The Prohibition of "Bittul Kli Mei-Heichano"
The mishna in Shabbat (42b) describes a Shabbat prohibition to place a vessel under oil that is dripping from a lit lantern. The mishna does not define the reason for this prohibition. Subsequently, the gemara cites R. Chisda, who both extends the prohibition and delimits it. Just as a vessel cannot be placed to collect oil from a lantern it similarly cannot be placed to collect a newly hatched egg. However, a vessel CAN be employed to cover an egg and prevent it from moving or being damaged. Although R. Chisda explores the scope of the mishna's prohibition, he does not provide an explanation for it. R. Yosef does offer an explanation: a usable vessel cannot be rendered unusable by placing it under muktzeh items. The Chakhamim established a prohibition of Ein Mevatlin Kli Mei-Heichano, prohibiting positioning a vessel so that muktzeh will fall upon the vessel and immobilize it. What R. Yosef does not explain is the rationale for this prohibition.
In two other locations in Shabbat (128b and 154b), Rashi claims that the Rabbinic prohibition is based upon the Biblical prohibition of soter. Just as dismantling a structure is forbidden, divesting a utensil of its utility by placing muktzeh upon it is similarly forbidden (Rabbinically). Interestingly, in his comments to the original gemara (Shabbat 42b), Rashi suggests a different paradigm for the prohibition. By immobilizing the vessel, the person has converted an otherwise portable item into an immovable part of the landscape. This activity is similar to CONSTRUCTION or boneh and is forbidden. Setting aside for the moment the apparent contradiction in Rashi, two different models of this issur emerge. It may be Rabbinically forbidden because it resembles soter, dismantling, or it may be Rabbinically forbidden because it resembles boneh, construction.
Several intriguing nafka minot emerge from this structural question. For example, would the prohibition apply to immobilizing items that are not classified as halakhic utensils or keilim? The gemara (43a) speaks of a possible prohibition against using bedposts or benches to support cross beams that are at risk of falling. By reinforcing the beams, the benches are immobilized for Shabbat and have been batel mei-heichano. Would the same prohibition apply if limbs of a tree were employed to strengthen the falling beams? Raw tree limbs are not halakhically considered vessels. If the prohibition consists in decommissioning a vessel similar to soter, it would be permissible to employ tree limbs; as they aren't vessels soter hasn't occurred. If, however, the prohibition stems from the similarity to boneh, any immobilization of ANY material would resemble construction and would be forbidden. The Magen Avraham (OC 313:14) prohibits the use of tree limbs, but the Sha'ar Tziyon cites the Eliyahu Rabba, who permits it.
An interesting test case pertains to items that can be moved but will not be used for non-muktzeh related reasons. Would placing items in these situations violate this prohibition? The gemara alludes to a prohibition of placing a vessel to collect dirty and potentially foul smelling rain water. The Beit Yosef (OC 338) questions this application since halakhically the vessel CAN be moved. Even though the undrinkable water is muktzeh, it can be removed from residential settings if its presence causes unusual discomfort (an exception to the prohibition of muktzeh known as graf shel re'i). The Beit Yosef answers that the gemara was merely prohibiting the collection of water in a NON-RESIDENTIAL situation, in which muktzeh would apply. In such a case, the water cannot be moved and the vessel is effectively immobilized.
A different solution would suggest that although halakhically muktzeh does not apply to the water and the kli CAN be moved, it WON’T be USED because the foul water will ruin any other substance. The vessel CAN be MOVED, but it WON’T be USED. If the prohibition is based on soter, any decommissioning of use – even if caused by non-halachic factors – would be forbidden. Even if the water is collected in residential settings and Halakha allows its removal, its collection has denatured the kli and resembles soter. If, however, the prohibition stems from boneh, only IMMOBILIZATION would cause an issur. Since halakhically the vessel CAN be moved, no issur has been committed. Perhaps the Beit Yosef viewed the issur as based on boneh; since water in residential settings can be moved, no construction-like immobilization has occurred. Our alternate interpretation suggest that even though halakhically the vessel can be moved, since it won't it has been immobilized and boneh has been performed.
Although the Rishonim do not address many issues regarding this prohibition, one major question emerges from a debate between the Ba'al Ha-Ma'or and the Rashbah in their comments to the gemara in Shabbat (154b). If a kli is TEMPORARILY decommissioned, would the violation entail? The simple reading of the gemara in Shabbat (43a) suggests that no violation exists. The gemara cites an example of placing a vessel underneath a newly hatched chick, which is muktze. Unlike an egg, which, once placed upon the kli, cannot dislodge itself, the chick will probably reposition itself. Since the decommissioning is only temporary, no issur has been committed. Similar conclusions emerge from the gemara in Shabbat (154b) allowing the placement of cushions underneath small muktzeh glass items to break their fall and prevent their shattering. Since the pillows can subsequently be dislodged and moved without breaking the muktzeh glass, only temporary decommissioning has occurred and no issur exists. This is indeed the ruling of the Ba'al Ha-Ma'or. The Rashbah disagrees and is forced to reconfigure these two gemarot. He concludes that even TEMPORARY decommissioning would violate the prohibition of ein mevatlin kli mei-heichano.
The Ba’al Ha-Ma’or and the Rashbah may be debating the nature of the prohibition. If the issur resembles soter, even temporary denaturing of the kli would be forbidden, as the Rashbah claims. However, if the issur stems from the similarity with boneh, perhaps only permanently immobilized objects qualify as construction, but not items which have been temporarily immobilized.
Perhaps these two models and the differences in their application can solve the apparent contradiction in Rashi. In his comments to the gemara in Shabbat 42b describing the decommissioning of a kli, he bases the issur on boneh; in his comments to Shabbat 128b and 154b regarding the use of pillows (to prevent shattering glass or serve as resting areas for injured animals), Rashi invokes soter as the source for the prohibition. The Pnei Yehoshua claims that utensils which are discussed by the gemara in Shabbat (43a) are not really candidates for SOTER, even if muktzeh is deposited on them. The kli is not really being decommissioned; it is being COMMISSIONED to contain an item! In fact, nothing prevents the deposit of an additional item into the kli. Of course, the UTILITY of the kli is somewhat limited since the vessel cannot be moved to an alternate location, but the notion of denaturing a vessel of its utility or soter does not apply. However, the concept of immobilizing a kli and performing a boneh-like activity does pertain, and Rashi therefore writes that boneh is the source of the prohibition.
In contrast, the subsequent gemarot (128b), 154b) describe pillows, which are generally not used in construction, and the concept of boneh therefore does not apply. However, since the glass instruments or the animal are firmly placed upon the pillow, it cannot be used for its standard function. The prohibition of soter has been violated, and Rashi therefore notes this issur and not the prohibition of boneh.