اعلم أن أسباب الغلط مع كثرتها راجعة إلى أمرين
Know that, despite their great number, the causes of error return to two matters.
The first is poor understanding (sūʾ al-fahm): failing to grasp a matter correctly. The second is false propositions resembling true ones (ishtibāh al-kawādhib bi-l-ṣawādiq).
A mistake need not begin with deliberate lying. Sometimes the mind misunderstands its subject; at other times, a false premise looks like a true or immediately evident one. These require different forms of correction.