exist.

But anything of this kind can only be temporally originated. Thus, it is called possible in one respect and temporally originated in another; possibility and temporal origination necessarily imply one another. As for calling something beginninglessly eternal, whose nonexistence is impossible, “possible” in the sense that it can either exist or not exist, this has no basis in either reason or language. Even supposing such usage to be valid, the dispute here is merely verbal.

Once these terminological conventions are understood, however, many difficulties arising from the ambiguity of the word “possible” disappear, as has been explained at length elsewhere.

The terminological difference concerning “possible” here is distinct from the distinction between the possible in the general sense, which is contrasted with the impossible, and the possible in the specific sense, which is contrasted with the necessary and the impossible. Indeed, according to the terminology just attributed to the ancients, even the possible in the specific sense applies only to what is temporally originated and can either exist or not exist. Whatever is posited as eternally necessary through another is not called possible according to this terminology.

As for the terminology of Ibn Sīnā and his followers, according to which the possible is whatever has a cause, Ibn Rushd said:

Whatever has a cause falls into two categories: the possible and the necessary. The necessary is that whose nonexistence is impossible; rather, it is eternally necessary through a cause. This is what the philosophers maintain concerning the celestial spheres, whereas what is genuinely possible is that which comes into being.