Bitul chametz - renouncing one's ownership and relationship with chametz - is a mainstay of the pre-Pesach preparations and assures that one will not violate the lav of bal yera'eh. Nevertheless, it is curiously absent from the mishnayot in the first two perakim of Pesachim. The mishnayot (primarily the first mishna of the first perek and the first mishna of the second perek) repeatedly refer to bedikat chametz - physically removing chametz and omit even a slight mention of bitul. Despite this omission the gemara in several instances is sure that bitul must be performed and that its performance is sufficient to avoid the issur of bal yera'eh: The gemara (6b) debates why it is that a person must still recite bitul even if he has already searched for, and assumedly located, all his chametz. The gemara (4b) further establishes that on a de-oraita level bedikat chametz is unnecessary since bitul would suffice (hence, the gemara maintains that bedika can be seen as a de-rabanan requirement in which even minors are granted reliability). While the gemara firmly establishes the viability of bitul, it does not disclose the manner in which it operates. Bedikat chametz by disposing of the chametz avoids the issur of bal yera'eh in a very clear manner. How does bitul accomplish this task?
According to Tosafot (4b), bitul is merely an implementation of HEFKER - the process by which a person renounces all ownership of his item. Once he no longer owns the chametz, he does not violate the issur of bal yera'eh - a prohibition to possess chametz during Pesach. However, according to Tosafot, since he is not ACTIVELY nullifying the chametz, he does not fulfill the biblical obligation of tashbitu. Nevertheless, he creates a situation in which he no longer violates bal yera'eh.
Those who disagree with Rabbenu Tam raise several questions which challenge this association between bitul and hefker. Most simply, the gemara does not refer to our process as one of hefker but instead designates it as bitul -suggesting a different process. Other questions, however, are not merely nominative but substantive: Classic hefker is guided by certain standards which do not appear to be operative in the case of bitul chametz. For example:
1. Hefker must be recited in the presence of three people (a miniature beit din) whereas bitul chametz apparently can be performed in private.
2. Hefker as a form of financial transaction cannot be performed on Shabbat, yet bitul can be executed on Shabbat (when Erev Pesach coincides with Shabbat).
3. Hefker must be enunciated whereas the gemara suggests that bitul doesn't have to be articulated; merely thinking and intending that chametz should be batel suffices.
In short, since bitul does not resemble classic hefker it must operate according to a different principle.
Two lines of argument are taken in defense of Rabbenu Tam: The Ra'avia (417) insists that bitul IS classic hefker and defends, issue by issue, the departures from the norms of classic hefker: Rabbenu Tam rules against R. Yossi who bans hefker on Shabbat. Thus, bitul as hefker CAN be performed on Shabbat. Furthermore, since bitul is performed in a domestic setting the presence of three people can be assumed. The Ra'avia can be called the purist position in that he preserves the direct association drawn by Rabbenu Tam between bitul and hefker.
By contrast, other defenders of the Rabbenu Tam elect to re-define bitul as a new and non-conventional form of hefker which would not be governed by the standard laws of hefker. This form CAN be performed on Shabbat (even if standard hefker cannot), CAN be said in private, and CAN be thought without being verbalized. Both the Maharam Chalawa and the Ran distinguish between two forms of hefker. However, the Ran actually attempts to define the essential difference between the two: In a standard case, hefker is a form of hakna'a - it closest resembles a transfer of ownership. Since a person enjoys full ownership the only manner by which he can renounce it is to engage in a direct form of hakna'a - active transfer of his ownership to a state of hefker. This hakna'a is prohibited on Shabbat, must be verbalized and requires the presence of three people. Bitul does not demand these standards as the chametz in question is not (or will not be) FULLY owned. Since it will be an issur hana'a (with regard to which ownership is limited) a full-blown hefker (an active transfer) is not at all necessary. Merely withdrawing from an item is sufficient since his ownership is hamstrung anyway. The Ran (and the Ritva) refers to this process as "siluk" and not classic hefker. Siluk can be performed on Shabbat and does not require verbalization. What is notable, according to these positions, is that bitul is only operative because chametz proper is not fully owned once the issur commences. This situation allows the gemara to stitch together a new 'reduced' form of bitul/siluk which is not subject to the classical guidelines of hefker.
Change in Relationship vs. Change in Object
What best characterizes Rabbenu Tam's position is that a person is not actively altering the inherent state of the chametz. Instead, he is merely modifying his relationship with the it (a relative rather than objective change). There are several Rishonim who argue and maintain that bitul redefines the actual halakhic status of the chametz: Rashi (4a) declares that "bitul removes the status of chametz and defines it as dirt which is not fit for ingestion." Similarly, the Rambam in Hilkhot Chametz U-matza (2:2) instructs that a person must recite bitul "and define it as dirt." This position appears consistent with the literal meaning of the word bitul (to nullify or reduce its significance). Although, objectively, the food is still edible in its owner's eyes it is considered dirt rather than food. A precedent for this subjective re-definition of food can be seen in the gemara (45b) which rules that a sheet of sour dough which has been designated by its owner as a chair loses its status of food regarding laws of tum'a and chametz. The halakhic status of food is not purely objective. Even edible foods if fated by their owners for alternate purposes do not retain their identity as 'okhel.'
