an eternally complete cause, and affirming such a cause necessarily entails that temporal events have no agent. This implication is self-evidently false; therefore the premise that yields it is likewise false—and that premise is the alleged eternity of some part of the cosmos. Since the premise is invalid, its opposite is true: not a single component of the universe is eternal.

Second, their claim entails an endless chain of causes and effects. They themselves concede the impossibility of such an infinite regress, and its falsity is proven by demonstrative arguments, as we have detailed elsewhere. We have shown that every effect is contingent, containing nothing that necessitates its own existence. To posit an infinite series of contingent things that lack any principle of necessity is no different from envisaging a finite series of nonexistent—or impossible—things. If one imagines an unending succession of causes that are themselves effects, it is tantamount to positing an infinite sequence of nonentities; and what is nonexistent cannot originate or act upon what exists. There is no need to elaborate further, for this is unanimously recognized by rational people. Some later writers, however, have raised objections—objections we have refuted in other works, as have al-Amidi, al-Abhari, and others.