Al-Askari (A.S.) gave their judgment on the admissibility of one circumstantial evidence information which is authentic. Similarly, Imam Al-Mahdi (a.j.t.f) declared the admissibility of circumstantial evidence and so on and so forth. These things are dealt with at length in the Eighth Discussion.
Some of our contemporary writers have said that the first person to distinguish himself in writing down these discussions in the form of a book was Hishan Bin Al-Hakam a student of Imam Jafar Sadiq (A.S.) who composed a book, titled, Kitab-ul-Alfaz Wa Mabahithiha, which is one of the important discussion of this branch of studies.
Our opinion is that there has been mentioned a book as referred to above among the books written by Hisham but its topic is not known. It cannot said as to whether this book deals with the discussion of words which belongs to the field of Jurisprudence or not. Nor does the statements of our contemporaries give any indication to this effect. But the correct position si that the first one to put down these discussions to book-form was Yunis Bin Abdur Rahman who was an ally to Yaqtin family. He wrote a book titled Ikhtilaf-ul-Hadith which deals with exactly an issue of principles of jurisprudence that is the question of balancing the views which are contradictory and exercising one’ discretion in giving a judgment. This is a part of the discussions relating to the Principle of Jurisprudence. He died in the beginning of the third century.
Other notable figures how did work in this field are as described below:
Ahmad Bin Muhammad Bin Khalid Al-Barqi wrote a book on contradictory opinions and question of giving judgments. He died in 274 A.H.
Muhammad Bin Abdul Rahman Bin Qabbah Ar-Razi has expressed his ideas on the availability of one piece of evidence, which is quite known. He di8ed in the beginning of the fourth century.
Muhammad Bin Muhammad Bin An-Numan known as Mufid.
He has a small book on Ilm-ul-Usul which is printed.
Ash-Sharif Murtada Ilm-ul-Huda Ali Bin Al-Hussain.
Allama has described him in AL-Khullasah as a man of all arts whose position is admitted by all. He was profound in knowledge and different studies, which included the knowledge of Usul-ul-Fiqh (Principles of Jurisprudence) which is a way of Principles of Law (Shariah). His ideas and opinions are quite well known in the books of both the Sunnite and the Shiite writers. He died in 436 A.H..
Ash-Shaikh abu Jafar Muhammad Bin Al-Hussain At-Tusi.
He is called Shaikh-ut-Tusi or simply as Ash-Shaikh. A number of his books on the Principles are found in print. he died in 460 A.H.
Sadad-ud-Din Mahmud Bin Ali Al-Humsi was also one of the scholars who were known for knowledge of Usul. He died during the sixth century.
Al Muhaqqiq Jafar Bin Al-Hassan Bin Yayha bin Said Al-Hilli.
HE is the author of Maarij-ul-Wusul Ila Ilm-il-Usul which has been printed. He also collected the fundamental rule relating to Ilm-ul-Usul in brief in a book form which is first of its kind. He died in 676 A.H.