When witnesses sign legal documents, what must they write so that their signatures will be recognized and confirmed?
According to the Mishna in Massekhet Gittin (87b), a person can write ben ish ploni ed – “the son of so-and-so, witness” – and that will suffice to identify the person. Similarly according to that Mishna, someone who simply signs his first name will also be recognized as a witness.
Our Gemara questions whether it is possible that a person will sign his father’s name – apparently as a show of honor to his father. This question is based on what is common practice in today’s world, that we have surnames or family names that identify members of a given family. This is evident from some names that retain an element of the original ancestor’s name, like Michaelson or Davidson.
Other examples of symbolic signatures are presented by the Gemara, as well.
According to the Gemara, when signing his name,
Rav would draw a fish.
Rabbi Ḥanina would draw a palm branch.
Rav Ḥisda drew the letter samekh
Rav Hoshaya drew the letter ayin.
Rava bar Rav Huna drew the mast of a ship.
According to the Rashbam, aside from Rav Ḥisda and Rav Hoshaya who made use of significant letters that appears in their names, we do not know why each of these Sages chose their particular symbol to be their representative signatures. He surmises that they must have had some special connection with the symbol, perhaps connected with their diet or some other aspect of their daily lives.
Recognizing that symbols such as these were used, the Gemara asks whether someone may have chosen to use his father’s name as a symbol. Today’s common practice notwithstanding, the Gemara argues that no one at that time would have been so impudent as to make use of his father’s name in that way.