Pesochim 27a says v'Savar Asniyah Ipcha Ki Heichi d'Neikum Rabanan l'Isura that Shmuel reversed the nusach of a braiso: Instead of the Rabonon saying mutar, Shmuel quoted it as saying that the Rabonon said ossur, and he did this so that people would follow his psak that it's ossur.
Pesochim 112a say something similar Im Bikashta le'Chanek Hitaleh b'Ilan Gadol.
Rashi in both places (and elsewhere) says that if you (i.e., a posek) want people to accept your psak, say your psak in the name of a great person (even though that person never said such a psak, or even (as Shmuel did) if he said the opposite, reverse it).
Mogen Avrohom 156:2 brings this idea but immediately quotes the Mishna in maseches Kallah that "he who says something in the name of a chochom from whom he did not learn it, causes the Shechina to depart". The Mogen Avrohom ends with Tzorech Iyun.
Regarding this concept of quoting a chochom who did not say something, and even quoting him as if he said the opposite, what is the Hallocho today? Such an idea could be easily misused (such as quoting a posek gadol to have paskened something and in truth he never did, or paskened the opposite).
Thanks and kol tuv,
Chaim
Dear Chaim,
I think the answer to your question is in Rashi there on the first Sugiya you quote (Peshachim 27a, D"H Ee Ba'is Eima). Rashi says that Shmuel reversed the Psakim in order sh'Lo Yeilchu Bnei Adam Acharei Rabim l'Hatir. In other words, Shmuel knew that the Halachah was like Rabee even though he was a Da'as Yachid (perhaps he knew that the Beis Din haGadol had ruled like that) and he was trying to save people from being wrongly lenient in the matter. People would apply their simplistic reasoning and invoke the Klal that the Halachah follows the Rabbim against the Yachid, even against Rabee. And in this case they would be wrong. What Shmuel was doing was, therefore, a Hora'as Sha'ah of sorts. He was trying to save people from being Nichshal in the Halachah, at the expense of the veracity of the Mesorah. It is certainly not something that someone is allowed to do simply to strengthen his Halachic opinion. Such a person that would do that is probably the subject of the Mishnah in Meseches Kallah that the Magen Avraham quotes.
I think we can say the same idea regarding the second Gemara you quote (Pesachim 112a) according to Rashi (according to the Rashbam and Rabbeinu Chananel, that Gemara poses no difficulty). Rashi there could be saying that in a situation where the Chacham (the Machzik Berachah on Orach Chaim (156) says the Gemara is only referring to a Chacham haHigi'a l'Hora'ah) knows that the Halachah is such and such, he is allowed to say it in the name of a famous rabbi in other sh'Yishma haBeri'os v'Yekablu Mimchah. Rashi is not suggesting that any Talmid is allowed to claim that Rav Ploni agrees with him just to advance his position.
In a similar vein, we have the Gemara in Beitzah (20a) that records the story of the Machlokes between Beis Shamai and Beis Hillel regarding Semichah. The Gemara says that Beis Shamai tried to establish that the Halachah followed their opinion but there was a Chacham there - Bava Ben Buta - who was actually a Talmid of Shamai who KNEW that the Halachah follows Beis Hillel in Semichah and he did some maneuvering that would influence the vote again Beis Shamai.
Kol Tuv,
Yonasan Sigler
This is not a Psak Halachah