It was stated (Daf Yomi: Gittin 19a): If a man writes over red paint writing with black ink on Shabbos, Rabbi Yochanan and Rish Lakish both agree that he is liable on two counts, one for writing (the two new black letters) and one for erasing. [One is only liable on Shabbos if he erases with the intention of writing two letters in its place. Here, in order to write the two new black letters, he must erase the red letters first.]
If he writes over black ink with black ink or red pigment with red pigment, he is not punishable. [This is because nothing has been accomplished with the new writing.]
If he goes over black ink with red pigment, some say he is punishable and some say he is not punishable. Some say he is punishable because he is erasing the previous writing. [He is not liable for writing because the original black writing was much clearer than the red one.] Some say he is not punishable because he is only ruining the previous writing.
Rish Lakish inquired of Rabbi Yochanan: If witnesses are unable to sign their names on a get, is it permissible to write their names for them in red pigment and let them go over it with black ink? Is the upper writing regarded as writing or not?
He replied: It is not regarded as writing.
Rish Lakish challenged him: But, didn’t our teacher teach us that in respect of Shabbos, the upper writing is regarded as writing?
He replied: Because we have a certain opinion, shall we practice stringently based upon it? [If the Beis HaMikdosh would be in existence, I wouldn’t tell that person that he is liable to bring a korban chatas for violating the Shabbos, for perhaps it is not a transgression and he will be bringing an unconsecrated animal into the Courtyard!]
Tosfos notes: It is evident from here that tracing over letters with the same color ink is not regarded as writing with respect to Shabbos or with respect to gittin. Accordingly, Tosfos asks from a Gemora below (20a) which states: If a get was initially not written lishmah, it can be rectified if the scribe traces over the letters lishmah! (The Gemora there discusses if this is the halacha according to all opinions or not.) Why should it be valid if he is using the same color ink again?
Tosfos answers that since the scribe is adding an important element to the writing, namely the lishmah of the get, it therefore constitutes an act of writing for the get. However, in our case, the second writing accomplished nothing, and therefore, it is not regarded as an act of writing.
The Minchas Chinuch (§ 32) poses the following question: If one, on Shabbos, would trace over the letters of a get that had previously not been written lishmah, what is the halacha? If we would say that the tracing lishmah constitutes an act of writing and the get will be valid, it will emerge that he intentionally violated the Shabbos and he will be regarded as a mummar, who is disqualified from writing a get! And if we rule that he, in fact, is a mummar and the get is invalid, it will emerge that his tracing did not accomplish anything and he did not violate the Shabbos, which in turn, will validate the get! The logic goes complete circle and we will never be able to execute him for transgressing the Shabbos, for his writing did not accomplish anything and therefore it did not constitute an act of writing, and we will not be able to validate the get, for if we would do so, it would emerge that he was a mummar at that time and the get is invalid!?
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