- שינוי קונה כתיבא ותנינא
Rabbah said: שינוי קונה כתיבא ותנינא – That a physical change to a stolen item causes the thief to acquire it is written in the Torah and taught in a Mishnah. The passuk says "והשיב את הגזלה אשר גזל" – and he shall return the stolen article that he stole. The last phrase teaches: אם כעין שגזל יחזיר – if the item is still as it was when he stole it, he shall return it, ואם לאו דמים בעלמא בעי שלומי – but if not (i.e., the thief changed it), he only needs to pay money. Two Mishnayos are quoted as sources. One Mishnah teaches that if one steals wood and makes it into utensils, or wool and makes it into garments, he pays its (original) value, and does not return the item. Another Mishnah teaches (regarding ראשית הגז – the first shearings, given to a Kohen) that if the owner of wool dyed it before giving it to a Kohen, he is exempt from giving it (here, he does not pay money either, since no specific Kohen had a right to it). These two Mishnayos demonstrate that a thief acquires a stolen item through changing it.
- Machlokes if יאוש קונה
Rabbah said: יאוש – Regarding despair (when the owner of a stolen item despairs of retrieving it), אמרי רבנן דניקני – the Rabbis say it causes the thief to acquire it. However, he was unsure if this law was d’Oraysa or d’Rabbonon. It may be d’Oraysa, akin to one who despairs of retrieving his lost item, after which one who finds it may keep it. However, it may be different from a lost item, which, when it was found, בהתירא אתיא לידיה – it came permissibly into his hand, since the owner had already despaired, whereas regarding a stolen item, דבאיסורא אתאי לידיה – which came into his hand illegally (before he despaired), he would not acquire it d’Oraysa. Rather, it would be a Rabbinical decree, מפני תקנת השבים – because of an enactment made to assist those wishing to repent (to ease their repentance by allowing a monetary payment, rather than having to retrieve and return the stolen item). Rav Yosef said: יאוש אינו קונה – Despair does not cause the thief to acquire it at all, ואפילו מדרבנן – even Rabbinically. He must return the stolen item.
- שינוי השם
Rav Yosef was challenged from a Mishnah which states regarding unprocessed hides: של גנב – Regarding [hides] stolen secretly by a thief, מחשבה מטמאתן – “thought” renders them susceptible to tumah. Because the owner despaired of retrieving them, the thief owns them, and his decision to use them as utensils (e.g., mats) without further processing them makes them susceptible to tumah. של גזלן אין מחשבה מטמאתן – But regarding [hides] stolen forcefully by a robber, thought does not render them susceptible to tumah. Because the owner knows who the robber is, he hopes to sue him in court and retrieve his hides. Rebbe Shimon holds the opposite is true (because the victim despairs of retrieving his hides from a robber who forcefully stole from him but hopes to retrieve those stolen secretly by discovering the thief). This proves that that a thief does acquire through the owner’s יאוש!? Rava said this challenge went unanswered for twenty-two years, until Rav Yosef became the head of the Yeshiva (upon Rabbah’s passing) and answered: שינוי השם כשינוי מעשה דמי – a change of name is like a physical change. Just as a physical change effects acquisition, because it was originally wood and is now a utensil (for example), regarding a change in name also, it was originally called a hide, and is now called a “tray” (for example).
