What is Rav Papa's question? The Mishnah clearly states, "One who eats [the
amount of food equal to] a fat date, *it and its pit*, is Chayav!"
(a) RASHI (DH b'Gar'inisah) explains that Rav Papa is asking about the
meaning of the words in the Mishnah. Does the Mishnah mean to say that the
Shi'ur is the size of a fat date *together with* its pit, or does the
Mishnah mean to say that the Shi'ur is the size of a fat date *or* the size
of its pit (both being the same size)? (We find in many places that the
letter "Vav" means "or.") That is Rav Papa's question.
(b) TOSFOS (DH Koseves) rejects Rashi's explanation, because if those were
the two sides of Rav Papa's question, he would not have asked such a
question. He would have surely assumed that the Mishnah means the size of a
date *together with* its pit. It is not possible that the Mishnah would be
saying the size of a date *or* the size of its pit, because it is impossible
for the two to be exactly the same size, and thus the Mishnah should have
said that whichever one is the smaller of the two is the Shi'ur for which
one is Chayav, and we would know that certainly if one ate the larger of the
two he would be Chayav.
Therefore, Tosfos suggests a different explanation for Rav Papa's question.
Rav Papa is not questioning the words "and its pit" in the Mishnah, but the
word "a fat date." When the Mishnah says that one who eats the amount of
food equal to "a fat date... and its pit" is Chayav, perhaps when it says
"it (a fat date)," that *already* refers to a complete date, together with
its pit, and when it says "and its pit" it means a *second* pit, effectively
making the Shi'ur *one Koseves and two pits* (its own pit, plus an extra
pit). The other possibility is that when the Mishnah says "a fat date," it
means the Koseves by itself, not including its pit. When the Mishnah then
adds "and its pit," it means a single edible date and a single pit.
(c) Tosfos cites the ARUCH who gives another explanation in the name of RAV
NISIM GA'ON, based on the Yerushalmi (this is also the preferred explanation
of the BACH in OC 612:1). The Yerushalmi says that when the Mishnah says
that the Shi'ur of Achilah on Yom Kipur is like "a date and its pit," its
intention is to exclude the *hollow space* in the date. Dates tend to have a
hollow space between the flesh of the fruit and the pit. If we were to
include that space in the Shi'ur, then the Shi'ur would be larger. The
Mishnah is telling us a Chumra -- one is Chayav for eating the smaller
Shi'ur of a date and its pit without the hollow space.
Rav Papa in our Gemara was asking whether the hollow space mentioned in the
Yerushalmi is including. When the Mishnah says that the Shi'ur is the size
of a date and its pit, does it mean to exclude the hollow space between the
date and the pit (that is, only "the date together with its pit"), or does
it mean "without its pit" -- that is, the date *without being snugly
attached* to its pit, but with a hollow space separating between them?
The BA'AL HA'ITUR also explains that Rav Papa was in doubt whether the
Mishnah means to include the hollow space in the size of a Koseves or not.
However, he explains the wording of Rav Papa in exactly the opposite manner.
When Rav Papa asks whether the Shi'ur is "a fat fig *along* with its pit,"
that means *with* its hollow space, because it refers to the fig the way
that it grows naturally. When he says that perhaps it refers to "a fat fig
without its pit," that means that the fig and the pit have been separated
from each other, and the Shi'ur of Achilah is ascertained by *combining* the
fig with its [removed] pit -- which means that the hollow space is *not*
taken into account.
The NETZIV (Meromei Sadeh) suggests that this is also the intention of
Rashi. (He is Gores at the end of Rashi "k'Kamoha *u'*Kegar'inasa.")