I performed an analysis on the hadith in Bukhari and came to the conclusion that most hadith (over 90%) are Gharib (single independent chain).
I then learned that a Gharib is not necessarily weak because the conditions for a hadith being authentic do not take into consideration the number of independent chains of narrators.
I also learned a little bit about Imam Shafi' and his debates with Ahl ul Kalam, Mu'tazila etc. regarding the authority of Ahad hadith.
I am curious to know if someone can summarise the opinions of past scholars on Ahad (Gharib, Aziz, Mashur) hadith being authoritative in fiqh.
It seems odd to me because in general Islam requires at least 2 witnesses for most matters. So what is the Quranic evidence for accepting a hadith by a single narrator? I say Quranic evidence because if we were to use hadith it would be circular reasoning.