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Kant, Immanuel (1724–1804)

Kant, Immanuel (1724–1804)
by Manfred Kuehn

Manfred Kuehn is Professor of Philosophy at Boston University, USA. He has received Fellowships from the Canada Council, the National Endowment for the Humanities, and the Institute of Advanced Studies of the University of Edinburgh. He has taught in Canada, Germany and the U.S.A., and was Visiting Professor at the University of Hamburg, Germany. Author affiliation details are correct at time of print publication.

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DOI: 10.5040/9781474255998-0295

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Immanuel Kant was born in Königsberg (East Prussia, today: Kaliningrad, Russia) on 22 April 1724 and died on 12 February 1804. After receiving his primary education at a local school and his secondary education at the Collegium Fridericianum in Königsberg, a pietistic institution regulated by the principles of August Hermann Francke , he attended the University of Königsberg. Inscribed in the registry of the university on 24 September 1740, he studied there until about 1748. His first book, Thoughts on the True Estimation of the Living Forces, which appeared in 1749, was written during the last three or four years of his studies. From 1748 to 1755, he worked as a private tutor for a number of families in the greater vicinity of Königsberg. Apparently he did not like teaching young children, and later in his life he jokingly assured his friends that there had perhaps never been a worse tutor than he had been. By contrast, he was highly effective as an academic teacher. Thus, he clearly inspired Johann Gottfried Herder , who praised him highly as his only true teacher. Kant began to teach at the University of Königsberg in 1755. In spite of his success as a teacher and writer, he did not obtain a chair in philosophy until 1770. Though Kant never left East Prussia, he knew the world quite well. He read the travel literature of the time extensively, and it is reported that he could, for instance, describe London Bridge in such vivid detail that listeners who had visited London could not believe he had not seen it with his own eyes. Königsberg, often described as a backwater town, was actually a substantial and cosmopolitan city with a thriving port. It enabled him to come to know people from many different countries. One of his best friends, Joseph Green, was a British merchant, for instance. Kant never married. He lived the rather uneventful life of a scholar. Only once did he have to deal with political adversity. In 1794, the Prussian censor, in the name of Frederick William II, king of Prussia, forbade him to write about religious subjects. Kant promised to obey. However, when the king died, he no longer felt bound by this promise. In 1798, he published another work on religion.

Kant’s intellectual life is usually divided into two periods: the ‘pre-critical period’ (1755–70), and the ‘critical period’ (1770–1804). During the first of these periods he published a number of works in the style of philosophizing then current. These works show that while Kant was deeply influenced by the philosophical thought of Gottfried Wilhelm Leibniz , Christian Wolff and their followers, he was also open to the ideas of such philosophers as John Locke, Francis Hutcheson, David Hume, Jean-Jacques Rousseau and Adam Smith, who had begun to have a great effect in German thought during that period. It would be a mistake to characterize Kant’s view between 1755 and 1770 as either a thoroughgoing rationalism or a traditional form of empiricism. Though he was convinced of the truth of Newton’s physics, he was far from clear on how this science of the phenomena was to be founded in a metaphysical system. Like most of his contemporaries, Kant during the 1750s and 1760s was an eclectic who did not dogmatically accept one fixed metaphysical system as the only possible explanation of the world. He was much more of a sceptic in metaphysical matters than is commonly realized. The most important works of this period are The Only Possible Basis for a Demonstration of the Existence of God (1762), An Enquiry into the Distinctness of the Fundamental Principles of Natural Theology and Morals (1764), Observations on the Feeling of the Beautiful and Sublime (1764) and Dreams of a Spirit-Seer (1766).

Kant’s critical period is said to begin with his so-called ‘Inaugural Dissertation’, entitled On the Form and Principles of the Sensible and the Intelligible World of 1770. Between 1771 and 1781, Kant published almost nothing. This period, also called ‘the silent years’, saw him working out the basic outlines of his later ‘critical philosophy’. Though he was well known to the educated Germans of his time for his early works, he became and remains truly famous on the basis of the works he published during his second period. The most important of these are the Critique of Pure Reason (1781, 2nd edn, 1787), Prolegomena to Any Future Metaphysics (1783), Foundations of the Metaphysics of Morals (1785), Metaphysical Foundations of Natural Science (1786), Critique of Practical Reason (1788), Critique of Judgement (1790) and Religion within the Limits of Mere Reason (1793).

