Thus, two avenues were open, and the debaters who inclined toward the doctrine of the world’s eternity—those ancient materialists among the Greeks, the followers of Aristotle and others—seized the opportunity. They imagined that if they could demonstrate the impossibility of the world’s coming into being after an everlasting span of divine inactivity, they would have refuted their opponents and established the pre-eternity of the universe and of the celestial spheres, in accordance with Aristotle’s view.
Ibn Sīnā says:
“The sound intellect, which has never erred, knows that if we posit an Essence that was inactive—that did nothing—and then later acted after previously not acting, something must have arisen: either a capacity, or a will, or some other cause. But if the state in which It acts is identical to the state in which It did not act, then It must remain inactive. Yet we have stipulated that It did act, so this amounts to combining two contraries. The contradiction arises only because we assumed an Essence suspended from action; if that assumption is false, its negation must be true.”
This, however, proves neither the eternity of the world nor the eternity of any part of it, nor the eternity of any specific act or product. On the contrary, it actually indicates the impossibility of anything in the world being eternal. Even were one to posit successive acts, if the state of the Essence throughout all time is identical to Its state in pre-eternity, without any change, then this particular contingent event could never issue from It: for the Essence existed while the event had not, and It is now as It ever was—therefore the event ought never to occur.
If it is said, “New circumstances have arisen in the world that rendered it ready for the act,” we reply: the discussion about that newly arisen circumstance is exactly the same as about any other. It is impossible for something to arise from an Essence whose state at the moment of occurrence is the same as before the occurrence, whether the arising is mediated or unmediated, for every emergent event requires that the full causal efficacy be present at the very moment