According to Rashi's definition (and Tosfos Shantz) of Lav Sh'kadmu Aseh, an Aseh that CAN be performed before the Lav is by definition not a "nitak l'aseh", and a violation of that Lav would make the transgressor chayiv malkos - the Aseh cannot fix the lav.
If so, why is Shiluach HaKan not a classical "Lav sh'kadmu aseh" and be chayiv malkus, even according to the Chachamim? (Rav Yehuda says it is in fact "lav sh'kadmu"). Not only can the Aseh be performed first, it's supposed to be performed first! Acc. to Rashi's definition of "lav sh'kadmu", Shiluach Hakan should not be "nitak l'aseh". (the same should hold true for Pe'ah as well, it seems, where the aseh is supposed to precede the lav.)
Ari Rosenstein, Ramat Beit Shemesh, Israel
See Chulin 141b, where the Gemara says that the reasoning of Rav Yehudah is that "'Shelach' m'Ikara Mashma" -- Rav Yehudah interprets the verse to mean that you shall send the mother bird before you take the young. However, the Chachamim understand the verse differently. They understand the verse to mean "if you took, then send it away." Although you must send the mother bird before you take the young, because of the Lav (and there is also an Aseh), nevertheless the reading of the verse is that if you took the mother b'Isur, then send it away.
Thank you for your reply.
However, isn't the very fact - even according to the Chochomim, who don't argue with Rav Yochanan - that the asei CAN be performed before the Lav, make the mitzva into a "lav sh'kodmu"? Tosfos on daf 16a ("v'ha ika") asks this very question for the case of mashkon.
The Gilyon HaShas on Rav Yochanan's klal refers us to Pesachim, where the same question is brought up in Tosfos regarding Korban Pesach.
Thank you again.
I think that the answer of Tosfos relates to your question exactly. Since, because of the Ribuy, the Halachah of "Chazaras ha'Avot" refers directly to the case of after, even though it can also be done before, since the Torah directly speaks about the after it is a Nitak l'Aseh. The same is true with "Shalach," if it is actually speaking about after taking the mother. However, with regard to Korban Pesach, the Aseh is discussing l'Chatchilah and, as Tosfos says, it means that once you take the meat out of its place, it is "b'Amod v'Hachzer" which is not a direct Aseh on the situation of *after* the Lav was transgressed, but rather it is the original Aseh which can be reinstated. This is a "Lav she'Kidmo Aseh."
Thank you again. But one last point - on your comment:
"as Tosfos says, it means that once you take the meat out of its place, it is "b'Amod v'Hachzer" which is not a direct Aseh on the situation of *after* the Lav was transgressed, but rather it is the original Aseh which can be reinstated. This is a "Lav she'Kidmo Aseh."
- the sugya on 15a is talking about an Ones, and the final answer of Rava near the bottom that creates a "lav ha'Nitak l'aseh" are exactly the same words - "b'Amod v'Hachzer". Rashi and Tosfos say this IS a new mitzva to make it nitak, and davka NOT Kidmu!
The determination of whether a Mitzvas Aseh applies *only* after the transgression of the Lav or even before the Lav is transgressed cannot be made from the words "Amod v'Hechzer." As you pointed out from the case of Ones, these words do not necessarily mean that the Aseh begins before the Lav is transgressed.
Rather, the reason that Tosfos in Pesachim (95a DH Lo Sotzi) assumes that the Mitzvah to return a Pesach to the house from which it was taken is a "Lav she'Kadmo Aseh" is because there is no *additional* verse to teach that *after* the Pesach was removed from the house, it must be returned. Rather, the obligation to return it is inferred from the verse that teaches one may not remove a Pesach from its house in the first place. That is why Tosfos assumes it is Kadmo Aseh, and questions why it should be called a "Lav ha'Nitak l'Aseh."
In the case of Ones (Makos 15a), the Chiyuv to remarry is inferred from an *extra* verse ("Kol Yamav"), which is written exclusively to teach that the Ones must remarry his victim *after* he divorces her. Therefore, this extra verse cannot be called "she'Kadmo Aseh."
I hope this clears things up.