Mr. Meyer visited his son Yoni for the holidays. At the Yizkor appeal for the poor, the shul distributed pledge cards with each member’s name. Guests received anonymous pledge cards.

Mr. Meyer vacillated how much to donate, and finally folded down one of the tabs. After Yom Kippur, he packed up quickly to get home at a reasonable hour, and forgot to leave a check for his donation.

Yoni came to visit for the first half of Sukkos. Mr. Meyer wanted to honor his pledge and send a check back with his son but no longer remembered exactly how much he had pledged. “What do you suggest?” Mr. Meyer asked.

“I’ll call the gabbai of the shul and see if he has it on record,” Yoni said.

“The pledge cards for members are named, but not for guests,” said the gabbai. “The anonymous pledge cards have a wide range of sums, so I can’t tell how much your father pledged.”

Mr. Meyer tried again to remember how much he pledged, but was unable to. He often gave $100, but sometimes $200 or $250, and on special occasions, even $360. He remembered vacillating between these sums, but could not remember what he had finally decided.

Mr. Meyer raised the question at the dinner table on Chol Hamoed.

“You only have to give what you’re sure of,” said one family member.

“Assume what you most often give,” suggested another.

“I think you should compromise and give the average, halfway between the minimum and maximum,” said a third.

“It’s going to tzedakah anyway,” piped up a fourth. “Give the max.”

Mr. Meyer decided to call Rabbi Dayan. “I don’t remember how much I pledged at the Yizkor appeal but it was somewhere between $100 and $360,” he said. “How much should I give?”

“There is a difference between a monetary claim and a pledge to charity,” replied Rabbi Dayan. “Regarding a monetary claim, the burden of proof is on the plaintiff. If neither party remembers how much was owed, the defendant has to pay only the sum that is certain” (C.M. 75:18).

“However, a pledge to charity is compared to a vow, which is a potential Torah prohibition,” continued Rabbi Dayan. “Therefore, regarding a questionable vow or pledge we follow the stringent possibility, as any other safek d’Oraisa” (Y.D. 208:1; 258:3).

“If there were only two possibilities, I understand following the higher amount,” said Mr. Meyer. “However, here the pledge could have been any amount from $100 to $360.”

“You are required to give, out of doubt, the maximum that you might have reasonably pledged,” replied Rabbi Dayan. “This is based on a mishnah (Menachos 106b) regarding one who forgets how much he consecrated to the Beis Hamikdash. He is required to give the amount regarding which you can comfortably say, ‘I didn’t pledge more than this.’

“Similarly, Chasam Sofer writes that if a person pledged to a specific cause but forgot which, he is required to donate to all the possible causes,” added Rabbi Dayan. “This is his responsibility to fulfill his pledge, but none of the causes can demand the money, since his obligation to them is doubtful” (Pischei Teshuvah, Y.D. 258:5).

“Nonetheless, Aruch Hashulchan (Y.D. 258:10) writes that in our situation the person can do hataras nedarim (annul his vow),” concluded Rabbi Dayan. “He can say that had he known that he would forget the amount that he pledged, he would not have committed. He would then be freed from the original pledge and can give what he wants” (see Derech Emunah, Matnos Aniyim 8:5[21]).