Kiddushin 41b - terumah and gerushin aren't comparable cases, because of kodesh and chol, so we can't learn one from the other.
Kiddushin 43a - same sugiya, meilah and shlichut yad are comparable cases, so we can apply Shnei ketuvim.
Question not addressed by gemara or rishonim - why are they comparable? meilah is kodesh, shlichut yad is chol?
thought: refer to the mishna in 2:8, where R Meir thinks that if you use hekdesh b'meizid it becomes chol (or m'challul) and b'shogeg it stays kadosh, R Yehudah thinks that if you use hekdesh b'shogeg it becomes chol and b'meizid it stays kadosh - perhaps the gemara is taking that line on board, and saying implicitly that meilah is dealing with chol. How Brisker is that? yay.
Kiddushin 43a - same sugiya, meilah and shlichut yad are comparable cases, so we can apply Shnei ketuvim.
Question not addressed by gemara or rishonim - why are they comparable? meilah is kodesh, shlichut yad is chol?
thought: refer to the mishna in 2:8, where R Meir thinks that if you use hekdesh b'meizid it becomes chol (or m'challul) and b'shogeg it stays kadosh, R Yehudah thinks that if you use hekdesh b'shogeg it becomes chol and b'meizid it stays kadosh - perhaps the gemara is taking that line on board, and saying implicitly that meilah is dealing with chol. How Brisker is that? yay.