contradiction only shows that one of the two conflicting claims is false, without specifying which one; for the falsehood may lie in their contention that knowledge necessarily entails ṣidq nafsānī (inward veracity) and is incompatible with falsehood, rather than in their allegation that the two can coexist and that knowledge does not entail truthfulness.
It may be said in reply, and this is
The Seventeenth Answer:
This completely undermines their attempt to establish knowledge of the truthfulness of the kalām nafsānī (inward speech) that subsists in Allah’s Essence. Once that collapses, it is of no benefit to them to affirm a speech that could be either true or false. Indeed, it does not even help them to posit a speech whose existence they can recognise only while it is false; for they have affirmed the khabar nafsānī (inward report) solely on the assumption that the report is a lie. Thus they have never known an inward report except one that is false. If they ascribe such a thing to Allah, that would constitute invalid disbelief, contrary to their own objective and to the unanimous agreement of all people, for no one (1) has ever held that Allah possesses speech inherent to His Essence that is false.
If, on the other hand, they do not affirm this, they have no means whatsoever of establishing the inward report, for in that case we know of no inward meaning that is true (2)—apart from knowledge itself and the like—whether present or absent. Divine report is never severed from knowledge. Therefore, if it is impossible to establish the report they allege (3), it is likewise impossible to describe it as true, for the existence of an attribute without its subject is impossible. It thus becomes clear that the method they adopted to prove the truth of the report destroys, for them, the very foundation of the khabar nafsānī; consequently, neither an inward report nor its truthfulness is established. Moreover, the method they pursued to prove kalām nafsānī, were it valid, would establish only a report that is false—and that is impossible. (4)