if it is possible for it to produce an effect and possible for it not to do so, both alternatives are possible and contingent. Its producing the effect would have no greater claim than its not doing so, were it not for another factor that brought about its producing that effect. The same argument would then apply to that factor’s producing its effect. This would entail that events coming into existence depend on an endless series of causes producing effects, none of which exists. Whatever depends on something nonexistent is itself nonexistent. Yet he rejects infinite regress even in lesser cases.”
This is a familiar issue in the Muʿtazilah’s discussions of the acts of the Lord and the acts of human beings. They address it in discussing the world’s coming into existence and divine decree. It is one of the points on which Ahl al-Sunnah, the philosophers, and others have gained the upper hand over them.
This is especially so since Abū al-Husayn also maintains that the act of an agent capable of acting depends on a motive, and that, when the fully sufficient motive exists, the act within the agent’s power must necessarily occur. His underlying position thus agrees with that of those among Ahl al-Sunnah and the philosophers who say that an event comes into existence while its coming into existence is necessary. This contradicts his statement that it comes into existence only while its coming into existence is contingent, not necessary.
Third: one may say, “Suppose we concede that a cause can exist and produce an effect while it remains possible for it not to do so, and that it singles out one circumstance rather than another for the effect to come into existence. If coming into existence and being singled out in this way are possible through a cause that produces an effect while it remains possible for it not to do so, then they are all the more possible through a cause that necessarily produces its effect.”
If it is said, “Where a cause necessarily produces its effect, its effect cannot fail to accompany it. This entails that events that come into existence are eternal, unlike the case of a cause whose producing its effect is contingent.”