What sort of answer is that? When he asked his question initially, it was
also an uncertainty!
(a) TOSFOS (DH v'Hadar) explains that perhaps at one point, Rebbi Yehoshua
ben Uza'ah thought that there was an answer to his question and that the
flour between the Kohen's fingers was either certainly Kometz or certainly
Shirayim. Upon further thought, though, he concluded that no such answer can
be given and that his original question remains, and thus the status of the
flour remains a Safek.
(b) TOSFOS answers further and says that the original question of Rebbi
Yehoshua ben Uza'ah was not whether the flour is considered Kometz or
Shirayim, but rather whether it is Kometz/Shirayim, or something else
entirely -- a Minchah which did not have Kemitzah performed with it in the
first place (i.e. "Tevel"). The reason to say that the flour is Tevel even
though a Kemitzah was -- in practice -- performed with it, is because flour
that is inside the Kohen's fist is fit to become Kometz only if the Kohen
*intends* for that flour to become the Kometz. Since people normally do not
consider what is between their fingers to be part of what they are holding
in their fist, perhaps the Kohen did not intend to sanctify the flour
between his fingers as Kometz, and it therefore cannot have the Kedushah of
"Kometz." On the other hand, it cannot be considered "Shirayim" since it
actually was within the fist. For this reason, it should remain with its
previous status of Tevel, Minchah flour with which Kemitzah had not been
performed. In other words, there were three possible answers to what the
status of the flour between the fingers is. Rebbi Yehoshua ben Uza'ah
concluded, though, that the flour cannot be considered Tevel. Rather, it is
considered Minchah with which Kemitzah was not done; it can only be either
Kemitzah or Shirayim.
What difference does it make if it is a two-way Safek or a three-way Safek?
Tosfos answers that if it is possible that the flour is Tevel, then if it
falls into another food, it will *not* become Batel even if there is a
quantity of food many times greater than the flour, because Tevel does not
become Batel.
(c) The RITVA answers that when it says that Rebbi Yehoshua ben Uza'ah
concluded that the status of the flour is a Safek, he concluded that it is
not Kometz and it is not Shirayim, but rather it consists of *both* Kometz
and Shirayim, we just do not know the exact point at which the flour between
the fingers ceases to be Kometz and begins to become Shirayim. This is
similar to the Safek of Bein ha'Shemashos (Shabbos 33b), the Ritva expains;
Bein ha'Shemashos is part day and part night, but we do not know where the
borderline is between day and night.
According to the Ritva, the continuation of the Gemara seems problematic.
The Gemara says that the flour that was between the Kohen's fingers may not
be burned before the Minchah, because "perhaps the flour is Shirayim." Why
does the Gemara say "perhaps" it is Shirayim? According to the Ritva, Rebbi
Yehoshua ben Uza'ah just concluded that it *definitely* contains Shirayim!
The Ritva must learn that the word "Dilma" here means "certainly" and not
"perhaps," as we find that the Ritva himself explains elsewhere (Eruvin 3a
and 48a).