…one hundred and sixty-one is odd, we need an intermediate step—that is, to divide the number; if it can be split into two equal halves we know that it is even.
We have already shown, in our discussion refuting their distinction between what is essential and what is merely necessary, that the difference does not in fact lie in the attribute as it inheres in the object. Evenness and oddness are as inseparable from even and odd numbers as numerosity is from number, color from whiteness and blackness, and corporeality from animality. Some necessary attributes are obvious to certain people as belonging to every instance, while for others their presence in some instances is hidden. The distinction, then, goes back to the human observer. Just as there are things we see and things we do not see, there are things we know and things we do not know. This in no way implies that the attributes we happen to know are components out of which the quiddity is composed—were it even possible for a quiddity to be composed of attributes—while the attributes we do not know are not among its components. How much more baseless, then, is the claim that a quiddity existing in the external world is composed of attributes subsisting in it, and that those attributes are its constitutive parts which precede it; such a claim is sheer falsehood.
Because Fakhr al-Razi and those like him shared this error with the logicians, they maintained that the middle term conceived in the mind is itself an external middle. This is false. I know of no earlier logician who said such a thing, nor have I seen it in the writings of Ibn Sīnā and the like; what I do find in his words is that the middle term is simply the evidence.
Al-Razi’s proof for this distinction—and the demonstration of its internal contradiction—can be exposed in thirteen ways. Consequently, when al-Razi advanced his claim, he incurred a contradiction even greater than that of the logicians themselves.
Al-Razi says: “The proof that whatever entails its consequent without a middle term is self-evident is that the quiddity, by virtue of what it is, necessitates that consequent; therefore, once we conceive the quiddity we must also conceive that it…”