Rashi explained that the reason for bedikas chameitz is to avoid a potential issur of bal yera’eh. Why were Chazal concerned for bal yera’eh when everyone, even someone who has done bedika, must do bittul as well? The Ran explains Rashi by offering an interesting historical analysis of the gemara. Ran writes that min hatorah, either bittul or bedika suffices. At the time of the Mishna, it would have been perfectly acceptable to do bedika alone, which is why the Mishnayos that discuss the takanah of bedika never mention bittul. In that context, the reason for bedika is to avoid bal yera’eh, as Rashi writes. At a later point, the Amoraim made an additional takanah that even one who does bedika should also do bittul – there is a double-protection against owning or eating chameitz on Pesach.
If bittul alone suffices, why did the Chachamim make a takanah that every person must do a bedika? Ran explains that bittul depends on the willingness of the owner of chameitz to declare chameitz ownerless and void. Faced with valuable chameitz or an appetizing piece of chameitz found in the middle of Pesach, who can insure that the owner of that chameitz remains steadfast in his willingness to renounce ownership? Perhaps the owner will regret, and mentally accept ownership of this newly found piece of chameitz, thereby violating bal yera’eh. Therefore, Chazal instituted bedika to try to insure all chameitz is removed and will not be found.
R’ Akiva Eiger asks on the Ran: bittul is not merely a decision the owner of the chameitz comes to, but is a verbal declaration through which the chameitz becomes ownerless. We have a rule in halacha that devarim sheb’lev ainam devarim – lit. words in the heart are meaningless, e.g. if I sold my car but had in the back of my mind that if I can’t find a better one the sale is invalid, unless I formally express that condition as part of the contract, it has no validity. The world of commerce does not recognize intent or thought as having legal standing. If so, asks R’ Akiva Eiger, why according to the Ran are we concerned lest someone might find chameitz in the middle of Pesach, mentally regret his bittul, and come to violate bal yera’eh – the mental regret of bittul is simply devarim sheb’lev, and devarim sheb’lev cannot undo an action! Once one has declared chameitz hefker through bittul, how can mental regret alone reverse the process and make one the owner of that chameitz?
R’ Akiva Eiger gives two fascinating answers – bli neder more to come…