The Mishna on today’s daf focuses on the role of an arev – someone who agrees to guarantee a loan. According to the Mishna, although the arev agreed to be responsible for the loan, nevertheless the lender cannot collect from him without first trying to collect from the borrower. In a case where the lender states clearly at the time of the loan that he wants to collect from either one of them, then he has the right to do so. Rabban Shimon ben Gamliel disagrees, ruling that in any case the lender must first collect from the borrower.
According to the conclusion of the Gemara, even the Tanna Kamma agrees that under ordinary circumstances when the borrower has the means to pay the loan, the lender cannot collect from the arev. The Gemara explains that the only disagreement between the Tanna Kamma and Rabban Shimon ben Gamliel is in the case of a kablan, that is, someone who says “give him a loan and I will pay you back.”
In explanation of the obligation of an arev to pay the loan in the event that the borrower cannot, Ameimar suggests that it is a case of asmakhta. As we learned above (daf 168 ), an asmakhta is a promise or agreement obligating the individual at some point in the future, should a specific event occur. As opposed to ordinary situations of a tenai – a standard agreement, that certainly takes effect – an asmakhta usually is an agreement based on the assumption that the condition will never actually take place. In our case we can assume that the arev anticipates that the borrower will pay the loan and that he does not really expect to pay.
According to this approach, whether or not an arev may actually have to pay should be dependent on the question of whether asmakhta kanya or not. Rav Ashi rejects this approach, arguing that we rule that an asmakhta does not create an obligation, yet people do co-sign loans. He concludes that in this case, the very fact that the arev is relied upon is sufficient to create the gemirut da’at – a conscious decision – necessary to overcome the doubts of the arev and to obligate him to pay.