He went on to compose, in the same discipline, The Criterion of Knowledge (Miʿyār al-ʿIlm) and The Touchstone of Reflection (Mahk al-Naẓar).

He also authored a book entitled The Just Balance (al-Qisṭās al-Mustaqīm), in which he laid out five “scales”: the three categorical syllogistic figures, the conjunctive hypothetical, and the disjunctive hypothetical. He replaced the philosophers’ technical jargon with examples drawn from Muslim discourse, claimed that these scales were taken from the prophets, and stated that he presented them to certain proponents of the doctrine of taʿlīm.

Further, he wrote a work on their doctrines (Maqāṣid al-Falāsifa) and another on their incoherence (Tahāfut al-Falāsifa), in which he pronounced them unbelievers on account of three issues: their claim that the world is eternal, their denial that God knows particulars, and their rejection of the resurrection.

In the conclusion of his writings he declared that their path is corrupt and leads to no certainty, censuring it even more severely than he did the method of the theologians. Yet this denunciation came only after he had deposited in his “restricted” books—such as al-Madnūn bihi ʿalā ghayri ahlihi—and elsewhere many of the very notions of their false discourse that contradict the religion of the Muslims, merely changing the terminology and expressing them in Muslim idiom.