Aristotle in a Cavepart ii · where the philosopher is followed, and left

All that Aristotle says about that which is beneath the sphere of the moon is in accordance with reasoning; these are things which have a known cause, which follow one upon the other, and concerning which it is clear and manifest where wisdom and natural science have their application. But regarding all that he says about the regions above the sphere of the moon, it is, with few exceptions, like guessing. Guide II:22

This is the central passage in Maimonides' relation to Aristotle, and one of the most candid avowals in medieval philosophy. Below the moon — physics, biology, the mechanics of generation and corruption — Aristotle has the argument; above the moon, the Philosopher is guessing, with great care, but guessing.

The distinction matters. Maimonides accepts the Aristotelian cosmos of his inheritors — Al-Farabi, Avicenna, Averroes — in its broad architecture: a hierarchy of celestial spheres, each moved by its own incorporeal intelligence; the active intellect (al-'aql al-fa'al) as the lowest of these intelligences and the source of human conceptual cognition; the unmoved mover as the highest. He accepts the structure because it follows from premises he shares.

The point of departure

Where he departs is on the question of the world's beginning. Aristotle's argument that the world is eternal (uncaused, beginningless, the spheres having always turned) is, Maimonides says, not a demonstration. It is a plausible inference from terrestrial physics extrapolated upward — and the extrapolation is the unsafe step. The same physics admits of a created world, if creation is conceived as the establishment of physics itself rather than as a temporal event within a prior physics.

We do not reject the eternity of the universe because certain passages in scripture confirm the creation of the universe... but because the proofs of the philosophers for the eternity of the universe are not conclusive. Guide II:25

The position is delicate. Maimonides will not say that scripture proves creation; he will only say that Aristotle has failed to prove eternity, and that creation is therefore permissible to the philosopher who is also a Jew. The reasonableness of the position is preserved; the obligation to scripture is preserved; the appearance of compromise is avoided.

The active intellect, more carefully

The other Aristotelian commitment Maimonides modifies — almost in passing, and yet decisively — is the doctrine of the active intellect. The Falasifa held that human cognition is the active intellect's emanation; that when one has a true conceptual thought, one has, in that moment, joined oneself to the active intellect.

Maimonides preserves the mechanism but withholds the apotheosis. The human intellect, perfected, may indeed apprehend what the active intellect emanates. But conjunction — the becoming-one with that intellect — is not a regular event, and the philosophers who promised it were promising more than they could deliver. He is careful here, more careful than his sources.

One reads II:22 and II:25 together as a single move: Aristotle's cosmology is to be accepted where it is demonstrated and held open where it is not. The unfashionable habit of admitting what one does not know is, in Maimonides, a methodological commitment, not a piety.

What the thread connects to

The same epistemic modesty governs Maimonides' treatment of prophecy (II:32–48) — there too, the philosopher's account is taken seriously and then constrained by what the texts actually report. And it governs the treatment of providence: a careful theory, then a careful concession. That thread is The Storm and Its Voice.