3. Al-Kalam al-‘Aqli and al-Kalam al-Naqli

Although ‘ilm al-kalam is a rational and discursive discipline, it consists of two parts from the viewpoint of the preliminaries and fundamentals used by it in arguments:

1. ‘aqli (rational);

2. naqli (transmitted, traditional).

The ‘aqli part of kalam consists of the material which is purely rational, and if there is any reference to naqli (tradition), it is for the sake of illumination and confirmation of a rational judgment. But in problems such as those related to Divine Unity, Prophethood, and some issues of Resurrection, reference to naql – the Book and the Prophet’s Sunnah – is not sufficient; the argument must be purely rational.

The naqli part of kalam, although it consists of issues related with the doctrines of the faith – and it is necessary to believe in them – but since these issues are subordinate to the issue of Prophethood, it is enough to quote evidence from the Divine Revelation or the definite ahadith of the Prophet (S), e.g. in issues linked with imamah (of course, in the Shi’ite faith, wherein belief in imamah is considered a part of usul al-Din), and most of the issues related with the Resurrection.