Immanuel Kant

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Article abstract: Kant vindicated the authority of science while preserving the autonomy of morals by means of a new system of thought called critical or transcendental philosophy.

Early Life

Immanuel Kant was the son of a harness maker and the grandson of a Scottish emigrant. As a child, Kant was especially close to his mother, a serene woman who possessed an incisive curiosity about the natural world and a great native intelligence. As one of nine children in a devout Lutheran Pietist family, Kant was reared to respect inner tranquillity, industry, truthfulness, godliness, and order as the highest goods in human life. Kant’s mother died when he was thirteen, but he remembered her throughout his life with deep devotion; he told his friends that she had planted and nurtured the first seed of good in him and that her teachings had both opened his mind and provided a healing influence on his life.

Perhaps the most remarkable feature of Kant’s life, especially in the light of his profound and pervasive influence on the history of Western thought, is his provinciality. Kant never left the environs of the town of Königsberg in which he was born. He was educated in the local high school, the Collegium Freidericianum, and later at the University of Königsberg. After completing his baccalaureate studies in 1746, he worked as a tutor for a number of local families. He was able to maintain his studies while working as a tutor and so was able to take his master’s degree at Königsberg in 1755. That same year, he was appointed to the post of privatdocent (private lecturer) in the university. He gave regular courses of lectures, which continued through his 1770 appointment to the professorship of logic and metaphysics. Kant’s early lectures and writings covered diverse topics, including physical geography, anthropology, mathematics, and theoretical physics, as well as logic, metaphysics, and moral philosophy.

Life’s Work

Kant did his most original and important work quite late in his life. His project of critical philosophy began with Kritik der reinen Vernunft (1781; The Critique of Pure Reason, 1838), on which he worked between 1775 and 1781. This work aimed to resolve the disputes of all contemporary and traditional metaphysics by reinterpreting the conditions for human knowledge. Kant viewed the whole history of metaphysical inquiry as a series of failures to establish conclusive truths of first principles concerning God, human freedom, and immortality. In particular, he observed that rational cosmology (that is, metaphysical speculation concerning the nature of the world and its origin) was prone toward generating conflicting demonstrations which appeared to be equally valid. Kant named these conflicting arguments “antinomies,” and he found them to be in a sense inherent in reason itself. In Kant’s view, the preponderance of antinomies in the history of thought cast doubt on the whole enterprise of metaphysics.

Juxtaposed to his preoccupation with the self-contradictory nature and uncertainty of metaphysics were Kant’s deep convictions about the value and trustworthiness of Isaac Newton’s mathematical science. Mathematics and natural science yielded genuine knowledge. Kant took this as a clue to the sort of reformation that was called for in metaphysics. By inquiring into what made mathematical science possible, Kant hoped to uncover the conditions under which true metaphysical knowledge is possible.

Here is Kant’s seminal discovery: What makes knowledge possible in mathematics or physics is man’s possession of necessarily true propositions which are universally recognized as correct without any reference to experience. An example of such a proposition in mathematics is, “The sum of the angles in a triangle are equal to two right angles.” The...

(This entire section contains 2144 words.)

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possession of such truths proves that man’s cognition of the world is not necessarily a product of experience or the functioning of his senses. From one’s senses one obtains raw intuitions, but these intuitions do not constitute authentic cognitions. Raw intuitions become substantive cognitions only when they are processed actively by the mind. The mind organizes and synthesizes the raw intuitions according to innate rules. Without the raw intuitions given by the senses a person could not be aware of any object, but without the active participation of the mind that person could form no conception of any object.

Kant reasoned that the certainty of science rested on the purity of its truths, that is, their independence of sensation. Nothing that was given to sense experience from the outside could be guaranteed even by science, for an additional observation might reveal an alternate sequence which would prove the scientist’s first conclusion to be neither always nor inevitably true—neither universal nor necessary. If observational science was to be certain, it must proceed from propositions that were pure of sensation, that were a priori, or “present from the very first.”

From this discovery, Kant devolved a new, chastened metaphysics, free of the liabilities of all previous metaphysical inquiry. He had determined that the mind actively supplied certain concepts to intuition or sensation before that raw material was perceived and subsequently cognized, prior to its being registered as experience at all. Accordingly, it was also clear that humans are not immediately in touch with things as they are in themselves. It is as if one views the world through a particular set of rose-colored glasses, glasses that one can never remove. Thus, according to Kant, previous metaphysicians had been misguided in their aspirations to know about the ultimate nature of things. What one can know, or make certain claims about, is one’s experience of things (the appearances of things), not things in themselves. Kant said that one must take for granted that “things-in-themselves” are real per se, but that they are not directly known to man. Rather, one knows appearances of these things, as mediated through one’s mind’s perceptual and cognitive apparatus. What one has no experience of, including the nature and existence of God and the fate of the soul, one can access only by faith, not speculative knowledge. Thus, the new Kantian metaphysics confined itself to determining the necessary features of all objects of possible experience and to determining the structures of the mind which themselves impart to all objects of possible experience the features that they of necessity have.

This strict limitation on objects of knowledge, this restriction on the valid application of pure human reason, did not end in pure skepticism for Kant. Kant claimed that he found it necessary to deny knowledge in order to make room for faith. With the elimination of dogmatic metaphysics, he had silenced those who made knowledge claims or arguments on either side of speculative metaphysical issues. It was of no use, for example, to argue for or against God’s existence, or to try to prove that men have or do not have free will. Such issues were beyond the ken of human understanding. Objections to morality and religion therefore carried no weight, since they mistook what was beyond the limits of human experience to be legitimate objects of human understanding. This engendered the other substantial phase of the Kantian philosophy, the writings on ethics and religion.

