[ ]Mapping the FamilyThe Bavli suggests that levirate marriage might, in theory, be mandated
even when it resulted in a man’s marrying a woman forbidden to him,
for example, his wife’s sister. While the Torah does not explicitly prohibit
levirate marriage in such cases, the prohibition can be derived through
exegesis. Further exegesis extends the prohibition to co-wives, even
though those women have no kinship ties to the potential levir beyond
their marriage to his deceased brother.
The Bavli acknowledges the oddity inherent in the extension of this
prohibition to co-wives. It does so by asking whether the prohibition
against co-wives of relatives should be extended to situations that do not
involve levirate marriage. The six relatives discussed in a subsequent
mishna constitute a “stricter” degree of prohibition because they are for-
bidden to both a man and his brother by the same father, and are thus
never subject to levirate marriage. According to Mishnah Yevamot :,
a man may marry the co-wives of these six relatives — a man’s mother,
his father’s wife (stepmother), his father’s sister, his sister by his father,
and the wife of his father’s brother, and the wife of his brother by his
father — if those women are widowed or divorced. The Bavli considers
the following possibility:
a. I might expand [the prohibition] to the six stricter relatives
and forbid their co-wives [should their husbands die or divorce
them].
b. You should say: Just as his wife’s sister is particular in that she is
a prohibited relative... but is permitted to marry his brothers
and is forbidden to her levir — and her co-wife is forbidden [as
well], so too any woman who is a prohibited relative... but is
permitted to marry his brothers and is forbidden to her levir, her
co-wife is forbidden.
c. This [reasoning] excludes these six stricter relatives, since they
are not permitted to marry his brothers — thus their co-wives
are permitted, for the [prohibition regarding the] co-wife only
applies to a brother {when the situation involves levirate}.^59According to the Bavli, the prohibition against co-wives applies only
when levirate is involved. A man may not marry his dead brother’s wife
if she is a close relative, nor may he marry her co-wife. However, a man
may marry a widow or divorcée, even if her previous husband was also