One is as follows:

This position entails that nothing comes into being, and that whatever does come into being does so without being brought into being by an originator. Clearly, the falsity of this is more evident than the falsity of an infinite regress or of a preference without a determining factor. For a complete cause that necessarily entails its effect is accompanied by that effect, and no part of its effect can come after it. Thus, no temporal occurrence can arise from this complete cause. Yet there is nothing from which contingent things can proceed other than the intrinsically necessary being, whom these philosophers call a complete cause. If temporal occurrences cannot proceed from Him, and there is nothing else to bring them into being, it follows that they come into being without an originator.

(Moreover, suppose that something other than Him brought them into being. If it were intrinsically necessary, the same argument would apply to it as to the first necessary being. Their fundamental premise is that the intrinsically necessary being is a complete cause whose effect must accompany it. According to their position, therefore, no temporal occurrence can proceed from a complete cause, either through an intermediary or without one. For if that intermediary were a necessary concomitant of His existence, it would be eternal along with Him, making it impossible for temporal occurrences to proceed from it. If it came into being, the same argument would apply to it as to any other temporal occurrence.

If, on the other hand, the originator of temporal occurrences were assumed not to be intrinsically necessary, it would be contingent and dependent upon a necessitating cause to bring it into existence. Then, if it were said to have been brought into being, it would itself be one of the temporal occurrences. If it were said to be eternal, it would have a complete cause that necessarily entailed it, and temporal occurrences could not then arise from it. For neither a contingent being nor any of its attributes or acts can exist except through the intrinsically necessary being.

Thus, if temporal occurrences are assumed to arise from an eternal contingent being that is the effect of an eternal cause, the question is: has a cause arisen within it