the father is a condition for the child’s existence, or clouds are a condition for rain—an infinite regress is not impossible. There is a well-known dispute concerning this, which has been discussed elsewhere.

Nothing in this supports the philosophers’ assertion that the celestial spheres are eternal. At most, it refutes the claim that temporal events must be finite in number.

It has already been explained more than once that the philosophers’ argument is invalid under either of the two contradictory assumptions. If the existence of an infinite succession is impossible, their position is invalid. If its existence is possible, there is nothing to prevent the existence of the celestial spheres from depending on preceding temporal events, with each event conditional upon what preceded it—just as they themselves say concerning events arising from a complete cause that necessarily entails its effect. This implies that their position entails that temporal events have no agent, if every event is conditional upon a preceding event.

According to them—and to others—a complete cause that necessarily entails its effect cannot produce anything new, whether through an intermediary or without one. That would entail some of its effects being delayed, so it would not be complete. Rather, it would contain a potentiality that had not been actualized, which contradicts their position.

Ibn Rushd said:

“Furthermore, their statement that the particular motion in question cannot occur until an infinite number of motions have elapsed before it is not conceded by their opponents. For their opponents maintain that only what has a beginning can come to an end, whereas what has no beginning—as