1) THE TYPE OF MITZVAS ASEH FROM WHICH WOMEN ARE EXEMPT
OPINIONS: The Gemara teaches that women are exempt from Mitzvos Aseh sheha'Zeman Gerama. When the Gemara mentions Mitzvos Aseh, does is it refer to any Mitzvah the Torah commands with the wording of an "Aseh," a Mitzvah to do an act (in contrast to a Mitzvah to refrain from doing an act), or does is it refer to any Mitzvah that is fulfilled actively, through "Kum v'Aseh" (in contrast to a Mitzvas Aseh that is fulfilled passively, through "Shev v'Al Ta'aseh," by merely refraining from doing a certain act)?
(a) REBBI AKIVA EIGER in a responsum (TESHUVOS REBBI AKIVA EIGER 3:80) praises the questioner for his suggestion that women are exempt only from Mitzvos Aseh which involve an action ("Kum v'Aseh"). He writes that this view has strong logical basis.
This view is also expressed by the PNEI YEHOSHUA in Beitzah (30a) and by the KESAV SOFER (OC 56). The Kesav Sofer adds that this view is consistent with the logic of the AVUDRAHAM for why women are exempt from Mitzvos Aseh sheha'Zeman Gerama. The Avudraham explains that women are exempt from such Mitzvos because they are occupied with their other responsibilities and cannot be limited to a certain time during which to perform a Mitzvah. A Mitzvah, even one limited to a certain time, which is accomplished passively (by doing nothing, or "Shev v'Al Ta'aseh") does not limit a woman and she is able to fulfill the Mitzvah while she fulfills her other obligations. (See Insights to Kidushin 35:2.)
A practical consequence of this view is a woman's obligation to observe the Inuyim of Yom Kippur other than the Inuyim of eating and drinking (such as washing, wearing leather shoes, and marital relations), according to the opinion that all of the Inuyim are mid'Oraisa. The Lo Ta'aseh and the liability for Kares for one who transgresses the Inuyim of Yom Kippur apply only to eating and drinking. If a woman is exempt from all Mitzvos Aseh, even those Mitzvos which are fulfilled passively, she should be exempt from the other Inuyim of Yom Kippur (because they are fulfilled passively). If, however, a woman is exempt only from Mitzvos Aseh which are fulfilled actively, she should be obligated to observe the additional Inuyim since those are Mitzvos Aseh which are fulfilled passively. (See MINCHAS CHINUCH 313:1.)
Another practical consequence of this view is whether a woman is obligated to observe Tosefes Shabbos, according to the opinion that Tosefes Shabbos is a Mitzvas Aseh d'Oraisa (see Rosh Hashanah 9a). If a woman is exempt from all Mitzvos Aseh sheha'Zeman Gerama, she should be exempt from Tosefes Shabbos as well. If a woman is exempt only from Mitzvos Aseh which are fulfilled actively, she should be obligated to fulfill the Mitzvas Aseh of Tosefes Shabbos (which is fulfilled passively). (This practical consequence is more relevant with regard to Tosefes Yom Tov and Tosefes Yom Kippur, because there are other grounds to obligate a woman in the Mitzvah of Tosefes Shabbos, such as the Hekesh of "Shamor" and "Zachor" which obligates women in all Mitzvos of Shabbos that apply to men. See MINCHAS CHINUCH 297:3.)
(b) However, REBBI AKIVA EIGER, the KESAV SOFER, and the TZELACH (Beitzah 30a; see also SHITAH MEKUBETZES there) point out that the Gemara does not differentiate between a Mitzvas Aseh fulfilled actively ("Kum v'Aseh") and a Mitzvas Aseh fulfilled passively ("Shev v'Al Ta'aseh"). The Gemara in Sukah (28b) cites a verse ("ha'Ezrach") to prove that a woman is obligated to observe Tosefes Inuy on Yom Kippur. The Gemara explains the reason why one might have thought that a woman is exempt: since there is no Lo Ta'aseh or Kares for transgressing Tosefes Inuy and it is only a Mitzvas Aseh, a woman should not be obligated in the Mitzvah. The Gemara there implies that unless a verse teaches otherwise (such as in the case of Tosefes Inuy), a woman is exempt from passive Mitzvos Aseh.
Perhaps one may contend that the Mitzvah of Inuy on Yom Kippur is not a passive Mitzvah but an active one. It is active because the person is required to alter his normal conduct by accepting the Tosefes Inuy and refraining from eating, and also because the Inuy leaves a physical impression on the body (it makes the person weak). (The CHELKAS YOAV OC 30 suggests a similar explanation.) Support for this argument may be found in TOSFOS in Nazir (28b, DH Beno) who suggests that although the Mitzvah of Chinuch applies only to a Mitzvah of "Kum v'Aseh," it nevertheless applies to Inuy on Yom Kippur because Inuy is a Mitzvah which is fulfilled actively ("Kum v'Aseh").
