According to Imāmī theologians, the existence of the Prophet (nabī) and the Imam (imām) is rationally necessary. By "necessity," they do not mean the mere goodness (ḥusn) of the Prophet's or Imam's existence; rather, on the basis of the rational principle of al-ḥusn wa al-qubḥ al-ʿaqliyyān (rational moral goodness and evil), they maintain that the existence of the Prophet and the Imam is indispensable for divine guidance (hidāyah). Several objections have been raised against this doctrine. First, it is argued that the knowledge conveyed by the Prophet and the Imam belongs to the sphere of human knowledge and is therefore fallible. Second, neither the Prophet nor the Imam has been present among all people in every age. Third, access to and understanding of religious texts can also be achieved by other human beings. On this basis, the necessity of prophethood and imamate has been subjected to serious criticism. The findings of the present study, however, reject these objections. First, not all forms of human knowledge are fallible; some are immune from error. Second, the absence of the Prophet or the Imam in certain periods is attributable to human misuse of free will and the absence of the conditions required for their manifest presence, and thus does not contradict the doctrine of luṭf (divine grace) or the occultation (ghaybah) of the Imam. Third, while the outward meanings of the revealed texts may be accessible to others, access to their inner meanings (buṭūn) is not attainable by everyone and is reserved exclusively for the divine prophets and saints (awliyāʾ). Employing a descriptive-analytical methodology, this article offers a critical examination of the claim that prophethood and imamate are not necessary, as advanced in the book The Theory of Imamate on the Scale of Critique.