Kant's Metaphysics Of Morality

Kant offers that his Groundwork of the Metaphysics of Morals “is nothing more than the identification and corroboration of the supreme principle of morality” (4:392). He maintains that people must use “practical philosophy”, or careful reasoning, in order to delineate the precise principle of human morality, which Kant later identifies and formulates as the categorical imperative. To understand this supreme principle of morality, Kant asserts the truth in two things: there exists morality, which regulates human behaviors and signifies good actions, and that this morality can be only understood through reason. Assuming that these are both true, it is not entirely clear what the ontological relationship is between human rationality and morality—whether

Yet, the constructivist view of Kantian ethics may present a contradiction: if morality is entirely constructed by human rationality, then there should not be a universal principle which one would need “to receive” in order to regulate decisions. Thus, as Kant rejects authority and experience, through reason and textual analysis, drawing both from Kant’s writing and Augustine’s City of God, it is imperative to reconcile the conflict between the realist—that morality exists independent of rationality—and constructivist readings of Kant’s ethics. That “in practical common reason, when it cultivates itself, a dialectic inadvertently unfolds [...] and one is therefore [unable] to find rest anywhere but in a complete critique of our reason” lends credence a constructivist

His choice to “take one’s route analytically from common cognition to the determination of its supreme principle” suggests a causality (Kant 4:392): “common cognition” guides the rational agent to the categorical imperative (the “supreme principle”), which allows the agent the ability to create moral legislation. Yet, Kant’s language here, describing his method of inquiry, is far from supportive of an entirely constructivist view of morality. His movement from “common cognition” to the “determination of its supreme principle” is rhetorical, not philosophical. The possessive pronoun “its” in the phrase “the determination of its supreme principle” suggests that, rather than common cognition being the guiding force of the supreme principle of morality, it is the principle which guides cognition. Hence, the supremacy of this principle over cognition and rationality contradicts the constructivist position that reason is the cause of