Nedarim: Hashavas Aveida and Perutah Shel Rav Yosef's Conceptual Problems

This shiur presents an intensive analysis of the Gemara (גמרא) in Nedarim dealing with hashavas aveida (returning lost objects) when one of the parties is a mudder (prohibited from deriving benefit from the other). Rabbi Zweig frames this as a shas sugya—a topic that runs through multiple tractates—and encourages students to work through it independently, as it involves extremely difficult conceptual questions. The Mishna establishes that a machsir (one who enables benefit) may not provide benefit to a mudder. The Gemara in Nedarim discusses whether one may return a lost object when the mudder is the baal aveida (owner of the lost item). One opinion states it is prohibited because komahadder lei meidem de'nafshe—you're returning his own property to him. Rabbi Zweig immediately raises several fundamental problems with this reasoning: First, the object has appreciated in value through the finder's efforts—if it was about to be run over by a truck and is now safe, there's clear added value. Second, the baal aveida would surely pay someone to retrieve his lost item, making the return a valuable service. Third, the Gemara in Kesubos 108a gives a completely different reason for why return is permitted—because it's a mitzvah (מצוה)—creating a contradiction between sugyos.