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:
(i) 'aqli
(rational);
(ii) 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 judgement. 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.
