According to the Shi‘a ‘ulama’, in proving a religious injunction

"According to the Shi‘a ‘ulama’, in proving a religious injunction, our proof should not necessarily be based on a Qur’anic verse or a hadith but a religious injunction in Islam can [also] be established through reasoning and a sound intellectual proof. As such, according to Islamic jurisprudence, citing an intellectual proof for proving wilayat al-faqih is in no way less important than citing transmitted proofs, such as Qur’anic verses and hadiths."

AYATOLLAH MISBAH YAZDI (R)