The third epistemological underpinning modern Usulrs uphold is the authori­tativeness of substantiated conjecture (.Hujjiyya al-zann al-mutabar).

In accordance with this underpinning, some forms of conjecture (or conjecture­generating evidence) are authoritative because their juristic utility in ijtihad is substantiated. As such, Usulrs opine that substantiated evidence, which they interchangeably refer to as amara, tariq, dalil, or dalil al-mutabarj is on the same epistemological pedestal as evidence that generates certainty.

For Usulrs, one of the most important forms of evidence that generates substantiated conjecture are isolated reports (akhbar al-ahad, sing. Khabar al-wahid) that express the tradition (sunna) of the infallible (ma^csum) Prophet and the Shi'ite Imams. As shown in chapter 1, during the formative develop­ment of Shi'ite legal theory, Mufid and Murtada initially rejected the utility of isolated reports in the deduction of Sharia knowledge and deemed them conjectural due to their erroneous nature and the possibility of them being prone to fabrication. Their viewpoint was, however, short-lived. Their student Tfisi was the first rationalist Usfili to argue that God sanctions the utility of conjecture generated from isolated reports that are transmitted by reliable Twelver narrators. The acceptance of isolated reports was further advocated during the medieval period by 'Allama al-Hilli. Hilli proposed that, irrespec­tive of whether isolated reports were transmitted by Twelvers or nonTwelvers, they could be utilised in the deduction of Sharia at the discretion of individ­ual jurists based on how they graded their reliability. Although Hilli's stance attracted cynicism from the Akhbaris, it is found that from the medieval up till the modern period, Usfilis have unanimously concurred on the juristic utility of graded isolated reports. Perhaps an overarching reason for this is that the Quran only contains around five hundred verses relating to Sharia precepts and hence the majority of Sharia knowledge is deduced from traditions of the Prophet and Shi'ite Imams that are transmitted through isolated reports.2

1 See prelude to modern Shi'ite legal theory in chapter 1.

2 It is important to note that within the UsQli thought the Quran is the primary source of Sharia knowledge. However, because it only contains around five hundred verses related to Sharia Therefore, rendering them as being non-authoritative would imply that a vast majority of already procured Sharia knowledge (as contained within the works offiqh) would become redundant.

In their bid to avoid the redundancy of Sharia, Usulrs have historically dem­onstrated various theories which, according to them, if applied correctly, can substantiate the authoritativeness of certain conjectural forms of evidence (including isolated reports) and reveal that God sanctions their juristic utility in Ijtihad.^{[10] [11] Amongst them, the two most comprehensive theories modern Usulrs usually allude to are the theory of insidad and the theory ofzann al-khass. The former advocates that, by default, all forms of conjecture-generating evi­dence are authoritative, except those whose juristic utility is prohibited by God. Meanwhile in contrast, the latter advocates that by default all forms of conjecture-generating evidence are not authoritative, except for those whose juristic utility is explicitly sanctioned by God.}

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