiyuv d'Oraisa, at all times and in all places. In his hometown, though, he did not enforce his view against the prevailing Minhag not to recite Birkas Kohanim. When his Talmidim came to Yerushalayim, they conducted themselves in accordance with his view. That practice spread to other places (primarily the Yeshivos) in Eretz Yisrael.
The MAHARIL (Chadashos #21), cited by the Beis Yosef, was asked why it is that in much of Europe ("Ashkenaz") the Kohanim only performed Birkas Kohanim on Yamim Tovim. He suggested two sources for the practice. First, it is because some say that a Kohen must immerse in a Mikvah before performing Birkas Kohanim, and it was too difficult to immerse every day in most of Europe.
Second, he says that doing Birkas Kohanim every day would cause "Bitul Melachah" and create a burden on workers who needed to be at work on time.
The BEIS YOSEF strongly rejects these reasons. Since Tevilah is not mentioned in the Gemara, why should that stringency -- the Chumra of immersing in a Mikvah before performing Birkas Kohanim -- cause one to annul the Mitzvas Aseh d'Oraisa of giving the Berachah. Moreover, the reason of Bitul Melachah is difficult to understand, because Birkas Kohanim does not take so much time that it should warrant this exemption. The Beis Yosef writes that, indeed, in all of Israel and Egypt the Kohanim performed Birkas Kohanim every day.
The DARCHEI MOSHE, however, defends the second reason of the Maharil, explaining that Bitul Melachah does not mean a delay from working, but rather it means that in Chutz la'Aretz, people toil so hard to earn a living that they are not able to arouse the proper Simchah that is necessary in order to perform Birkas Kohanim. Even on Shabbos, their minds are so distracted by their past and future plans for earning a living that they do not reach the proper level of Simchah. The only time they are able to perform the Birkas Kohanim with the appropriate degree of Simchah is on Yom Tov, when the Mitzvah of "v'Samachta b'Chagecha" makes them truly joyful, enabling them to perform Birkas Kohanim with Simchah.
In the Shulchan Aruch, the Rema adds that even on Yom Tov, the Kohanim perform Birkas Kohanim only during Tefilas Musaf when they are about to leave the synagogue and experience the joy of Simchas Yom Tov. This is the source for the practice of most communities outside of Israel.
The Vilna Ga'on is said to have attempted to re-institute Birkas Kohanim on a daily basis in his community, but he received a sign from heaven not to do so. When his students arrived in Eretz Yisrael, they revived the practice of the daily Birkas Kohanim among the Ashkenazic communities. Nowadays, many Ashkenazic communities in Eretz Yisrael perform Birkas Kohanim every day, although some communities (such as Haifa and most communities in the Galilee) perform Birkas Kohanim only on Shabbos and Yom Tov. In Chutz la'Aretz, only Sefardic communities perform Birkas Kohanim on a daily basis.