Kant may be said to have tried to answer three fundamental questions, namely, ‘What can I know?’, ‘What ought I to do?’ and ‘What may I hope for?’ (Critique of Pure Reason, pp. B 832f.). He addressed the first of these questions mainly in his speculative philosophy, the Critique of Pure Reason, often simply referred to as his ‘first Critique’, the Prolegomena and the Metaphysical Foundations of Natural Science. In the first Critique, the most fundamental work, Kant attempts to show that traditional metaphysics rests on a fundamental mistake: it presupposes that we can make substantive knowledge claims about the world independently of experience. Kant characterizes such claims as ‘synthetic a priori’, contrasting them with experiential claims that are ‘synthetic a posteriori’ and merely analytic propositions. Empiricists argue that synthetic a posteriori and analytic propositions or judgements exhaust all knowledge claims. This is also known today as ‘Hume’s Fork’. Kant agrees to a large extent with the empiricists, arguing that it is impossible to know anything a priori about the world as it is independently of our cognitive apparatus. Though we can make certain synthetic a priori claims, these claims are not about reality per se, but only about reality as it is experienced by beings such as ourselves. He rejects, however, the empiricist thesis that therefore all knowledge claims are either empirical or analytic. Rather, he argues that we can know the world only because we possess certain cognitive principles that enable us to have the experience we have. These cognitive principles are a priori. We can make certain claims a priori about the world as it must appear to us. These a priori epistemic conditions are described by Kant as different ‘forms’ to which knowledge is necessarily subject. He distinguishes three such forms, namely (1) the forms of sensibility, (2) the forms of the understanding, and (3) the forms of reason.

(1) The forms of sensibility consist of space and time. They are not characteristics of the ‘things in themselves’, but are only subjective conditions for our knowledge of the world. However, because we cannot but view the world as spatial and temporal, things in space and time, or ‘the appearances’, are objective for us. Kant says that they are ‘empirically real’, but ‘transcendentally ideal’. If we were constituted differently, namely as purely intelligent beings with intellectual intuition, we might be able to ‘see’ things as they are in themselves and not just as they appear to us. Our knowledge is further dependent on (2) the forms of the understanding, or on a number of basic a priori concepts. Kant, borrowing a term from Aristotle, calls these basic concepts Categories. They include for him basic concepts of quantity (unity, plurality, totality), quality (reality, negation, limitation), relation (inherence, causality, community) and modality (possibility/impossibility, existence/non-existence, necessity/ contingency). They appear to have a more extended application than space and time because we seem to be able to make claims about things that are not part of our spatio-temporal world. Many philosophers, for instance, use the concept of causality in talking and devising proofs about God who, they also claim, is neither in space nor in time. Kant believes that this is a mistake. He argues that the use of the categories is restricted to spatio-temporal objects, or appearances. His Transcendental Deduction, one of the most difficult passages in the first Critique, is essentially an attempt to establish this restriction on our use of the categories. One of the most important consequences of this part of Kant’s view is that the traditional proofs concerning the nature of the soul, the world and God must be unsound. They cannot establish knowledge in any sense. If they are taken as establishing knowledge, they inevitably lead us to contradict ourselves. Indeed, the dialectical parts of Kant’s first Critique, namely The Paralogisms of Pure Reason and The Antinomy of Pure Reason, are attempts at exposing the fallacious character of all the arguments developed by traditional metaphysicians. (3) This does not mean that Kant believed that the proofs are entirely useless. They address fundamental questions that are unavoidable for us. He believed that they are expressions of deep ‘interests’ of reason that cannot simply be dismissed. Metaphysical speculation is as inevitable for us as is breathing. Indeed, it is part of the human tragedy that our ‘reason has this particular fate that in one species of its knowledge it is burdened by questions which, as prescribed by the very nature of reason itself, it is not able to ignore, but which, as transcending all its powers, it is also not able to answer’ (Critique of Pure Reason, p. Avii). These questions concern the forms of reason, i.e. what Kant calls the ‘transcendental ideas’. The ideas, which comprise for Kant only those of God, freedom, and immortality, do not afford any kind of knowledge beyond that which is possible through space and time and the categories. They can give rise only to a kind of rational faith. But metaphysics can only be concerned with the presuppositions of experience.

