Many people contradict themselves on this principle. If we proceed on the correct view, there is nothing further to discuss. But if we wish to present an argument encompassing both views, we say:
[Fifth]
A contingent being does not come into actual existence merely through another contingent being whose existence has not been actualized. Rather, its existence is actualized only through that which brings it into existence.
Accordingly, if we suppose that all of them are contingent beings, none of which has come into actual existence, the condition for the existence of any contingent being is not fulfilled, and none of them exists. For whenever you consider a contingent being as needing an agent to bring it into existence, its existence has not yet been actualized in that state. So long as it still needs to be brought into existence, it does not exist: being existent is incompatible with still needing to become existent. Thus, there would be no existent being among them, and hence nothing through which the condition for a contingent being’s existence could be fulfilled—much less anything that could originate a contingent being or act as its agent. No contingent being would therefore exist, yet contingent beings do exist. Consequently, an infinite regress of contingent beings, each causing another’s existence, is impossible. This is what was to be demonstrated.
Know that an infinite regress of causes is impossible, and its impossibility is evident to the innate dispositions of all rational people. Earlier speculative thinkers therefore did not dwell at length on establishing this, whereas later thinkers began to elaborate its proof. One reason for this was their confusing an infinite regress of effects, namely acts, with an infinite regress of causes, namely agents. Jahm ibn Safwān, Abū al-Hudhayl al-‘Allāf, and their followers among the adherents of the innovated speculative theology condemned by the early generations and the imams—a path followed by adherents among the Mu‘tazilah, Kullābiyyah, Karrāmiyyah, and others—held all of this to be impossible.
For this reason, they refused to affirm: “The Lord has always spoken whenever He wills.” They then differed over whether His speech is created or whether speech as a whole has a temporal beginning