Muslims may agree on some means of attaining knowledge in both categories, as they agree that the Quran serves as evidence in both, broadly speaking. They may disagree over other means—for example, whether practical rulings concerning good and evil, obligation and prohibition can be known through reason as well as revelation, or only through revelation. They also disagree over whether revelation originates these rulings or merely discloses them, just as it discloses realities that exist in themselves.

The same applies to using the Book, the Sunnah, and consensus as evidence concerning the major questions in the first category, such as the divine attributes, divine decree, and other matters. This is accepted by the adherents of the Sunnah and the community across their various groups. Yet many proponents of religious innovation reject this, arguing on the basis of their own doctrines that revelation cannot establish these matters and that they are instead established through reason (1).

Indeed, many of the Qadariyyah and the Mu‘tazilah claim that the Quran cannot validly be used as evidence for Allah’s wisdom and justice, or for His being the Creator of all things and having power over all things. The Jahmiyyah among them, together with their followers among some of the Ash‘ariyyah and others, claim that it cannot validly be used as evidence for Allah’s knowledge and power, worship of Him, or His being established over the Throne.

Some extremists among the proponents of religious innovation claim that the Quran and hadith cannot validly be used as evidence for any matters requiring certainty whatsoever, basing this on their allegation that verbal indications do not yield certainty. Many proponents of religious innovation also claim that hadiths received with acceptance cannot be used as evidence concerning the divine attributes, divine decree, and similar matters in which certainty and conviction are required.