Siman 114 Prayers for Wind, Rain and Dew
When do we start to say "gevurot geshamim?" R. Eliezer says, From the first holiday [of Sukkot]. R. Yehoshua says, From the last holiday [of Sukkot, Shemini Atzeret]. R. Yehoshua said to him, Since rains are a bad omen during Sukkot, why should one mention them? R. Eliezer replied to him, I did not say one should ask [for rain], just mention "Who makes the wind blow and the rains fall in their season." He said, According to this, one should mention them all the time! [He replied,] We mention the rains only when rain is imminent.
R. Yehuda says, If you descend [to lead prayers] on the first holiday of Sukkot, mention [rain] in the last [prayer - Musaf], but not in the first [prayer - Shacharit]. On the first holiday of Pesach - mention in the first, but not in the last (Mishna, beginning of Ta'anit).
It is taught [in a beraita]: The sages did not require mentioning dew and wind, but you may say them if you want. Why [is there no requirement]? - because they are never withheld. ... R. Chanina said, Therefore if you say "meshiv ha-ruach" in the summer you do not need to go back, [but] if you said "morid ha-geshem" you must go back. If you omit "meshiv ha-ruach" in the winter you do not need to go back, but if you omit "morid ha-geshem" you must go back. (Gemara Ta'anit 3a and b)
Why don't we mention [rain] at night [in Ma'ariv]? Because not everybody is there [not everybody comes to Ma'ariv]. Why don't we mention it in Shacharit? Because someone who hears that it is mentioned in Shacharit will assume that they started mentioning rain in Ma'ariv, and [in coming years] will come to start the mention in Ma'ariv; now that he sees that they don't mention it in the first [Shacharit] and mention it in the last [Musaf], he knows that they didn't start at night. ... The individual is forbidden to mention until the Shaliach Tzibur does so ... it is all dependent on the Shaliach Tzibur.
R. Zeora said in the name of R. Chanina, if you mention dew in the time of rain, don't go back; rain in the time of dew, go back. But did we not learn that the sages did not require mention of dew and wind, but one may say them if one wishes? [Likewise, even though mention of rain is not required in the summer it should be permitted!] You can't compare one who curses [mentions rain in the summer when it is a bane] to one who doesn't bless and doesn't curse [omits mention of dew].
If you prayed but don't remember what you mentioned: R. Yochanan says, For thirty days there is a presumption you said what you are USED to saying, from then on, what you SHOULD be saying (Yerushalmi Ta'anit 1:1).
We mention gevurot geshamim in "techiyat ha-metim" and ask in the blessing of years [mevarekh ha-shanim] ... Why? R. Yosef said, Since it [rain] is considered like resurrection, therefore [mentioning rain] was established in "techiyat ha-metim". ... Since it is [a cause of] livelihood, [asking for rain] was established in the prayer for livelihood [birkat ha-shanim]. (Mishna and Gemara, Berakhot 33a)
Almost the entire siman, except for se'ifim 7 and 9, states rules which are explicit in one of the gemarot cited.
We see from the SA se'if 1 that the halakha is according to R. Yehuda, who has the last word in the mishna. Other opinions mentioned in the gemara are brought down in MB s.k. 2. The reasoning behind these opinions is taken seriously; the a priori reasonability of starting at night has a consequence for "bedi'avad" (see s.k. 2) and the reason the gemara brings for starting at Musaf implies a completely different consequence for the starting time according to Nusach Ashkenaz - s.k. 3.
What about an individual who is praying at home - is his prayer also dependent on that of the Shaliach Tzibur in Beit Knesset? See s.k. 16.
PLACES WHERE RAIN IS NEEDED IN THE SUMMER
This is mentioned in SA se'if 4, MB 22, BH d.h. Ve-afilu. The gemara on Ta'anit 14b explains that if a particular person needs rain out of season, he should make his request in the blessing of Shome'a Tefilla. Even so, the Jews of Ninveh asked Rebbi if perhaps they should mention rain in the summer, since they also need rain then. They supposed that a community might be different than an individual. Rebbi sent a reply that they are considered like an individual. Even though there is a beraita that says that during the period of exile the times of mentioning and requesting rain are no longer centered around Eretz Yisrael but rather are dependent on the time and place, Rebbi disputes this beraita; alternatively, he interprets it to mean an individual request in Shome'a Tefilla.
