can give preference to one of the two equivalent alternatives within his power without a determining factor.] (1)

That determining factor cannot come from the servant, because the same argument applies to it as applies to the servant’s act. If the servant’s power is what determines it, then an agent endowed with power can determine only through a determining factor. Thus, the determining factor must be [from Allah, and when the determining factor exists] (2), the act must necessarily exist (3); otherwise, it would not be a complete determining factor. For if, after the determining factor came into existence, the act could (4) either exist or not exist just as before that factor existed, it would remain merely possible—and the existence of a possible thing cannot prevail over its nonexistence except through a determining factor. There must therefore be a complete determining factor whose existence necessitates the existence of the act.

If the servant’s act can arise only through a determining factor from Allah Most High, and the existence of that determining factor necessitates the existence (5) of the act, then his act is like all other originated events that occur through causes created by Allah Most High, upon whose existence the event must necessarily occur.

This is what it means for the Lord [Blessed and Exalted] to be the Creator (6) of the servant’s act. It means that Allah Most High creates in the servant complete power and decisive will; when both exist (7), the act must necessarily exist, because (8) they constitute a complete cause of the act. Whenever the complete cause exists, its effect must necessarily exist.