One of the many mitzvos we have in this week’s parsha is the mitzvah of hashovas aveidah, the mitzvah to return lost items to their rightful owner (Devorim 22:1-3).
The halachah is that if the original owner has lost hope of ever finding his item (yi’ush) then the finder may keep it. The Gemara in Bava Metzia (21b) cites a machlokes if yi’ush shelo mida’as [despairing without knowledge] is considered yi’ush or not. Abaye holds: If one would despair from something if he knew that he dropped it, but he does not know that he dropped it, it is not considered as if he despaired. Rava holds: It is as if he despaired.
The Gemara continues: If something has a siman [sign], no one considers it as if he despaired. Even if we hear him despair later, the finder may not keep it, since when he picked it up it was forbidden to keep it. (He was obligated to announce it to try to return it to the owner, as normally, one who loses something with a siman expects to get it back by telling the siman.) If, however, something was taken by a high tide or an overflowing river, all agree that even if it has a siman, the Torah lets the finder keep it. The entire machlokes is about something that has no siman. Abaye does not consider it as if the owner despaired, because he does not know yet and Rava considers it as if the owner despaired, for when he finds out, he will despair.
The Gemara then brings various attempted proofs for Rava. The Mishnah (Bava Metzia 21b) says: “If one finds scattered coins he may keep them”, presumably in such a case the owner doesn’t know that he lost it, yet the finder may keep it, which would seem that we take on yi’ush shelo mida’as [despairing without knowledge] is considered yi’ush, like Rava?
The Gemara then refutes this proof, with a famous ruling of R’ Yitzchok: אדם עשוי למשמש בכיסו בכל שעה ושעה – “People constantly check their pockets”, therefore, it’s likely that the owner already gave up hope before the money was found.
The question is, if R’ Yitzchok is correct, why is there a din in taught in Shabbos (12a): חייב אדם למשמש בבגדו ערב שבת עם חשכה – “A person must check his garment on erev Shabbos (lest there is something in one of the pockets, and he will come to carry in the reshus ha'rabim on Shabbos).” If people constantly check their pockets, then even without this din they will check their pockets, and not come to carry on Shabbos?
