Thursday, July 14, 2005

Did Chazal have scientific facts that no one else had?

R' Feldman brings this claim as one of his proofs that Chazal's science is Torah M'Sinai.

How else could we explain numerous examples where the Sages had scientific information which no scientist of their time had? How were they so precise in their calculations of the New Moon? How did they know that hemophilia is transmitted by the mother’s DNA, a fact discovered relatively recently?1 How did they know that “a drop exudes from the brain and develops into semen” 2 without having known that the pituitary gland, located at the base of the brain, emits a hormone which controls the production of semen. None of this could have been discovered by experimentation Either they had a tradition directly teaching them these facts, or they knew them by applying principles which were part of the Oral Torah regarding the inner workings of the world. Thus they knew the precise cycle of the moon; they knew that there was a relationship between the coagulation of blood and motherhood; and they knew that there was a relationship between the brain and male reproduction.

Let us examine each one of his proofs and see if they hold water.

1. How were they so precise in their calculations of the New Moon?
Were they really anymore precise then the scientists of their time? I don't think so. Ancient civilizations were able to calculate the movement of the moon quite well. Here is a quote from Wikipedia:
The calendar is based on mean lunar conjunctions called "molads" spaced precisely 29 days, 12 hours, and 793 parts apart. Actual conjunctions vary from the molads by up to 7 hours in each direction due to the nonuniform velocity of the moon. This value for the interval between molads (the mean synodic month) was measured by Babylonians before 300 BCE and was adopted by the Greek astronomer Hipparchus and the Alexandrian astronomer Ptolemy. Its remarkable accuracy was achieved using records of lunar eclipses from the eighth to fifth centuries BCE.

We see clearly that the Babylonian and Greek astronomers (who lived around the same time as Chazal) were able to make the same precise calculations

Chazal (Hillel II) set up the calendar that we use. This calendar is very accurate but not 100% accurate. Again from Wikipedia:

However, the assumption that 19 years exactly equal 235 months is wrong, so the average length of a 19 year cycle is too long (compared with 19 tropical years) by about 0.088 days or just over 2 hours. Thus on average the calendar gets further out of step with the tropical year by roughly one day in 216 years. If the intention of the calendar is that Pesach should fall on the first full moon after the vernal equinox, this is still the case in most years. However, at present three times in 19 years Pesach is a month late (as in 2005). Clearly, this problem will get worse over time

If R' Feldman is right, the calendar should not lose any days after all they got this knowledge Torah M'Sinai.

2. How did they know that hemophilia is transmitted by the mother’s DNA, a fact discovered relatively recently?

The answer to this is very simple. Chazal in Niddah write

איש מזריע בו לובן שממנו גידים ועצמות ... אשא מזרעת אודם שממנו עור בשר ודם
The man provides the white from which the bones and sinews grow ... the women provides the red from which the skin, meat, and blood come

Chazal thought that the blood comes from the women and therefore it made sense that a blood disease would go through the mother. However this has nothing to do with DNA. They believed this due to a mistaken idea that the blood of a person comes from his mother. Coincidentally, this mistake about the blood coming from the mother allowed them to get things right by hemophilia.

3. How did they know that “a drop exudes from the brain and develops into semen” 2 without having known that the pituitary gland, located at the base of the brain, emits a hormone which controls the production of semen.

Their statement was actually incorrect. Nothing exudes from the brain and develops into semen. The pituitary gland release hormones which stimulate the production of semen, but the hormones from the pituitary gland do not themselves turn into semen.

In short, I believe that I have shown that none of these proofs are proofs whatsoever.

On the other hand there is a whole list of statements Chazal that do contradict science. I will mention just one here and I leave it to the reader to decide what is more compelling.

The gemara in Bava Basra 25b has a dispute between R' Eliezer and R' Yeshoshua about the movement of the sun. The gemara has a similar dispute in Pesachim 94.

R' Eliezer says that the world is like a three-walled building; the north side is not covered; The sun travels along the inside of the building during the day. When the sun reaches the northwest corner, it goes above the building (therefore we can't see it, and goes eastward overnight, and rises in the northeast in the morning).

R. Yehoshua says, the world is like a box, the north side is covered;

1. When the sun reaches the northwest corner, it goes (through a window) in back of the box.
2. "Holech El Darom v'Sovev El Tzafon" - the sun (always) travels along the south by day, and circles around the north side by night.

It is absolutely clear that the above is incorrect. We know that the world is not covered by anything and the sun doesn't go behind it. We know that there is no window that the sun goes out at night. We know that the Earth spins and this is what causes the Sun to rise and set and we know that the Earth revolves around the Sun. These are not theories, they are facts and they are undisputable.

