During a shiur, I heard the Dayan of the Chasam Sofer first sold his chametz, and then bought chametz to burn. Why would someone specifically sell their chametz before biur chametz?
The whole point of selling the chametz began when the Jews moved to Poland and started having a lot of whiskey in their barrels because they were running the inns. Up until that time, people would be able to go to the local market and sell the small amount that was left. Once the large amounts of whiskey started to accumulate, and the local nobleman and the local peasnatry who might have bought it could not be trusted to not drink it all up and never pay what they owed, people would sell it, keep it sealed in the basement and then buy it back after Pesach.
However, selling the chametz and then buying it back shows that the chametz has value. The mitzvah of tashbisu on the other hand requires showing that the chametz is valueless as expressed in the bitul of the chametz. The statement of the Chasam Sofer below explains this concept. Thus selling the chametz (as done by the Dayan of the Chasam Sofer) will allow a person to avoid the isur of owning chametz. However, it would not fulfill the positive mitzvah of destruction and showing that it is vvalueless. The Dayan of the Chasam Sofer was ensuring that both aspects of this were demonstrated explicitly.
There is a dispute between Rabbi Yehuda and the Chachamim in the Mishna (Pesachim 21a) whether the mitzva of tashbisu s’or mibataichem requires burning, or if crumbling chametz and dispersing it in the wind or tossing it into the sea suffices. The basic Halacha follows the view of the Chachamim that any means of destruction is valid, although the minhag is that fire is preferred. (For this reason, when Erev Pesach falls on Shabbos, we flush chametz down the toilet.) Wouldn’t a sale to a gentile also fulfill the mitzva?
The Minchas Chinuch (9) famously ponders whether one who owns no chametz must acquire some in order to destroy it on Erev Pesach. Does tashbisu require an act of elimination, or simply that one not possess chametz? He concludes that the Torah mandates an act of hashbasa.
But does hashbasa require physical elimination, or would a legal act that removes the chametz from its owner’s possession be effective?
The Rishonim say that one could fulfill the mitzva of tashbisu with bitul. And they say—with the notable exception of the Ran—that bitul means making one’s chametz ownerless.
So if bitul, wherein the chametz is untouched but its ownership is changed, constitutes tashbisu, why wouldn’t selling it to a gentile qualify as well?
It would appear that the answer is this: Tashbisu requires that one treat his chametz as worthless, something he no longer values. (See, for example, the bitul formula, in which we declare that our chametz “should be batel and be ownerless like the dust of the earth.”) Both physically destroying chametz and relinquishing ownership of it via pronouncement demonstrate that the chametz no longer holds value for its owner. But selling would indicate the opposite. Offering an item for sale shows that the seller values it and expects that others will do so as well. He sells his chametz to exchange it for another valuable commodity, money. One who sells his chametz certainly won’t violate bal yeira’eh uval yimatzai, because he no longer owns it. But neither will he fulfill tashbisu if it requires an eliminative act.
The Rashash (Pesachim 21b) suggests that one could fulfill tashbisu on Erev Pesach by eating chametz and letting his gastric juices consume it. But we don’t find that option mentioned by the Rishonim and Acharonim, and this could be the reason: Eating something does not demonstrate that one doesn’t value it, it does the inverse.
A similar argument is made by the Chasam Sofer. The Tosefta (Pesachim 2:12) discusses the case of a man who finds himself on a ship before Pesach in possession of chametz. Were he to destroy his chametz provisions, he would starve before reaching land. The Tosefta says he should sell or gift it to a gentile passenger, but it adds the caveat (per the text of the Geonim) that one must not engage in pretense; the sale must be real. The Tevu’os Shor (Bechor Shor, Pesachim 21a) offers a novel understanding of contemporary mechiras chametz: It is indeed ha’arama, a pretense, but because bitul eliminates the possibility of Biblical violation (Pesachim 4b, 10a), the prohibition of chametz is only mideRabbanan, and a ha’arama-based sale is sufficient on the deRabbanan level as a reinforcement of one’s bitul. The Chasam Sofer rejects this understanding, arguing, as above, that the sentiment that underlies sale is the opposite of that behind bitul: Bitul means I don’t value the chametz, selling means I do. The sale of one’s chametz, far from fortifying his bitul, would undermine it.