"... we are not in duty bound to defend the opinions of the sages of the Talmud, concerning medicine, physics and astronomy, as right in every respect simply because we know the sages to be great men with a full knowledge of all things regarding the Torah, in its various details." -- Rabbeinu Avraham Ben HaRambam in Discourse on the Sayings of the Rabbis
- He is a recognized traditional Jewish authority.
- He answers these questions quite clearly: Chazal's authority in religious matters does not carry over directly to their statements about the natural world.
The attitude of the orthodox Jew towards the scientific matter embedded in this colossal mass of Jewish religious learning may be best summed up in the words of R. Abraham Maimuni [Rabbeinu Avraham], the great son of the greatest codifier of Jewish law and the foremost Jewish philosopher of the Middle Ages.Not that Rabbeinu Avraham was the first to make this point. Rav Sherira Gaon writes in a similar vein: "We must inform you that our Sages were not physicians. They may mention medical matters which they noticed here and there in their time, but these are not meant to be a mitzvah." Nevertheless, Rabbeinu Avraham's statement is arguably the clearest and most expansive medieval statement on the topic.
There are, however, traditionalists who take a more fundamentalist approach to the science of the Talmud. For them, it is important to show Rabbeinu Avraham's Discourse is an outlier; mainstream traditional Judaism rejects Rabbeinu Avraham's viewpoint, and we should do so as well. For example, Rabbi Aharon Feldman states that Rabbeinu Avraham's view was shared by various traditional authorities , but is now "a minority opinion which has been rejected by most authorities" and and while "[t]hey were permitted to hold this opinion; we are not."
Rabbi Moshe Meiselman  takes this approach one step further. In his opinion, the Discourse is incongruent with the views of any mainstream traditional authorities, past or present, including Rabbeinu Avraham's own writings . In addition, the text itself is suspect and should be given little to no weight. In other words, the Discourse is such an outlier that it is not to be believed .
In this series of posts, we hope to show that Rabbeinu Avraham's approach is well within the mainstream of authorities both in Rav Avraham’s time and ours, and that it is a completely reliable indicator of Rabbeinu Avraham's opinions as well those of his father. We'll address the purported contradictions between the Discourse and the Rambam. We'll also attempt to show that attempts to cast doubt on the text and translation of the Discourse are without foundation. Let us begin with a short summary of the Discourse.
A Brief Summary of the Discourse(The Hebrew text of the discourse can be found here and a partial English translation is here.)
The stated goal of the Discourse is to explain apparently fantastic Derashot (interpretations or homilies) and stories of Chazal. The reader of these statements can commit two kinds of error: (1) mocking of the words of Chazal or denying their truth, (2) or taking what they say at face value as describing a strange and unfamiliar world where miracles are commonplace. The key to understanding these fantastic stories is to understand that they often contain a hidden esoteric lesson in addition to their plain meaning. To this end, the Discourse classifies, with examples, various types of derashot and stories of Chazal and explains the proper attitude towards each one.
This leads to the following question: what to do with medical or scientific claims of Chazal which are intended literally, yet appear to be false? For example, Pesachim 94a implies that the earth is flat and is surrounded by a sky-shell (Rakia) of specific “thickness”.  Dr. Fred Rosner points out that you can find a mix of true and false observations in the Talmud’s treatment of rabies.  Countless additional examples could be produced. Are we to treat all of these statements as parables?
Rabbeinu Avraham’s solution is to propose a different approach entirely to these scientific and medical matters. In matters of medicine, nature and astronomy, we are required to come to our own understanding of the matter and not rely on authority. This contrasts with explanations of the Torah, where we rely on the statements of Chazal, Rabbeinu Avraham points to the discussion on Pesachim 94b as proof that Chazal themselves took this attitude; in a scientific dispute between the Jewish and Gentile sages, they stated that “their view is preferable to ours”. We treat the scientific statements of Chazal as we treat the scientific claims of all people in all eras: those supported by evidence are to be accepted, while those not so supported are rejected.  It is only after Rabbeinu Avraham explains his approach to scientific matters, that he goes on to classify the derashot and stories of Chazal. 
This approach towards Chazal is anathema to some modern authorities, as we described above. These authorities claim that the approach of the Discourse is novel and in opposition to other traditional authorities including the Rambam. In our next post, we will place the Discourse in historical context and show that it aligns exactly with the positions of the Rambam.
Comments are both welcome and encouraged. I'll make every effort to address any questions or arguments posted in the comments.
Edit: you can find a listing of other Rationalist Judiasm posts related to the book Torah, Chazal and Science here: http://www.rationalistjudaism.com/2013/10/torah-chazal-and-science.html
Notes: Rabbi Feldman mentions Rav Sherira Gaon, the Rambam, the Pachad Yizchok, Rav Samson Raphael Hirsch and Rav Eliyahu Dessler (as reported by his student Rav Aryeh Carmel).
 Torah, Chazal and Science (henceforth TCS).
 Rabbi Meiselman writes that the Discourse indeed implies that "Chazal's Mesorah is authoritative with respect to halachah, but not with respect to realia," but that
... such a position cannot possibly attributed to Rabbeinu Avraham ... this was certainly not the Rambam's opinion". (TCS p. 105) Furthermore, "the tone is ... highly disturbing" and "[I]t is hard to imagine ... that any mainstream halachic authority could have penned these words." The Discourse advocates a "radical position ... not even hinted at in any of Rabbeinu Avraham's writings. ... It is at odds with the Rambam's position. ... [A] similar position by Azariah De Rossi ... prompted Rav Yosef Karo to ... order ... his books be burnt. (TCS pg. 115; ellipses mine) "[I]t is surely unsound to base a revolutionary new approach to Torah upon this document."
Our Rabbis taught that five things were mentioned in connection with a mad dog: its mouth is open, its saliva is dripping, its ears flap, its tail hangs between its thighs, and it walks on the edge of the road. Some say it also barks without its voice being heard.
The Talmudic discussion then mentions that even if a person only rubs against the mad dog, there is danger, and he should remove and destroy his clothes. Samuel further said that one should kill it by throwing something at it, avoiding direct contact with the rabid animal. From these Talmudic statements, it is obvious that the etiology of rabies was not at all understood, although the symptomatology was correctly recognized. The outsized authority of Aristotle slowed down the the development of modern physics and astronomy. Had more the natural philosophers and scientists throughout the ages taken Rabbeinu Avraham’s approach, the era of modern empirical science might have ushered in at an earlier time.
 He classifies the derashot of Chazal into five categories: (1) Those that are literal and intended to be understood as such; (2) Those where there is a literal meaning and and esoteric meaning and where the literal meaning is to be discarded in favor the the esoteric meaning; (3) Those where the literal meaning is intended, but is very difficult to interpret and thus often mislead the reader; (4) Homiletics on Pesukim which, while they take the form of “explanations” of a pasuk, are actually just the opinion of the author and are neither the true meaning of the pasuk, nor an explanation received as part of the Oral Torah. Rabbeinu Avraham opines that this category actually constitutes a majority of derashot;(5) Those which are exaggerations.
He also classifies the stories of Chazal as follows: (1) True stories told for halachic implications, their moral lessons, their lessons in correct belief or because they contain an unusual or surprising element; (2) Stories which occurred in dreams, but are told as stories that happened with the understanding the intelligent reader will understand that could only be dreams, such as those that involve demons. If the reader takes these literally, he is lead to believe possible that which is impossible; (3) Stories which actually happened, but are described in exaggerated fashion in a way that an intelligent reader will be understand that they are exaggerated; (4) True stories that are told in the form of a parable and riddle so that only the truly wise could understand them.