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\1) Rambam (Maimonides, 1138–1204)
- On Chazal’s astronomy being time-bound:
Rambam, Guide for the Perplexed III:14. Here’s the standard Friedländer translation (verbatim):
“You must, however, not expect that everything our Sages say respecting astronomical matters should agree with observation, for mathematics were not fully developed in those days; and their statements were not based on the authority of the Prophets, but on the knowledge which they either themselves possessed or derived from contemporary men of science.” Internet Sacred Text Archive
- On following demonstration, even if it forces reinterpretation:
In Guide II:25, Rambam says that if Aristotle had proven the eternity of the world, we would have been religiously bound to interpret Torah verses accordingly (i.e., demonstrative science would drive peshat re-reading). Cambridge University Press & Assessment - On what counts as knowledge (and what does not):
In the Letter on Astrology, he writes that a person should believe only what is supported by rational proof, the senses, or trustworthy tradition—explicitly dismissing the scientific pretensions of popular astrology of his day. Contemporary Thinkers
Together, these show Rambam treats “science” as empirical and revisable—and insists that many inherited scientific ideas (even when widely held) are products of their time.
2) R. Avraham b. ha-Rambam (c. 1186–1237)
- On Chazal’s scientific statements reflecting their era’s experts:
In his famous essay on Aggadah (Ma’amar ‘al ha-Derashot ve-al ha-Aggadot), he writes that Chazal’s statements in medicine/astronomy were not prophetic mesorah but drawn from the scholars of their generations; hence they may be mistaken and need not be defended as timeless science. (See discussions and modern editions; the core claim is widely quoted in scholarship.) Google Books
3) R. Yehudah HaLevi (c. 1075–1141) — Kuzari
- Philosophy and “nature” shaped by climate and locale:
In Kuzari 1:63, he ties differences in human dispositions and opinions to “climate, countries, foods and water, [and] the spheres, stars and constellations.” The thrust is that what passes for “philosophy/natural science” is often conditioned by time and place—especially Greek thought. Sefaria
4) Ralbag / Gersonides (1288–1344)
- Science is what can be built from math, physics, and observation now:
Ralbag insists that astronomy is a science only for one who is both a mathematician and a natural philosopher, i.e., grounded in the best methods of his time; he also reports and revises models based on his own observations (eclipses, planetary motions). Stanford Encyclopedia of Philosophy
Ralbag’s practice (new instruments, new data → revised models) is an explicit medieval admission that our astronomical knowledge is provisional and advances with observation—hence limited by one’s era.
5) Gemara on Astronomy vs. Chazal
In the sugya about the sun’s path, the Gemara itself has R’ Yehuda HaNasi concede:
“נראין דבריהם מדברינו” — “Their [the non-Jewish astronomers’] words appear more correct than ours.” (Pesachim 94b) Wikisource
6) Ḥasdai Crescas (c. 1340–1410) – Or HaShem vs. Aristotelian “science”
Crescas repeatedly argues that key Aristotelian “proofs” in physics/metaphysics are not demonstrative (i.e., not necessary truths). The upshot: the reigning science of his locale/era isn’t absolute. For example, in Or HaShem he organizes a section “ביאור ההקדמות בדברי הפילוסופים ובמופתי הרב” precisely to examine and undercut those assumptions and demonstrations; the work as a whole is known for rejecting Aristotle’s physics as non-compelling. (You can browse Or HaShem and summaries here.) Wikisource
Paraphrase of Crescas’s thrust (not a single line quote): Aristotelian claims lack necessary demonstration; they’re conjectural—and thus contingent on the scientific conventions of their time/place. (Overview discussions: Shvid, “Ḥasdai Crescas,” and other introductions.) Daat
7) R. Yosef Albo (c. 1380–1444) – Sefer ha-Ikkarim
Albo follows Crescas’s line that much of the philosophers’ physics/metaphysics is סברא/השערה (opinion/conjecture), not certainty—hence not binding against received Torah. This explicitly relativizes the “science” he inherited. See standard introductions summarizing his critique and dependence on Crescas. Yeshivat Har Etzion
8) “Nishtanu ha-tevaʿim” (Rishonim as a group)
A recurring Rishonic move is to say “the natures have changed”, i.e., empirical statements from earlier eras were true for their time and milieu but not universally/eternally. Classic loci include Tosafists (e.g., discussions around Yevamot 12b) and early Rishonim/payeṭanim; see overviews that trace this claim back to Rishonim explicitly.
Formulation:
“נשתנו הטבעים — changes occurred in the creatures over time… so Ḥazal’s statements referred to the nature they knew in their days.” (Survey article) Wikipedia
For the sugya background itself (Yevamot 12b), see the daf entry and notes; the later Rishonic discussion uses that context to articulate “changed nature.” daf-yomi.com
9) Ran (R. Nissim of Gerona, 14th c.) – Derashot haRan
Ran distinguishes revealed Torah from human study of nature, stating that things “which deal with nature and its explanation” ought to be taught openly—i.e., they’re empirical, public, and investigable, not sacrosanct dogma.
“For, beyond a doubt, anything which deals with nature itself and the explanation thereof should not be concealed, but… publicized.” (Derashah 1) Sefaria
This doesn’t by itself say “time-bound,” but it locates natural knowledge in the human, observable realm, which his broader discourse treats as contingent rather than prophetic/absolute.
Rashi
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Pesachim 94b – on Rebbe’s concession to the astronomers and the “hot-at-night springs” proof
Rashi explains the phenomenon that served as Rebbe’s rayah, spelling out a physical model that assumes the sun heats subterranean waters at night:
“שביום מעיינות צוננין… ואף על פי שמי נהרות חמין הן ביום … אבל תכף נביעתן הן צונן ביום…” (ad loc.).
Text of the sugya with that line is here; the note quotes Rashi’s point explicitly. Wikisource
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Ta’anit 25b, s.v. “bein tehomah ila’ah letata’ah” – Rashi lays out the (ancient) cosmology in plain terms:
“בין הרקיע לאוקיינוס היכא דנשקי ארעא ורקיע; תהומא עלאה – מים העליונים…”
This shows Rashi working with the period’s model of firmament above / ocean below and “upper waters.”Tosafot
Tosafot Pesachim 94a, s.v. “Rabbi Yehuda omer…” – two stages of sunset and the sun entering the thickness of the firmament
Tosafot reconcile the 4-mil vs. 3¾-mil sugyot by positing:“…משעה שמתחלת החמה ליכנס בעובי הרקיע עד הלילה הוי ד’ מילין…”
This is a straight use of the era’s astronomical picture (sun “entering” the raki‘a), i.e., science as then understood. Sefaria
- (Background to cite when applying it halakhically)
The Yere’im and then Tur OḤ 455 ground mayim shelanu in the “sun-under-earth at night” model that follows those astronomers—an applied acceptance of the contemporary cosmology that Rebbe said “נראין.” (See the survey and notes pulling the sources together.) yahadut.org.il