We left off yesterday with a question on the Rambam. Given that aveilus is a begins at kevura and aninus ends at kevurah, it seems that there is no overlap between the two. How then can the Rambam use the pasuk of “V’achalti chatas ha’yom,” from which we learn hilchos aninus, namely that an onein may not eat kodshim, as the source for a chiyuv of aveilus d’oraysa?
Rav Soloveitchik (Shiurim l’Zecher Aba Mori vol 2) answers this question by first setting down the following yesod: aveilus, though primarily demarcated by restrictions on the aveil, is actually a kum v’aseh, a positive kiyum mitzvah. Not wearing shoes, not bathing, not sitting on a chair, etc. are not ends in themselves, but are primarily designed to elicit a certain mindset of mourning.
Though nihugei aveilus, the prohibitions that the aveil must observe, do not apply until after kevurah, that does not mean a person is an onein and not an aveil to that point. A person has a shem aveil, he wears the hat of onein/aveil simultaneously, from the moment of his relative’s death. However, just as aninus exempts the mourner from all other positive mitzvos, it also exempts the mourner from the positive kiyum of aveilus as well.
Kevurah is not the mechayeiv of aveilus; the mechayeiv is misah, exactly like aninus. Kevurah merely brings to a close the state of aninus, which exempted the mourner from practicing nihugei aveilus, and m’meila those obligations set in.
Rav Soloveitchik has a number of proofs that the shem aveil applies earlier than kevurah. 1) Under certain circumstances (see M"K 22) where the body is shipped of for burial, aveilus sets in immediately for those mourners who stay behind and do not travel with it. Kevurah has not yet happened, but nihugei aveilus begin because the period of aninus comes to a close at that point. 2) The view of the SM”K (which we do not accept l’halacha) is that although we do not begin counting shiva until burial, nihugei aveilus begin from the time of the relative's death. Why do these days not count for shiva if nihugei aveilus apply? Because, answers the Rav, the prohibitions of nihugei aveilus do not make for a positive kiyum.