There are a number of important questions on some of the points that the
Rashbam makes in his explanation of this Sugya.
First, the Rashbam (near the beginning of DH Amar Lei) explains that the
claimant did not have witnesses to testify that he was the original owner of
the land. Rather, he was relying on the admission of the Machzik to prove
his ownership of the land. Why, then, does the Rashbam write later (in DH
Amar Lei, and DH v'At) that the Machzik would have won the case had he said,
"I saw the third party buy it from you," but only if the Machzik had
occupied the field for three years? Even if he had not occupied the field
for three years, he should be believed with a Migu that he could have said
that the field never belonged to the claimant, since there are no witnesses
to contradict that statement! (TOSFOS 30a, DH Lav)
Second, the Rashbam (DH Zil) writes that the claimant won the case because
the Machzik did not occupy the field for three years. This seems to
contradict what he wrote earlier -- that even if the Machzik did occupy the
field for three years, he still loses the case because he does not have a
definitive claim to validate his occupancy of the field ("Chazakah she'Ein
Imah Ta'anah"). (BEIS HA'LEVI (3:36:2), PNEI SHLOMO, KEHILOS YAKOV (#20))
Moreover, the Rashbam repeatedly mentions that the Sugya is discussing a
case in which the Machzik had not occupied the field for three years (end of
DH Amar Lei, DH v'At, DH Zil). If the Halachah of our Gemara applies whether
or not the Machzik had a Chazakah of three years, as the Rashbam initially
writes, then why does he later write that in the case of our Gemara the
Machzik did not have a Chazakah of three years?
(a) With regard to the first question, the DERISHAH (CM 146:24) and the BEIS
HA'LEVI (3:36) explain that the Machzik will not be believed to say that he
saw the third party purchase the field from the claimant (or that he himself
purchased the field from the claimant) with a Migu that he could have said
that the field never belonged to the claimant, if he did not occupy the
field for three years. The reason for this is because it is so uncommon for
a person to lose his Shtar within three years of the purchase of a field
that the lack of a Shtar is tantamount to testimony of witnesses that he did
not purchase the field. The Migu is thus a "Migu b'Makom Edim" which is not
a valid Migu (as the Gemara says on 31a).
When the Mishnah in Kesuvos (15b) says that a person is believed to say
"this field was your father's and I purchased it from him" because he could
have said that the field was always his, the Mishnah must be referring to a
person who had occupied the field for three years.
However, the Rashbam seems to contradict this elsewhere (29b, DH Alav, and
34a, DH Ela, as the YOSEF DA'AS points out).
In addition, in the beginning of the Rashbam's explanation, the Rashbam
himself writes that the only reason why the Machzik's claim cannot win the
case for him is because he did not witness the third party purchase the
field from the original owner. This implies that had he witnessed the
purchase, even though he did not have a Chazakah of three years, he would
have been believed. (SHACH CM 146:13)
Similarly, in the end of the Rashbam's explanation here (DH Amar Lei), when
he discusses what the Halachah is in this case, in which the Machzik did not
have a Chazakah of three years, he writes that even if witnesses testify
that the third party occupied the field for at least one day, the Machzik
would not win the case since *he* did not occupy the field for three years.
If the Rashbam holds that the Machzik would not win even if he said that he
saw the third party buy the field, then he should have included that point
in his statement. The Rashbam should had added that whether the Machzik
brings testimony that the third party occupied the field for a day, *or*
whether the Machzik claims that he saw the third party purchase the field,
he will not win the case. The Rashbam's omission again implies that he
agrees to Tosfos' assertion that the Machzik *would* win in such a case,
where he claims that he saw the third party purchase the field, because he
has a Migu. (Shach loc. cit.)
With regard to the second question (why does the Rashbam imply that the
Machzik would have won had he had a Chazakah of three years), the Beis
ha'Levi explains as follows. The reason the position of the Machzik is
considered a "Chazakah she'Ein Imah Ta'anah," a Chazakah that has no claim,
is because the Machzik does not have personal knowledge that the third party
purchased the field from the claimant. The Machzik does have, however,
personal knowledge that the third party *claimed* that he bought the field
from the claimant. The Beis ha'Levi points out that later in Bava Basra
(135a) Rava and Abaye argue whether or not a claim based on what was heard
from another person is considered a "Bari" claim, a claim of certainty. Rava
rules that it *is* considered a Ta'anas Bari, while Abaye does not consider
it to be a Ta'anas Bari. The Halachah follows the opinion of Abaye in this
regard.
In the beginning of the Sugya, the Rashbam explains the Gemara according to
the Halachic opinion (on 135a), that what one hears from a third party is
not considered a valid claim. This makes our case into a "Chazakah she'Ein
Imah Ta'anah," and therefore even if the Machzik occupied the field for
three years, he would not win the case.
However, later (in DH Zil) the Rashbam is explaining the ruling of Rava. It
is Rava who maintains that this would be considered a "Chazakah she'Yesh
Imah Ta'anah," as per his ruling later (on 135a). That is why the Rashbam
explains that Rava would have ruled differently had the Machzik had a
Chazakah of three years.
