Q: I lent a friend $50. When I asked him to repay, he replied that although he did inquire about a loan, he doesn’t remember whether he ended up borrowing. Does he have to pay? What if he admits borrowing, but doesn’t remember if he repaid already?

A: When a person is uncertain whether he borrowed, he is not required to pay without evidence, even if the plaintiff claims with certainty. Nonetheless, one who wants to fulfill his obligation towards heaven should pay if the lender claims with certainty (C.M. 75:9). This is only meritorious, though, not required (Shach 88:36).

On the other hand, if a person definitely borrowed and is uncertain whether he repaid, the borrower must pay if the lender claims with certainty that the loan was not repaid (75:9).

The rationale for the distinction is as follows: When the defendant is in possession of the money, the burden of the proof is upon the plaintiff when there is any doubt (“hamotzi mei’chaveiro alav ha’raaya”). However, when there is a known debt, the known status quo of debt supports the definite claim of the lender against the uncertain claim of the borrower. Therefore, the borrower must repay the loan if he cannot counter with a definite claim that he already paid (Shach 75:23).