Rebbi Akiva Eiger and the Kesav Sofer suggest further that the verse which teaches that a woman is obligated in Tosefes Inuy is the source that a woman is obligated in all Mitzvos Aseh which are performed passively ("Shev v'Al Ta'aseh").
The Gemara here may provide another proof that a woman is exempt from passive Mitzvos Aseh sheha'Zeman Gerama. The Gemara derives from the Mitzvah of "Mora Av v'Em" (the fear of one's parents) that women are obligated to observe Mitzvos Aseh she'Ein ha'Zeman Gerama. "Mora" is a passive Mitzvah (as is evident from the Gemara earlier, end of 31b), and nevertheless women are obligated only because it is a Mitzvas Aseh she'Ein ha'Zeman Gerama. This implies that women indeed are exempt from passive Mitzvos limited to a certain time.
The Acharonim who do not mention this proof apparently consider "Mora" an active Mitzvah since it occasionally involves an act. (For example, a woman who sits in her father's seat is obligated to vacate the seat.)
Although the Kesav Sofer infers from TOSFOS in Kesuvos (47a, DH d'Masar) that women are obligated in Tosefes Yom Tov (which implies that Tosfos maintains that women are obligated in Mitzvos Aseh which are fulfilled passively), the Kesav Sofer and other Acharonim cite many Rishonim who clearly reject this logic and equate all Mitzvos Aseh sheha'Zeman Gerama and do not differentiate between those fulfilled passively and those fulfilled actively. This is the opinion of TOSFOS here (DH Ma'akeh) who writes that women are exempt from the Mitzvas Aseh of Shevisah on Yom Tov and are obligated only in the Lo Ta'aseh. This is also the view of the RAMBAN, RITVA, and RAN, who write that women would have been exempt from the Mitzvas Aseh of Shevisas Yom Tov had it not been associated with a Lo Ta'aseh.
(The questioner who asked Rebbi Akiva Eiger about a woman's obligation in Mitzvos Aseh apparently suggested that the "Yesh Mefarshim" cited by Tosfos perhaps disagrees with Tosfos on this point. The "Yesh Mefarshim" maintains that women are obligated to fulfill passive Mitzvos Aseh sheha'Zeman Gerama. This is how the "Yesh Mefarshim" would answer the question which Tosfos poses on his opinion. This may also be the opinion of Tosfos in Kesuvos cited by the Kesav Sofer.)
It follows that according to most Rishonim, women should be exempt from the Inuyim of Yom Kippur (other than eating and drinking), and from Tosefes Yom Tov (and from the Mitzvos Aseh of Shevisas Behemah v'Avadim on Yom Tov). (See Insights to Rosh Hashanah 9:1.)
2) THE LOGIC FOR "SHNEI KESUVIM HA'BA'IM K'ECHAD MELAMDIN"
QUESTION: The Gemara mentions the dispute about "Shnei Kesuvim ha'Ba'im k'Echad." According to one opinion, when the Torah expresses a certain law in two different categories of Halachah, that law cannot be applied to all other subjects. Another opinion maintains that when the Torah expresses a certain law in two different categories of Halachah, that law may be applied to all other subjects.
RASHI earlier (24a, DH Ein Melamdin) explains the logic of the opinion that "Shnei Kesuvim ha'Ba'im k'Echad Ein Melamdin." When the Torah expresses the same law in two different places, it shows that the law is limited to those two subjects and cannot be applied to other areas through a Binyan Av. The fact that the Torah finds it necessary to repeat the law a second time shows that the law cannot be applied to other areas of Halachah.
What is the logic of the opinion that the law does apply to all other areas when the Torah mentions it in two places?
ANSWER: The SEFER KERISUS (5:1:1, cited by HALICHOS OLAM 4:4:2) cites the Gemara which teaches that when a law is derived through a Kal va'Chomer, the verse still may go out of its way to write it explicitly ("Tarach v'Chasav Lah Kra"). Similarly, when a law is derived through a Binyan Av, the verse may still go out of its way to write it (TOSFOS to Shabbos 131b, DH Iy; RAN to Nedarim 3a, DH Lindor). Therefore, the Torah may write a law explicitly even when it is derived through a Binyan Av because "Tarach v'Chasav Lah Kra," and thus the first place it is written may teach that it applies to all other areas of Halachah. If, however, the Torah writes the law a third time, then "Ein Melamdin" -- it cannot be applied to all other areas because the verse would not go out of its way to repeat the Halachah twice when it may be derived through a Binyan Av. (See also Insights to Chulin 117:2.)