Nida page 2b and 3a

With all the notes that I wrote about this subject, I thought I should write in short what is the question on the Rambam, and the answer of Rav Shach. [Laws of Truma, chapter 5, law 24] The idea is this. The case of the barrel is not a case of Tuma and purity, and therefore we do not learn from Sota to this case. However, the case of the mikve is a case of tuma and purity. However both are cases of two hazakot. Therefore, both the sages and R Shimon hold both are at least (at minimum) cases of doubt. But the Sages learn also from Sota to the case of the mikve, and therefore they hold it is a case of certainty. Therefore, the Rambam in both cases decided the law like the sages. The case of the Mikve is one of certainly, and the case of the barrel is a case of doubt. [The question still remains that the Gemara says the case of the barrel is like R Shimon and the sages would say that is a case of certainty]. The problem on this answer of Rav Shach for the Rambam however is that it seems to go against the simple understanding of the first answer of the gemara. In this first answer, it looks that R Shimon does not hold with the idea of two hazakot. In fact, it looks like the gemara says the opposite. It says both R Shimon and the sages learn from sota, and it is only R Shimon who does not hold with the idea of two hazakot.[[The idea of two hazakot is that there is a hazaka of now along with a hazaka of the body against one hazaka of the body.]]=================================================With all the notes that I wrote about this subject, I thought I should write in short what is the question on the רמב’’ם, and the answer of רב שך. The idea is this. The case of the חבית is not a case of טומאה and purity, and therefore we do not learn from סוטה to this case. However, the case of the מקוה הנמדד ונמצא חסר is a case of טומאה and purity. However both are cases of two חזקות. Therefore, both the חכמים and ר’ שמעוןhold both are at least (at minimum) cases of doubt. But the חכמים learn also from סוטה to the case of the מקוה הנמדד ונמצא חסר, and therefore they hold it is a case of certainty. Therefore, the רמב’’ם in both cases decided the law like the חכמים. The case of the מקוה הנמדד ונמצא חסר is one of ודאי, and the case of the חבית is a case of doubt. [The question still remains that the גמרא says the case of the חבית is like ר’ שמעוןand the חכמים would say that is a case of certainty]. The problem on this answer of רב שך for the רמב’’ם however is that it seems to go against the simple understanding of the first answer of the גמרא. In this first answer, it looks that ר’ שמעוןdoes not hold with the idea of two חזקות. In fact, it looks like the גמרא says the opposite. It says both ר’ שמעוןand the חכמים learn from סוטה, and it is only ר’ שמעוןwho does not hold with the idea of two חזקות. [The idea of two חזקות is that there is a חזקה of השתא along with a חזקה of the body against one חזקה of the body.]