Scientific and Philosophical Mistakes
There's a certain mistake that I used to make all the time, out of ignorance, but which now I only make when I'm writing sloppily. It's to describe Chazal as making "scientific mistakes." I now know that Chazal did not make scientific mistakes.
Not every mistaken belief about the natural world is a scientific mistake. A scientific mistake is when one engages in the scientific process and, for whatever reason, emerges with a mistaken conclusion. To quote one definition, science is systematized knowledge derived from observation, and experimentation carried out in order to determine the nature or principles of what is being studied. But a mistake which did not involve engaging in the scientific process is simply a mistaken belief about the natural world.
I think it could be argued that the steady-state theory of the universe held until the Big Bang became accepted was not a scientific mistake. To my knowledge, it wasn't as though the steady-state theory was based upon any experimentation. Rather, it was simply a holdover from the beliefs of antiquity.
Likewise, Chazal rarely engaged in what we would call science. Statements about the sun going behind the sky at night, or about mice being generated from dirt, are not scientific mistakes; they are simply mistaken beliefs about the natural world. (But it is sometimes cumbersome to write that, which is why I sometimes takes the sloppy shortcut and write "scientific mistakes.")
I noticed a similar error in a different context. I once challenged a certain protege of YBT (a very unusual yeshivah which teaches that Maimonidean-style philosophy is the sole legitimate and traditional path of emunah) to account for Rav Moshe Taku, a Tosafist who believed that God is corporeal. He replied that Rav Moshe Taku "made a philosophical mistake."
For the last few months, I have been working on a translation of Rav Moshe Taku's Kesav Tamim. I'm about two-thirds of the way through, and one thing that I can say for certain is that Rav Moshe Taku did not make a philosophical mistake. That's not to say that I agree with Rav Taku's position that God is spatially located vertically above us in heaven and that God has substance and appears in a variety of human forms; with my education, it's impossible for me to subscribe to such a view. But his corporealist view is a mistake about a theological matter, not a philosophical mistake.
Rav Moshe Taku did not engage in philosophy. He was far more familiar with philosophy that many of his predecessors in Ashkenaz, who had probably never even read Rav Saadiah Gaon's "Book of Beliefs," and certainly did not actively engage in dispute with philosophy as he did. In fact, the early scholars in Ashkenaz were barely aware of philosophy at all. In Prof. Avraham Grossman's article "Rashi's Rejection of Philosophy - Divine and Human Wisdoms Juxtaposed," he writes as follows:
It is generally agreed that Rashi's work contains no direct reference to philosophy, a field that exerted no apparent influence on his writing. Scholarship has customarily held that this is due to a lack of knowledge of the subject on Rashi's part. While interest in philosophy was not prevalent in the Christian Europe of Rashi's time, among the Jews in Moslem lands it enjoyed widespread appeal thanks to the significant role played by science and philosophy within Moslem society. This fundamental statement is certainly true. Apparently, however, although Rashi had no intimate knowledge of philosophical study and its nature, he did possess a general knowledge of it, which generated in him an aversion to the subject. He indirectly urged people to keep their distance from it... I wish to emphasize that Rashi was not familiar with any philosophical works, nor was he acquainted with philosophers in his environment or had read their work. Nevertheless, as someone whose entire literary activity was infused by a rare intellectual curiosity he was exposed to this field, if only by way of general knowledge.
Rav Taku actively engaged those who wrote about philosophy. But he did not engage in philosophy. And thus he did not make a philosophical mistake.