How Should an Areiv Express His Commitment? 

Rav Yitzchok Grossman , Rosh Kollel of Greater Washington and Dayan at the Bais HaVaad

Question: Is there a specific way a guarantor has to express his guarantorship on the loan? Does he have to say “I am accepting to be an areiv,” or is it enough for him to just say that he will take care of the debt if necessary? 

Answer: This is the subject of a major machlokes amongst Acharonim, which is rooted in a debate about how arvus works.

Some Acharonim, based on a Rashbam, say that arvus is a form of shlichus. When the areiv takes responsibility, he is, in effect, telling the lender to lend the money to the borrower on his behalf, thereby making the lender his shaliach. This shlichus is what triggers the areiv’s liability. According to this reason, it is necessary for the areiv to explicitly say that he is accepting arvus in order for the shlichus to take effect. 

Others disagree and say that arvus is not a real shlichus; rather, it is simply the areiv saying that the lender can rely on him to repay the loan if the borrower reneges. Therefore, it is sufficient for the areiv to say that he accepts liability and no special language is needed.  

Question: According to either view, does the sum of the loan need to be specified by the areiv? 

Answer: Whether a concrete sum needs to be specified for the arvus to be valid is a machlokes in the Rishonim and Acharonim.  

The opinion of the Rambam is that an areiv is not liable if he doesn’t specify an amount. Many Rishonim disagree, with some saying that the Rambam is a da’as yachid in this regard and the halacha does not follow his opinion. Others say that there are other opinions that agree with the Rambam, which would give his opinion more standing in halacha. According to them, the areiv would be able to say “Kim Li” like the opinion of the Rambam.