When the gemarah comes out that what "umodeh R' yehoshua" meant was that hes not modeh in a case of bari veshema but he is modeh in the case of the mishnah that the guy has a migu. the gemarah explains the difference saying that this case is not "shor shochut lephoneicha" so migu works.
if this is true what is he being modeh to R'gamlel? they seem to be clearly arguing about whether you say a migu in a case that IS shor shochut lephoneicha. what, then, does "UMODEH" in our mishna mean? hes modeh that there is such a concept as migu?!?!
you see by R' Gamliel being modeh it works out good because what hes saying is that i agree that the woman isnt believed in a case of bari v'bari. ! help
Yirmi Lederer, Miami Beach US
Yes, that is correct. Rebbi Yehoshua is being Modeh that a Migu helps. According to Rashi, he is only partially being Modeh; a Migu in fact does not help most of the time, only when it is Migu d'Iy Ba'i Shasik. (The Ramban takes Rashi to task on this point, which he considers to be very odd, see Insights.) According to Tosfos, it means that Rebbi Yehoshua is Modeh that even a regular Migu helps.
Rav Dov Zupnick mentioned to me that maybe there is no question that a normal Migu helps to acquit someone from payment. The Mishnah here is discussing, though, a Migu that allows a person to collect money (that was once someone else's, by his own admission), see Ritva and Rishonim here. If so, the Gemara is saying that Rebbi Yehoshua admits that a Migu can be used to even to collect money if the only thing that makes us think the money is someone else's is his own admission.
-Mordecai