Kant's Moral Philosophy: Freedom, Immortality, and God

According to Kant, morality requires certain conditions, the so-called postulates of practical reason. Kant calls them postulates because, although not demonstrable by theoretical reason, he says they can and should be supported by practical reason, as they are necessary conditions of morality itself. For Kant, these postulates of practical reason are:

Freedom. Freedom cannot be proven scientifically because it is not the subject of intuition, but it must be admitted from practical reason as a condition of the possibility of moral law, which for Kant is a fact ("factum morale.") The relationship between moral law and freedom is expressed by Kant in this sentence: "Freedom is the raison d'être (essendi ratio) of the moral law," and "morality or moral law is the reason that I may know freedom (ratio cognoscendi of freedom)."

The Immortality of the Soul. Kant argues that we are commanded to aspire to virtue, that is, the right and full alignment of our will with the moral law. This perfection is unattainable in a temporary or limited existence. Thus, it can only be realized in an indefinite process, i.e., immortality. Moreover, if no one is immortal, there would be no way to adequately reward merit. Immortality is the only just reward for the righteous.

The Existence of God. Kant states that the disagreement we find in the world between being and ought-to-be requires the existence of God as a reality in whom being and ought-to-be are identified and in whom there is the perfect union of virtue and happiness. That is, God must exist because without God there would be no way to guarantee perfect happiness.

Kant answers these questions primarily in his works: Groundwork of the Metaphysics of Morals (1785) and Critique of Practical Reason (1788).

The originality of Kantian ethics is its proposal of a formal ethic, as opposed to material ethics.

Material ethics pursue certain actions, ordered to a good considered as a supreme or ultimate goal (e.g., Epicureanism, Aristotelianism, etc.).

Kant rejects material ethics for three reasons:

• a. Because they are empirical or "a posteriori": their content is drawn from experience.
• b. Because their precepts are hypothetical, i.e., conditioned.
• c. Because they are heteronomous, that is, in them the law is not dictated by personal conscience.

In contrast to materialistic ethics, Kant proposes an ethic that is autonomous, formal, and duty-based:

An Autonomous Ethic: because the moral law comes only from practical reason, which is universal legislation (it gives itself the law).

An Ethic of Duty: moral action is that which is done under duty and respect for duty. An action is good when, in addition to being under duty, it is out of respect for law and duty. (In the example of the sellers, those who act morally sell goods at a fair price with no other motivation than duty, not the one who sells at a higher price or sells at the right price out of fear of losing customers).

Formal Ethics: i.e., empty of specific content, not tied to conditional requirements. This ethic is expressed through a categorical imperative that commands unconditionally. Kant offered various formulations of the categorical imperative that can be called the Kantian moral maxims.