Mitzvos Laav Lehanos Nitnu

Chaim B. has an interesting post about the concept of mitzvos laav lehanos nitnu. Basically, the issue being dealt with is as follows:

We find that by mitzvos d'oraysah, the Baal Hamaor (daf 7b in Dapei HaRif in Rosh HaShanah)says that mitzvos laav lehanos nitnu applies. This means that even if one is mudar hanaah from someone else, the neder wouldn't apply to mitzvos d'oraysah, because that is not considered hanaah. However, mitzvos d'rabbanan are considered hanaah, so the mudar hanaah would not be allowed to help the other guy to fulfill a mitzvah d'rabbanan.

The question here is that the whole thing is counter-intuitive. If I can't give someone hanaah, wouldn't helping someone fulfill a mitzvah d'oraysah be more hanaah than a mitzvah d'rabbanan? If I'm allowed to help him fulfill a d'oraysah, surely I should be allowed to help him fulfill a d'rabbanan.

Here is the answer that Chaim B. brings from R' Shimon Shkop:

We apply the principle of mitzvos lav l’henos nitnu to mitzvos d’oraysa because the act is inherently defined as a ma’aseh mitzvah. However, a mitzvah derabbanan is not inherently a ma’aseh mitzvah; its performance is just a means to accomplish the goal of obeying Chazal and not violating "lo tasur". Therefore, since the act itself is not a mitvah, the neder is chal.

So, basically, R' Shimon is explaining to us that a mitzvah d'rabbanan is not really an "inherent mitzvah".

Here is the answer Chaim B. quotes from R' Soloveitchik:

RYBS argues that where the Torah labels an act as a mitzvah, it cannot be excluded by a neder because it is by definition not an act of hana’ah. However, by dinim derabbanan, the act itself is not defined by the Torah as a ma’aseh mitzvah and therefore the hana’ah received is considered a direct benefit resulting from the performance.

It seems that the basic answer in both these approaches is that the idea of mitzvos laav lehanos nitnu is not a sevara that a mitzvah is not hanaah. If that were the case, so it should be a kal v'chomer - if a mitzvah d'oraysah's fulfillment is not hanaah, surely fulfilling a d'rabbanan is not.

Rather, the idea of mitzvos laav lehanos nitnu is that it is a din. The din is that if it has a shem mitzvah, so the hanaah is not considered hanaah (at least as far as the din of mudar hanaah).

Now, the way I understand RYBS is rather simply that a mitzvah d'rabbanan has no shem mitzvah on a d'oraysah level. This seems very reasonable. The shem mitzvah is only a shem mitzvah d'rabbanan. M'meilah, the mudar hanaah is assur in this case because on a d'orayssa level there is no shem mitzvah to cause the hanaah not to be considered hanaah.

R' Shimon addition to this seems a bit unnecessary. R' Shimon is adding that a mitzvah d'rabban is not a mitzvah inherently because it "is just a means to accomplish the goal of obeying Chazal and not violating "lo tasur". As if it really would be a maaseh mitvah if not for this philosophical reason behind mitzvos d'rabbanan. Why the need for a philosophical reason? Obviously a mitzvah d'rabbanan is not a maaseh mitzvah on a d'oraysah level. It's by definition. Any thoughts?