Some will try to answer that the gemara was talking allegorically and wasn't describing reality. That is clearly not true for 2 reasons:
1. The gemara in Pesachim brings a dispute between the Chachamim and the non-Jews about where the sun goes at night. They were clearly arguing with the non-Jews about reality and not about some deep concept in kabbala.
2. The Rishonim when they discuss shitas R' Tam about Tzeis Hakochavim, all bring this gemara down and they all mention the sun going out the window. They clearly held that Chazal were describing reality.

I am still waiting for a pshat in this geamra other then Chazal were mistaken in science. So far, I haven't heard or seen a single pshat that comes close to explaining the sugya.

The above is only a drop in the bucket of the conflicts. I could easily bring at least 10 more, obvious contradictions.

To sum up, I believe that I have refuted all of R' Feldman's proofs, however, I have not yet seen anyone explain how the gemara in Pesachim and Bava Basra does not contradict the scientific facts that we know.


Anonymous said...

great post!

Noam S said...

Agreed with anonymous. However, now that you accept that chazal could be wrong about hard sciences like astronomy, could they be wrong on social science? or anything else?I posted this question on my blog:

still waiting for responses.

Anonymous said...

Should I also accept this statement:

"The period between 70 and 1178 is a transition period between the two forms, with the gradual adoption of more and more of the rules characteristic of the modern form."

First, I don't accept the wikipedia article as authoritative. One thing to realize about any secular historical analysis of chazal is that they will start with the assumption that it is based on scientific knowledge of the time (primarily looking for external sources - but they might accept some method where the Chachamim could have figured it out given what the current scientists estimate about what they would have been able to observe), and seek to find the source for that. So, without examining the primary sources, you have to take everything with large grains of salt.

Of course the accomplishment of the calendar is the combining of the lunar cycle with the solar one, not so much accurately following a lunar cycle. As far as I understand, the solar cycle was the point of uncertainty in the science of Chazal's time.

"If R' Feldman is right, the calendar should not lose any days after all they got this knowledge Torah M'Sinai."

Not really. The discrepency is too small to include in normative calculations. There is a reason that the prefered Torah method is not to use the calculations. The calculations are meant to last until the prefered method of a Sanhedrin is restored.

"However this has nothing to do with DNA."

While I agree that it overstates it to say that Chazal knew about DNA, the point is that their method produces a correct answer that they shouldn't otherwise be expected to get. Your response seems to be: "Lucky guess."

If that is your perspective, no amount of evidence would satisfy you. In every case you could say they had some other system for determining it (obviously) and that other system was wrong (because scientists today don't use it) so the result was coincidence.

bluke said...

Regarding DNA, given that R' Feldman is the one who is trying to prove something he needs to show that DNA is the only answer, he certainly hasn't.

If as I stated based on the gemara in Nidda that they believed this because they thought the blood came from the mother, they believed something true, but did not know what they believed. But the problem here is much deeper. For even if we allow that they knew that the bleeding disease was inherited through the mother it hardly follows that they had the concept of hemophilia - which to the modern ear speaks of clotting factors – or of an X- chromosome, with which the disease is associated. If they did know that bleeding to death followed the mother, they very well could have known it by careful and laborious observations.

In other words, there is absolutely no proof that Chazal had any great knowledge.

bluke said...

The point from the Wikipedia was that the Greek and Babylonian astronomers were also able to calculate the movement of the moon very accurately. No one disputes this (the Rambam quotes from some of these books).

Since Rav Feldman wishes to establish the independence of our Sages astronomical knowledge, it is he who must be able to prove that our Sages did not learn the great bulk of their mathematics and astronomy from others. He has not done so.

bluke said...


Here is a general answer. Rav Feldman is trying to prove that Chazal had knowledge that no one else had, and therefore it must have been Torah M'Sinai. If I can come up with a plausible alternative source of knowledge for this information, he has no proof. He may believe otherwise, but he hasn't proved anything.

In 2 of the cases (in the 3rd Chazal's statement contradicts modern science), I pointed out alternative sources of knowledge (namely Greek and Babylonian astronomers, and the fact that they believed that the mother contributed the blood). These are at least as plausible as saying they got it Torah M'Sinai and therefore as I stated above he cannot bring a proof from these cases.

Anonymous said...

"and the fact that they believed that the mother contributed the blood"

Is not an alternative source of knowledge. It is part and parcel of the question (unless you find a source for that in Greek and Babylonian science - and you already quoted the Ramban as saying the Greeks had an alternate view). That was my point. When you said this: "If they did know that bleeding to death followed the mother, they very well could have known it by careful and laborious observations" you made my point even stronger. You will insist that it was a lucky guess, no matter how many things are brought - it could always have been observed.

