Here's the summary of the first part of the third and final shiur on the first sugia of Sanhedrin.
The Two Sides of the Debate
So last time we mentioned the debate over what is the Torah requirement for the number of judges needed to hear a case of הודעות והלוות:
- Rebbe Abahu and Rava say the Torah requires 3 judges, all of them סמוכים
- Chazal reduced this requirement to 3 הדיותות שלא לנעול דלת בפני לווין
- Rav Acha says the Torah requires 1 judge for הודעות והלוות, and it's a machloket rishonim if he needs to be סמוך
- Chazal increased this number because of יושבי קרנות
The Difficult Baraita
The gemara(סנהדרין ד ב) brings a baraita which seems to contradict both of these opinions. Here we discover a new track, a מומחה לרבים, which doesn't require 3, even מדרבנן:
תנו רבנן דיני ממונות בשלשה ואם היה מומחה לרבים דן אפילו יחידי
So how do we explain this according to the two opinions?
- According to Rebbe Abahu and Rava, Chazal reduced the requirement to 3 הדיותות OR 1 מומחה לרבים
- According to Rav Acha, Chazal didn't increase the requirement to 3 in the case of a מומחה לרבים because in that case there is no worry of יושבי קרנות
This works for Tosfot(ד"ה ואם) but Rashi(ד"ה דן) only quotes the רב אחא side of the machloket. So why does Rashi think the baraita is incompatible with Rebbe Abahu/Rava?
Rav Markus suggested that it's because Rashi understands that Rebbi Abahu always requires a Beit Din, so it's inconceivable that Chazal would ever reduce the requirement to a single judge, according to him.