I have encountered many varieties of discourse on this subject and others—more than there is room to discuss here. Many disagreements are merely verbal, or reflect diversity rather than contradiction.

The first occurs, for example, when the meaning of an expression used by one person is the same as that of an expression the other does not use, although the two expressions differ. They dispute because an expression means one thing in the terminology of one and something else in that of the other. This is common.

The second occurs when one person advances a sound form of knowledge and evidence, while the other advances another sound form.

Many disagreements on this subject fall into these categories, while many others concern substantive meaning. Substantive disagreement concerns either whether something is or is not the case, or whether something is obligatory or its obligation is waived.

Thus, disagreement over the validity of the argument from accidents and similar arguments is substantive. The same applies to disagreement over whether this argument must be used to establish faith, whether the validity of faith depends upon it, and similar questions.

Since discourse on these innovated topics was originally taken from the Muʿtazilah, the Jahmiyyah, and others like them, and since these groups had discussed the first obligation—whether it is rational inquiry, intention, doubt, or knowledge—many of those affiliated with