Zechiyah and Shlichus: The Relationship Between Acting for Another's Benefit and Agency

The shiur analyzes Tosafos (תוספות)'s fundamental question about the relationship between zechiyah (acting for someone's benefit) and shlichus (agency) in Jewish law. Tosafos begins by establishing that zechiyah operates through the principle of shlichus - we assume (anan sa'hadi) that the beneficiary would want to appoint the actor as his agent. This creates a logical problem: if a katan (minor) cannot legally appoint a shliach according to the Gemara (גמרא) in Gittin, how can anyone act for his benefit through zechiyah? Tosafos presents two distinct approaches to resolve this difficulty. In his first answer, he maintains that zechiyah is fundamentally based on shlichus, but argues that a katan is only excluded from the general laws of shlichus when the matter involves potential detriment. When something is purely beneficial (zechus gamur), even a katan can be included in the framework of agency. The logic is that for matters like separating terumah, where there might be different preferences about how much to give, we cannot assume what someone truly wants. But for clear benefits, no such uncertainty exists.