This position presents us with an intriguing prospect: The gemara (4b) informs us that bitul alone, even when not paired with bedika, solves the problem of bal yera'eh. Would the recitation of bitul alone be considered a fulfillment of the mitzva of tashbitu - the biblical mitzva which demands removal of chametz? Rabbenu Tam who views bitul as hefker was forced to admit that it does not constitute an exercise of tashbitu since it only severs the relationship between owner and item (and does not entail an essential change within the item proper). If bitul re-defines the chametz as dirt we might consider it a form of tashbitu. Indeed, Rashi's comments to the gemara (4b) and the Rambam's elaboration do give this impression.
This view of bitul also provokes a fascinating query: After bitul, can a person actually eat this bread which is now considered dirt? The Mikhtam actually cites a position which allows EATING CHAMETZ AFTER BITUL. However, it seems self-evident that by attempting to eat this dirt, he is in fact re-defining it as food (else, why would he eat it) and removing the status of dirt. The status of these items as defined by its owner is fluid not concrete; what a few moments ago was declared dirt (through bitul) can now be classified as food when it is actually eaten.
Though permitting eating seems unlikely even according to this approach, what about allowing hana'a from this dirt? By using it for household purposes, an owner is not removing the identity of dirt (for even dirt is sometimes used for these purposes though it is never eaten). Since it remains dirt and not chametz these uses should be permissible. This question is posed by the Maharam Chalawa and might force us to re-assess the concept of bitul as 'converting' chametz into dirt.
We have examined two positions which might be viewed as polar opposites of one another. According to Rabbenu Tam, bitul doesn't alter the chametz itself but frees the owner from his chametz. According to Rashi and the Rambam bitul renders the chametz as dirt on which there is no prohibition of bal yera'eh.
A third view is adopted by the Ramban and his talmid, Rabbenu David. We will first analyze Rabbenu David's explanation since it is more apparent: Once the issur begins, a person will not own the chametz AT ALL. (Whereas the Ran casts this as limited ownership Rabbenu David views the post-issur state as one in which the person has NO ownership whatsoever.) In fact, from a certain perspective the issur of bal yera'eh should not apply at all since the issur has canceled his ownership. The issur of bal yera'eh is a function of the person's concern and interest for the chametz. Even though he doesn't legally own it, he is still interested and engaged in this chametz. This INTEREST (which the Rabbenu David refers to as 'da'atei iluyei') is prohibited. By performing bitul, he renounces, in a sense, this interest and disengages himself from the chametz. Rabbenu David in explaining the mechanism of bitul provides a unique and unorthodox definition of the actual issur of bal yera'eh. It is not ownership which is prohibited but concern and entanglement.
One question, however, still presents itself according to Rabbenu David: Why can't bitul be performed after the issur has already commenced (see gemara bottom of 6b). If bitul is hefker or a subjective re-definition as dirt it clearly must be executed prior to the onset of issur. After the issur starts, the chametz is no longer owned; only a ba'al can perform hefker and only an owner can subjectively re-define food as dirt. However, according to the Rabbenu David, bitul merely releases the person from any link or connection to the chametz. Why can't this release be performed after the issur has begun?
Whereas the Rabbenu David's position is unmistakable, the Ramban's is plagued by uncertainties, ambiguities, and apparent inconsistencies. A true understanding of the many layers of the Ramban's manifesto on bitul would require a careful reading of his commentary - line by line. Though the context of this shiur does not allow this (at least in a group sense) I will outline certain highlights.
1) What is clear is that the Ramban tilts toward a Rashi-Rambam stance and away from the Rabbenu Tam's position of hefker. He also determines that bitul 'works off' of the fact that a person does not have full ownership since the chametz is assur. In contrast to the Rabbenu David, the Ramban asserts that some limited form of ownership remains and is revoked through bitul. What exactly this residual ownership is, is never clearly stated.
2) The Ramban appears to vacillate in terms of HOW bitul repeals this residual ownership. At one stage, he expresses that he cancels this limited ownership and yet, he consistently sees bitul as that which defines the chametz as dirt (in fact, the Maharam Chalawa assumed that the Ramban's position was identical to Rashi's and the Rambam's). It is not entirely clear whether bitul defines chametz as dirt or renounces limited ownership.
3) Toward the end of his commentary, the Ramban compares bitul to ye'ush - a state of despair and giving up hope. If someone loses an item and despairs of ever finding it, the one who does find it can keep it. This comparison would be reminiscent of the Rabbenu David's approach since it doesn't actively re-define the chametz nor does it formally renounce ownership.
4) These questions raised in the Ramban are not merely semantic or theoretical. They would influence a host of halakhic issues ranging from whether bitul can be performed through a shaliach (see the Ritva) to whether it must be spoken or can even be thought of as the gemara suggests.