This study offers an analytical and comparative examination of two fundamental approaches in moral philosophy: Kant’s deontological ethics and Ayatollah Misbah Yazdi’s teleological ethics. The central problem concerns whether morality can be explained solely on the basis of duty, independent of any ultimate end, or whether a teleological account can be justified without relying on practical reason and the intrinsic goodness or badness of actions. Employing an analytical–comparative method and drawing directly on the primary works of both thinkers, the research critically evaluates the foundations and implications of each approach.

The findings reveal that Kant’s ethical system—despite its formal coherence and emphasis on the autonomy of reason—presents an abstract and incomplete view of moral action, due to its neglect of moral teleology and the ultimate happiness of human beings. In contrast, Misbah Yazdi’s teleological ethics, by defining human perfection and nearness to God as the ultimate purpose, offers a framework capable of providing meaning and orientation to moral actions. Nonetheless, reinforcing its sense of obligation and rational foundation requires acknowledging intrinsic moral values and utilizing practical reason to discover the objective reality of ethical norms.

Accordingly, rational deontology grounded in intrinsic goodness and badness constitutes the valid foundation of moral obligation, while the teleological dimension gains legitimacy only in dependence upon these epistemic principles. Thus, in the Islamic ethical framework, the moral end acquires meaning not independently but through the discernment of practical reason, and it attains validity solely within the bounds of rational duty-based ethics