al-Rāzī fell short in two respects:

First, he does not infer the Maker’s existence from coming into being itself. Rather, he takes coming into being as evidence of the contingency of that which comes into being. He then says that whatever is contingent must have a determining cause. The contingency he affirms is the same as that affirmed by Ibn Sīnā: a contingency shared by both the beginningless and that which comes into being. He thus regards the beginningless and eternal as contingent, admitting both existence and nonexistence. In this they departed from their predecessors and all other rational thinkers, who agree that whatever is contingent, admitting both existence and nonexistence, must have come into being.

Ibn Sīnā and his followers agree with everyone else on this, but contradict themselves. This has been discussed at length elsewhere, including our discussion of what al-Rāzī says about establishing the Maker’s existence at the beginning of al-Matālib al-ʿāliya and al-Arbaʿīn. We explained the invalidity of this reasoning and that, on this assumption, they have no proof for establishing the Necessary Existent.

Second, his characterization of this as an inference from the coming into being of attributes and accidents is unsound. Rather, it rests on the doctrine of the indivisible atom.

We have mentioned elsewhere that these thinkers based such arguments on the doctrine of the indivisible atom: that bodies are composed of indivisible atoms, and that what comes into being is merely the atoms’ combination and separation, motion and rest—these four being what they call the states of being—or the coming into being of other accidents. They thus regard the transformation and origination of entities as nothing more than changes in accidents.