The following shiurim represent the development of the ideas of eino mitkavei, psik reisha and lo nicha lei. We began first outside of the area of Hilkhot Shabbat to show the force of intent (Nazir, Kilayim). The fundamental conceptual question that we kept returning to was what is the nature of the ptur of eino mitkavein and how does psik reisha impact that process. We based our discussion on the framework outline by Reb Elchanan Wasserman (see below for a brief summary).
I did not try to articulate a clear position of the Rambam. While Reb Chaim (and the Brisker tradition) take it for granted that the Rambam held like the Aruch, the Hazon Ish was not convinced. I am not sure that it is possible to ascertain exactly what the position of the Rambam was. He seemed to pasken locally without ever articulating a principle regarding psik reisha d’lo nicha leih.
I am still not settled regarding the bottom line of how we pasken in a case that eino mitkaven psik reisha d’lo nicha on a drabanan. While the Rema, Magen Avraham, Rebbi Akiva Eiger, Gra and Shevitat haShabat all seem to be machmir, there are conflicting indication in the Mishna Berura, Shemirat Shabbat and Rav Ovadia. In a terrific essay Rabbi Willig seems to be totally meikel in this case against the what appears to be the weight of Ashkenazi achronim.
I am putting six sets of mekorot as well as the five audio files of the shiurim that I gave on these topics.
- Sources for general introduction to Eino Mitkavein (link).
- Sources for general introduction to Psik Reisha (link).
- Sources for Psak of Tosafot and Aruch. We worked off of the Tosafot in Shabbat 103 and not Yoma 34b/35a (link).
- A summary of Reb Elchanan’s Hakira regarding the heter of Psik Reisha (ki-mitkavein vs. tziruf maasim) (link).
- A chart that summarizes the psak of the Shulchan Aruch along with Magen Avraham and Taz, as well as Mishna Berura and Aruch ha-Shulchan in key cases (link).
- Though I did not give shiur dealing directly with these mekorot, this is the material for Safek Psik Reisha (From Taz to Rav David Tzi Hoffman) (link).
Eino Mitkavein Psik Reisha – Conceptual Intro
Psik Reisha Psak – Aruch and Tosafot – #1
Psik Reisha Psak – Aruch and Tosafot – #2
Psik Reisha Lmaaseh – Shulchan Aruch
Psik Reisha Lmaaseh – Clarifying Lo Nicha Lei and Drabanan