If, then, something new comes into existence, that occurrence must itself have a newly-arisen cause, which yields an infinite regress. Their assertion—“Had He not been a complete agent and then became complete”—entails only an infinite regress in the effects, not in the agents, for it is conceivable, on their own premises, that successive, serial volitions and cognitions may subsist in Him. Such a sequence they regard as permissible; when a later volition coincides with an earlier one, the effects occur. This answer was advanced by a group among them, al-Abhari in particular, and it is stronger than the reply al-Razi dubbed “the dazzling proof.” Abu al-Barakat and others concede its validity, whereas Ibn Sina and the like have nothing with which to refute it save the same arguments they use to deny the divine attributes—and their denial of the attributes is thoroughly unsound.

Furthermore, one may say that the evidence proving the impossibility of an infinite regress in complete causation concerns only absolute causation; it does not show that anything in the universe is eternal. The philosophers may retort to the theologians, “This consequence follows from your own principles.” When they do, one can respond on the theologians’ behalf: an infinite regress is either impossible or possible. If it is impossible, your doctrine of the world’s past-eternity and the perpetual motion of the celestial spheres collapses; and once that doctrine falls, the argument marshaled for it collapses a fortiori, for a false claim can never rest on a sound proof. If, on the other hand, an infinite regress is possible, then this very argument is nullified. Thus, on either assumption, the proof is invalid. If it be said, “Abu ‘Ali Ibn al-Haytham, Ibn Sina, and al-Suhrawardi…”