"in the 3rd Chazal's statement contradicts modern science"

I don't think so. I know that some cutting edge fertility treatments involve the spine, because something there affects the sperm, so I don't think the common knowledge facts about sperm production is the current stuff. Anyway, what you are doing on that instance is interpreting the Chazal differently, which is why I didn't bother with it. He says they are talking about the potential and cause (this is actually how it describes it in Tanya as well), you are looking for actual sperm in the brain.

Anonymous said...

Excellent - one of the main parts of the letter where i thought that there might be some logical reason to side with R; Feldman agianst slfkin, but you cleared it up.

bluke said...


"and the fact that they believed that the mother contributed the blood"

This was a widely held belief among the Greeks as well.

Anonymous said...

"This was a widely held belief among the Greeks as well."

What is your source for that?

bluke said...


Here is a challenge for you. Tell me pshat in the gemara pesachim 94 and bava basra 25b where Chazal did not make mistakes in science.

bluke said...


I don't remember the source but what does it matter, you must admit that the statement is wrong? The blood does not come from mother and the bones from the father.

Anonymous said...

"I don't remember the source but what does it matter,"

You quoted a Ramban that attributed a different opinion to the Greeks.

"you must admit that the statement is wrong? The blood does not come from mother and the bones from the father."

There are many ways to understand that statement, so its truth would depend on how you interpret it.

"Tell me pshat in the gemara pesachim 94 and bava basra 25b"

We already discussed this. Since your definition of fact here is things accepted by scientists, rather than actual observed phenomena, and since you ascribe phenomena such as orbiting satelites as requiring a rotating earth to explain them (even though that is not strictly true - although scientists explain it by a rotating earth), there is no point in further debating the matter.

bluke said...


That is a copout. That gemara makes statements that clearly contradict reality. How do you resolve them?

Anonymous said...

Regarding Rav Feldman's claim about Chazal's knowledge that hemophilia is carried by the mother's genes, Bluke is correct that it is based on Chazal's belief that the blood is inherited from the mother. See the SA YD 263:2 where the Mechaber paskins that the law applies equally to a man whose 2 sons died from Milah(even from a different wife). The Rema says that some argue & say it only applies to a woman, but because of the doubt one should be Machmir even in the case of a man. Gra writes that the source of those who say that it only applies to the woman is from the Agudah who bases it on the Gemara that the blood of a child is inherited from the woman.
So we see that Bluke is correct on the reason. Even the law is not clear cut in conjunction with science. Rabbi feldman has distorted the Halacha to put a favorable spin on it.

Anonymous said...

"That is a copout."

Which part?

"That gemara makes statements that clearly contradict reality. How do you resolve them?"

The general approach is to better understand the gemara and better understand reality. Generally such contradictions come from a poverty in knowledge of one or the other, often both.

You seem to want to take the words of the chachamim as attempts and precise physical descriptions. I don't accept that view. They describe things accurately, but abstractly. For two reasons, one that is the nature of the transmission of such concepts in Torah (Rambam Yisodeh HaTorah 4:10), and as the Shilo writes, Torah speaks to the higher worlds and hints at the physical, not the other way around. So, especially when the matter doesn't concern halacha, we can expect it to be vague, and require serious study to apply any conclusions from the concept.

There is no real point in discussing specifics, because as your post shows, you will just insist on a literal interpretation and then insist it must be wrong, and any part that is right is coincidence, because after all, something else is wrong anyway.

Besides, if you are looking for conclusive interpretations of the gemarah, you came to the wrong guy.

bluke said...

I am not insisting on aliteral interpretation, but when the gemara has a machlokes between the Chachamim and teh non-Jews about where the Sun goes at night, that was clearly a dispute over reality and Chazal's view does not fit in with what we know as reality.

Anonymous said...

"I am not insisting on a literal interpretation"

Your comments about the pituitary gland seem to suggest otherwise. If your point was it wasn't proof, because you could interpret chazal differently, ok. That will still leave open the question of why they thought the brain had anything to do with it. But your point seemed to be more that no, the chazal must mean it in the most literal sense.

"that was clearly a dispute over reality "

By literal, I don't mean that the whole discussion is non-physical, although in this case the whole discussion certainly informs about non-physical ideas, as the Maharal says. What I mean is how literally and narrowly you take the words.

"and Chazal's view does not fit in with what we know as reality."

Which is the flip side of the problem. What we "know" as reality has multiple layers of certainty. You have to be willing to challenge your assumptions and your certainty here, otherwise there is nothing to say.

Stephen Gould may think that denying common decent is the equivalent of a flat earth theory, but willingness to actually have a sense of skepticism recognizes different layers of certainty exist, and the former can never be on the level of the latter.

BrooklynWolf said...

You're conflating two different issues regarding the accuracy of the calendar.

