of knowing with certainty that this universal proposition is true without that same knowledge being all the more accessible in particular instances.

If it is said:

“Knowledge of particular things is not what is intended, for demonstration yields only knowledge of a universal proposition. Conclusions known through demonstration can therefore only be universal, as they themselves maintain. Universals, however, are universal only in the mind, not in external reality.”

The reply is:

On this assumption, demonstration yields no knowledge of anything that exists, but only of things conceived in the mind whose realization in external reality is unknown. If demonstration provides no knowledge of anything that exists, it is of very little benefit—indeed, of no benefit at all. Yet they do not maintain this; rather, they use it to acquire knowledge of external and metaphysical realities. The truth of the matter, however, as we have explained elsewhere, is that inquiries in natural philosophy which concern not necessary universals but generalizations holding for the most part do not achieve the intended purpose of demonstration.

As for “metaphysics,” their universal propositions in this field are even more unsound than those of natural philosophy. Most of their discourse concerning it consists of false conjectures, far from being true propositions from which a demonstration could be constructed. Thus, we have been told through an unbroken chain of transmission that al-Khūnajī, the distinguished logician of his age and author of Kashf Asrār al-Mantiq (Unveiling the Secrets of Logic), al-Mūjaz (The Epitome), and other works, said as he lay dying: “I am dying, yet I have not come to know