Immanuel Kant (1724-1804) Deontological ethics, categorical imperative, transcendental idealism
Kant synthesized early modern rationalism and empiricism, and explored metaphysics, epistemology, ethics, political philosophy, and aesthetics with great intellectual power. Kant's “critical philosophy” is set forth in his three Critiques: the Critique of Pure Reason (1781, 1787), the Critique of Practical Reason (1788), and the Critique of the Power of Judgment (1790). The fundamental idea is that of human autonomy through the exercise of reason and duty. He argues that the human understanding is the source of the general laws of nature that structure all our experience; and that human reason gives itself the moral law.
In Critique of Pure Reason, Kant writes, “If we take away the subject [Humans], or even only the subjective constitution of our senses in general, then not only the nature and relations of objects in space and time, but even space and time themselves disappear; and that these, as appearances, cannot exist in themselves, but only in us. What may be the nature of objects considered as things in themselves and without reference to the receptivity of our sensibility is quite unknown to us.”
He proposes a kind of "Copernican Revolution-in-reverse", saying that: "Up to now it has been assumed that all our cognition must conform to the objects; but ... let us once try whether we do not get farther with the problems of metaphysics by assuming that the objects must conform to our cognition."
Kant is regarded as the “father” of deontological ethics, asserting the necessity of duty as an absolute moral category. He agreed with Plato that it is not natural for humans to prefer evil to good, and he agreed with the Roman statesman-philosopher Cicero that every moment of our lives involves duty. He believed that true freedom rests only in fulfilling one’s moral duty, and that all people have an innate sense of moral duty.
Kant defines virtue as “the moral strength of a human being’s will in fulfilling his duty.” According to his definition, the moral person fulfills his duty even when not inclined to do so, and not because he fears the consequences of failing to perform the duty. Further, he who does his duty only to appear virtuous is not moral. Only the person who does his duty because it is his duty is moral. This is Kant’s argument for the universal nature of duty:
Everyone recognizes that they had duties and obligations.
Therefore, duty is a universal human experience.
Duty is the basis of Moral Law.
As all humans recognize duty, the Moral Law applies to all humans.
To Kant, one acts morally only when one acts out of an innate sense of duty. Acting to please others or to achieve personal happiness cannot be regarded as moral. Such acts are done out of self-interest or as a slave to inclination. Such a person is not truly free since, for Kant, true freedom requires that the individual be completely autonomous and guided only by the categorical imperative. Kant’s categorical imperative is granted to maxims that are universalized. If a proposed action can be shown to be true for all people, in all places, at all times - it is binding and absolute, allowing no exceptions. If it cannot be universalized, one ought not to perform the proposed act.
According to Kant, intentionally telling a lie is always immoral since the universalizing of lying would lead to social disorder and disintegration.
For Kant, recognition of one's duty depended on one's own autonomous reason and "holy will." Kant’s categorical imperative is tied to his argument for the existence of God. He believed that God is just and will judge all people according to His justice. Since it is evident that immoral people are not judged in this life, Kant argues there must necessarily be an afterlife in which the Moral Law will be fulfilled. The truly free individual performs his duty at each moment out of his free will because his will has been made holy. This is how Kant, the theology professor, balanced the question of free will and divine calling/appointment/election.
Related reading: Why You Have to Love David Hume; Theories of Knowledge: Hume and Kant