and nonexistence. Indeed, a contingent being exists only when that which necessitates its existence is present. So long as it remains open to both existence and nonexistence, it does not exist; once that which necessitates its existence is present, it exists. Accordingly, a contingent being cannot, of itself, necessitate the existence of another contingent being. Rather, a contingent being’s existence can be necessitated only by a necessary being. A necessary being is necessary either in itself or through another. What is necessary through another is contingent in itself and exists only through that which necessitates its existence. Thus, an infinite regress of contingent beings, in which one contingent being necessitates the existence of another, is impossible. Rather, the other’s existence is necessitated only by what is necessary.
Whatever is contingent and remains merely contingent is not necessary, either in itself or through another. If, then, an infinite regress of beings admitting both existence and nonexistence is supposed, without any self-existent being among them, they retain their contingent nature, and none of them is necessary. All the more, then, none of them can necessitate the existence of any contingent being. Consequently, no contingent being would exist. Yet contingent beings do exist. This is a contradiction.
This contradiction follows only because we supposed contingent beings to exist through other contingent beings that have no existence of themselves, without there being any being necessary in itself.
Know that people have disagreed concerning contingent beings: does their existence require something that necessitates it, such that, in its presence, they are either necessarily existent or incapable of nonexistence? Or can something arise through which their existence is favored while nonexistence remains possible, so that they exist through something that makes existence prevail, even though nonexistence remains possible?
The first is the view of the majority; the second is the view of those among the Mu‘tazilah and similar groups who hold this position.