However, the Rambam in his commentary on the mishna (Ta'anit 1:2) seems to rule like this beraita! The Rosh (Responsa 4:10) also rules this way. The Rosh points out that Rebbi's reply to the community of Ninveh was that as an isolated city they are considered like an individual; but if an entire country needs rain in the summer, as is the case in all of central Europe, then they should indeed mention and ask all year.
The Beit Yosef concludes that the custom is against the opinion of the Rosh. Even so, the Bi'ur Halakha d.h. Ve-afilu understands from the ruling in SA 117 that regarding asking this is only lekhatchila, but bedi'avad the Beit Yosef admits that one who has acted according to the Rosh's ruling can not be compelled to go back. (This is reasonable but not actually obvious from the text.) From this the BH draws certain conclusions for our siman.
TEXTUAL JUDAISM AND THE LIVING TORAH
In his introduction to the Beit Yosef, R. Yosef Karo clearly asserts that since it is impossible for someone of his stature to set himself up as arbiter among the great Rishonim, for his rulings will be based on the majority of the opinions of the Rif, the Rambam, and the Rosh. Yet, here we have a case where the Rambam and the Rosh agree that an entire country which needs rain can mention and ask for rain in the summer, while the Rif does not dispute this ruling since he does not relate to this case. Although the Rambam's ruling is in the commentary to the Mishna, this has the same status as the Mishneh Torah - so I understand from Kesef Mishneh, also written by R. Yosef Karo, to Hilkhot Talmud Torah 3:10 at the end - and in addition, the Beit Yosef on our siman claims that the Mishneh Torah also rules like the commentary to the Mishna. How can the Beit Yosef rule against them?!
The Beit Yosef emphasizes that the custom of the entire world contradicts the Rosh's ruling. He also suggests that this ruling was never accepted in practice. How can we weigh these factors against the authority of the written sources?
There is a general difference in approach among poskim regarding how to weigh local custom against textual authority. The Tosafot in many places endeavor to reconcile the text with the custom (see for excample, Shabbat 48a d.h. De-zeitim); other sages more readily condemn custom on the authority of the plain sense of the text.
It seems that several factors bear on the relative importance:
1. How universal is the custom? Responsa frequently point out that the reaction to a seldom-encountered situation can not be considered a "custom" - merely a precedent.
2. Among whom is the custom widespread? If we are certain that even scholars and meticulous people conducted themselves in a certain way, this has more weight than the behavior of the common people, pious though they may be.
3. Are opinions opposing the custom recognized? Sometimes we find statements to the effect that if a community had been aware that a great authority opposed their custom, they would not have adopted it. Conversely, a custom may be defended by pointing out that it was upheld even though opposing views were clearly known.
4. Perhaps in an area of halakha whose basis is in custom, though it subsequently achieved the status of binding halakha, we should give greater weight to custom.
In our case, the Beit Yosef perceived that the custom of going according to Eretz Yisrael was universal, even among scholars, and even among people who were certainly aware of the statements of the Rambam and the Rosh. In addition, he may have considered the "customary" aspect of prayer to have special importance - the fact that we pray as a community renders special importance to community customs. Therefore, even though the Beit Yosef is, according to his own assertion, an extreme "textualist," in this case he was persuaded to rule in accordance with custom.
Almost all Acharonim are extremely reluctant to dispute Rishonim - though there are notable exceptions, such as the Maharshal (who lived, in any case, close to the era of the Rishonim). However, many later scholars do feel that however unworthy they may be, it is their responsibility as decisors to decide AMONG the Rishonim. The Beit Yosef's reticence in this regard is far from universal.
A lot of noise is still being made regarding an article written a couple of years ago by a leading scholar of Judaism (who is also a Talmid Chakham, though the two do not always go together) who posits that only recently have texts taken such a central role in Jewish life. He claims that before World War II custom was king, and accepted customs of respectable communities were not scrutinized in the light of codes. I can not comment on the historical reality of three generations ago, but I think we should keep in mind that the tension between custom and written authority is an ancient one, and the "advocacy" of texts is hardly a new idea.