• Rav Moshe Taragin
The Shakh authored a pamphlet entitled "Takfo Kohen" which addresses the laws governing personal appropriation of non-collectible debts.  At the age of seventeen, the Shakh penned a work that has reshaped the halakhic attitude toward this behavior.  This event was so monumental that it triggered numerous responses to the work - both critiques as well as defenses.  Some of the more renowned responses include works by Rav Yonatan Eibeshitz, Rabeinu Yaakov mi'Lissa (author of the Netivot), and Rabeinu Yehuda the brother of the Ketzot Ha-Choshen in his seminal work entitled "Kuntrus Ha-sfeikot."  Much of the discussion surrounds a pivotal sugya in Masekhet Bava Metzia (6a-b).  The mishna had addressed a situation in which two parties jointly lodged exclusive claims to an item – a dispute which mandates a division of the disputed item.  The ensuing gemara questions how we should rule if one disputant were to unilaterally grab the disputed item.  Would the lack of response in any way indicate that the "grabber" indeed deserves the item? This question launches a broader consideration of the laws of tefisa – unilateral seizure of disputed items. 
     The subsequent gemara probes several cases, most notably the situation of an animal which may or may not be the firstborn and might - as a bekhor - actually belong to a kohen.  This case seems to be paradigmatic of the general situation.  Generally, disputes which cannot be resolved through hard evidence or other judicial vehicles (rov, migu, chazaka etc.) are decided in favor of the current possessor, based upon the sweeping and foundational principle known as "ha-motzi mei-chavero alav ha-r'aya (the one who seeks to extract an item from its current possessor is burdened with furnishing evidence).  In the absence of any evidence, the item remains where it is currently lodged.  Consequently, an animal which might be a bekhor cannot be awarded to the kohen and thus remains with the owner.  What would occur if the kohen seized the animal, claiming that it was truly his?  Would we now award the animal to him, since he is currently the possessor? Or would we sustain the original situation in which, prior to the commandeering of the item, it was possessed by the original owner?
     The gemara does not issue an unambiguous conclusion to this question, but the overwhelming majority of Rishonim read several innuendoes as suggesting that the commandeering would not be successful and the item would be returned to the pre-seizure possessor.  The logic of this position is fully consistent with the aforementioned principle of ha-motzi mei-chavero – a concept which is both basic and extensive.  Having triumphed through ha-motzi mei-chavero, it is unlikely that the possessor should be vulnerable to unilateral seizure.
     Though the logic is compelling, this shitta seems to be contradicted by two gemarot in Ketuvot – each of which suggests a scenario of successful seizure.  Tosafot and the Ramban issue decidedly different solutions to these exceptions, and the resolutions they pose are revealing as to their definitions of seizure and the general status of muchzak (possessor). 
     Tosafot (Bava Metzia 6b and Ketuvot 20a) claim that there are two independent conditions which allow successful tefisa (seizure).  If the snatcher is convinced he is correct and lodges a definite claim to the item, his seizure is successful.  Alternatively (and it is not fully clear from Tosafot whether he accepts each criterion independently or wavers about which criterion to accept), if the grabbing occurred before the safek was established (meaning, before the dispute emerged), the seizure would be valid.  In the instance of the kohen, he grabs after the uncertainty (regarding the status of the disputed sheep) has developed, and he can have no certainty about his claim (since he has no record of the birthing past of the mother animal).  Without either condition, his grabbing will almost certainly fail.
     An interesting pattern emerges from Tosafot.  Despite the low incidence of success, tefisa is a legitimate halakhic tool.  If a person through seizing behaves or appears as a thief, of course we will order the item's return.  Assuming, though, that he backs up his grabbing with a confident claim, he will succeed.  And even in the absence of such a claim, if he anticipates the dispute and grabs – again, so that he doesn't appear to be stealing an item - he will succeed.  By offering these conditions to explain the exceptional cases of successful tefisa, Tosafot essentially validate tefisa as a broad and legitimate logical category.  Practically, it will rarely be successful, but logically, it remains a legitimate recourse.
     This position is quite revealing about the nature of muchzak and the reason we favor the possessor.  One could argue that the possessor enjoys a built-in proof of ownership: if he is grasping the item in question, then he probably owns it!  How else did he acquire it?  We don't generally assume that people are thieves!  That component certainly does not apply to a person who seized; we know exactly how he acquired the item – he grabbed it believing it to be his!  By backing the person who grabbed and recognizing him as the new muchzak, we are basically strictly adhering to the physical state.  Whoever is currently in physical possession of an item triumphs in a dispute which provides no hardcore evidence.  Hence, the grabber can be victorious in creating a state where he now enjoys physical dominance – as long as he avoids acting as a thief (he grabs before the dispute unfurled or he grabs with a certain claim of ownership). 
Next week's shiur will iy"H explore the Ramban's solutions to the problematic gemarot in Ketuvot and the perspective of muchzak which these answers reflect.