bava metzia pg 13a, shulhan aruch vol 4 hoshen mishpat chapter 29 law 13

I was thinking that one could explain the argument between the Rif and Rashba in the opposite way that Rav Shach does, i.e., that the Rif holds once a document of a loan or a document that shows there is a loan that the borrower must make the loan even though so far there is only a document and a kinyan sudar (acquisition by means of exchange of a handkerchief). This would correspond to the opinion of Rav Asi (Bava Metzia page 13 side a) that a document showing a loan was made is not fully valid until it reaches the hands of the lender. Still if it is found in the street, we return it to the lender because the document is at least halfway valid. This is no different than any usual document of a loan that even though it is fully valid and in the hands of the lender, we still do not collect on it until the witnesses come again to court to validate their signatures. The opposite opinion would be that of the Rashba that there is no obligation to make a loan even though there is already a valid document of a loan. That is to say that until the second that money is exchanged, neither thee lender nor borrower have to go through with the deal, but the document is fully valid even before it reaches the hands of the lender. Again, that is no different than any document of a loan that is fully valid and yet cannot be collected until witnesses come to repeat their original testimony.======I was thinking that one could explain the argument between the and רשב''א in the opposite way that רב שך does, i.e., that the רי’’ף holds once a שטר of a loan or a שטר that shows there is a loan that the מלווה must make the loan even though so far there is only a שטר and a קנין סודר (acquisition by means of exchange of a handkerchief). This would correspond to the opinion of רב אסי (בבא מציעא דף י''ג ע''א page 13 side a) that a שטר showing a loan was made is not fully valid until it reaches the hands of the מלווה. Still if it is found in the street, we return it to the מלווה because theשטר is at least halfway valid. This is no different than any usual שטר of a loan that even though it is fully valid and in the hands of the מלווה, we still do not collect on it until the witnesses come again to court to validate their signatures. The opposite opinion would be that of the רשב''א that there is no obligation to make a loan even though there is already a valid שטר of a loan. That is to say that until the second that money is exchanged, neither the lender nor borrower have to go through with the deal, but the שטר is fully valid even before it reaches the hands of the מלווה. Again, that is no different than any שטר of a loan that is fully valid, and yet cannot be collected until witnesses come to repeat their original testimony.