Although Kant set limits on speculative reason, he granted a practical employment of reason that articulated postulates, articles of faith, in matters where discursive knowledge was impossible. Kant saw that humans as a matter of fact made moral commitments and acted as if they had free will. This did not involve an illegitimate metaphysical knowledge claim but rather a postulate born of practical necessity. Kant’s Grundlegung zur Metaphysik der Sitten (1785; Foundations of the Metaphysics of Morals, 1950) and his Kritik der praktischen Vernunft (1788; The Critique of Practical Reason, 1873) were devoted to working out such rational principles of morality.

Kant’s analysis of morality revealed that an agent’s goodness was not some quality of his behavior, nor a quality of his desire to cause some particular state of affairs. Goodness involved doing one’s duty solely for the sake of so doing. Duty was what conformed with the moral law that Kant called the “categorical imperative.” This stipulated that an action was moral if and only if one could will that it should become a universal law. The categorical imperative thus enunciated a purely formal, logical criterion for morality whose hallmark was a demand for complete impartiality.

The next ten years of Kant’s life were spent in vigorous productivity. Among the twenty or so books and treatises composed during this time were enormously influential works on aesthetics, Kritik der Urteilskraft (1790; The Critique of Judgment, 1892), on rational theology and ethics; Die Religion innerhalb der Grenzen der blossen Vernunft (1793; Religion Within the Boundaries of Pure Reason, 1838); and the famous essay on political theory, Zum ewigen Frieden (1795; Perpetual Peace, 1796), in which Kant proposed the creation of a federation or league of nations as an antidote to international conflict resolution. Kant’s powers began to fail in his last years. He gave up lecturing in 1799, and as he lost his eyesight and intellectual clarity, he slowly faded away. Almost all of Königsberg and many persons from all over Germany attended his funeral.


Immanuel Kant said that his project could be codified in the following three questions: What can I know? What ought I to do? For what may I hope? These are the questions that have occupied every philosopher in the history of Western thought, but Kant’s answers to them dramatically altered how they were approached by all of his successors. No one before Kant had regarded human minds as actively operative organisms which drew their material from the senses while shaping this material autonomously, according to their own laws. His discovery that the mind forms its cognitions itself supplanted all previous epistemological theories and quickly became a philosophical commonplace. Since Kant, no one has been able to neglect the transforming and intrusive influence of the observer’s cognizing process upon the object of observation. This insight spawned the whole twentieth century analytic movement in philosophy, which emphasizes logic and theory of knowledge and rejects metaphysics. It also gave rise to anti-Kantian theories of human experience offered by G. W. F. Hegel, Edmond Husserl, John Dewey, and Alfred North Whitehead.

The influence of Kant’s deontological, antinaturalistic moral views was also very strong, especially among later ethical intuitionists. Yet it is a mistake to separate Kant’s ethical thought from his overall system. The richest meaning of the moral doctrines emerges when they are seen as the central focus of his overall systematic approach to philosophy. The whole system yields a doctrine of wisdom concerning the human condition: What humans can know is extremely limited, but this fact need not be regarded as regrettable or disappointing, for it testifies to the wise adaptation of man’s cognitive faculties to his practical vocation. If we had a clearer vision of the true natures of things, we would always do what we ought, but then we would not be acting out of a pure motive to do our duty. We would be acting rather out of fear or hope of reward. Thus we would lose the opportunity to manifest goodwill, which Kant called the only thing in the world (or even out of this world) which can be taken as good without qualification.


Broad, C. D. Kant: An Introduction. New York: Cambridge University Press, 1978. Broad, a distinguished philosopher in his own right, provides a close textual commentary of Kant’s three critiques. The book’s fifteen-page general introduction is most helpful for newcomers to Kantian philosophy; the rest of the book is an invaluable companion for one attempting to read Kantian texts for the first time.

Cassirer, Ernst. Kant’s Life and Thought. Translated by James Hayden. New Haven, Conn.: Yale University Press, 1981. Cassirer was an influential neo-Kantian and offers here an eminently readable intellectual biography of Kant. This substantial work is well indexed.

Hartnack, Justus. Immanuel Kant: An Explanation of His Theory of Knowledge and Moral Philosophy. Atlantic Highlands, N.J.: Humanities Press, 1974. A concise exposition of these two main aspects of Kant’s thought.

Hendel, Charles W., ed. The Philosophy of Kant and Our Modern World. New York: Liberal Arts Press, 1957. This is a series of lectures given at Yale University, which focus on the twentieth century legacy of Kantian thought. Contains a helpful bibliography of Kantian scholarship, including many classical sources.

Kemp, John. The Philosophy of Kant. New York: Oxford University Press, 1968. This book offers an exposition of Kant’s epistemology, practical philosophy, and aesthetics in less than one hundred pages. It is very well indexed, and contains an annotated bibliography.

Körner, Stephan. Kant. Baltimore: Penguin Books, 1955. This overview of Kant’s thought is concise, though quite technical. It would serve to help an advanced student interpret some of the nuances of Kant’s system. It is well indexed and includes a short bibliography.