[Avodah] Rambam Hilchot Kiddush Hachodesh

[Micha Berger]

On Sat, Dec 09, 2017 at 10:59:26PM +0200, Ben Waxman via Avodah wrote:
: 1) Rambam Hilchot Kiddush Hachodesh 3:1 makes it clear that anyone
: who sees the new moon and can get to Jerusalem by the following
: evening should go. How would that work today....

And then think what happens if the calculations were for a long month. The
guy invests all that effort just to get to locked Lishkas haGazis doors. I
would be frustrated.

But to get to your question. I think that's a taqanah in order to insure
that there is eidus. Rather than everyone saying someone else will go.

There is no how that would work today, since you need a Sanhedrin to make
it work. But isn't this a derabbnan, to make sure all those who see the
moon don't assume someone else will go, and there ends up not having 2
kosher eidim? So, if the the next Sanhedrin finds that too many people
are coming / would come and we're far from needing such a guarantee,
they can repeal this din.


: 2) Rambam Hilchot Kiddush Hachodes 2:10 says clearly that once the
: beit din declares the new month, that is it, even if they know that
: they made a mistake. Yet in 3:15 and 16 Rambam writes that in the
: situation where no witnesses came on the 30th, if witnesses come
: later in the month and are able to prove that they did see the moon
: come out on the 29th, that month's calendar is redone. Is this not
: an obvious contradiction? I assume that I am reading 3:15 and 16
: incorrectly or that I am getting something wrong here.

The famous story of the calendar dispute between Rabban Gamliel and R'
Yehoshua (RH 2:8-9) includes R' Aqiva saying,
    "Eileh mo'adei H' asher tiqre'u osam" --
    bein bizmanan, bein shelo bizmanan,
    ein Li mo'ados ela eilu.

Which is what the Rambam is saying in 2:10. He quotes R' Aqiva's
prooftext.

In that mishnah, both R' Gamliel and R' Yehoshua knew the metzi'us, they
were arguing over whether to accept the eidim despite a flaw in their
story. They may have even been arguing about the cheshbon, and whether
there was a need to accept whatever eidim one had. The beginning of
mishnah 9 has R' Gamliel ordering R' Yehoshua to show up "beyom
haKippurim shechal lihyos *becheshbonkha*".

There may be a difference between making a mistake in terms of
decision-making and making one because they were working with bad or
incomplete data. 2:20 is about their decision being wrong, 3:15-16 is
about a lack of eidus. An error in the cheshbon or perhaps decision in
general vs an error in facts. While this guess about p' 2 is less than
compelling, it would seem that in p' 3 he is empowering a BD to go back to
their cheshbon when they were forced by a lack of testimony to lengthen
the month despite it. After all, 3:15 describes BD sitting all of the
30th, meaning wanting a short month, without witnesses comming. So I
feel more comfortable with that part of the guess. Maybe R' Yehoshua
would have renegged without needing R' Aqiva had other eidim arrived
days later to corroborate the first two.

: 3) Later in the book Rambam goes on at length and in extreme detail
: about how to calculate the moon's position. He adds that we know
: these calculations from science and that since we no longer have a
: tradition about this matter from the nevi'im, it is fine to use
: outside sources. Seeing this made me wonder why we don't apply this
: rule in other areas. For example, I had read that we don't make
: matza from barley because we don't have a tradition as to how it
: takes barley to become chameitz. So why not measure it?

But lemaaseh we don't, because we need a Sanhedrin to make a RC. For
that matter, we even pad when we say Qiddush Levanah, making the one
day difference irrelevent. So what halakhah lemaaseh is the Rambam
talking about, that relies on the calculations? Giving license to
the next Sanhedrin?

I am not even sure we know the scientific difference between chameitz
and sirchah. Or even if there is one. Why is dough made with 100%
juice a different thing than if the juice were diluted, or if it were
all water? If we don't know what it is we should measure, how can we
use science to measure it?

I think it has to be something like that, because the lack of barley
matzah isn't a modern issue. And the ability to measure rising doesn't
require some modern measuring equipment. So, why was the question left
unsolved by centuries of acharonim if it were resolable?

Similarly, we know the medical communities' various definitions of
death. (They're all pretty similar.) But we don't know if halachic misah
would use the same definition. But even those who stick with heart death
would use the latest scientific tools to determine whether or not the
person had their last heartbeat (lo aleinu).

So I would posit the issue is a chiluq between using science to determine
the physical state vs having a pesaq as to what physical state needs
determining.

Tir'u baTov!
-Micha

-- 
Micha Berger             Like a bird, man can reach undreamed-of
micha at aishdas.org        heights as long as he works his wings.
http://www.aishdas.org   But if he relaxes them for but one minute,
Fax: (270) 514-1507      he plummets downward.   - Rav Yisrael Salanter