[Avodah] kezayit

[Micha Berger via Avodah]

On Wed, Apr 01, 2015 at 10:30:53PM +0300, Eli Turkel via Avodah wrote:
: There recently appeared a sefer "Keren Zavit" by Nadav Shenrav on parshat
: hashavua that has a very nice combination of science and Torah.
: 
: On parshat Tzav he brings a question on the shitah of the Nodah BeYuhuda
: that eggs doubled in size.

AISI, there are three distinct questions that generally get lumped together
in the annual kezayis discussion:

1- Is "kezayis" a constant volume, or is it pinned to the average olive,
or perhaps the average among some subset of breeds of olive as breeding,
care and climate change?

R' Chaim Volozhiner and the Avnei Neizer say the latter.

You might remember my post from last Jan at.
<http://aishdas.org/avodah/vol33/v33n006.shtml#01>.

The AhS OC 363:34 says that lehalakhah an ammah is the person involved's
forearm. E.g. when measuring 4 amos for tiltul, the din is more chamur
for me than for taller people. When coming to mavui or techum, where
you need a single pesaq for a whole town, you need a standardized ammah,
"ameru chakhamim denimdod lechumerah" it's the length of the arm of some
very high percentile of the people relying on it (and possibly 100%) --
"debevadei yeish anashim shezehu midasan". (Also, when dealing with
someone with a handicap or amputation, you need to use estimates.)

To me this seems to feed RCV's approach. Because both assume that
measurements are not absolute, but based on the set of whatevers involved.

For example, the AhS's position about the standard ammah would imply
that a community that is atypically tall would use a longer ammah
for techum than in a ghettod population whose malnutrition stunted
their typical growth.

2- If kezayis is a constant volume, do all the accepted overestimates
performed and accumulated one atop the other unwind when we have more
information about chazal's zeisim? Or do we say that the bottom of the
range of measurments that dominate common pratice in one's qehillah is
binding as pesaq, and one can't just ignore the now huge safety margin?

This is what I argued here when RNS's paper came out
http://www.zootorah.org/RationalistJudaism/TheEvolutionOfTtheOlive.pdf

(And if so, is that extra amount considered as deOraisa as the original
olive volume, because it's a pesaq in a din deOraisa? Or is it a
harchaqah, and thus derabban?

3- The actual specifics
3a- If the answe to #2 is that we do roll back the kezayis based on
better information about what it was, the metzi'us specifics can still
be argued. Such as asking (as I did in passing in #1) which subset of
olives to average.
3b- And if the answer is that we don't, then there are halachic process
details to ask about.

But I think many discussions, including our own previous years'
iterations, stuble because they blur these topics rather than keeping them
separate, which in turn would force dealing with them in the sequence
I gave as well. (Because #2 depends on one kind of answer to #1, and #3
has different flavors depending on #2.)

Tir'u baTov!
-Micha

-- 
Micha Berger             Despair is the worst of ailments. No worries
micha at aishdas.org        are justified except: "Why am I so worried?"
http://www.aishdas.org                         - Rav Yisrael Salanter
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