its essence, the third alternative, namely possibility, so that, considered in itself, it is something that is neither necessary nor impossible.

The reply is that this division entails denying both contradictories, for either the presence of the cause or its absence must be conjoined with it. Both contradictories—the presence of the cause and its absence—cannot be denied together. The supposition offered as an alternative to these two—that neither the presence of the cause nor its absence is conjoined with it—thus amounts to denying both contradictories, excluding both the existence of the cause and its nonexistence. This is impossible.

Accordingly, possibility is established only on an impossible supposition, and whatever is established only on an impossible supposition is itself impossible. Thus, the possibility they have asserted—namely, that it is neither necessary nor impossible—can obtain only on an impossible supposition: the denial of both contradictories. It is therefore impossible.

This makes clear that such possibility has no reality outside the mind. Possibility can only be conceived of in something that exists at one time and is nonexistent at another. As for something that exists and cannot admit nonexistence at all, it is not a possible entity. Likewise, something nonexistent that cannot admit existence at all is not a possible entity. An example is the opposites of the Creator’s attributes of perfection: incapacity, ignorance, and the like are nonexistent in Him and cannot exist in Him at all. Similarly, His life, power, and knowledge are inseparable concomitants of His essence and cannot admit nonexistence at all. Rather, their existence is necessary and their nonexistence impossible. They are not among possible things, which admit both existence and nonexistence. The following clarifies this: