‘Ali (may Allah be pleased with him) is considered infallible, and therefore he must be the Imam. They also argue that the Imam must be explicitly designated (mansūs), and since ‘Ali (may Allah be pleased with him) was not designated by consensus, it follows necessarily that he is the Imam. See: Minhaj al-Karāmah fī Ma‘rifat al-Imāmah (The Path of Honor in the Knowledge of the Imamate) by Ibn al-Mutahhar, pp. 145–146; ‘Aqā’id al-Imāmīyah al-Ithnā‘Ashariyyah (Doctrines of the Twelver Imami Shi‘ah) by al-Zanjānī, vol. 1, pp. 41–43, 77–78; vol. 3, pp. 181–182, 189. ‘Ismah (infallibility) has been defined as “a strength of the intellect whereby one cannot be overcome, even though one is capable of all sins…”. Shaykh al-Islām (may Allah have mercy on him) refuted this position with several objective arguments; the reader may consult his discussion in Minhāj al-Sunnah al-Nabawiyyah fī Naqd Kalām al-Shī‘ah wa al-Qadarīyah (The Methodology of the Prophetic Sunnah in Refuting the Writings of the Shi‘ah and the Qadarites), vol. 3, pp. 246–270. For a concise refutation of the Rafidah’s claim that the Imam must be infallible and explicitly designated, see: – Mukhtaṣar Minhāj al-Sunnah al-Nabawiyyah (Abridged Path of the Prophetic Sunnah) by Ibn Taymiyyah, abridged by al-Ḥāfiẓ al-Dhahabī, pp. 405–415. – al-Radd ‘alā al-Rāfiḍah (Refutation of the Rafidah) by Shaykh Muḥammad ibn ‘Abd al-Wahhāb, pp. 27–28, 34. – Mukhtaṣar al-Tuḥfah al-Ithnā‘Ashariyyah (Abridged Gift of the Twelvers) by al-Dahlawī, pp. 116, 120, 122, 177–179, 181–182. (1) The original reads al-ittiḥād (union), which is a mistake. The reading confirmed by manuscripts S and T is al-tawātur (consecutive transmission). Al-tawātur denotes a report whose authenticity is known as a necessity; its isnād must preserve this condition continuously from the first to the last narrator. It is divided into lafẓī tawātur (verbal tawātur) and ma‘nawī tawātur (conceptual tawātur). Al-ahād (single reports) are those that are not tawātur. See: ‘Ulūm al-Ḥadīth (Sciences of Ḥadīth) by Ibn al-Ṣalāḥ, pp. 241–242; Nuzhat al-Naẓar (Delight of the Gaze) by Ibn Ḥajar, pp. 18–25; Ta‘rīb al-Rāwī (Training the Narrator) by al-Suyūṭī, vol. 2, pp. 176–179. (2) In the printed edition it reads wa al-ijmā‘ (and consensus).