QUESTION: Rebbi Yehudah maintains that "Semuchin" -- the method of deriving
Halachos through the proximity of one verse to another -- can only be used
if there is a compelling reason ("Muchach") to do so (for example, one of
the verses being expounded is out of place and belongs somewhere else), or
if one of the verses is extra ("Mufneh").
One such incident of Semuchin that Rebbi Yehudah expounds is the verse, "Lo
Yikach Ish Es Eshes Aviv, v'Lo Yigaleh Kenaf Aviv" -- "A man shall not take
the wife of his father, and he shall not uncover the cloak of his father"
(Devarim 23:1). Rebbi Yehudah utilizes Semuchin to derive that the phrase
"Lo Yegaleh Kenaf Aviv" is teaching that one may not marry "Anusas Aviv," a
woman who was raped by his father. Which verse is extra ("Mufneh"), such
that Rebbi Yehudah can apply Semuchin? The Gemara says that the Torah did
not have to add "Lo Yegaleh Kenaf Aviv," since we already know from the
first half of the verse that a person may not take his father's wife. Since
the second half of the verse is extra, it must be teaching us, through
Semuchin (proximity to the previous Parashah which deals with the laws of
rape), that it is prohibited to marry "Anusas Aviv."
The Rabanan, who argue with Rebbi Yehudah and permit a man to marry a woman
who was raped by his father, understand the verse differently. They say that
"Lo Yegaleh Kenaf Aviv" is not teaching the prohibition of "Anusas Aviv,"
but rather it is teaching the prohibition of marrying the "Shomeres Yavam"
of one's father (a woman who is bound to do Yibum with one's father, but has
not yet performed Yibum or Chalitzah).
Why, then, when explaining the view of Rebbi Yehudah, does the Gemara say
that the second half of the verse is repetitive? We see from the Rabanan
that it is not repetitive -- it is teaching the Isur of "Shomeres Yavam" of
one's father! Consequently, that part of the verse is not extra, and thus
Rebbi Yehudah should not be able to apply Semuchin to learn the Isur of
"Anusas Aviv!" (TOSFOS DH Im Ken)
(a) TOSFOS says that Rebbi Yehudah considers only one word to be extra, not
the entire second half of the verse. If it was teaching only the Isur of
"Shomeres Yavam," then it would have said, "v'Lo Yegaleh *Kenafav*," without
adding the extra word "Aviv," since it already said "Aviv" in the middle of
the verse and it is clear that "Aviv" (his father) is the subject of the
verse. Since the word "Aviv" is extraneous, Rebbi Yehudah has license to
(b) The RIVAN answers that there is another reason why Rebbi Yehudah does
not accept that the verse is referring to "Shomeres Yavam" of one's father.
This woman who is bound to do Yibum with her deceased husband's brother (the
man's father) is already prohibited to him with two Mitzvos Lo Ta'aseh --
the Isur of a Yevamah marrying anyone other than her husband's brother
("Isur Yevamah la'Shuk"), and the Isur of Eshes Achi Aviv (she is the wife
of the father's brother, which is an Ervah to the father's son). If this
verse is referring to the "Shomeres Yavam" of one's father, then it is
teaching a *third* Lo Ta'aseh for something that is already prohibited with
two Isurim! To add a third Lo Ta'aseh is illogical. Even though the first
half of the verse is adding an additional Lo Ta'aseh for the Isur of Eshes
Aviv, that is only a second Lo Ta'aseh; the verse would *not* teach a third
Lo Ta'aseh. Therefore, Rebbi Yehudah understands that the verse must be
referring only to Eshes Aviv, and thus the second half of the verse is extra
and is teaching something by way of Semuchin -- the Isur of Anusas Aviv.
(This appears to be the approach of Rashi DH Lichtevei as well.)