פירוש על קידושין 69:20

R. Yohanan b. Beroka holds that women are obligated in the mitzvah of procreation. This leaves them exempt only from Talmud Torah—so why not use that as a paradigm and make them exempt from PNTB commandments?
The answer—there is another PNTB commandment for which they are exempt—redeeming the first born. Only the father is obligated to redeem his first born.

R. Yohanan b. Beroka holds that women are obligated to procreate and to fear their parents—so we now have a situation of two verses that come as one, and therefore we should not have a rule that women are obligated in PNTB commandments.

The Talmud now will explain why both verses are necessary and therefore are not really a case of “two verses that come as one.” The Torah had to explicitly obligate a woman in procreation (according to R. Yohanan b. Beroka) for otherwise I would have thought that she is exempt because the Torah instructs humankind to “conquer” and women’s nature is not to conquer (this can be certainly be disputed, but there are people who might agree that men have a greater tendency towards war).

If the Torah had not taught that women are obligated to fear their parents I might have thought that they are exempt because women often do not have the opportunity to fear their parents because they are with their husband (we learned this above). Therefore, the Torah had to teach that they are obligated.
Since both verses are necessary this is not a case of two verses that come as one.

The Papunians, those from a place called Papuna, have another source for the exemption of women from all positive time-bound commandments. The verse in Exodus compares the Torah to tefillin. And since we know that women are exempt from tefillin (because tefillin is compared to Torah study), women are exempt from all such mitzvoth. And if they are exempt from time-bound commandments, they must be obligated in non-time bound ones.

The Papunians, those from a place called Papuna, have another source for the exemption of women from all positive time-bound commandments. The verse in Exodus compares the Torah to tefillin. And since we know that women are exempt from tefillin (because tefillin is compared to Torah study), women are exempt from all such mitzvoth. And if they are exempt from time-bound commandments, they must be obligated in non-time bound ones.

R. Meir holds that tefillin are not time-bound. R. Meir holds that they must be worn all the time. So what is his source for women being obligated in positive non-time bound commandments? The answer is that he holds that two verses that come as one do not teach. Therefore, matzah and gathering cannot serve as a paradigm to obligate women in positive time-bound commandments.

R. Judah has a bigger problem—he too holds that tefillin are not a time-bound commandment. Plus he holds that two verses that come as one can teach about others. So why then do we not hold that matzah and gathering teach that they are obligated?
The answer is that we have a third verse, the obligation to rejoice on festivals. R. Judah holds that they are obligated for this mitzvah as well. And since everyone holds that when three verses come as one do not teach, we now have no source to obligate women for positive time-bound commandments.

One source for the rule that women are obligated in negative commandments is Numbers 5:6 which explicitly mentions both males and females.

The first verse in parshat Mishpatim uses the plural—“before them.” Thus women are obligated in all civil laws.

There are three derivations of the general rule—the first from a verse about atonement for accidental sins, the second about civil law, and the third about paying a ransom when an animal murders a human being. Why do we need all three?
The first would not be sufficient to teach that women are subject to all civil law because women did not engage in commerce as did men.
The second, about civil law, would not be sufficient to teach that if an animal kills a woman the owner must pay a ransom because women are not obligated in all commandments, as are men. (I know, this is a bit of an ugly one. But I do think it is a faithful representation of what happens when you exempt people from commandments. You might start to think that there life is less worthy than those fully commanded. This seems to be what might have happened to at least one strand of rabbinic thought).
If all we had was the third rule we might have thought that in that case, men and women were equated because it is a matter of life. But in cases of atonement or civil laws, they are not equal. Therefore we need all three derivations to teach that they are equal in all negative commandments.

There are three derivations of the general rule—the first from a verse about atonement for accidental sins, the second about civil law, and the third about paying a ransom when an animal murders a human being. Why do we need all three?
The first would not be sufficient to teach that women are subject to all civil law because women did not engage in commerce as did men.
The second, about civil law, would not be sufficient to teach that if an animal kills a woman the owner must pay a ransom because women are not obligated in all commandments, as are men. (I know, this is a bit of an ugly one. But I do think it is a faithful representation of what happens when you exempt people from commandments. You might start to think that there life is less worthy than those fully commanded. This seems to be what might have happened to at least one strand of rabbinic thought).
If all we had was the third rule we might have thought that in that case, men and women were equated because it is a matter of life. But in cases of atonement or civil laws, they are not equal. Therefore we need all three derivations to teach that they are equal in all negative commandments.