Mendelssohn and Kant on the Immortality of the Soul

Mendelssohn argued for the immortality of the soul in his 1767 best-seller Phaedo. Kant’s argument for the postulate of immortality in the first two Critiques was not dissimilar to Mendelssohn’s; both may have drawn on the influential Vocation of Man by Johann Joachim Spalding. But in his 1793 Religion within the Boundaries of Mere Reason, published after the death of Mendelssohn, Kant argued that the radical nature of human freedom means that a human being can undertake a change of heart from evil to good at any time, thereby undercutting any need to postulate immortality.

Proofs of the Existence of God in the Critique of Pure Reason and Morning Hours

This chapter examines Kant’s continued criticism of the classical arguments for the existence of God in the Critique of Pure Reason and his critique of his own earlier new argument for God as the ground of all possibility. Kant’s conclusion is that belief in the existence of God must be defended on practical rather than theoretical grounds. In Morning Hours Mendelssohn defended the ontological and cosmological arguments and added a new argument from the incompleteness of human knowledge. Mendelssohn does not accept Kant’s argument for belief in God on moral grounds only but instead adopts a pragmatic position that we have no choice but to rely on the results of the unimpaired use of our own cognitive powers.

Prologue

In 1762, both Mendelssohn and Kant submitted essays in response to the Berlin Academy’s question on the possibility of using the mathematical method in philosophy, specifically natural theology and morality. Mendelssohn won first prize for his argument that both mathematics and philosophy tie conceptual analyses to reality by experience, while Kant won honorable mention for an early version of his position that the methods of mathematics and philosophy are essentially different. After this, the two philosophers could not avoid taking account of the views of each other.

Judaism, Christianity, and the Religion of Pure Reason

This chapter reads Kant’s Religion as a response to Part II of Mendelssohn’s Jerusalem. Mendelssohn had argued that different peoples can have different ways of practicing the common religion of reason, and that the commandments of Judaism are intended only as occasions for reflection, valid for Jews, on these truths, while other religions can get at them in different ways. In the first two parts of his Religion, Kant argued that the central ideas of Christianity are uniquely well-suited as symbols of the religion of reason, and he further argued in Part III of the book that morality requires a single church of practitioners. However, he then argued that this church must be “invisible” and ultimately transcend all scriptural religion. Mendelssohn’s insistence on the acceptance of religious diversity seems more plausible than Kant’s confidence in the ultimate transcendence of all visible churches.

Freedom of Religion in Mendelssohn and Kant

This chapter compares the two philosophers’ great arguments for separation of church and state. Mendelssohn’s argument is contained in Part I of his 1783 Jerusalem. He holds that the state and any church employ two different means to the same end, human happiness, and that the state’s coercive methods have no place in religious practice. His argument is based on the religious premise that God is pleased only by the free rather than forced convictions of humans. Kant does not treat the separation of church and state in his 1793 Religion at all, because for him religious liberty is an immediate consequence of every human’s innate right to freedom, which is both the objective but also the limit of all state power. Religious liberty can therefore be treated from a purely political point of view, as Kant does in his 1797 Doctrine of Right.

Mendelssohn, Kant, and Idealism

After examining the dispute between Mendelssohn and Kant over the ideality of time in 1770, this chapter argues that Kant’s addition of a “Refutation of Idealism” to the second edition of the Critique of Pure Reason in 1787 is a response to Mendelssohn’s treatment of idealism in his 1785 Morning Hours. Both defend the position that Kant calls empirical realism, but only Kant defends it by means of a transcendental argument that knowledge of external objects is a necessary condition of empirical self-knowledge, although only within the framework of transcendental idealism. Mendelssohn accepts that human experience can never tell us how things are in themselves, but does not accept Kant’s outright denial of the non-spatiality and non-temporality of things in themselves.

Mendelssohn, Kant, and Enlightenment

This chapter contrasts the two philosophers’ 1784 essays on the question “What is Enlightenment?” True to his faith in theoretical reason, Mendelssohn interprets enlightenment as growth in knowledge, while true to his own faith in practical reason Kant interprets it more as moral maturity, willingness to take responsibility, especially in politics, rather than being passively led by external authority. Next the dispute between Mendelssohn and F.H. Jacobi over whether reason can prove the existence of God or it can be believed only by a leap of faith is examined, and Kant’s intervention in his essay “What Does It Mean to Orient Oneself in Thought?,” published in 1786 after the death of Mendelssohn, is then considered: Kant takes the side of reason in this dispute, but only of practical reason.

Mendelssohn’s and Kant’s Aesthetics Compared

This chapter argues that there is less difference between the two philosophers’ basic conceptions of aesthetic experience than Kant’s critique of aesthetic “perfectionism” seems to suggest. But the basic difference remains that the emotional impact of aesthetic experience is central to Mendelssohn’s account of the “main principles” of the arts, while Kant tries to keep the emotions at arm’s length even in his account of “aesthetic ideas,” which present moral ideas that anyone else would take to be accompanied with profound emotions.

Kant’s Aesthetics

Kant transforms Mendelssohn’s theory of mental activities in aesthetic experience into his own central idea of the free play of imagination and understanding, and builds his analysis of aesthetic experience and judgments of taste on this basis. Kant organizes his theory of fine art around the concept of genius, which incorporates some elements of Mendelssohn’s account of human artistry and Charles Batteux’s theory of artistic expression, and tacitly accepts Mendelssohn’s distinction between our response to the merits of an artistic representation and to those of what it represents.

Mendelssohn’s Aesthetics

Mendelssohn made his mark early with his writings on aesthetics, beginning with the Letters on Sentiments of 1755. He argues that we respond to both the perfections of objects represented by works of art and the works of art as representations themselves, and thus can have “mixed sentiments,” for example in the case of beautiful presentations of tragic events. We enjoy the activity of both our perceptual and cognitive and our conative and emotional powers in such aesthetic experience. Mendelssohn further developed this view in Morning Hours, although in the radically different context of explaining how God can approve of the best of all possible worlds in the absence of desire, which would be an impossible imperfection on his part.