[Avodah] Spontaneous Generation

[Micha Berger]

On Sun, Jul 01, 2012 at 02:23:41AM -0400, cantorwolberg at cox.net wrote:
: The above statement regarding lice created only by perspiration has been disproven and is no longer controversial. 
: Would the above halacha permitting lice to be killed therefore be invalid? Or does any halacha which has been proven
: to be based on faulty information still have to remain? (lo plug)   

There are a number of approaches discussed here in the past:

1- The notion of nishtanah hateva, which by most understandings of the
phrase would be okay when the issue could be changed by breeding,
a stretch when it would require very rapid evolution, and very hard to
explain when the field isn't biology. (The sun now travels a different
path than 2 millenia ago?)

R' Avraham ben haRamabam undestands "teva" differently than the "most"
of the prior paragraph. He translates the phrase "our theories of nature
changed". And so halakhah changes as scientific theory does.

2- In order to be meiqil, you need every reason lequlah to be valid. But
in order to be machmir, only one reason needs to hold. The Vilna Gaon
suggests that whenever we are given the reason for a halakhah, there
are other, unstated reasons. Therefore, the while Vilna Gaon (and RAYKook)
would change the halakhah when our understanding of the realia changes --
they only accept doing so lechumerah.

3- In shiur, R' Dovid Lifshitz addressed the question of the kashrus of
maggots found within the meat. There are two causes for having a maggot
large enough (not microscopic) to be a kashrus issue: the egg, and the
meat the larva and maggot ate to allow it to grow to that size. RDL said
that since the initial maggot eggs are microscopic, they don't count. Leaving
one cause that does count -- the meat.

Leaving us at the same place as the gemara -- the maggots are "born from"
the meat.

(Over time, I spun this into a general theory about halakhah related to
the world as we directly experience it rather than the world as we can
scientifically understand it. Since Greek Natural Philosophy tends to
match the former, chazal's "science" is usually still valid for the sake
of pesaq.)

4- The Kesef Mishnah (Mamrim 2:2) says that halakhah lose malleability
with the closing of the gemara and the end of the Sanhedrin. By the
rules of the legal process, decisions made based on the old understanding
are still binding.

5- The CI (Yavamos 57:3 and on AZ 9a) also has a cut-off date where
malleability ends. But his is the year 4000, the generation of the
mishnah, at the end of the two millenia of Torah. Hashem wanted us
to decide the law based on how the world was understood during those
millenia.

(Citations by RGS
<http://www.aishdas.org/toratemet/science.html>. My exposition doesn't
match his, reflecting more conclusions reached during prior iterations
on the topic.)

Tir'u baTov!
-Micha

-- 
Micha Berger             Rescue me from the desire to win every
micha at aishdas.org        argument and to always be right.
http://www.aishdas.org              - Rav Nassan of Breslav
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