This was the opening shiur on Masechet Shabbat being given at the Mann home on behalf of the HIR.
In this shiur we dealt with the complicated topic of categories in Halakha (and law in general). The Mishna in Keritut (3:9) as well as the opening sugya in Bava Kama were used as background the first mishna in Clal Gadol (ch. 7 of Shabbat, pg. 73b). We are going to return to a careful reading those mishnayot in the next shiur now that we have some of the bigger picture.
One important aspect that becomes clear by comparing the Mishna in Keritut with Hilkhot Shabbat is that much of our concept of categories and their import is based on Rebbi Akiva’s read of system. This lead to an important conversation about the relative worth of a legal system with thin categories(Rebbi Eliezer) on the one hand, as opposed to a legal system with a think categories (Rebbi Akiva). It is not clear to me how this might work in a secular system, but these types of questions of legal theory will dominate the shiur for a few more sessions.
You can see the mekorot at this link.
In addition, here is the audio file from the shiur: