Sunday, April 10, 2016

What is Chometz?

When I learned about Pesach as a kid, I was taught that when flour and water are mixed together the mixture begins to rise after eighteen minutes, and this makes it chometz. The implication was that this was a physical change. Before eighteen minutes the dough had not yet begun to rise, and so it was still kosher l'Pesach. After eighteen minutes, it was chometz.

The problem here is that this isn't the way the world works. Yeast is a naturally-occurring parasite that lives on grains and other produce. When it is wet it metabolizes starches and sugar to make more of itself, giving off gasses in the process. It is these gasses that make bread rise. Eighteen is a magic number in Judaism, but yeast doesn't know that. Fermentation begins as soon as the water and flour are mixed together, not eighteen minutes later.

The problem can be solved by reclassifying chometz as a legal rather than a descriptive definition. Dough becomes chometz after eighteen minutes because that's the rule rather than because of some physical change. This sidesteps the empirical problem, but leaves two others.

The first is that this wasn't the original understanding. When the halacha was first formulated, people didn't know about microorganisms like yeast or how their lifecycles affect our baking. They just knew that if you mixed flour and water and left it alone long enough in a warm place, it would rise, and that by adding a bit of already-risen dough to a new batch, you could make it rise faster. Why this happened was a mystery. It wasn't until the invention of the microscope in the 1600s that it was discovered that there were tiny things on grain, and it wasn't until the mid-1800s that it was understood that these things were alive and were what made bread rise.

Given their lack of modern knowledge, it was reasonable for the formulators of the halachos of chometz to assume that it took some time for whatever it was that made bread rise to start working. If you watch a batch of dough, it certainly seems that it takes a while before anything happens. The importance of eighteen led them to use that number, and for millennia it was thought that dough doesn't begin to rise until eighteen minutes after the water and flour are mixed together. It is only in the last hundred and fifty years, when we learned how it really works, that it became necessary to reclassify chometz as a legal rather than a physical definition.

The second problem is that it makes the definition of chometz arbitrary. There is no discernible difference between a batch of dough that has been sitting for seventeen minutes and one that has been sitting for nineteen minutes. Instead of something real, chometz becomes a rule in a game we're playing called "Judaism." It's no longer that chometz is a different kind of thing than non-chometz, and we avoid that thing during Pesach because the nature of the holiday is such that chometz affects us differently than it does the rest of the year. Instead, chometz and non-chometz are separated only by  the rules of the game. They are the same thing, but the rules say that after eighteen minutes we call dough "chometz" and treat it as if it were different than non-chometz.

Some try to save the sense of chometz and non-chometz really being different types of things by shunting the difference off into the metaphysical world. Although here, in the physical world, we don't see a difference, in the olam haemes there is a profound spiritual difference between them. Putting aside the oddity of people who decry the corrosive effects of "Greek wisdom" embracing a Platonic conception of the cosmos, this is obviously a post-hoc attempt to save the reality of the distinction between chometz and non-chometz. Right up until we knew differently, it was assumed that there was a real physical difference. As soon as we found out how fermentation really works, the difference was shunted off into an inaccessible metaphysical world where it is safe from empirical investigation.

One of the first major figures to change the underpinnings of halachos from physical to metaphysical was the Maharal, who lived through the beginning of the Scientific Revolution in the mid-1500s. That this trend emerged just as we began to discover how the world really works should make it obvious that it was not so much a revelation about the true nature of halacha as it was an attempt to keep halacha from becoming irrelevant as it's real-world justifications were cut out from under it.

For most of its history, the halachos of chometz were thought to rest on a real difference between chometz and non-chometz. They were different kinds of stuff, and so it made sense to treat them differently. As soon as it was discovered that's not so, chometz became just a rule in the Judaism game, weakly bolstered by the unknowable assertion that metaphysically, they really are different. This is the danger that science poses to religion. Rules that were once simply a reflection of reality become arbitrary, and those who want them to be more than that are left to petulantly insist that their game is real after all,  in an inaccessible higher reality that small-minded materialists refuse to acknowledge just because there is no reason to posit its existence other than to keep religious rules from becoming arbitrary.


  1. Some try to save the sense of chometz and non-chometz really being different types of things by shunting the difference off into the metaphysical world. Although here, in the physical world, we don't see a difference, in the olam haemes there is a profound spiritual difference between them.

    And here I thought that transsubstantiation was just a Catholic thing.

    What is it about bread that makes some people go all metaphysical?

    1. Haven't seen you around in a long time. Hi!

      It's not exactly transubstantiation, but it does make an interesting parallel.

  2. I didn't know you had your own blog. This is the first post I've read and it's great. Kol hakavod! I'll be reading thru prior ones as time allows. I'm also Rational Thinker from Harry's blog but there's no Disqus sign in here so I'm using ah-pee-chorus.

    1. I second your assessment of this post and think it's really an excellent analysis of the topic.

      On another Passover-related matter, I find it quite surprising that there's still been no reaction that I'm aware of by skeptical bloggers to Prof. Joshua Berman's essay defending the historicity of the Exodus.

    2. I skimmed through the article. It's an interesting read, though a bit long for online reading.

      The beginning of the article implies that he's setting out to save the historicity of the Exodus story. Yet if you add the word "traditional," he's in agreement with the statement he quotes from R' Wolbe that the [traditional ] Exodus story didn't happen. Did small a group of Semitic slaves escape from Egypt and migrate to Canaan? Very possibly, especially given his arguments. But so what? If it was a few hundred families, then the great nation is not so great, and the shevatim, rather than impressive entities, are instead just extended families of a couple of hundred people each. The Exodus story is impressive because the Israelite nation was liberated with "signs and wonders" and given the Torah at Har Sinai.

      He's advocating treating Biblical accounts as we do other ancient mythology that gives historical details. Fair enough, but then we have to strip out the mythical elements, as he says scholars do with all mythology. We can treat the biblical story as a piece of evidence that there was probably a group who left Egypt. We can't treat it as evidence for the maakos or divine revelation.

      What's interesting is that he looks at the Biblical account as if everything is true except the Exodus, and then uses those other elements to show how the Exodus could have happened. But some of those things, like a centralized place of worship in the midbar, which he cites to show that the camp couldn't have been big enough for millions of people, may have been a retrojection by people during the Temple era of their own form of worship back into the myths about their ancestors.

    3. Thanks for the timely response.

      Your summary is actually a very close reflection of my own reaction after first reading the article.

      At any rate, since his parting assurance that we can utter the words “We were slaves to a pharaoh in Egypt" with 'confidence and integrity' does not -- based on everything else he says -- extend to the more magical elements in the Haggadah ( splitting of the sea, manna falling out of the sky, etc.), I guess I'll just have to wait for confirmation of these claims from another source.

      But something tells me that you wouldn't advise me to hold my breath...

    4. Hey, I remember you from failedmessiah. Scott didn't like you much, did he? Lol.