The Role of Reason in the Authority of Khabar-e Wāhid

The fundamentals of the authority of khabar-e wāhid, as one of the pillars of inference and ijtihad in Shiite jurisprudence, is common grounds between the science of hadith and the science of the principles of Islamic jurisprudence. One of the important proofs of the validity of khabar-e wāhid, about which, unlike other evidence, there is considerably common agreement, is that reason signifies its authority. Since this issue has been considered from the three hadithi, Akhbāri and Usuli perspectives, the establishment of a common discourse among them appears to be difficult. The theory of the proponents of the rational validity of khabar-e wāhid, in both its meanings, that is, the reading of Sheikh Tusi denoting the symmetry of reason and the reading of Mohaghegh Helli recognizing the expediency of rationality as a document of rational validity, was faced with constraints and openings after them, especially among the later scholars, and the later scholars and contemporaries have considered acting upon khabar-e wāhid binding in the form of three theories: the theory of ilm ijmāli about the issuance of khabar-e wāhid and emphasis on acting according to it depending on the authority of ilm ijmāli, the eternality theory of Fazil Tuni denoting the inevitability of relying on khabar-e wahid for the sake of preserving religious obligations and rulings and Sheikh Mohammad Taghi Isfahāni’s theory of reliance on conjectures considering the obstruction of the gate of knowledge and the impossibility of obtaining a final verdict, on the one hand, and the necessity of performing religious obligations, on the other. After reviewing all these three theories, the view of martyrs Sayyid Mohammad Bāqer Sadr and Sayyid Mohammad Kazem Yazdi, i.e. in the absence of rational prohibition, khabar-e wāhid has rational validity, was proved to be well-founded.