I found the following explanation on the gemara Kesubos daf 15a of KOL KAVU'A, K'MECHETZAH AL MECHETZAH DAMI. I have a question on this so please read. The Kollel wrote in Background to the Daf:
>> KOL D'PARISH ME'RUBA PARISH ... KOL KAVU'A K'MECHETZEH AL MECHETZEH DAMI (ROV V'KAVU'A - Following the Majority when in Doubt)
(a) When in doubt as to the nature of an object, one may assume that it carries the same Halachic status of the majority of such items. This is known as Halech Achar ha'Rov - follow the majority rule. For instance, if a piece of meat is found lying on the street (or in the hands of a non-Jew in the street), and most of the meat in that town is kosher, one may safely assume that the meat is kosher (Shemos 23:2, Chulin 11a).
(b) This is only true, however, if the item in question has been separated (Parish) from its place of origination. In such a situation, we assume that "Kol d'Parish me'Ruba Parish" - "that which separated did so from the majority". If the doubt arose while the object was still in its proper "place" (Kavu'a), then one may not follow the Rov. Rather, the status of the item remains in doubt. For instance, if one purchases meat and then cannot recall if he did so from a kosher or non-kosher store, he may not assume that the meat is kosher simply because most of the stores in that town sell kosher meat. Since the doubt regarding its status initially arose while it was still in its proper place (i.e. the store), one may not Halachically assume that it is kosher any more than he must assume that it is non-kosher. This rule is termed "Kol Kavu'a k'Mechtza Al Mechtza Dami" - "anything in its established place is viewed as an even doubt".<<
Why does it make a difference if the doubt arose while it was still in its proper place (i.e. the store) before it was separated from the other pieces of meat in the store? Isn't the doubt about a piece of meat that is currently separated? When he was in the store he knew what type of store it was!
Please explain the concept of Kol Kavua Kemechtza al mechtza and when we say that.
Thanks ah gutten moed!
1) It should be made clear that the law of Kavu'a is a Gezeras ha'Kasuv which the Gemara (end of 15a) explains is derived from a verse referring to the person who threw the stone into the group of 9 Yisraelim and 1 Kena'ani. Because of the Din of Kavu'a we consider this as being a group of 5 Yisraelim and 5 Kena'anim, and he is Patur.
2) One of the Rishonim, the Re'ah (cited in the Mesivta edition of the Gemara here, in Yalkut Bi'urim, page 211), writes (DH Gezeirah) that the Din of Kavu'a applies only when the buyer does not know from which store he bought the meat. In that case, the doubt first arose in the Kavu'a place, and it follows that we say Kol Kavu'a m'Mechtzeh Al Mechtzeh Dami.
According to this, the buyer was not aware at the time from which store he was buying. The difference between Kavu'a and Parish is that in the case of Parish, at the time the meat was bought it was known what had been bought, and it was only after the meat left the store that any doubt arose.
3) Another possibility is mentioned by the Hafla'ah (Rav Pinchas ha'Levi Horowitz, the Rebbi of the Chasam Sofer) on Daf 15a (to Tosfos DH Prat). He writes that if there are 10 stores and it became known that one of them sells Tereifah meat but we do not know which is the Tereifah store, this is an example of Kavu'a and all meat purchased in town is forbidden mid'Oraisa.
4) I should make one or two points slightly clearer.
An important principle in the Sugya of Kavu'a and Parish is that the crucial aspect is where the doubt (about the piece of meat, etc.) arose. The Poskim refer to this by saying that we require "Nolad ha'Safek b'Makom ha'Kevi'us" -- "the doubt was 'born' in the Kavu'a place."
5) This idea is explained by the Chidushei ha'Ran in Pesachim (end of 9b, DH v'Lakach). He writes that what determines whether something is Kavu'a or Parish is the place where the doubt was "born." The words of the Ran are that we go after the place "d'Misyaled Bei Sfeika" -- where the doubt arose.
6) Therefore, the Ran writes that when somebody bought meat and does not know from where he bought it, the doubt was "born" in the stores. Since the doubt arose in the store, which is a Kavu'a place, it follows that we apply the Halachah of Kavu'a, and even 1 out of 10 is considered as 5 out of 5 and consequently the meat is forbidden because of a Safek d'Oraisa that it might be from a Tereifah store.
7) We see from the Ran the same thing that I wrote above, that the scenario being discussed is where he did not know what kind of store it was when he was in the store. This must be referring to somebody who did his shopping very quickly without thinking what he was buying. Perhaps he bought items in a few different stores and did not notice at the time which was Kosher and which was not.
8) We see from the continuation of the Ran that he admits that this is a rather unusual scenario. The Ran continues that if he found the meat in the street, even though it is clear that the meat originated from one of the stores, nevertheless we say that the doubt concerning whether this meat is Kosher or not was "born" now ("Nolad ha'Safek Achshav"). This is because we assume that at the time the meat left the store, we knew which store it had come from (i.e. usually one knows, when inside the store, whether the meat is Kosher or not). It follows that when we find the meat in the street we assume that the doubt started now. Therefore, since the doubt was "born" in the street, it is a Din of Parish, and we follow the majority of meat in town, and the piece is deemed Kosher.
9) In summary, the crucial point is where the doubt started. If it was "born" in the Kavu'a place, then we say "half and half" and the meat is Tereifah. If the doubt was "born" in the street, then we follow the majority.
Kol Tuv,
Dovid Bloom
Thank you for this explanation. I still don't understand the literal meaning of kol kavua. Kavua means set how does that apply to the halacha of kol kavua kemechtza al mechtza? What is being called kavua or "set?"
Thanks!
Another translation of "Kavu'a" is "fixed." There are 9 kosher stores and 1 Tereifah store in town. Because the stores have a fixed place and are all recognizable, we do not say that in case of doubt we go after the majority, but rather we say "Kol Kavu'a k'Mechtzah Al Mechtzah Dami" -- since the Tereifah store is fixed in its place we consider it as if there are 5 Tereifah stores.
Kol Tuv,
Dovid Bloom