The guemara explains we must teach the machlokes between rebbi and chachomim or we could have thought rebbi held his position because of a safek. What kind of safek is it? Safek metzius? Ask the eidim what are they being meyid! Safek din? He's a Tanna this is a derabanan he is the one being meisaken the din, no??
David , Montreal Canada
Dear David,
The Rishonim differ how to learn Rebbe- Rabanan (before the "Safek").
According to Tosfos, there is no difference whether the witness mentions his signature or the original loan- according to Rebbe its only accepted as validation on the signature and needs a second witness, and according to the Rabanan its considered direct validation of the loan without second help, and even if they don't remember the loan. According to the Rambam, it's only if he remembers the loan.
Now if Rebbe calls it Safek, it means Rebbe is making the Din in a Safek manner, weighing both sides.
All the best,
Reuven Weiner