Another approach to our second question is suggested by the KEHILOS YAKOV
(#20). The Gemara does not simply rule that the claimant wins the case.
Rather, the Gemara adds that the Machzik is not a "Ba'al Devarim" of the
claimant at all -- he cannot even bring the case to court (as explained by
TOSFOS 30a, end of DH Lav, in the name of RABEINU CHANANEL and the GE'ONIM).
Perhaps the Rashbam holds that if the Machzik would have occupied the field
for three years, then even if his Chazakah would be a "Chazakah she'Ein Imah
Ta'anah," he would be considered to be at least a party in the case and he
would be able to bring the claimant to court. He might lose in court, but
the claimant would not be able to ignore his claim entirely. Since the
Gemara rules that the Machzik cannot even bring the claimant to court, it
must be that he did not have a Chazakah of three years.
This explanation is difficult to understand since the reason the Machzik
cannot bring the case to court according to the Ge'onim is because he admits
that he does not have a definitive claim to the field. What difference,
then, does it make whether or not he had a Chazakah of three years?
In addition, according to both explanations, it is clear from Rava's words
that the Sugya is discussing a case in which the Machzik did not have a
Chazakah of three years. Why, then, does the Rashbam write at the beginning
of the Sugya ((DH Amar Lei) and at the end of the Sugya (DH Amar Rava) that
the Machzik could have occupied the field for three years?
(b) There are two ways to explain the incident recorded in our Gemara. The
first way is the way we have understood until now -- the reason why the
Machzik's claim was not accepted is because he did not know on his own that
the third party purchased the field from the original owner. However, we may
suggest another way to understand the Gemara, as follows. Perhaps the
Machzik *did* make a definitive claim that he *saw* the third party buy the
field from the original owner (the Rishonim were not Gores the words "d'Amar
Li," see Bach #4). Why, then, was his claim not accepted? Apparently, his
claim was not accepted because he did not occupy the field for three years.
Why was the Machzik not believed with a Migu that he could have said that
the field never belonged to the claimant? It must be that the claimant had
witnesses who testified that he once owned the field.
According to this explanation, when the claimant said, "Lav ka'Modis" -- "Do
you not admit that the field was mine," he did not mean to say that he was
basing his claim of ownership on the admission of the Machzik. Rather, he
meant that the Machzik must admit that the field belonged to him, since the
claimant either had witnesses or it was known to all that he once owned the
field.
The reason why the claimant won the case is because the Machzik had a Shtar
only from the third party, and the third party did not have a Shtar that he
bought it from the claimant. Since the Machzik did not occupy the field for
three years, he did not have a Migu and therefore he lost the case.
(This might be the intention of RABEINU GERSHOM on 30a. The ALIYOS D'RABEINU
YONAH also seems to give a similar explanation.)
It seems that the Rashbam originally explained the Gemara according to the
second way of understanding it. Later, he changed his mind and explained the
Gemara in accordance with the first way of understanding it (he changed his
mind based on the words "Lav ka'Modis," which imply that the claimant did
not have witnesses to prove his prior ownership of the field). As we
mentioned elsewhere (see Insights to Bava Kama 18:1 (end)), when Rashi (or
the Rashbam) changed an explanation, he often added the new explanation
before the original explanation, but left the original explanation in place.
At most, he took out the comments that explicitly contradicted the new
explanation.
The comments of the Rashbam in the beginning of the Sugya (DH Amar Lei)
until the words "Aval Hichzik" (and in DH v'Lo ka'Modis and DH Amar Rava)
reflect his final explanation, in which the Machzik *did* have a Chazakah of
three years, but he did *not* have a valid claim. All of the other comments
of the Rashbam reflect his original explanation, in which the Machzik did
*not* have a Chazakah of three years, but he *did* have a valid claim.
This answers the questions that we asked. We first asked why the Rashbam
writes that the Machzik is believed to say that he saw the third party
purchase the field from the claimant if the Machzik had occupied the field
for three years. Why does the Machzik not have a Migu that he could have
claimed that the field never belonged to the claimant? The answer is that
the Rashbam, at that point, was following his original explanation, that the
claimant had witnesses who testified about his prior ownership of the field.
This is also why the Rashbam does not discuss (at the end of DH Amar Lei)
what the Halachah is when the Machzik said that he saw the third party buy
the field from the original owner but did not have a Chazakah of three years
(as we asked above in the name of the Shach). The Rashbam did not have to
discuss this case, because that case itself was the case of the Gemara. When
the Rashbam in the beginning of the Sugya (beginning of DH Amar Lei, as we
quoted above in the name of the Shach) implied that there *is* a Migu, he
was following his later explanation, that the claimant had no testimony
about his prior ownership.
This answers our second question as well. When the Rashbam (end of DH Amar
Lei, DH v'At, DH Zil) writes that the Machzik did not occupy the field for
three years, and if he would have occupied the field for three years he
would have won the case, he is following his original explanation, that the
claimant brought testimony to prove his prior ownership.