However, Rava says that he's not believed about his involvement, since one is not believed on a relative, and a person is his own relative. So we split his words and only believe the part that Ploni did that action, but not that it was done to you.
Tosfos asks why is this different to what Rava said in Kesuvos? Over there Rava says that if witnesses on a document said that they signed the documents but they were forced to on the threat of losing their money, they are not believed that they were forced and the owner of the document can collect. Since he has no right to sign falsely for loss of money, we can't believe him. Why don't we believe him part way, that he was forced, but we don't believe through loss of money, but because their very life was threatened. So we should believed that they were forced and the loan is no good.
Tosfos answers that since the whole institute of having to verify the witnesses' signatures are only rabbinic, from the Torah we assume all documents are valid, we don't invalidate a document unless he specifically says a good reason why it's invalid and not if he we need to split his words.
Alternatively, since most times someone is forced to sign falsely on a document is not through threat of his life, we assume that his life was never in danger unless he specifically says so.
Rabbi Chaim Smulowitz
If you ever though that Tosfos was beyond you. Think again. A few more free copies of Gemara and Tosfos: Sukka 2a-11a is still available
at
tosfos.ecwid.com
Limud Torah e-S'farim tosfos.ecwid.com
Limud Torah e-Sefarim