Kant attempts to answer the question ‘What ought I to do?’ in moral philosophy or ethics, as developed in the Foundations of the Metaphysics of Morals, the Critique of Practical Reason (the second Critique) as well as in his Metaphysics of Morals. These works must, however, also be seen in the context of his historical and political writings, which were published mainly in the form of shorter and more popular essays, such as ‘What is Enlightenment?’ (1784) and On Eternal Peace (1795), which show how closely moral and political philosophy are connected for Kant.

Kant is a deontologist in ethics. Vehemently opposed to any form of consequentialism and any form of hedonism or eudaemonism, he considers the concept of duty as central for morality. Furthermore, he believes that what is our duty concerns primarily the will and can only be determined by reason. Therefore reason assumes for him the highest importance in his ethics. Whereas much of his theoretical work was concerned with showing that reason has much less power than was assumed by his rationalistic predecessors, Kant’s moral philosophy may be seen as an attempt to show that morality is the exclusive domain of reason. In this, he is more of an intellectualist than most of his rationalistic predecessors. The only thing in this world that can be called good without qualification is a ‘good will’. The goodness of the will must be found in the principle of its volition. We can determine what is willing in the right way by applying a principle that he calls the ‘categorical imperative’. It states that I should always act in such a way that the maxim of my action can become a universal law. This is often also called the ‘principle of universalization’, and it has received the most attention in the literature. Kant offers three explications of this categorical imperative. The first is in terms of laws of nature, the second in terms of ends and the third in terms of the complete determination of all maxims. According to the second explication, I should always treat humanity whether in my own person or that of anybody else, as an end and never simply as a means. This gives rise, according to Kant, to the third explication of the categorical imperative, namely that I should look at myself as an autonomous human being who is subject to the moral law only insofar as he/ she freely legislates moral law for himself/herself. We can regard ourselves as the authors of this law, and we are therefore truly autonomous. This concept of ‘autonomy’ is co-extensive with the concept of freedom; and morality requires freedom. Therefore we must assume that we are free insofar as we are moral or rational beings.

Since ‘freedom’ is also one of the basic ideas to which theoretical reason leads us, it forms the point at which the two Critiques come together. Kant believes that the second Critique shows that ‘freedom’ is a genuine concept, i.e. not a mere thought, but something that has a genuine foundation in morality. Nevertheless, Kant insists that we cannot know ourselves to be free in any strict sense. It is our moral experience, or perhaps better the experience of our morality, that gives us the right to believe in the reality of freedom. Furthermore, morality and freedom also give us the right to believe in the reality of two other ideas of reason, namely those of ‘God’ and ‘immortality of the Soul’. He argues that we must ‘postulate’ the reality of these ideas in order to be able to act as moral beings in this world. Without immortality and God we would be condemned to moral despair. Moral action should lead to greater good in this world, but it usually does not. Happiness and worthiness to be happy do not usually go together in this world. If we want to establish a connection between the two, we must assume that they will be made to coincide by God in the long run. In this way, the notions of ‘God’ and ‘immortality,’ as prerequisites for the realization of the summum bonum or the highest good, make possible the moral enterprise for Kant, and therefore we must believe in their reality.

Belief in these three concepts is central to Kant’s so-called ‘moral faith’. This belief is the answer to the third question, or the question ‘What may I hope for?’ Though Kant himself was not religious and was opposed to any form of external religious worship, he did believe that morality inevitably leads us to the acceptance of certain tenets of traditional theism. In his essays on religious matters and especially in his Religion within the Limits of Mere Reason, Kant attempts to develop the parallels between revealed religion and philosophical theology. He claims, in true Enlightenment fashion, that all that is essential in religion can be reduced to morality. Accordingly, he finds it necessary to criticize severely established religion as engaging in mere idolatry in its institutions and demands concerning the fulfilment of merely formal requirements. What, according to Kant, we may hope for, then, is that our moral actions ultimately do make a difference.

