is within people’s souls, declaring without proof that it is not knowledge. Their failure to experience it within themselves does not imply that others have not experienced it—especially when those reporting it describe the certainty within themselves, reporting from someone whose knowledge, truthfulness, and understanding of what he says they do not doubt.

Such is the case with the leading scholars of the Muslims, the early generations of this community, and the bearers of authoritative proof. They describe the certainty, assurance, and necessary knowledge they possess. This is illustrated by the account preserved about Najm al-Dīn al-Kubrā, when two speculative theologians visited him: one was Abū ‘Abd Allāh al-Rāzī, and the other was a Mu‘tazilī theologian.

They said, “Shaykh, we have heard that you possess certain knowledge.”

He replied, “Yes, I possess certain knowledge.”

They asked, “How is that possible? We have been debating since the beginning of the day until now, yet neither of us has been able to establish a proof against the other.” —I think the account concerned establishing the truth of Islam.—

He replied, “I do not know what you two are talking about, but I possess certain knowledge.”

They said, “Describe certain knowledge to us.”

He replied, “Certain knowledge, as we understand it, consists of impressions that come upon souls and that souls are unable to repel.”

They began repeating, “Impressions that come upon souls and that souls are unable to repel,” expressing their admiration for this answer.

This is because speculative theologians divide knowledge into necessary and acquired, or self-evident and inferential. Inferential, acquired knowledge must ultimately rest upon necessary or self-evident premises. These require no proof; otherwise, circular reasoning or an infinite regress would follow.

Necessary knowledge is that which