However, if one intends to identify a first cause of the existence of the world, one may choose to call that “god” even if one does not know the precise nature of the first cause. And even the first cause has its difficulties, since a cause will itself need another cause. “It is difficult or impossible,” he wrote, “to prove against the philosophers that there cannot be an infinite regress in causes of the same kind, of which one can exist without the other.” Thus the postulate of a designer or creator only raises the unanswerable question of who designed the designer or created the creator.

