I wanted to buy a box of crackers. On the top shelf in the (non-Jewish owned) grocery store, I saw the overstock, where they had 5 boxes of the crackers wrapped together with clear plastic. I assume that is how the manufacturer sends them out. So since it was a good price, I decided to get 5 boxes, and rather than take 5 individual boxes, I took the five that were wrapped together. At the checkout, the non-Jewish cashier scanned the 5-pack, as well as the rest of my groceries, and I paid and left. Later, looking over my receipt, I noticed that I was only charged for one box of crackers. The cashier must have assumed that it was the price for the 5-pack, but the scanned code was clearly for only one box. I’m pretty sure I don’t have to go and tell the cashier or the store, since it was their mistake, however, my question is this: Can I go back to the store, and to the same cashier, with another 5-pack, knowing that she will scan it the same way and i will only have to pay for one box?
Answer:
It is not permitted to make use of the “mistake doctrine” on a lechatchilah level. According to many authorities the concept of ta’uso muteres is specific to a mistake that was made inadvertantly, which one is not obligated to correct. It is not permitted to intentionally cause a mistake.
Going back to the store and trying to buy a 5-pack for the price of a single box would be considered ‘intentional deception,’ and is therefore not permitted.
Sources: Although the Gemara (Bava Kama 113) writes that the “mistake” of a non-Jew is permitted, many write that this applies specifically on a bedieved level. See Rambam, Hilchot Geneivah 7:8; Mordechai, end of Bava Basra (563); Chinuch 258; Yam Shel Shlomo Bava Kama 10:20; Machaneh Ephraim, Hilchot Gezeilah 4; see also Sema 283:6, 359:3.
The case in the question is delicate, but based on these sources, it is not permitted.