The first is the measurement of the lunar period. Chazal were correct as to the lunar period (29 days, 12 hours and so on). Many people assume that that is how long is takes for the moon to orbit the earth, and, without knowledge of modern astronomy, there is no way they could accurately measure that. However, that's not really correct. The period that Chazal (and the Babylonians) measured was the synodic period of the moon. Simply stated, the synodic period is the amount of time it takes for any given object (in this case, the moon) to return to the same position in the sky relative to the sun. It measured entirely on *observation*. As such, it shouldn't be too difficult, even in ancient times, to come up with this measure. But Chazal were accurate in their measurement of the lunar period (using the synodic period).

The second issue is with regard to calendrical drifting. The problem here is that over a 19-year period, 235 lunar months are about two hours longer than 235 solar months. When the months were determined on the basis of observation and witnesses testimony, this wasn't an issue, as the court could always correct if it necessary. However, with the pre-determined calendar set up by Hillel, this isn't the case.

In any event, there *is* no solution to this problem. You simply divide the number of hours in the period involved into an even number of days. As a result, as long as we're not figuring the calendar on an ad-hoc basis (as we did back in Jerusalem), then we're going to have drift. As it is, we currently celebrate Pesach about five days later than they did in Rashi's day and about eight or nine days later than in Hillel's day, when the calendar was set up.

But I don't think that Rav Feldman intended to mean the accuracy of the calendar in this regard. He was referring to the synodic period of the moon.

The Wolf

Anonymous said...

One should note that according to the Tzemach David, R' David Gans, the quote of r' Gamliel in Rosh Hashana 25A giving the length of the mean synodic month as 29 d 6 h and 2/3 h and 73 chalikim is actually a later scribal addition and the original text siad only 6 h and 2/3 of an hour. The adding of the additional 73 chalikim is inconsistent with the language of the Gemara. If one looks at the text it seems to be giving the length of the minimal synodic month NOT the length of a mean synodic month and later scholarly suggestions that the original text simply stated that a lunar month could not be less that
29d 6h have a lot of merit.
Lastly the almost accurate figure of 6 hrs and 793 chalikim was known to contemporary scientists of the period and can be found in the works of Ptolemy. It seems to be an unproven assumption, by authorities who are not experts on ancient science , that
"the Sages had scientific information which no scientist of their time had".
BTW is it also K'firah to believe that the sages did NOT have scientific information which "no scientist of their time had"? (correct statements based on mistaken assumptions are not scientific information)

bluke said...


I know that. I guess I should have been more explicit. My point was that just like they got the synodic period according to R' Feldman Torah M'Sinai or with Ruach Hakodesh, you would think that they would have gotten the calendar the same way (especially according to the Rambam that the calendar is a halacha l'moshe m'sinai).

Rebeljew said...


Game, Set Match

Well done

Anonymous said...

Rav Feldman's proof from hemophilia is astonishing. Firstly, the poskim disagree whether the halacha of a woman whose 2 children died from Milah, applies equally to a man. See the SA YD 263:2. Those who hold that it applies only to the mother base their reasoning on the Talmudic belief that the blood is inherited from the mother. See the Taz & Gra there who give that reason. Thirdly, the Halacha states that for the 3'rd child you wait until the child gets older & stronger before performing the milah. If they understood hemophilia, it would not help to wait when the child is older & stronger.

Anonymous said...

Doesn't Artscroll to Bava Basra 25 explain the Gemara as talking about revolutions and orbits and such just but in allegorical terms. It's not meant to be Kabbalistic, just to be understood by the layman of the 6th century.

I don't think it matters if Chazal were arguing with gentiles on the matter, because they weren't being esoteric, but rather as practical as they could be, with the understanding they had.

Didn't the Chachamim and the Wise Men of Athens have debates in the Mishnah (I don't recall where) on all sorts of scientific matters (e.g. the length of time it takes for a snake to conceive). I think that I heard that they were talking in parables. So it's possible that the Gemara in Pesachim was recording a discussion that was not meant to be literal and scientific about the heavens, and not Kabbalistic either.

bluke said...

A few points.

It is hard to imagine that they were arguing in parables about the where the sun goes at night. What were the non-Jews saying they were also arguing in parables?

The gemara in pesachim says that Rebbe said that it looks like the non-Jews are right because the underground water is hot. That certainly sounds like a dispute in reality.

The Rishonim when they discuss the sugya l'halacha of when is Tzeis Hakochavim quote this gemara, which means that they understood it was dealing with reality. They also talk about the sun going through the window.

bluke said...

If I made valid points then how can you say that they didn't make mistakes. Everyone agrees that the Rambam, R' Hai Gaon, the Ramban and in later times, the Maharam Schick, R' Hirsch, R' Dessler, all hold that Chazal could mistakes.