90a middle
The gemoro says that acc to sumchus, we know that the chulin temeyim becomes trumah midoiraisa, (even if he paid that bemezid) because you can be mekadesh an isha with this money, rashi explains because of reb ilois drosho.
Why doesn't the gemoro just bring a raye from the same braisa by the case of shogeg, if shogeg works, then obviously its a good tashlumin midoiraisa?
The same question at the bottom of the omud.
The gemoro says that we know that the zerikas dam tomey is hurtze midoiraisa even by a mezid, because we have a braisa that says so. Why not bring a raye from shogeg, if it works betumah then we know it works betumah by mezid as well?
Avrumi Hersh, London england
1) It seems that a similar question is asked by the Tosfos Yeshanim (DH v'Ha Hacha). He does not mention Shogeg but he asks why the Gemara needs to mention the fact that the money cannot be used for Kidushin. The Gemara should instead have said that we know that the Terumah is effective mid'Oraisa since it is only the Rabanan who said that the Terumah does not work and that the fruit remains Chulin (since it was done b'Mezid, as the question is being asked on Rebbi Meir, as Rashi writes).
2) The Tosfos Yeshanim answers that if we would have said this, it could mean that when done b'Mezid, the Terumah does not go to the Kohen at all but instead goes straight back to the owners. It is still Terumah and a non-Kohen will not be allowed to eat it. The fact that we proved it from the Kohen marrying the woman proves that it does go to the Kohen.
3) It seems that we now can use the question and answer of the Tosfos Yeshanim to answer your question about Shogeg. The fact that Shogeg works does not prove that if it was done b'Mezid that it is a good Tashlumin mid'Oraisa. It is possible that it is not a Tashlumin mid'Oraisa and does not go to the Kohen at all. The ownership of the Terumah goes back to the original owners but remains permitted to eat only to Kohanim since it is Terumah.
This is why we have to prove it from the fact that the Kohen can marry a woman with this money. This proves that the Terumah belongs to the Kohen and did not go back to the originsl owners.
Yasher Koach
Dovid Bloom
2) The second question is asked by the Shemen Roke'ach:
a) The Sefer Daf Al Hadaf here cites the Teshuvos Shemen Roke'ach (1:33) who asks: Why does the Gemara need to cite the Beraisa about "what does the Tzitz atone for?" The fact that the Tzitz provides Ritzuy b'Shogeg proves that mid'Oraisa it can also provide Ritzuy b'Mezid! A proof that if it is Meratzeh b'Shogeg then it can also be Meratzeh b'Mezid is from Rashi above (89a, DH Dilma Pasha) who writes that the fact that something is effective b'Shogeg shows that the Kedushah holds also b'Mezid. Another proof is from Tosfos in Pesachim (80b, DH Nizrak) who writes that wherever we make a distinction between Shogeg and Mezid, it is only mid'Rabanan that Ritzuy is effective. This shows that whenver there is Rituy mid'Oraisa there is no difference between Shogeg and Mezid.
b) The Shemen Roke'ach (DH v'NLAN"D) answers that it is only according to Rav Chisda that it is necessary for the Gemara here to cite the Beraisa. See the Maharsha to Yevamos 89a (DH Gemara v'Rami) who says that according to Rav Nasan b'Rebbi Oshiya there is no difference betrween Shogeg and Mezid, but according to Rav Chisda there is a difference between Shogeg and Mezid.
Kol Tuv,
Dovid Bloom