Kant's Critique of Practical Reason and Moral Philosophy

Ethics 3.LA: Kantian Practical Reason

The Shift to Practical Philosophy

Once the shift in the realm of theoretical philosophy is practiced, the way opens to the Critique of Practical Reason and the fundamental question: "What should I do?" The ethical nature of this issue leads Kant to formulate the necessary form of a moral action, which must respect the principles of freedom and autonomy central to Enlightenment discourse.

The A Priori of Moral Action

It is necessary to investigate the a priori nature of moral action and the form it must take to be considered moral. Consequently, transcendental reason, now practical, is presented as containing the a priori form of moral action. The imperatives of ethics, defined as formal, must be categorical and take the form of the categorical imperative of duty.

Formulations of the Categorical Imperative

• Universality: The first statement refers to the universal nature that Kant sought for his ethics program.
• Dignity: The second statement establishes the dignity of man as a limit on the exercise of freedom.
• Kingdom of Ends: The third statement concerns the goal of moral behavior, creating a kingdom of ends.

The kingdom of ends is the space in which the dignity of every human being is respected; man is an end in himself, unlike things that lack dignity. Kant's late state, or the so-called enlightened state, is a reformulation of the rule of law. Unlike contractualist authors, the rule of law for Kant is not established in principle but is expected to be implemented indefinitely throughout history; it is a permanent state in the process of formation.

Goodwill and the Postulates of Reason

Goodwill is the assurance that individuals channel their actions toward the establishment of such a kingdom of ends; it is the heart of the foundation of morality.

Metaphysical Postulates

Regarding the metaphysical ideas incorporated as postulates of practical reason, Kant understands the following:

• Freedom: A postulate of moral action because morality cannot exist without freedom.
• God: A mediate postulate that serves as an ideal of perfection.
• Immortality of the Soul: A mediate postulate that allows one to maintain hope beyond the limits of theoretical reason.