necessary either; it is therefore necessary through something else. Whatever is other than the aggregate of contingent beings and its individual members is necessary. This is the meaning of his statement:

“Either this proceeds in an infinite regress, in which case every individual member of the chain is contingent in itself, and the aggregate depends upon those members; it too is therefore not necessary, but is necessary through something else.”

However, his words “Either this proceeds in an infinite regress” require the alternative: “Or it does not.” It has been said that he omitted this for brevity, since it was precisely his intended conclusion. The meaning is that, if contingent beings do not regress indefinitely, they terminate in that which is necessary in existence—and this is what he sought to establish.

Had he instead used the wording “If this proceeds in an infinite regress,” that would have been the appropriate expression for what he sought to establish.

He then explained this argument in detail, after having presented it in outline, saying:

“If contingent beings form an infinite regress, each being an effect, they require a cause external to their individual members, for either they have a cause, or they do not