Yevamot 8: Sisters as Rival Wives

The Gemara continues to unravel the halacha regarding yibum in the case of the sister of the wife of a deceased husband.  In an effort to better understand this halacha, the rabbis debate the principle of juxtapositioning (among others).  They wonder about the timing of events and whether there might exist a window of time in which yibum might be permitted, though it would otherwise be forbidden.  Further, they wonder about rival wives in this context; arguments are shared on both sides of this debate.  The rabbis debate whether or not a positive mitzvah overrides a prohibition that would incur karet.  Rival wives may or may not be permitted to the yibum.

Forbidden relatives are a large part of determining how yibum operates.  The rabbis suggest that as long as she is alive, a woman's sister is not permitted to her husband's.  However, once she dies, her sister is permitted.  More controversial today, though - if a woman is divorced, her sister is still forbidden to her ex-husband.  Why would the rabbis protect this relationship between sisters so carefully?

We return to the verse discussed intermittently throughout this Masechet, Leviticus 18:18: "You shall not take a woman to her sister, to be a rival to her, to uncover her nakedness, with her in her lifetime."  The rabbis agree that "with her" is superfluous and must be explained.  The consensus is that these words refer to the yibum having intercourse with her.  

Amud (b) teaches that a yevama can be married without her consent, for this verse proves that intercourse will be part of the act of marriage, regardless of her consent.  After they are married, the yibum is allowed to divorce her and remarry her if he wishes.  This is very different from the ordinary standards of marriage.  Normally women are allowed to refuse a marriage arrangement.  Further, in yibum, generally women are allowed to perform chalitza to refuse her husband's brother.  She is not required to marry and then receive a get.

I understand that I am missing many pieces of this puzzle thus far.  However, the larger picture is becoming more apparent: the rabbis are sketching out our rules of engagement.  Those rules have to change according to circumstance.  Unfortunately, our rules as they have been presented are sometimes at odds with each other.  Thus the rabbis have to talk themselves through the potential meanings of each contradiction.  We notice again our rabbis determining the fate of women's lives as creatures who are equal parts property and human being.  

People's lives are at stake.  I continually wonder whether or not the rabbis were aware of the power inherent in their words.  One halachic decision could direct the lives of hundreds of thousands of people over dozens of generations.  Such responsibility... We know that our rabbis took themselves very seriously.  But did they take their work seriously - beyond the interpretation of G-d's words toward facilitation of lives led with dignity?