This is because taking a bath for Janabah is a pre-requisite for fasting...

This is because taking a bath for Janabah is a pre-requisite for fasting, which cannot be valid without it, just as ablution is pre-requisite of prayers and there can be no prayers without ablution. Naturally, the jurist tries to study these laws of Fiqh in the light of those principles of ‘ Ilm’ul Usul .

He then finds himself facing contradiction, because according to Fiqh , taking a bath is obligatory on the Mukallaf before the beginning of the period of fasting where as ‘ Ilm’ul Usul has laid down that the pre-requisite of anything becomes obligatory only in the context of the obligation of that thing and not before the latter becomes obligatory.

Thus this law of Fiqh forces the jurist to study anew that principle of ‘ Ilm’ul Usul and to consider the way of reconciling it to the reality of the legal situation. As a result of that new ideas on ‘ Ilm’ul Usul come into being to delineate, extend and explain that principle of ‘ Ilm’ul Usul in such a way as to reconcile it to the facts of the case. This is a real example.

Thus the difficulty in explaining the obligation of taking a bath before the beginning of the period of fasting was revealed during studies and research on Fiqh . The first study on Fiqh to have revealed it was the discussion by Ibn Idris in "As-Sara'ir", even though he didn't succeed in solving it. The discovery of this difficulty led to many abstruse studies on ‘ Ilm’ul Usul dealing with the way to reconcile its principles to the real legal situations.

These are the studies that today are known as " Buhuthul Muqaddimatil Mafutah " (studies on the elusive pre-requisites). ‘ Ilm’ul Kalam (Scholastic theology): This played an important role in replenishing and extending thinking on ‘ Ilm’ul Usul , especially in the first and second eras. This is because studies on ‘ Ilm’ul Kalam were widespread and very influential in the general outlook of the Muslim theologians when ‘ Ilm’ul Usul began to make its first appearance.

Thus it was only natural that ‘ Ilm’ul Usul should rely on ‘ Ilm’ul Kalam and seek inspiration from it. An example of this is the theory of rational good and evil. This theory of ‘ Ilm’ul Kalam states that human reason can perceive, quite apart from any authentic text of the Shari’ah , the evil of certain acts like injustice and treachery, and the goodness of others like justice, faithfulness and honesty.

This theory was used by ‘ Ilm’ul Usul in the second era to show the validity of Ijma' (consensus) as a proof, i.e.