The verse in the Torah that cautions against lying, “MiDvar Sheker Tirchak” - stay away from a false matter, is the subject of a three-way debate. The Chofetz Chaim rules in his, “Ahavas Chessed” that with this verse, the Torah intends to prohibit one from telling a lie. This position is in accordance with the view of some Rishonim (Halachic authorities that lived during the 11th to 15th centuries).
Other Rishonim believe, that the verse intends to provide advice i.e., it is not advisable to lie, but the Torah does not mean to actually prohibit it. A third opinion believes that the Torah means to prohibit a lie, but only when judges are adjudicating the law (which is the context in which the verse is stated). Generally speaking, the view of the Chofetz Chaim is normative Halacha and therefore, we would consider telling a lie to be a Torah prohibition.
However, the prohibition of Geneivas Da’as is more serious. Regarding Geneivas Da’as, all opinions agree that it is a clear, outright prohibition to deceive someone. According to the Sefer Yereim and the Ritvah it is a Torah prohibition (MiDoraisa). According to the Smak, the prohibition is from the Sages (MiDerabanan).
The Mishna in Bava Metzia (59b) tells us that it is forbidden to mix older produce with newer produce and sell them together as one package. The Gemorah in Bava Metziah (60b) cites additional cases of Geneivas Da’as such as where a seller makes animals and animal skins look newer through artificial means. These cases would appear to be similar to your case where you are altering your report to give a false impression (the same way that animal skins and produce in the cases above are being altered to give a false impression).
QUESTION
One of the members of the classroom was collecting our reports that had come due. My friend placed her report in the middle of the collected stack. She had neglected to complete her report and she later admitted to me that the report that she placed in the middle of the stack was really just a single page that contained a few lines of the report’s conclusion that she had labeled as, “Page 2”. Her intent was to fool the teacher into thinking that during the report collection process, “Page 1” got lost in the shuffle and that the teacher would not have the heart to force her to redo the first page. What does the Halacha say about such a practice?
ANSWER
This practice is likely a violation of the prohibition of Geneivas Da’as (deception). This prohibition is generally defined as fooling or deceiving others by performing an action (like your friend did, by handing in, “Page 2” of her assignment when there never was a, “Page 1”. Geneivas Da’as is worse than lying as we will see below.
The Gemara in Chulin (94a) cites a Baraisah which discusses four examples of actions that are forbidden because of Geneivas Da’as. 1] One is not allowed to repeatedly invite someone to a meal when one knows that he will not accept the invitation. 2] It is forbidden to repeatedly offer gifts to someone when one knows that he will not accept the gifts. 3] One is not allowed to honor a guest by opening up a new barrel of wine and thereby show the guest that the owner is willing to risk the spoilage of the wine that is not drunk for the sake of his honor, when the barrel was sold already and therefore the owner will not incur a loss. This is only permitted if the owner informs the guest of the actual reason that he has opened it. 4] It is forbidden to offer someone oil from an empty flask to anoint himself with, when one knows full well that the person will refuse it. If, however, he is offering the oil to show his fondness for the person, then it is permitted (according to Rashi). The element of deception in all of the above, is that one is creating the false impression that one is willing to go out of one’s way for his friend or guest when that is not one’s real intention.
