I reply: The substance of this argument is the very same material as the proof cited by the questioner; for the root of the whole matter is that, whenever two necessary beings are posited, the necessity of existence must be an effect, either of the essence or of something else—yet the necessity of existence cannot be an effect. If a necessary being is posited, its species is not confined to that single individual; and since it is not confined, it is impermissible to claim that the necessity of existence is what produces (1) its individuation and particularity. Were that so, the species would be limited to that individual alone, and the necessity of existence would itself become specified, which is the very opposite of the intended conclusion. Hence the relations that belong to the individual must be other than the necessity of existence. Accordingly, whether the necessity of existence is inseparable from that individual or merely incidental to it, it must still be caused by it, for the necessity of existence is obtained only through it—just as humanity is realized in a given person only by something other than humanity, namely the matter that bears it. Yet what is necessary in and of itself cannot be an effect.

This is the furthest point to which their reasoning leads. Abū Ḥāmid, by the light of his native insight, detected its falsity and declared, “This division is erroneous,” illustrating the matter with the example of colourhood; and the illustration he gave is apt. Nevertheless, although he exposed the fundamental flaw of the proof, he did not indicate where its premises must be rejected. That question depends on a prior discussion of essence and existence, the distinction between the two, the individuals of a species and their substrates, and similar foundational issues in which they themselves went astray, so that the truth became confused for them and they in turn confused others. Many of those who attempt to refute them agree with them in those unsound principles, or at least in some of them, and thus fall into contradiction in their rebuttals just as their opponents contradict themselves in their own discourse. Something of this sort is found in the writings of al-Rāzī, and in much of what appears in the writings of