So we try to establish the Machlokes between Rebbi Elazar and Raban Shimon ben Gamliel (who both say 'Ma'alin li'Kehunah al-Pi Eid Echad') where we initially assumed the Safek's father to be a Kohen; then, after a Kol (a rumor) began to spread that he was a ben Gerushah or a ben Chalutzah, one witness reinstated him as a Kasher Kohen - after which two witnesses testified that he was a ben Gerushah or a ben Chalutzah, and finally a second witness testified that he was Kasher

The Tana could not begin the case with one witness who came to consolidate the Safek's status as a Kohen - because (in similar vein to what we explained earlier) why would one witness need to testify at all, unless he had been removed due to a Kol?

Assuming that both Tana'im agree that two witnesses who testify separately can combine to form one unit, we try to explain their Machlokes as being - whether 'Chaishinan le'Zilusa de'bei Dina' (Rebbi Elazar), or 'Lo Chaishinan ... ' (Raban Shimon be Gamliel).

Even if Rebbi Elazar is concerned about Zilusa de'bei Dina, he will nevertheless permit Beis-Din to reinstate the Safek after having removed him following the Kol - because removing a Safek after a Kol is not a ruling that cannot be rescinded, but a temporary measure until Beis-Din are able to establish his Kashrus.

We refute the above interpretation of the Machlokes, based on the fact that they argue in the case where one witness came at the end - because if Rebbi Elazar's reason was 'Chaishinan le'Zilusa de'bei Dina', then he ought to have argued with Raban Shimon ben Gamliel even if the two witnesses who declare the Safek Kasher came together at the end.

The basis of their Machlokes must therefore be - whether we combine the testimonies of two witnesses who testify independently (Raban Shimon ben Gamliel) or not (Rebbi Elazar).

In spite of the fact that the two pairs of witnesses contradict each other, the Safek Kohen is Kasher according to Raban Shimon ben Gamliel - because we place him on the Chazakah that he acquired after the first witness declared him a Kohen.

In fact, this Machlokes is synonymous with another Machlokes Tana'im in a Beraisa, where the Tana Kama requires two witnesses to appear in Beis-Din simultaneously. Rebbi Nasan - validates their testimony even if one testifies today and the other one, tomorrow.

In the same Beraisa, the Tana Kama requires the two witnesses to have witnessed the transaction simultaneously. Rebbi Yehoshua ben Korchah - accepts their testimony even if they witnessed the transaction at different times.

It is possible for two witnesses to witness the same transaction at two different times - either if, for example, one of them witnessed a loan taking place, and the other one heard the debtor admit that he was Chayav to pay, or if one of them saw Reuven borrow a Manah from Shimon on Sunday, and the other one saw him borrow a Manah on Monday (see Rashash).

According to the Tana Kama - seeing as the two testimonies cover two different scenarios or transactions, they cannot combine to form one testimony.

In any event, we have vindicated Rav Nachman, who is not concerned about Zilusa de'bei Dina - because both Rebbi Elazar and Raban Shimon ben Gamliel hold like that.

When, after producing a Sh'tar to substantiate that he purchased a field from Shimon, the latter countered that the Sh'tar was a forgery - Reuven leaned across and whispered in Rabah's ear that the Sh'tar was indeed forged, but that he had lost the original one.

On the one hand ...

... Rabah accepted Reuven's argument - on the basis of a 'Migu' (since he could have insisted that the Sh'tar was Kasher); on the other ...

... Rav Yosef objected - because, seeing as, by Reuven's own admission, the Sh'tar upon which he based his claim was invalid, it was a 'Migu be'Makom Eidim' and he could not be believed.

Reuven can not have had a Chazakah on the field - because if he had, he would not have been relying solely on the Sh'tar, and it would no longer be a 'Migu be'Makom Eidim'.

Despite the fact that Reuven would have to substantiate the Sh'tar, Rabah thought that Reuven had a 'Migu' - because it was not a straightforward forgery, but a Kasher Sh'tar written for another loan, in which case the witnesses would readily substantiate their signatures.

Alternatively, it was a Sh'tar Amanah (which Shimon wrote on trust, anticipating that he would later borrow money from Reuven) - or even a forged Sh'tar, and Reuven had hired false witnesses to corroborate the signatures.

Rabah and Rav Yosef followed their same respective lines of thought when, in a similar episode - but where Reuven was claiming a hundred Zuz.

Rav Idi bar Avin ruled like Rabah in the first case - because the field was in Reuven's R'shus, and like Rav Yosef in the second - because the money was in Shimon's.

Despite the fact that, who was Muchzak was not the issue, but whose line of thought was correct, Rav Idi bar Avin inconsistent ruling was based on the fact - that he was uncertain like whom to rule, so he applied the principle that pertains to all cases of Safek 'ha'Motzi me'Chavero, alav ha'Re'ayah'.

Rav Idi bar Avin's ruling does not clash with the ruling in 'Yesh Nochlin' where we conclude that apart from 'Sadeh', 'Inyan' and 'Mechtzah', the Halachah is like Rabah throughout Shas - seeing as here too, we rule like Rabah in one of the two cases.

There was a case where an Areiv (guarantor) claimed a hundred Zuz from the debtor and maintained that he had paid the creditor, and produced a Sh'tar to that effect. He was (not a regular Areiv, from whom the creditor cannot claim before having gone to the debtor, but) - an Areiv Kablan (who undertook to pay the debt instead of the debtor as soon as it fell due) or else the creditor had stipulated at the time of the debt that he could claim from whoever he wished.

When the debtor claimed that he had already paid him, he (the Areiv) conceded that this was indeed the case, but added - that he (the debtor) subsequently took the money back from him on loan.

When Rav Idi bar Avin (of all people) asked him what the Halachah was in this case, Abaye replied - that Rav Idi himself had just ruled in a rather similar case, like Rav Yosef, and that it was therefore obvious that the money should remain where it was (in the hands of the debtor).

The basis of Rav Idi bar Avin's Safek however, was that this case might be worse (from the point of view of the debtor) than the previous one - due to the fact that, unlike there, where the creditor had admitted that there had been another Sh'tar, and that the one that he produced was basically a forgery, the Sh'tar that the Areiv produced was the only one, and was basically authentic.

Abaye nevertheless considered the two cases comparable - because of the principle that we learned in Kesuvos, that 'once a Sh'tar has been used to claim with, it becomes Pasul and cannot be re-used', which renders this Sh'tar no better than the one in the previous case.

Abaye would have obligated the debtor to pay - had the Areiv claimed that he returned the money to the debtor because the coins were badly worn or discolored, thereby negating the payment and reinstating the original debt.