Tosfos on Ger Katan: Two Approaches to Zechiyah in Conversion

The shiur analyzes a complex piece of Tosfos in Kesubos regarding ger katan (a minor convert) and the role of zechiyah sh'lo b'fanav (conferring benefit upon someone not present). Rabbi Zweig begins by identifying a fundamental machlokes between two Tosfos. In our Gemara (גמרא), Tosfos asks why a ger katan should work at all, since there's no shlichus for a minor, and therefore no zechiyah even m'derabbanan. However, Tosfos in Sanhedrin asks a broader question: even adult converts should be problematic since there's no din of shlichus by non-Jews at all. This leads to two possible understandings of what zechiyah accomplishes in conversion. The first possibility is that zechiyah is needed for the maaseh tevillah — to transform a simple act of immersion into a proper conversion ritual done l'shem geyrus. Since a minor lacks daas to have the proper intent, beis din must act on his behalf through zechiyah. The second possibility is that zechiyah is required for the chalos geyrus itself — actually becoming Jewish. This would apply even to adults, as suggested by Tosfos in Sanhedrin.