How can it be that when the bed is immersed in separate pieces, it does not
become Tahor? According to Rebbi Eliezer, the parts of a dismantled bed are
not considered to be a Kli, but rather a broken Kli. We know that whenever a
Kli which is Tamei is broken, it loses its Tum'ah (because it is no longer a
Kli) -- which is why a bed cannot become Tamei unless fully assembled,
according to Rebbi Eliezer. How, then, can Rebbi Eliezer say that the
separate pieces of a dismantled bed must be reassembled and require Tevilah
to become Tahor -- they are already Tahor!
(a) TOSFOS, the ROSH, and the RASH (in Kelim) explain that indeed, a bed
that is Tamei becomes Tahor when it is dismantled according to Rebbi
Eliezer. Nevertheless, when the bed is reassembled, it will *revert back to
its state of Tum'ah* and will need Tevilah. Tevilah does not work while it
is dismantled because the Tum'ah does not return until it is reassembled.
There are two problems with this answer. First, the RASH himself asks from
the beginning of the Mishnah in Kelim which says explicitly that if half of
a bed was stolen, even if one gets back the stolen part and puts the bed
back together, it does not revert back to its old Tum'ah that it had before
it was taken apart and stolen!
Second, the Mishnah (Kelim 11:1) tells us that the only type of Kli which
regains its old Tum'ah when it is repaired is a metal Kli. Other types of
Kelim become Tahor when they are taken apart and remain Tahor when
reassembled. The wooden bed, therefore, should also remain Tahor when
reassembled! (VILNA GA'ON, Kelim 18:7)
To answer the first question, the RASH says that when half a bed is
*stolen*, one despairs of ever putting it back together again. Therefore, it
is considered to be irrevocably destroyed, and even if one does put it back
together it will not revert back to its old Tum'ah. In the case of our
Gemara, all the pieces of the bed are available and one plans to reassemble
the bed, and thus it reverts back to its old Tum'ah when reassembled.
This might also answer the second question. Although normally, broken Kelim
(that are not of metal) do not become Tamei when reassembled, this type of
Kli is different. Since it is common to dismantle and reassemble beds, it is
not considered a broken Kli when it is dismantled, and thus it returns to
its Tum'ah when it is reassembled. However, if it is not considered broken,
then why can it not be Mekabel Tum'ah when dismantled? Rebbi Eliezer is
teaching that in order to be Mekabel Tum'ah, in addition to not being
broken, it must also be usable. Even though the dismantled bed is not
considered broken, since it is not usable it is not Mekabel Tum'ah.
(b) The VILNA GA'ON (Kelim 18:7,9) explains that when Rebbi Eliezer states
that the bed is only Metamei when it is whole, he does not mean that when it
is dismantled it becomes Tahor. Rather, if it was already Tamei before it
was dismantled, it *remains* Tamei when dismantled, because it is not really
considered to be a broken Kli. However, if the bed was Tahor when it was
dismantled, and now a part of the bed touches something that is Tamei, it
cannot become Tamei. The parts of a dismantled bed cannot acquire new
Tum'ah.
Rebbi Eliezer's statement that the bed only becomes Tahor in its whole state
means that it can only become Tahor when it is reassembled, but until then
it remains Tamei. (It cannot be immersed in its disassembled state, because
it is Tamei only due to what it used to be (a useable bed); in such a state
it can only become Tahor in the same state in which it was when it became
Tamei.)
(c) TOSFOS and the RASH cite sources from the Tosefta for an entirely
different way of understanding Rebbi Eliezer. Rebbi Eliezer does not mean
that a bed becomes Tamei *only* when it is assembled. Rather, he means that
it becomes Tamei *even* when it is assembled. "Chavilah" does not mean that
the bed is completely assembled; rather, it means that as little as one slat
and two legs ("Aruchah u'Shnei Kera'ayim") are assembled. This means that
any part of a bed that is dismantled remains Tamei, and even can become
Tamei. However, if a few of the pieces of the bed are attached to each
other, by touching the leg of the assemblage, the entire bundle of pieces
becomes Tamei (the Tum'ah spreads to the slat and to the other leg). The
Chachamim who argue say that *only* the parts that were touched, and they do
not transfer the Tum'ah to the other pieces attached to them. Since it is
not a whole bed, it is not considered a single cohesive unit to spread the
Tum'ah throughout the other parts. When the bed is completely assembled, the
entire bed becomes Tamei if any part of it is touched by a person who is
Tameil.
When Rebbi Eliezer says that a bed becomes Tahor only when it is a
"Chavilah," he means that since he considers an "Aruchah u'Shnei Kera'ayim"
to be a coherent unit, one may be Tovel it all at once, and we do not say
that the point at which they are connected is a Chatzitzah. The Chachamim
argue and say that the parts of the Tamei bed must each be immersed
separately, because the points at which they are connected are considered
Chatzitzos. Only when all the parts are assembled into a complete bed is the
entire bed viewed as a single unit and may be immersed all together; when
the parts are not completely assembled into one complete bed, each piece is
viewed as a separate part and must be immersed separately.