The gemara (Pesachim 5) quotes Rabbi Akiva’s proof that “yom harishon” which is designated for bi’ur chameitz must mean Erev Pesach because chameitz may not be burned on Yom Tov. The gemara draws a number of conclusions from R’ Akiva’s proof, among them that R’ Akiva holds that chameitz must be eliminated by burning. The Pnei Yehoshua asks: according to the chiddush of Rashi (Beitzah 27b) which we discussed yesterday, namely, that the prohibition of burning of kodshim which are tamei on Yom Tov or Shabbos includes any form of elimination, what proof does the gemara have that R’ Akiva holds chameitz must literally be burned? Just as with respect to getting rid of tamei kodhsim any form of elimination is subsumed under the header of “burning” because of the sevara of “achshivei” (see yesterday’s post), so too, perhaps R’ Akiva holds that any means of eliminating chameitz is halachically designated as bi’ur because of the sevara of “achshivei”.
The Noda b’Yehudah (O.C. 15) answers this question by distinguishing between the mitzvah of burning tamei kodshim and the mitzvah of tashbisu. The mitzvah of burning kodshim is incumbent upon anyone who finds kodshim temei’im; the focus of the mitzvah is eliminating objects which are tamei. There is no comparable mitzvah to go around and eliminate all chameitz from the world; if you don’t own the chameitz, you don’t have to burn it. (It is tempting to link this distinction to the safeik of the Minchas Chinuch discussed last week.) The mitzvah is a chovas hagavra upon the owner of chameitz, not a function of the object.
Where the focus is eliminating tumah, the sevara of achshivei tells us that all forms of elimination are subsumed under the melacha of burning because they fulfill the more general goal of disposal. However, the same cannot be said with respect to eliminating chameitz. We never find something which is categorized as a melacha for one person but not another. It cannot be that the owner of chameitz who tosses his bread into a public trashbin has violated Shabbos but the identical act performed by a neighbor who is not the owner of the chameitz is permissible. The definition of melacha is absolute, not relative to the person performing the act.
Getting back to the point raised in previous posts, R’ Soloveitchik’s explanation of the Rambam that disposing of chameitz of Shabbos is prohibited because of the sevara of achshivei contradicts this Noda b’Yehudah and leaves unresolved how to explain Rashi in Pesachim 5. Tzarich iyun on how RYBS would deal with these points – something to work on.