Yevamot

MISHNAH. A WOMAN WHOSE HUSBAND AND RIVAL WENT TO A COUNTRY BEYOND THE SEA, AND TO WHOM PEOPLE CAME AND SAID, 'YOUR HUSBAND IS DEAD', MUST NEITHER MARRY AGAIN  NOR CONTRACT LEVIRATE MARRIAGE  UNTIL SHE HAS ASCERTAINED WHETHER HER RIVAL IS PREGNANT.  IF SHE HAD  A MOTHER-IN-LAW  SHE NEED NOT APPREHEND [THE POSSIBILITY OF THE BIRTH OF ANOTHER SON];  BUT IF SHE DEPARTED WHILE PREGNANT [SUCH POSSIBILITY] MUST BE TAKEN INTO CONSIDERATION.  R. JOSHUA RULED; SHE NEED NOT APPREHEND [SUCH A POSSIBILITY]. GEMARA. What is implied by  'HER RIVAL'?  — It is this that we are told: {The possibility of a birth in respect] of that rival  need be apprehended; in respect of another rival, however, it need not be apprehended. MUST NEITHER MARRY AGAIN NOR CONTRACT LEVIRATE MARRIAGE etc. It is quite proper that she shall not contract levirate marriage since it is possible that [her rival] is pregnant and that she would in consequence cause an infringement  [of the prohibition against marriage] of a brother's wife, which is Pentateuchal; but why should she not marry [a stranger]? The majority of women should be taken as a criterion  and the majority of women conceive and bear children! Must it then  be assumed that [the ruling is that of] R. Meir who takes a minority also into consideration?  — It may even be said [to represent the view of] the Rabbis; for the Rabbis follow  the majority principle only where the majority is actually present  as, for instance, in the case of 'nine shops'  and 'Sanhedrin',  but in respect of a majority that is not actually present  the Rabbis were not guided by the majority principle. Behold the case of a minor boy and a minor girl, where the majority is one that is not actually present and the Rabbis nevertheless follow the majority principle; for it was taught: A minor, whether male or female, may neither perform nor submit to halizah, nor may he contract levirate marriage; so R. Meir. They said to R. Meir: You spoke well [when you ruled] that 'He may neither perform nor submit to halizah', since in the Pentateuchal section  man was written,  and we draw a comparison between 'woman' and man.  What, however, is the reason why he may not contract levirate marriage? He replied: Because a minor male might be found to be a saris;  a minor female might be found to be incapable of procreation; and thus the law of incest would be violated. The Rabbis, however, maintain, 'Follow the majority of male minors'; and the majority of male minors are not sarisin;  'Follow the majority of female minors' and the majority of female minors are not incapable of procreation!  — But, clearly, [it must be admitted], our Mishnah represents the view of R. Meir. How have you explained it?  That it is in agreement with the view of  R. Meir? Read, then, the final clause: IF SHE HAD A MOTHER-IN-LAW SHE NEED NOT APPREHEND [THE POSSIBILITY OF THE BIRTH OF ANOTHER SON]; but why? One should be guided by the majority of women, and the majority of women conceive and bear while a minority miscarry, and, since all those who bear [produce] a half of males and a half of females, the minority of those who miscarry should be added to the half [of those who bear] females, and so the males would constitute a minority which  should be taken into consideration!  — It is possible that since the woman was confirmed  in her status of permissibility to strangers  [the possibility of the birth of a levir] was not taken by him  into consideration. In the first clause, then,  where she was confirmed in the status of eligibility for the levirate marriage,  let her contract the levirate marriage! — R. Nahman replied in the name of Rabbah b. Abbuha: In the first clause where a prohibition which is subject to the penalty of kareth [is involved, the possibility of the birth of a son]  had to be provided against; in the final clause, however, where a prohibitory law [only is involved]  no [such possibility]  was taken into consideration. Said Raba: Consider: The one [prohibition] is Pentateuchal and the other also is Pentateuchal;  what matters it, then, whether the prohibition is one involving kareth or whether it is only a mere prohibitory law? — Rather, said Raba;