The first mishna of Bava Batra discusses the construction of walls which divide between neighbors. One view asserts that construction of walls is mandatory since halakha demands privacy ("hezek re'iya shemeih hezek"—literally, visual damage is considered damage). An alternate view suggests that erection of walls is voluntary since halakha does not legislate privacy ("hezek re'iya eino shemeih hezek"—literally, visual damage is not considered damage). However, if two neighbors jointly agree to construct a wall, their understanding binds them, and the wall must be constructed according to halakhic guidelines.
The gemara questions the second position, that construction is only mandatory if voluntarily agreed to. Assuming the two neighbors settled upon the construction, why can't they withdraw their commitment? Even assuming that they have performed an act of kinyan (acquisition) to solidify their commitment, such a kinyan would be non-binding. Kinyan, typically is performed upon a monetary and tangible entity: a house is sold through executing one of the methods of kinyan for real estate, while a cow is acquired by performing meshikha, drawing the animal into one’s domain. In each case, a concrete item is being sold and is the object of the kinyan. Performing a kinyan upon an ACTION, rather than an item, is not legally binding and is referred to as kinyan devarim. Just as a person cannot perform a kinyan to obligate himself to take a walk, it should be similarly impossible for a neighbor to obligate himself to build a wall. Such an agreement—even is anchored by a kinyan—should not compel either party.
The gemara does not clarify the reason that a kinyan cannot affect actions. At first glance, we may suggest that two parties cannot reach the necessary level of AGREEMENT, or da'at, when selling something as abstract as an action. Several gemarot deny the validity of a kinyan upon a "davar she-lo ba le-olam," a future item that has not yet appeared or emerged (see shiur - see shiur- vbm-torah.org/archive/metho57/18bah.doc). Many authorities reason that the disqualification of kinyan on future objects is based upon the inability to properly reach "gemirat da'at," a meeting of the minds between buyer and seller. In addition to the performance of a demonstrative ACT of kinyan, every transaction requires an underlying agreement between the parties. When describing items that do not yet exist, halakha can never be certain that the participants are serious in their commitments; clearly a person would be more than willing to sell the luxury car he does not yet own. Analogously, the defect of kinyan devarim may stem from the inability of the participants in this kinyan to reach full agreement. Unlike items, actions are more vague; thus, the difficulty in defining these actions may obstruct the attainment of gemirat da’at and may ultimately disqualify the kinyan.
It seems probable that the Ramban adopts this approach. The Bet Yosef (CM 195) cites a teshuva (responsum) of the Ramban that if TWO acts of kinyan were executed upon an action, the kinyan would be binding. The gemara refers to a situation in which a kinyan chalipin (exchange) was performed to launch a kinyan to split a courtyard; if the neighbors performed chalipin twice, or, conceivably, if they drafted a shtar (document) in addition to performing chalipin, the kinyan would be valid. The Mishneh Le-melekh, in his commentary to the Rambam in Hilkhot Mekhira 5:14, cites this position, as well as those who dispute it. It would appear that the Ramban believes that kinyan devarim is flawed because we cannot be ASSURED that the parties are truly serious. By enacting a 'double kinyan,' their earnestness is exhibited and the kinyan is legitimate. Had the flaw of kinyan devarim been more internal, perhaps a double kinyan would not be effective.
However, a different picture emerges from a statement of the Ri Migash to Bava Batra 140b. Halakha allows for a shekhiv mei-ra, a dying person, to effect the transfer of his estate by issuing verbal instructions. Even though halakhic transfer require physical acts of kinyan, "divrei shekhiv mei-ra ki-khtuvin ve-khimsurin damu"—his verbal requests are sufficient and no ma’aseh kinyan is necessary. In a striking statement, the Ri Migash claims that a shekhiv mei-ra may verbally instruct a kinyan devarim which is binding. For example, if he instructs that a child should 'take' some of his money (even if he does not legally transfer that money), the order is binding. Undoubtedly, he viewed the flaw of kinyan devarim as an inability to perform requisite acts of ma’aseh kinyan. Portable items can be lifted or physically relocated, while land can be repaired (kinyan chazaka). What form of ma'aseh kinyan could possibly be performed upon ACTIONS? Consequently, a shekhiv mei-ra who is halakhically empowered to effect transfer without performing any ma’aseh kinyan CAN effect a kinyan devarim. In his comments to Bava Batra (148b), the Ramban disagrees with the Ri Migash and disqualifies a shekhiv mei-ra from kinyan devarim. Presumably, this coincides with his previously stated position that kinyan devarim is ruined by the absence of seriousness. As such, a shekhiv mei-ra would also be incapable of kinyan devarim, because in his case as well, we would question the level of seriousness. Effectively, the Ramban and the Ri Migash dispute the nature of the kinyan devarim disqualification. According to the Ramban, it stems from an absence of seriousness; whereas according to the Ri Migash, it is based upon the inability to structure a physical ma’aseh kinyan upon abstract actions.
Yet another picture emerges from the statements of the Ran to Bava Batra 3a. Though a commitment to perform an action, such as dividing a tract of land, is a kinyan devarim and consequently invalid, a commitment to deliver money to another is binding. If a person announces, "I will give you $100," he is obligated to deliver that sum to the other party, even though no other independent kinyan was performed upon the actual money. Perhaps the Ran understood the issue of kinyan devarim a bit differently: even assuming the existence of sufficient 'seriousness' and even assuming the possibility of a ma'aseh kinyan (perhaps by executing an abstract ma'aseh kinyan, such as chalipin), an action cannot be the SUBJECT or content of a kinyan. The legal processes of kinyan transfer SPECIFIC items or land but not ACTIONS. By identifying a specific and quantifiable action, the Ran's kinyan may be effective. In fact an interesting mishna in Bava Metzi’a (75a) may reinforce the Ran's position. In discussing various laws of shomerim (watchmen), the mishna describes a situation in which two people agree to work for each other on a rotational basis ("nakesh imi va-anakesh imkha"—literally, "Weed with me and I will weed with you."). One may have questioned the validity of this agreement since they are merely offering reciprocal kinyanei devarim. Based upon the Ran's statements, this mishna seems more plausible. By identifying a specific and quantifiable action (which may even have assigned market value), a legal kinyan can apply. The flaw of conventional kinyan devarim lies in the absence of any definite 'entity' (action or item) upon which the legal kinyan can take effect. Dividing land is too vague and has no predefined monetary value; therefore, it cannot be the subject of a kinyan.
To summarize: we have isolated three potential flaws of kinyan devarim. In each instance, we detected the potential flaw by examining an exception (a situation in which kinyan devarim would be effective) and appreciating the non-viability of kinyan devarim in light of the exceptional case in which it succeeds.
This shiur attempted to define the potential defects of kinyan devarim. It targeted three potential issues: the level of seriousness, the action that typically enacts a kinyan and the actual effect of the kinyan, any of which may not apply to Devarim or actions. In classic Talmudic language, these three aspects are referred to as da'at, ma'aseh and challot respectively. Therefore the classic formulation of this question would be: "Is the disqualification of kinyan devarim based upon a lack of da'at, an inability to perform ma'aseh kinyan, or a fundamental incompatibility between the challot of a kinyan and devarim (actions)?"