In Part I we saw Tosfos’ distinction between the case of dropping an object and the case of shooting an arrow at an object with respect to the issue of basar m’ikara azlinan. The Ketzos (390:1) claims that not all Rishonim agree, and one of his proofs comes from a very famous question of the Nimukei Yosef.
The gemara (B.K. 22) quotes R’ Yochanan’s view that damage caused by fire is similar to damage caused by shooting an arrow (isho m’shum chitzo): the person who starts the fire or shoots the arrow has no control over what subsequently happens, but is still responsible for the result. If I shoot an arrow and five minutes later it hits and destroys and object, even though I may be sitting under a tree when the damage occurs, it is as if I took a hammer at that moment and smashed the object; the same is true if I light a fire and it later burns down a house. The Nimukei Yosef asks: if so, how am I allowed to light Shabbos candles? Even though when the candles are burning I am sitting and enjoying my seudah, just like the archer sitting under a tree is viewed as if he at that moment smashed whatever the arrow hit, so too, I should be viewed as if I were engaged in the act of kindling for the duration of the candle’s burn!
The way the Ketzos interprets the Nimukei Yosef’s answer takes us back (see part I) to the case of an object dropped from the roof (disclaimer: it is by no means it clear that this is actually what the N.Y. meant). The reason the person who dropped the object is liable for breaking it and not the person who swings at it and smashes it on its way down is because basar m’ikara azlinan, we view the object as if it was broken from the second it was dropped, even before it actually hits the ground. So too, the person who shoots an arrow or lights a fire is not chayav because he is considered to be causing damage later when the arrow hits or the fire rages, but rather he is chayav because basar m’ikara azlinan, we anticipate the damage which will occur and consider it done already from the moment the arrow leaves the bow or the fire is lit.
Why are you allowed to light Shabbos candles? Because the principle of basar m'ikara azlinan tells as that the burning which occurs later is considered to have already happened the moment the candle was lit.
But didn’t Tosfos tell us that this sevara of basar m’ikara applies only when you act directly on an object, like dropping it off a roof, not when you indirectly cause damage, like shooting an arrow at it? QED, says the Ketzos, the Nimukei Yosef disagrees with Tosfos.
This is the context which (in my opinion) is needed to appreciate the question posed to R' Tzvi Pesach Frank. Here we go: I understand that I am allowed to light Shabbos candles because the candles which burn as I eat my meal are treated halachically -- basar m'ikara azlinan -- as if their burning was done already before Shabbos even started. However, this Friday I also have to light Chanukah candles, and those candles must burn after dark for me to fulfill my mitzvah. If I light those candles before Shabbos starts, and based on the N.Y. I treat the burning of the candle in the future as a fait accompli from that moment it is lit, how am I yotzei the mitzvah of lighting neiros Chanukah after dark? The lighting and burning finished their job before Shabbos started, while it was still light out!
I think there is more than one way to skin this cat. Bl"n I'll follow up with R' T.P. Frank's answer.