Kant’s Critique of Judgement, the third Critique, is often simply read as a treatise in aesthetics; and its first part, the Critique of Aesthetic Judgement, deals essentially with aesthetic problems. However, apart from addressing the problem concerning the validity and characteristics of aesthetic judgements, Kant also deals in this work with the problem of the unity of his own system, the general problem of the apparent purposive-ness of nature, and the problems arising from a presumed necessity of applying teleological concepts in biology and some theological concerns. The Critique of Aesthetic Judgement tries to solve the problem of the validity of aesthetic judgements. This problem arises from a peculiarity of the claims we make about aesthetic matters. When we claim, for instance, that ‘This painting by Rembrandt is beautiful’, or that ‘The Grand Canyon is sublime’, we express our feelings, and do not make claims to objective knowledge. At the same time, such claims, which may be called judgements of taste, are meant to be more than mere reports of what we feel. We are convinced that there is more to such judgements, that they state something of universal significance. What justifies such convictions? Kant argues that although aesthetic judgements are based on feeling, their claim to objective validity is not based on these feelings themselves but upon a priori principles of judgement that are preconditions for such feelings. The results of Kant’s discussion of the beautiful and the sublime are the following definitions: (1) the ‘beautiful is what pleases in the mere estimate formed of it (consequently not by the intervention of any feeling of sense in accordance with a concept of the understanding). From this it follows immediately that it must please apart from all interest’; (2) the ‘sublime is what pleases immediately because of its opposition to sense’ (AA 5, p. 267).

In the second part, the Critique of Teleological Judgement, Kant argues that mechanical accounts of nature cannot make sense of organic form. They cannot explain the origin even of a blade of grass. Nature seems to be designed. Everything seems to have a function. To account for this, Kant takes over the traditional claim that ‘Everything in nature is good for something; nothing in it is in vain.’ For Kant this is a principle of reason. While it is for him (in contrast to his predecessors) a subjective principle, i.e. a maxim, and a merely regulative and not constitutive principle, it is nevertheless a clue that can guide us in the study of nature. Therefore, it is indeed a principle inherent in scientific praxis. Since it is just a maxim, it does not need a deduction. The problem of teleology gives rise to the problem of design, and design seems to lead almost naturally to theology. Kant discusses pantheism and theism as solutions to the problem of teleology. His claim is that both fail. The Spinozistic idea of a unified substrate that underlies both thought and nature (extension) can never give rise to the idea of finality, and the concept of living matter is inconceivable in any case. While theism also fails, it has an advantage over all other systems: because it attributes an intelligence to the original being it adopts the best mode of rescuing the finality of nature from being a merely empty ideal. It also introduces ‘an intentional causality for its production’. Still, teleology is neither a branch of natural science nor a branch of theology. It belongs to the science of the critique, namely the critique of judgement.

The Religion within the Limits of Mere Reason consists of four essays, the most famous of them is ‘Of the Radical Evil in Human Nature’. Its Preface sounds a tone of defiance:

Morality, insofar as it is based on the concept of the human being as one who is free but who also, just because of this freedom, binds himself through his reason to unconditional laws, is in need neither of the idea of another being above him in order that he recognize his duty nor of an incentive other than the law itself in order that he observe it.

 --(Religion and Rational Theology, p. 57)

If we find such a need in us, it is our own fault. Only moral service will make us pleasing to a moral God. Prayer, liturgy, pilgrimages and confessions are worthless. Nothing good will be accomplished by such forms of worship, and they may even lead to fanaticism and thus to ‘the moral death of reason, without which there can be no religion, because, like all morality in general, religion must be founded on principles’ (Religion and Rational Theology, p. 194). The question ‘What may we hope for?’ is thus closely connected with another question, which Kant sometimes formulated as the question that comprises the other three, namely, ‘What is Man?’ This is a question that is answered by anthropology. Kant even suggests at times that anthropology, which is an attempt at settling the question of the purpose of mankind, is the ultimate philosophical discipline.

In his essay ‘On the Old Saw “That May be Right in Theory, but it Won’t Work in Practice”’, published in 1793, he argued that if moral progress were impossible for mankind, the trials and tribulations of every person striving for virtue would be nothing but a farce. It would also be repugnant to a wise creator of the world. Kant argued that we have ‘the innate duty […] so to affect posterity through each member in the sequence of generations in which I live, simply as a human being, that future generations will become continually better’ (On the Old Saw, ed. Miller, p. 77). We may perhaps never reach the certainty that there is indeed such progress, but this does not invalidate for Kant the maxim that we should work towards this progress and the belief that it is practically feasible.

