In your point by point review of daf89 Yebamot at the bottom of the daf you wrote:
"...it does not appear like Chachamim uproot the Torah. I heard in the name of Rav Moshe Shternbuch that surely Chachamim can uproot. The question is whether or not they ever did so."
My question is, do you mean to say that R. Shternbuch says that the Chachamim can uproot a deoraisa prohibition of the Torah?
If so, does that apply only to Chazal or even in our day? And do you know what the source of this idea is??
Although I saw various opinions of the reshonim I wonder what specifically R.Shternbuch was refering to?
Thank you,
Yiftach Paltrowitz
Har Nof, Jerusalem
I understood that R. Shternbuch holds that mid'Oraisa, there is no distinction between Shev v'Al Ta'aseh and Kum Aseh. We can ask your first question according to everyone: do Chachamim nowadays have Ko'ach to forbid something nowadays through Shev v'Al Ta'aseh? It seems to me that there is a Machlokes about this.
The Beis Yosef (YD 334 (Sa'ifim 10-11 in Tur ha'Shalem) DH Kosav ha'Rashba) cites Ge'onim who enacted a severe Cherem for one who transgressed their decrees. We do not circumcise his sons, we do not bury his relatives. Rav Paltoy Gaon ordered to cut a man's Tzitzis, and not to teach Torah to his children. We Mevatel Mitzvos mid'Oraisa! The Beis Yosef says that this is because the Ge'onim were like a Sanhedrin, but nowadays we do not conduct this way.
This connotes that we could decree, but we consider it improper to do so.
The Magid Mishneh (Chametz u'Matzah 5:20) likewise says that we should not make decrees after the Ge'onim. (He discussed a stringency about making Matzah. This is not a decree to override a Mitzvah, but it could cause that one will not be able to fulfill the Mitzvah.)
The Rosh (Shabbos 2:15) asks how Ge'onim, who came after the Talmud was sealed, were able to decree not to say Aneinu at Ma'ariv and Shacharis of a Ta'anis.
The Aruch ha'Shulchan (OC 580:1) says that the Ge'onim could not have decreed to fast on certain days, some of which are Rosh Chodesh, for after the Talmud was sealed, we cannot decree on all of Yisrael. Rather, they taught that it is proper to fast.
They hold that even Ge'onim could not enact against mid'Rabanan laws, even b'Shev v'Al Ta'aseh all the more so against Torah!
I assumed that R. Shternbuch learned from Tosfos. (Perhaps what he said was to explain Tosfos.) How can Tosfos say that Chachamim have the power when there is Ta'am v'Smach, and it does not look like an Akirah? Mid'Oraisa, what does it matter whether or not it looks like we uproot the Torah? Rather, surely mid'Oraisa they can. However, the Gemara asks if they would do so if it will be blatant that they override the Torah.
Perhaps we can say so according to other Shitos. What is the Sevara to distinguish Shev v'Al Ta'aseh from Kum Aseh? If we learn from Eliyahu, he transgressed b'Kum Aseh! Elav Tishma'un does not distinguish! However, there are Shitos that say that Aseh Docheh Lo Sa'aseh or Ein Aseh Docheh Aseh really depends on Shev v'Al Ta'aseh or Kum Aseh, e.g. Sha'agas Aryeh (33, cited in Halachos for Yevamos 7). Davka those Shitos would have a Sevara to distinguish here as well, but it is not clear to me why these matters should be equated.
P. Feldman