Overview

I-A. The bulk of this article consists of quotations from post-Talmudic sources indicating that the scientific knowledge of the Talmudic sages (henceforth, Chazal) was less than perfect. These sources are divided into four principal classes:

Class A sources indicate that scientific assertions found in the Talmud may be incorrect, even if they are uncontested in the Talmud.

Class B sources indicate that not every scientific belief of every Talmudic sage was necessarily correct. These sources may not specify that errors are possible in uncontested scientific assertions found (specifically) in the Talmud. Since Class A is just an "extreme" subset of Class B (any source belonging to Class A belongs to Class B as well; see below), I have "double-listed" Class A sources in Class B as well, so that Class B does not appear deceptively small.

Class C sources indicate that Chazal relied on the scientific knowledge, research and scientists of their times. These sources do not directly discuss whether Chazal's scientific beliefs were always correct.

Class D sources merely suggest that Chazal were not all-knowing in matters of science – though I do not believe that this assertion requires sources to justify it at all.

Unless I am mistaken, each class is a subset of the subsequent ones. That is, the sources in Class A also qualify for Classes B, C and D; those in Class B qualify for C and D; and those in Class C could correctly be classed in D. I reason as follows:

Each scientific assertion advocated in the Talmud reflects the scientific belief of at least one Talmudic sage. Therefore, if, as per Class A, scientific assertions found in the Talmud may be incorrect, it follows that at least some Talmudic sage may have held an incorrect scientific belief; this is the defining thesis of Class B.

If (one or) some of the Talmudic sages' scientific beliefs might have been incorrect, as per Class B, then where did their incorrect beliefs come from? Not, surely, from a divine source – God would not make a scientific error. The source must have been a fallible, human one. This having been established, I think it eminently reasonable to posit that their beliefs – at least the wrong ones – came from the science and scientists of their era (possibly as a heritage from previous eras); this is the defining thesis of Class C.

Finally, if Chazal were relying on the science and scientists of their era, as per Class C, then they could not have been scientifically omniscient unless either (a) their scientists were scientifically omniscient, or (b) the entire massive corpus of scientific knowledge came to them divinely, except for certain pieces of information which scientists had to fill in for them. Neither (a) nor (b) is plausible, and thus we conclude that Chazal were not scientifically omniscient, as per Class D.

Within each class, sources are divided into three groups:

Group 1 sources are explicit. (What they are explicit about depends, of course, on the class to which they belong.) I have tried to be fairly conservative in what I judge "explicit."

Group 2 sources are what I have called "indicative." An indicative source seems impossible to explain reasonably unless one supposes that its author accepted the thesis under which it is classified. It is not, however, explicit.

A Group 3 source is one whose most probable meaning (in my opinion, of course) implies the particular viewpoint I have linked it with. It could also be assigned a different, yet still reasonable – albeit less likely – interpretation, according to which its implication would be different.

In cases where I have quoted multiple passages from one individual, I have classed that individual in the first section to which he can be assigned (i.e., A before B, B before C; 1 before 2, 2 before 3; etc.), and all quotations of him appear together in that spot. I have indicated which quotations are out of place as a result, and to which class and group they properly belong.

Sources bounded by question marks are ones I have not yet been able to gain access to; I have read about them in secondary sources only.

The Talmud and other classical rabbinic sources record scores of disputes between Talmudic-era rabbis concerning what are, at least on the surface, questions of scientific fact. These records would seem to constitute strong evidence in favour of (B) (and hence (C) and (D) as well). Numerous other passages in the Talmud and contemporaneous writings record instances in which a Talmudic rabbi consulted with doctors or other scientific experts regarding matters of scientific fact or opinion. These passages would seem, in turn, to constitute strong evidence in favour of (C), as well as being indicative of (B). I have listed some of these Talmudic-era sources in Section II.

I discovered much of this information with the help of secondary sources, including Rabbi Natan Slifkin's book Mysterious Creatures (Jerusalem: Targum, 2003) and his website, http://zootorah.com/controversy; Rabbi Gil Student's website, http://hirhurim.blogspot.com/; the Open Access Project (http://www.yasharbooks.com/Open/) at Yashar Books' website; Torah and Science, by Judah Landa (Hoboken, NJ: Ktav, 1991); and two fine books by Rabbi Dr. Yehudah Levi: Facing Current Challenges (Jerusalem: Hemed, 1998; especially Chap. 33 with accompanying endnotes), and The Science in Torah (Jerusalem: Feldheim, 2004). Please understand that this list began as mere personal notes and has evolved only somewhat beyond that stage of development, so it may strike you as cryptic, unhelpful, incomplete, poorly written, badly edited, inconsistent in style, or in other ways flawed. One flaw I hope you will not find is factual error. If you believe that any of this information is misinterpreted or wrong, please say so in the comments. Also, if you have any sources or other information to add to this list, I would be delighted if you would be kind enough to share your knowledge in the comments too. I will update this post periodically with additions and corrections.