This week we continue with practical examples of Geneivas Daas that are
discussed by the Rabbis, and how these apply to modern day life:
The Gemara states that a wine seller should not open barrels of wine, when
the other person will think that he opened the barrel for him, when in
truth, the seller would have done it anyway for his own needs. Rather, the
seller has to inform him of the truth. This law is brought down in Shulchan
Aruch and has applications in present day circumstances. For example, if a
person opens something like a bottle of soda, or a packet of soup nuts,
(which are things that deteriorate after a few days of opening) for his
friend when, in truth he was going to open it anyway, he must inform his
friend of this.
If, however, he would, in truth have opened the item for him, even if doing
so would have caused a loss, then he is permitted to do so even when, in
reality he would have opened it anyway.