Defining Yad in Nedarim: Chalus vs. Neder Commitments

This shiur conducts a deep analysis of Nedarim 6a, focusing on the Gemara (גמרא)'s question of whether yad (incomplete or abbreviated language) is effective for kiddushin, and by extension, for all forms of nedarim and hekdesh. Rabbi Zweig begins by presenting two fundamentally different approaches to understanding the Gemara's discussion. According to Tosafos (תוספות), the reason "ve'at nami" works for kiddushin is that the man previously said "harei at mekudeshes li" to the first woman, establishing a complete lashon that can now be borrowed or extended. The Ran and Rosh, however, understand that yad works whenever there is no safek regarding the speaker's intent—when we definitively know what the person means, the incomplete language is effective. Rabbi Zweig raises a fundamental difficulty with the Ran/Rosh approach: If kiddushin merely requires clarity of intent rather than specific words, what is the Gemara's question about whether yad works? If we know what the person means, it should be effective; if we don't, it shouldn't. Why do we need to derive anything from the laws of hekdesh? The very fact that the Gemara asks whether we can learn yad for kiddushin from nedarim/hekdesh suggests that something beyond mere clarity is required. Furthermore, if clarity alone suffices, why does the Gemara discuss whether to say "ve'at chazon" (meaning this one specifically) versus "ve'at nami" (meaning this one also)? The Gemara seems to be creating a doubt about intent, which contradicts the premise that we know what he means.