[Avodah] May one add matzah meal or pieces of bread to a

[David Riceman]

>> 
>> RMB:
> 
> There are two basic approaches to understanding halakhah: Brisk and Telzh.
> 
>> 1. It is a din. In other words the halacha states that cooking in a kli
>> sheini is not called cooking. We find for example that bishul bchama is
>> permitted even though it cooks.
> 
> Brisk.
> 
>> 2. It is a metzius, the gemara is telling us an empirical fact, that in
>> general a kli sheini doesn't cook.
> 
> Telzh.

Or 3: it is a convention.  Bishul on Shabbos is how people normally cook (IIRC RMF suggests this in one of his tshuvos).  Many years ago one of my rebbeim suggested that microwaves and solar hot water heaters weren’t bishul d’orayysa because they were uncommon, but that their status might change as they became more common.

David Riceman