Al-Rāzī answered that this argument entails an infinite regress of causes, which is impossible; al-Ārmūy therefore took issue with him in Lubāb al-Arbaʿīn.

Al-Rāzī states in al-Arbaʿīn: Those who claim the world is without beginning advance several proofs. The first is this: there is no doubt that the chain of contingent beings must ultimately terminate in the Necessary Existent. We say, then, that everything required for the Exalted One to be an effective agent in bringing those beings into existence is either held to have been present from pre-eternity or not.

If everything requisite for causal efficacy was present from pre-eternity, then either the effect must accompany its presence, or it need not. If it must, the perpetual existence of the cause would entail the perpetual existence of the effect. If it need not, then it is possible for the cause to exist while those effects are absent.

Let us therefore conceive of His essence together with all the factors deemed necessary for causal efficacy—once alongside the existence of the effects and once in their absence. The selection of the one moment rather than the other for the effect’s occurrence must either be due to some particular factor that makes that moment more deserving of the effect’s existence, or not. If it is due to such a factor, then that determinant itself counts among the conditions of causal efficacy, and so must already have been present beforehand. If, then, whatever is indispensable for efficacy