While Kant’s contemporaries (such as Moses Mendelssohn , Christian Garve , Johann Georg Heinrich Feder and Johann August Eberhard , for instance) could find little to appreciate in his works, Kant’s critical philosophy had a tremendous influence on the younger generation. Karl Leonhard Reinhold , Karl Christian Schmid , Johann Bering and others soon became followers. Others, such as Salomon Maimon , Jacob Sigismund Beck and Johann Gottlieb Fichte , began independently to transform his ideas. Still others, such as Friedrich Heinrich Jacobi and Gottlieb Ernst (Aenesidemus) Schulze , began to criticize Kantian philosophy as a significant mistake, thus opening up the way for German idealism. The ideas of Fichte, Friedrich Wilhelm von Schelling and Georg Wilhelm Friedrich Hegel cannot be understood without Kant. Yet, their philosophy soon began to overshadow that of Kant. In the second half of the nineteenth century Kant’s ideas experienced a renaissance. The neo-Kantians, under the motto ‘Back to Kant’, argued that the idealists had misunderstood Kant, and that his epistemology and his ethics provided the best models for philosophizing in a scientific age. Many recent philosophers in English-speaking countries would seem to agree with this sentiment.


Gesammelte Schriften , ed. Preußische Akademie der Wissenschaften et al. (Berlin, 1900–).

The Cambridge Edition of the Works of Immanuel Kant, ed. Paul Guyer and Allen W. Wood (Cambridge, 1992–); Theoretical Philosophy, 1755–1770 (1992); Critique of Pure Reason (1998); Practical Philosophy (1996); Critique of the Power of Judgement (2000); Correspondence, 1759–1799 (1999); Opus Postumum (1993); Religion and Rational Theology (1996); Lectures on Logic (1992); Lectures on Ethics (1997); Lectures on Metaphysics (1997).

Further reading

Allison, Henry, Kant’s Transcendental Idealism (New Haven, 1983).

Allison Henry , Kant’s Theory of Freedom (Cambridge, 1990).

Ameriks, Karl, Kant’s Theory of Mind. An Analysis of the Paralogisms of Pure Reason , new edn (Oxford, 2000).

Ameriks Karl , Kant and the Fate of Autonomy (Cambridge, 2000).

Beck, White, Commentary on Kant’s Critique of Practical Reason (Chicago, 1960).

Beck Lewis White , Essays on Kant and Hume (New Haven, 1978).

Beiner, Ronald and William James Booth, Kant and Political Philosophy: The Contemporary Legacy (New Haven, 1996).

Cassirer, Ernst, Kant’s Life and Thought , trans. J. Haden, introduction by S. Körner (New Haven, 1981).

Friedman, Michael, Kant and the Exact Sciences (Cambridge, 1992).

Guyer, Paul, Kant and the Claims of Knowledge (Cambridge, 1987).

Guyer Paul , The Cambridge Companion to Kant (Cambridge, 1992).

Guyer Paul , Kant and the Experience of Freedom (Cambridge, 1993).

Guyer Paul , The Cambridge Companion to Kant and Modern Philosophy (Cambridge 2006).

Heidegger, Martin, Kant and the Problem of Metaphysics , trans. J.S. Churchill (Bloomington, 1962).

Herman, Barbara, The Practice of Moral Judgement (Cambridge, Mass., 1993).

Kersting, Wolfgang, Wohlgeordnete Freiheit (Berlin, 1984).

Klemme, Heiner F., Kants Philosophie des Subjekts. Systematische und entwicklungsgeschichtliche Untersuchungen zum Verhältnis von Selbstbewußtsein und Selbsterkenntnis (Hamburg, 1996).

Klemme, F., Manfred Kuehn and Dieter Schönecker (eds), Moralische Motivation. Kant und die Alternativen (Hamburg, 2006).

Kitcher, Patricia, Kant’s Transcendental Psychology (New York, 1993).

Körner, Stephan, Kant (Harmondsworth, 1975).

Kuehn, Manfred, Kant: A Biography (Cambridge, 2001).

Makkreel, Rudi, Imagination and Interpretation in Kant: The Hermeneutical Import of the Critique of Judgement (Chicago, 1990).

Paton, H.J., The Categorical Imperative (London, 1947).

Strawson, Peter F., The Bounds of Sense. An Essay on Kant’s Critique of Pure Reason (London, 1966).

Walker, Ralph S., Kant (London, 1978).

Walsh, W.H., Kant’s Criticism of Metaphysics (Chicago, 1975).

Willaschek, Marcus et al. (eds.), Kant-Lexikon (Berlin and Boston, 2015).

Williams, Howard (ed.), Essays on Kant’s Political Philosophy (Cardiff, 1992).

Yovel, Yirmiyahu, Kant and the Philosophy of History (Princeton, New Jersey, 1989).