Chullin Daf 10 צולין דַף 10

Amoraim discuss: השוחט בסכין – if one shechts with a knife (without examining it immediately before shechitah), ונמצאת פגומה – and it is found afterwards to be nicked, Rav Huna says that even if he broke bones with it all day before it was checked, the shechitah is invalid, because חיישינן שמא בעור נפגמה – we are concerned that perhaps it was nicked by cutting [the animal’s] hide as he began shechting. Rav Chisda says the shechitah is valid, since the knife may have been nicked when breaking a bone. Rav Chisda reasons: עצם ודאי פוגם – a bone definitely causes nicks, עור ספק פוגם ספק לא פוגם – but animal hide may cause nicks and may not cause nicks. It is thus a case of ספק and ודאי, ואין ספק מוציא מידי ודאי – and an uncertainty does not remove something from certainty (i.e., we assume the nick developed from smashing a bone). The Gemara later rules like Rav Huna where he did not break a bone with the knife after the shechitah, and like Rav Chisda where he did break a bone. [Rav Chisda himself validates a shechitah even where he did not break a bone afterwards, because we assume the knife was nicked on the מפרקת – neck bone after cutting the סימנים.

Rav Chisda is challenged from a Baraisa, which teaches that a tamei who immersed in a mikveh and later discovered a חציצה on himself, the טבילה is invalid, even if he handled that material the whole day after the טבילה, unless he is certain he had no חציצה beforehand. Thus, the ספק חציצה does invalidate his apparent tevilah, and we do not assume the חציצה developed afterwards!? Although he had a prior חזקה of tumah, this animal also had a prior חזקה of being forbidden!? The Gemara suggests that in Rav Chisda’s case, הרי שחוטה לפניך – it is shechted before you, and its former חזקה is nullified. However, it objects that in the Baraisa’s case, too, הרי טבל לפניך – he has immersed before you, and should be presumed tahor!? The Gemara counters: הא איתילידא ביה ריעותא – but a cause for concern developed in [the tamei person], since a חציצה was discovered, undermining the apparent tevilah. In Rav Chisda’s case, however, סכין איתרעאי בהמה לא איתרעאי – although the knife developed a cause for concern, the animal itself did not develop a cause for concern (whereas in the case of טבילה, the חציצה was found on the person’s body).

The Gemara asks: מנא הא מלתא דאמור רבנן – from where do we derive this concept that the Rabbis said: אוקי מילתא אחזקיה – keep a thing on its prior known status until proven otherwise? Rebbe Yonasan brings proof from the law of נגעי בתים – [tzaraas] afflictions of houses, where the Kohen is instructed to leave the house after examining the נגע, and close off the house for seven days. But perhaps as he goes out of the house, בצר ליה שיעורא – the [נגע] shrinks to less than the minimum size, and the “closing-off” is ineffective!? It must be that we establish the נגע on its prior חזקה of sufficient size. Rav Acha bar Yaakov questioned this source, because perhaps the Kohen walks out backwards and see the נגע as he leaves, without relying on חזקה!? Although Abaye objects to this suggestion (first, that going out backwards is not called “going out,” and second, a נגע behind the door still cannot be seen), Rava rebuts both objections. Rav Acha bar Yaakov is challenged from a Baraisa which darshens that a Kohen is able to “close off” a house from his own home, out of sight of the נגע, but he says it refers to a line of people from the afflicted house to the Kohen’s, informing him that the נגע maintained its size.