This week we begin a new series on the prohibition known as geneivas daas,
which is literally translated as stealing one’s mind. It refers to various
forms of deceit where a person feels that someone else is doing them some
kind of favor when in truth they are not. We will discuss the many details
of this prohibition in the coming weeks.
The source of this prohibition is the Gemara in Chullin, 94a. The Gemara
states; “Shmuel says, it is forbidden to deceive (gonev daas) people, even
non-Jews. From there, the Gemara learns that it is forbidden to send to a
non-Jew a thigh (yerech) of an animal with its gid hanasheh… This is
because the non-Jew will think that the Jew sent him a kosher thigh (from
which the forbidden gid was removed) but in truth that is not the case. The
Gemara brings another example of geneivat daat in the story involving Shmuel
and his servant . A non-Jew helped them pass over a bridge, and the shamash
paid the non-Jew with a treif chicken. Shmuel was angry with the shamash,
because the non-Jew would think that the shamash gave him a kosher chicken,
and in this way the shamash was deceiving the non-Jew.
In the following weeks we will discuss the various opinions amongst the
authorities as to the exact nature of this prohibition.