Kiddushin 2a: Shava Kesef Ki-Kesef and the Nature of Ritual Value (Part 1)

This shiur analyzes the fundamental question of how shava kesef (non-cash goods) can be equivalent to kesef (money/silver) for kiddushin, when the Torah (תורה) explicitly requires kesef. Rabbi Zweig begins by presenting a dispute between the Rashba and the Rambam (רמב"ם) regarding a case where a woman receives an item worth far less than its usual market value (a needle worth a tenth of a perutah given as if it were worth a perutah). The Rashba holds this creates a safek kiddushin (uncertain marriage), while the Rambam rules it is definitively invalid for kiddushin but valid for other monetary transfers like ta'anei mitnin (gift stipulations). The shiur explores how Tosfos approaches the sugya differently from other Rishonim. While most Rishonim begin by asking why shava kesef works for kinyan (property acquisition), Tosfos skips this question entirely and proceeds directly to kiddushin. Rabbi Zweig explains that Tosfos understands the fundamental problem with shava kesef is not that it's a different object than what the Torah specified, but rather that it lacks absolute value. Money has intrinsic, absolute worth (a specific weight of silver or standardized currency), while goods have only relative value that fluctuates based on location, time, supply, demand, and even the specific recipient's needs. By citing Rav Kahana's case (Pidyon HaBen with a head covering worth two shekalim accepted as five because it was especially valuable to the recipient), Tosfos demonstrates that shava kesef includes even subjective, individual valuations.