Study Eruvin folio 36A with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
Text Excerpt
רבא אמר: התם תרי חזקי לקולא, והכא חדא חזקה לקולא.
Rava said: That is not the way to resolve the apparent contradiction between the two rulings; rather, there is a difference between the cases with regard to the ritual impurity itself: There, with regard to touching a person who was later found dead, there are two presumptions supporting leniency, whereas here, with respect to the teruma being used for an eiruv, there is only one presumption supporting leniency. How so? With regard to one who touched another person who was later found to be dead, there are two presumptions of purity: Firstly, the person who was found dead was previously alive, and the presumption is that he remained in that state until we know with certainty that he was dead. Secondly, the one who touched that person was previously pure, and he remains in that presumptive state until we know with certainty that he became impure. Therefore, R' Meir had adequate reason to be lenient. However, with regard to teruma, only one presumption exists, that the teruma was previously pure and presumably remained in that state until proven otherwise. Since there is no additional presumption, R' Meir ruled stringently.
קשיא דרבי יוסי אדרבי יוסי!
All the difficulties raised above are based on the seemingly conflicting statements of R' Meir. Yet it would appear that there is also a contradiction between one statement of R' Yosei and another statement of R' Yosei, for he was stringent with regard to the doubts involving ritual baths but lenient with regard to doubts involving eiruv.
אמר רב הונא בר חיננא: שאני טומאה, הואיל ויש לה עיקר מן התורה. שבת נמי דאורייתא היא? קסבר רבי יוסי: תחומין דרבנן.
Rav Huna bar Ḥinnana said: The law with regard to ritual impurity is different, since it has a basis in the Torah. Therefore, R' Yosei was stringent even with respect to immersion performed in order to remove impurity that is only of rabbinic origin. The Talmud asks: The prohibitions of Shabbat limits are also prohibited by Torah law; why isn’t R' Yosei stringent about them as well? The Talmud answers: R' Yosei holds: The laws of Shabbat limits are by rabbinic law, not by Torah law.