[Avodah] Yeast isn't chameitz

[Michael Makovi]

> ...any argument for why lice have no mamashus would apply to airborn yeast.
> R' Micha Berger

A difference I see:

Lice, it is possible that Hazal decided the halakhah based on their
science, and that the law is not a Sinaitic one, but rather, one based
purely on human knowledge and reasoning. That is, based on the
scientific knowledge that lice spontaneously reproduce, the halakhah
is such-and-such. (Of course, some argue that lice eggs are small
enough that they are k'ilu spontaneously-generating. Rabbi Aryeh
Carmell proposes that spontaneous generation is a post-facto
explanation for preexisting halakhah; he notes that Rambam's
explanation of this halakhah provides an alternate reasoning (based on
Rambam's science) but preserves the same halakhah (i.e. lice can be
killed, no nakfa mina with the Gemara's explanation). Today,
explaining the tiny eggs = k'ilu spontaneous generation would be
repeating this method.)

As for yeast, it seems to me that apparently, the halakhah, due to a
Sinaitic hok, simply doesn't care about yeast. Stam, fruit juice
doesn't make hametz, and stam, matzah cannot become hametz. In other
words, it'd have no relationship with science, whatsoever. Of course,
were we to actually ask Hazal where they got their definition of
hametz from, we might be instead told that it was based on their
scientific experimentation, i.e. they experimented with various
concoctions and saw what leavened. If the latter, then lice and hametz
would perhaps be in one category, along with treifot contradicted by
modern science, etc. Perhaps, even, Hazal would have said that baking
powder produces hametz, had they known about it! Heck, perhaps they'd
even say that non-wheat grains, if combined with pure gluten from
another source, and then water, also produce hametz - who knows? But
my personal feeling is that hametz is rather a technical definition
without correspondence in science. But I may be wrong.

Michael Makovi