“Can you please move the fan to the blue bedroom?” Mrs. Abrams asked her husband. “B’ezrat Hashem, guests will be sleeping there on Shabbos.”
Mr. Abrams wriggled the plug out of the wall and moved the fan to the blue bedroom. He plugged the fan in, but it didn’t go on. He tried another outlet, but it still didn’t work.
“It seems that the fan died,” Mr. Abrams told his wife. “It’s not turning on. I’ll buy a new one tomorrow.”
“Please take the fan outside, then,” Mrs. Abrams said. “Tomorrow is bulk pickup.”
Mr. Abrams took the fan out to the curb. He met his neighbor, Mr. Green. “What are you doing with that fan?” Mr. Green asked.
“It stopped working,” Mr. Abrams replied. “I’m leaving it for bulk pickup.”
“Can I have the fan?” asked Mr. Green. “I’d like the parts.”
“Sure,” said Mr. Abrams. “I have no use for it.”
Mr. Green took the fan. He first tried changing the plug, and the fan came to life.
“The fan was fine,” Mr. Green told Mr. Abrams the following day. “It just needed a new plug.”
“Then I’d like the fan back,” said Mr. Abrams. “I disposed of it because I thought the motor went. It was in error.”
“Motor or plug, the fan was broken,” said Mr. Green. “You didn’t bother to check what the problem was. You were throwing out the fan, and let me have it. If I hadn’t taken the fan, it would now be sitting in a garbage dump!”
“Obviously, I’ll pay you for the repair,” said Mr. Abrams, “but I think that you should return the fan.”
The two approached Rabbi Dayan and asked, “Does Mr. Green have to return the fan?”
“A sale or gift rooted in clear error is void,” replied Rabbi Dayan (C.M. 66:34; 232:2; 253:5; Sma 126:46).
“Nonetheless, the Gemara (Krisus 24a) addresses the case of an ox that beis din sentenced to death based on witnesses who said that it had gored someone, but the witnesses were afterwards debunked as eidim zomemim (conspiring witnesses). Rabi Yochanan rules that whoever takes possession of the ox now acquires it, since the owner relinquished ownership of the ox when it was sentenced (Hil. Nizkei Mammon 11:13).
Seemingly, the owner relinquished ownership of the ox in error, based on the false witnesses. Ketzos (142:1; 406:2) derives from this that hefker rooted in error is valid.
Nesivos (142:3) and other Acharonim reject this, and maintain that hefker in error is also void.
Some therefore explain Rabi Yochanan’s ruling that the owner relinquished the ox is on account of yei’ush, since the owner expected it to be put to death, and yei’ush is valid even in error (Nesivos 262:3; Mishpat Shalom 194:2; Maharam Shick Y.D. #391). Others explain that the ox was not relinquished in error, since at that time the ruling was valid; the subsequent debunking of the witnesses is a new occurrence (Aruch HaShulchan 405:28; see also Beis Yitzchak O.C. #76:3-4).
Hence, HaRav Y. Zilberstein, shlita, writes in Chashukei Chemed (Eruvin 7a, ftnt. 1) that if someone disposed of a refrigerator and his neighbor took it, but it was only a faulty plug, he must return it, since it was a clear error.
Here, too, seemingly, Mr. Abrams disposed of the fan in error; had he known that it was only the plug, he would have kept it.
“Perhaps we can distinguish, though, between a large item, such as a refrigerator, which a person clearly wouldn’t dispose of because of a faulty plug, and a small item, like a fan, which a person might not bother to fix,” concluded Rabbi Dayan. “We find that Responsa Be’er Yitzchak (Y.D. #23) rules that when a person mistakenly assumed a certain halacha relevant to the purchase, but didn’t bother to check whether it was correct, he cannot claim an erroneous purchase that would void the sale.”
Verdict: Many rule that hefker rooted in error is void, like other transactions. Nonetheless, where yei’ush is applicable, or where it was not in error at that moment, some rule that it is valid.