1) A THIEF WHO SOLD THE STOLEN ITEM ON CREDIT
QUESTION: The Gemara says that a Ganav who stole an item and sold it on credit (he received no money for it) is obligated to pay Arba'ah v'Chamishah.
How did the Ganav effect a Kinyan if he received no money in exchange for the stolen item? It must be that the buyer acquired the item through Meshichah. However, Meshichah is a Kinyan d'Rabanan. How can a Kinyan d'Rabanan obligate the Ganav to pay Arba'ah v'Chamishah mid'Oraisa?
ANSWER: This Gemara supports the principle discussed by the Acharonim (see CHAZON ISH 17:16, PRI YITZCHAK, and others) that a Kinyan d'Rabanan suffices for a Halachah d'Oraisa; when the Rabanan institute that a certain act should accomplish a Kinyan, that act is considered on par with any Kinyan d'Oraisa and can be Makneh the object to the recipient for all intents and purposes.
The DEVAR AVRAHAM (1:1:15-16) explains the reason for this as follows. The Gemara in Bava Metzia (74a) teaches that any act that becomes generally accepted as an act that finalizes a sale ("Situmta") accomplishes a Kinyan d'Oraisa. A Kinyan instituted by the Rabanan is no less than the Kinyan of "Situmta." (See Insights to Gitin 36b.)
2) A THIEF WHO STEALS AN ITEM AND THEN MAKES IT "HEFKER" OR SELLS IT BACK TO THE ORIGINAL OWNER
OPINIONS: The Gemara quotes a Beraisa which teaches that a Ganav is Chayav for Arba'ah v'Chamishah not only when he sells the item in the normal manner of a sale, but even when he transfers it to another's ownership in other ways, such as by making it Hekdesh, selling it on credit, bartering it, or giving it as a gift.
The Acharonim discuss other situations in which the Ganav transfers the stolen animal to a different domain in a manner other than that of a normal Mechirah.
1. What is the Halachah in the case of a Ganav who steals an item and then makes it Hefker?
(a) The TO'AFOS RE'EM on the Sefer ha'Yere'im (Mitzvah 124:10) writes that the Ganav is exempt from Arba'ah v'Chamishah in such a case, because making the item Hefker does not qualify as a sale.
(b) The MISHKENOS YISRAEL (#21) rules that a Ganav is Chayav for Arba'ah v'Chamishah in such a case. Making the stolen item Hefker is comparable to giving the stolen item to someone else as a gift. The only difference is that when one makes it Hefker, he gives it to the public and not to an individual person.
The To'afos Re'em argues with this view. A Ganav is exempt from Arba'ah v'Chamishah when he sells the item to two people jointly, and thus he is also exempt when he gives the item as a gift to two or more people. Accordingly, he is exempt when he makes the item Hefker.
Another difficulty is that the Mishkenos Yisrael seems to assume that the act of making an item Hefker is an act of giving the item to the public. However, according to many Acharonim this is not how Hefker works. Rather, when a person makes an item Hefker, he merely withdraws his ownership from the item. His act of Hefker does not transfer the item to the public's ownership, but merely creates the right for anyone to come and acquire the item for himself. Accordingly, making an item Hefker is not comparable to giving an item as a gift.
2. What is the Halachah in the case of a Ganav who steals an item and then sells it to the original owner (from whom he stole it in the first place)?
(a) The TO'AFOS RE'EM rules that the Ganav is exempt in such a case. His ruling is based on the Mechilta which says, "Just as the Mechirah must be done to a Reshus outside of his (the original owner's) Reshus, so, too, the Tevichah must be done outside of his Reshus." It is clear from the Mechilta that the Ganav is Chayav for Arba'ah v'Chamishah only when he sells the animal to someone other than the original owner.
(b) The MISHKENOS YISRAEL (ibid.) rules that the Ganav is Chayav for Arba'ah v'Chamishah in such a case. Since he sold the animal, to whom he sold it makes no difference. It is not clear how the Mishkenos Yisrael addresses the proof of the To'afos Re'em from the Mechilta.
(c) The OR HA'CHAIM (Shemos 23:3) gives a novel explanation for a Ganav's obligation of Arba'ah v'Chamishah. He writes that the obligation applies whenever the stolen animal is no longer found in his possession -- even when there are no witnesses that he slaughtered or sold it! When the animal is not found in his possession, it may be assumed that he slaughtered or sold it. The verse requires him to pay Kefel only when the stolen animal is found in his possession. When it is not found in his possession, he must pay Arba'ah v'Chamishah.
He explains that this is the reason behind the apparent repetitiveness in the verse, "Im Himatzei Timatzei..." -- "If the theft be at all found... he shall pay double" (Shemos 22:3). One "Himatzei" teaches that there are witnesses who testify that he stole the item, and the second "Timatzei" teaches that it was found in his possession. Only when both conditions are met is he obligated to pay Kefel. He proves this from the Gemara here which teaches that when the Ganav removes the stolen animal from his possession in any manner, he is Chayav for Arba'ah v'Chamishah.
2) HE HIT IT WITH A STAFF
QUESTION: Rebbi Elazar states that when people saw the Ganav hiding in the woods when he stole and slaughtered (or sold) the animal, he is Chayav for Arba'ah v'Chamishah. The Gemara asks why is he Chayav if he did no act of Kinyan, such as Meshichah, to acquire the animal through Geneivah? Rav Chisda animals that the case is where the Ganav hit the animal with his staff and made it move. Such an act is an act of Kinyan.
Why does Rav Chisda say that the Ganav hit the animal and made it move? He acquires it even if he merely called to it and it came to him, as this is a valid Kinyan for an animal.
(a) The PNEI YEHOSHUA earlier (56b) writes that Rav Chisda's answer is "Lav Davka," and the Gemara means that even if the Ganav called to the animal and it came to him, he acquired it through Geneivah. (The Pnei Yehoshua there explains why the Gemara specifically mentions the case of hitting the animal and not calling out to it, but his explanation applies only to that Sugya and not to the Sugya here.)
(b) The ME'IRI (56b) writes that the only situation in which calling to the animal and having it come in response to one's voice is considered Meshichah is where one buys the animal or receives it as a gift. In those cases of Kinyan, the one who acquires the animal has the consent of the original owner. In contrast, to acquire the animal with a Kinyan Geneivah, it does not suffice to have the animal come in response to one's beckoning. Rather, the Ganav must do a physical act of Meshichah or hit the animal with his staff. (I. Alsheich)