What Motivates the Gemara - and Edim Zomimin Not Sold as Slaves

We covered two main issues in last night's shiur:

a) What motivated the Gemara to offer an unlikely explanation of the Tanna Kamma - R. Yishmael Machloket as it relates to the payment of כופר based on value of Nizak vs. Mazik
b) The suggestion of Rav Hamnunah #1 as to why Edim Zomimin are not sold as slaves
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a) What motivated the Gemara to offer an unlikely explanation of the Tanna Kamma - R. Yishmael Machloket 
 

If you recall, the Gemara initially suggests that the basis of the TK/RY machloket regarding value of nizak / mazik was a function of whether כופרא is כפרה or ממונא.  According to TK, the value of nizak is paid since kufra is compensatory to the nizak's family; according to RY, the ox owner pays the value of the mazik since kufra is an atonement, and one is paying for the "value" of his OWN soul. 

This linkage is then broken by the Gemara, the suggestion being that both Tannaim hold that kufra is indeed kapara, but that the machloket between them hinges on whether or not to learn the Gezeira Shava from the case of the aborted fetuses.  According to the TK, we do learn such a Gezeira Shava and therefore the case למטה - below - is also based on דמי ניזק; according to RY, we do not learn such a Gezeira Shava, and therefore the ונתן פדיון נפשו reflects both the agenda of the payment (כפרה) and the basis of the payment (דמי מזיק)

What prompted the Gemara to go in this direction? What advantage does the Gemara see in promoting this latter approach?

We explained last night that it is an attempt to understand the opening baraita - ד דברים נאמרו בעדים זוממים as truly reflective of a consensus of opinion:
According to the first approach on the machloket TK and RY - that it's only RY who holds that כופרה  is כפרה, then we have to say that the original baraita, though it seemed to be a consensus view, is really only the view of one Tanna.  This is difficult to say!
According to the new proposal, though, in which both TK and RY hold that כופרה is כפרה - we can maintain that the opening baraita is indeed לדברי הכל - everyone's view - and that's why it is represented as such!'
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b) The suggestion of Rav Hamnunah #1 as to why Edim Zomimin are not sold as slaves

We spent a lot of time on the structure of this piece and noted two sections, both of which said סבר רב המנונא למימר הני מילי etc; we firstly pointed out that הני מילי are words of limitation -namely, narrowing the case of the baraita.  As opposed to understanding the baraita as a blanket statement that edim are NEVER sold as slaves, R. Hamnunah seems to limit this to a narrow situation, contrary to the plain pshat of the baraita.

Secondly, we noted that the Gemara seems to be rephrasing Rav Hamnunah a few lines later.  This is because there is an apparent kashya/difficulty with what he seems to have said.  The difficulty is so great that the Gemara concludes that he never really made the first statement.  What was the kashya in between that prompted the Gemara to rephrase Rav Hamnunah?

We spent the last part of the class going back over the הני מילי of Rav Hamnunah: He maintains that the only time the edim are not sold is when the accused has money; with this as the cas, they are not deemed to be conspiring to sell him; therefore, they are not sold.  However, notes RH, if they accused does not have money, then they are deemed to have conspired to sell him and they themselves are sold.

Although this is logical, it definitely "turns the baraita on its head" because the previous three cases of the baraita are all examples of halachot that, in a blanket fashion, do not apply to Edim Zomimin.  Rav Hamnunah seems to be saying that the fourth case is different because it's only not applicable to edim due to specific circumstances, not in principle.

The kashya of the Gemara on this version of RH will preoccupy us tonight!