The Last Steps of Rav Yehuda Amar Rav

Tosafot's final pshat in עדות שקר העדתי is that the admission by one witness of the false testimony was followed by a hazama of them both.  According to this pshat, the obligation to pay devolves on the other ed -- the ed left holding the bag, as one student put it.   Why? They were both huzam, but the ed that admitted his guilt prior to the hazama is relieved of the payment, which is a special penalty of the Torah, ka'asher zamam...We explained that there was perhaps a policy reason for the Torah to relieve the person of his penalty if he "comes clean" and does teshuva...

This new pshat is followed by the Gemara's kashya/difficulty: "Does he have the ability to do this? Once he has testified, he cannot withdraw his testimony" in Hebrew כיון שהגיד שוב אינו חוזר ומגיד; I tried to argue last night that there was a serious "hava amina" - or assumption in the Gemara that - despite the fact that one cannot withdraw testimony - and the ramifications of the false testimony do impact on the initial accused - the penalty of "ka'asher zamam" functions differently - and is mitigated by an admission...the Gemara's retort is that the two are intertwined: You cannot possibly separate the irreversible nature of the edut/testimony from the penalty of the ka'asher zamam - one flows from the other!  So since the testimony cannot be withdrawn, neither can the "ka'asher zamam" be cancelled...

This leaves us in a real difficulty - because we don't yet have a pshat in Rav Yehuda/Rav - all of our efforts have been in vain!

The Gemara's response: the case is that one ed came to a second Beit Din and admitted that he and his friend (who doesn't admit this) were huzam in a first Beit Din.  He, the contrite ed, has to pay.  That's what Rav Yehuda/Rav was referring to!

The Gemara's response? This approach is unlike that of R. Akiva, who holds that admission of Hazama = admission of a Knas, and R. Akiva holds that מודה בקנס פטור.  We explained that although Rav could in fact disagree with R. Akiva....but the Gemara was searching for a consensus - a way of saying that Rav agreed with all of Tannaim...

New Pshat?  The ed adds a detail: we were also מחוייב ממון - obligated to pay - this transforms it into a pure monetary obligation, and takes it out of the realm of Knas, such that R. Akiva could even agree that the admission generates an obligation to pay.

The chiddush? Even though the basis of the admission is that only one ed reported the event, and he cannot obligate his friend, his admission was enough to obligate him (the admitting ed) to pay!